3266 lines
100 KiB
Plaintext
3266 lines
100 KiB
Plaintext
/* ---------- To make a malloc.h, start cutting here ------------ */
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/*
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A version of malloc/free/realloc written by Doug Lea and released to the
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public domain. Send questions/comments/complaints/performance data
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to dl@cs.oswego.edu
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* VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee)
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Note: There may be an updated version of this malloc obtainable at
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ftp://g.oswego.edu/pub/misc/malloc.c
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Check before installing!
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* Why use this malloc?
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This is not the fastest, most space-conserving, most portable, or
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most tunable malloc ever written. However it is among the fastest
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while also being among the most space-conserving, portable and tunable.
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Consistent balance across these factors results in a good general-purpose
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allocator. For a high-level description, see
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http://g.oswego.edu/dl/html/malloc.html
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* Synopsis of public routines
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(Much fuller descriptions are contained in the program documentation below.)
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malloc(size_t n);
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Return a pointer to a newly allocated chunk of at least n bytes, or null
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if no space is available.
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free(Void_t* p);
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Release the chunk of memory pointed to by p, or no effect if p is null.
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realloc(Void_t* p, size_t n);
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Return a pointer to a chunk of size n that contains the same data
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as does chunk p up to the minimum of (n, p's size) bytes, or null
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if no space is available. The returned pointer may or may not be
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the same as p. If p is null, equivalent to malloc. Unless the
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#define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
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size argument of zero (re)allocates a minimum-sized chunk.
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memalign(size_t alignment, size_t n);
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Return a pointer to a newly allocated chunk of n bytes, aligned
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in accord with the alignment argument, which must be a power of
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two.
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valloc(size_t n);
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Equivalent to memalign(pagesize, n), where pagesize is the page
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size of the system (or as near to this as can be figured out from
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all the includes/defines below.)
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pvalloc(size_t n);
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Equivalent to valloc(minimum-page-that-holds(n)), that is,
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round up n to nearest pagesize.
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calloc(size_t unit, size_t quantity);
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Returns a pointer to quantity * unit bytes, with all locations
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set to zero.
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cfree(Void_t* p);
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Equivalent to free(p).
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malloc_trim(size_t pad);
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Release all but pad bytes of freed top-most memory back
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to the system. Return 1 if successful, else 0.
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malloc_usable_size(Void_t* p);
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Report the number usable allocated bytes associated with allocated
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chunk p. This may or may not report more bytes than were requested,
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due to alignment and minimum size constraints.
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malloc_stats();
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Prints brief summary statistics on stderr.
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mallinfo()
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Returns (by copy) a struct containing various summary statistics.
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mallopt(int parameter_number, int parameter_value)
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Changes one of the tunable parameters described below. Returns
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1 if successful in changing the parameter, else 0.
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* Vital statistics:
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Alignment: 8-byte
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8 byte alignment is currently hardwired into the design. This
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seems to suffice for all current machines and C compilers.
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Assumed pointer representation: 4 or 8 bytes
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Code for 8-byte pointers is untested by me but has worked
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reliably by Wolfram Gloger, who contributed most of the
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changes supporting this.
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Assumed size_t representation: 4 or 8 bytes
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Note that size_t is allowed to be 4 bytes even if pointers are 8.
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Minimum overhead per allocated chunk: 4 or 8 bytes
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Each malloced chunk has a hidden overhead of 4 bytes holding size
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and status information.
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Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
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8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
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When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
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ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
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needed; 4 (8) for a trailing size field
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and 8 (16) bytes for free list pointers. Thus, the minimum
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allocatable size is 16/24/32 bytes.
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Even a request for zero bytes (i.e., malloc(0)) returns a
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pointer to something of the minimum allocatable size.
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Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
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8-byte size_t: 2^63 - 16 bytes
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It is assumed that (possibly signed) size_t bit values suffice to
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represent chunk sizes. `Possibly signed' is due to the fact
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that `size_t' may be defined on a system as either a signed or
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an unsigned type. To be conservative, values that would appear
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as negative numbers are avoided.
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Requests for sizes with a negative sign bit when the request
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size is treaded as a long will return null.
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Maximum overhead wastage per allocated chunk: normally 15 bytes
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Alignnment demands, plus the minimum allocatable size restriction
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make the normal worst-case wastage 15 bytes (i.e., up to 15
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more bytes will be allocated than were requested in malloc), with
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two exceptions:
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1. Because requests for zero bytes allocate non-zero space,
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the worst case wastage for a request of zero bytes is 24 bytes.
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2. For requests >= mmap_threshold that are serviced via
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mmap(), the worst case wastage is 8 bytes plus the remainder
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from a system page (the minimal mmap unit); typically 4096 bytes.
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* Limitations
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Here are some features that are NOT currently supported
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* No user-definable hooks for callbacks and the like.
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* No automated mechanism for fully checking that all accesses
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to malloced memory stay within their bounds.
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* No support for compaction.
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* Synopsis of compile-time options:
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People have reported using previous versions of this malloc on all
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versions of Unix, sometimes by tweaking some of the defines
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below. It has been tested most extensively on Solaris and
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Linux. It is also reported to work on WIN32 platforms.
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People have also reported adapting this malloc for use in
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stand-alone embedded systems.
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The implementation is in straight, hand-tuned ANSI C. Among other
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consequences, it uses a lot of macros. Because of this, to be at
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all usable, this code should be compiled using an optimizing compiler
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(for example gcc -O2) that can simplify expressions and control
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paths.
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__STD_C (default: derived from C compiler defines)
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Nonzero if using ANSI-standard C compiler, a C++ compiler, or
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a C compiler sufficiently close to ANSI to get away with it.
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DEBUG (default: NOT defined)
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Define to enable debugging. Adds fairly extensive assertion-based
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checking to help track down memory errors, but noticeably slows down
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execution.
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REALLOC_ZERO_BYTES_FREES (default: NOT defined)
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Define this if you think that realloc(p, 0) should be equivalent
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to free(p). Otherwise, since malloc returns a unique pointer for
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malloc(0), so does realloc(p, 0).
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HAVE_MEMCPY (default: defined)
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Define if you are not otherwise using ANSI STD C, but still
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have memcpy and memset in your C library and want to use them.
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Otherwise, simple internal versions are supplied.
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USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
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Define as 1 if you want the C library versions of memset and
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memcpy called in realloc and calloc (otherwise macro versions are used).
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At least on some platforms, the simple macro versions usually
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outperform libc versions.
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HAVE_MMAP (default: defined as 1)
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Define to non-zero to optionally make malloc() use mmap() to
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allocate very large blocks.
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HAVE_MREMAP (default: defined as 0 unless Linux libc set)
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Define to non-zero to optionally make realloc() use mremap() to
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reallocate very large blocks.
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malloc_getpagesize (default: derived from system #includes)
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Either a constant or routine call returning the system page size.
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HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
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Optionally define if you are on a system with a /usr/include/malloc.h
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that declares struct mallinfo. It is not at all necessary to
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define this even if you do, but will ensure consistency.
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INTERNAL_SIZE_T (default: size_t)
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Define to a 32-bit type (probably `unsigned int') if you are on a
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64-bit machine, yet do not want or need to allow malloc requests of
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greater than 2^31 to be handled. This saves space, especially for
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very small chunks.
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INTERNAL_LINUX_C_LIB (default: NOT defined)
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Defined only when compiled as part of Linux libc.
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Also note that there is some odd internal name-mangling via defines
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(for example, internally, `malloc' is named `mALLOc') needed
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when compiling in this case. These look funny but don't otherwise
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affect anything.
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WIN32 (default: undefined)
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Define this on MS win (95, nt) platforms to compile in sbrk emulation.
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LACKS_UNISTD_H (default: undefined if not WIN32)
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Define this if your system does not have a <unistd.h>.
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LACKS_SYS_PARAM_H (default: undefined if not WIN32)
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Define this if your system does not have a <sys/param.h>.
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MORECORE (default: sbrk)
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The name of the routine to call to obtain more memory from the system.
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MORECORE_FAILURE (default: -1)
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The value returned upon failure of MORECORE.
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MORECORE_CLEARS (default 1)
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true (1) if the routine mapped to MORECORE zeroes out memory (which
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holds for sbrk).
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DEFAULT_TRIM_THRESHOLD
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DEFAULT_TOP_PAD
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DEFAULT_MMAP_THRESHOLD
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DEFAULT_MMAP_MAX
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Default values of tunable parameters (described in detail below)
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controlling interaction with host system routines (sbrk, mmap, etc).
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These values may also be changed dynamically via mallopt(). The
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preset defaults are those that give best performance for typical
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programs/systems.
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USE_DL_PREFIX (default: undefined)
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Prefix all public routines with the string 'dl'. Useful to
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quickly avoid procedure declaration conflicts and linker symbol
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conflicts with existing memory allocation routines.
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*/
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/* Preliminaries */
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#ifndef __STD_C
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#ifdef __STDC__
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#define __STD_C 1
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#else
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#if __cplusplus
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#define __STD_C 1
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#else
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#define __STD_C 0
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#endif /*__cplusplus*/
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#endif /*__STDC__*/
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#endif /*__STD_C*/
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#ifndef Void_t
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#if (__STD_C || defined(WIN32))
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#define Void_t void
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#else
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#define Void_t char
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#endif
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#endif /*Void_t*/
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#if __STD_C
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#include <stddef.h> /* for size_t */
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#else
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#include <sys/types.h>
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <stdio.h> /* needed for malloc_stats */
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/*
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Compile-time options
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*/
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/*
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Debugging:
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Because freed chunks may be overwritten with link fields, this
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malloc will often die when freed memory is overwritten by user
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programs. This can be very effective (albeit in an annoying way)
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in helping track down dangling pointers.
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If you compile with -DDEBUG, a number of assertion checks are
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enabled that will catch more memory errors. You probably won't be
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able to make much sense of the actual assertion errors, but they
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should help you locate incorrectly overwritten memory. The
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checking is fairly extensive, and will slow down execution
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noticeably. Calling malloc_stats or mallinfo with DEBUG set will
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attempt to check every non-mmapped allocated and free chunk in the
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course of computing the summmaries. (By nature, mmapped regions
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cannot be checked very much automatically.)
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Setting DEBUG may also be helpful if you are trying to modify
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this code. The assertions in the check routines spell out in more
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detail the assumptions and invariants underlying the algorithms.
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*/
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#if DEBUG
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#include <assert.h>
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#else
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#define assert(x) ((void)0)
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#endif
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/*
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INTERNAL_SIZE_T is the word-size used for internal bookkeeping
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of chunk sizes. On a 64-bit machine, you can reduce malloc
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overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
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at the expense of not being able to handle requests greater than
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2^31. This limitation is hardly ever a concern; you are encouraged
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to set this. However, the default version is the same as size_t.
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*/
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#ifndef INTERNAL_SIZE_T
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#define INTERNAL_SIZE_T size_t
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#endif
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/*
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REALLOC_ZERO_BYTES_FREES should be set if a call to
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realloc with zero bytes should be the same as a call to free.
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Some people think it should. Otherwise, since this malloc
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returns a unique pointer for malloc(0), so does realloc(p, 0).
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*/
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/* #define REALLOC_ZERO_BYTES_FREES */
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/*
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WIN32 causes an emulation of sbrk to be compiled in
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mmap-based options are not currently supported in WIN32.
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*/
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/* #define WIN32 */
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#ifdef WIN32
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#define MORECORE wsbrk
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#define HAVE_MMAP 0
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#define LACKS_UNISTD_H
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#define LACKS_SYS_PARAM_H
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/*
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Include 'windows.h' to get the necessary declarations for the
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Microsoft Visual C++ data structures and routines used in the 'sbrk'
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emulation.
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Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft
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Visual C++ header files are included.
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*/
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#define WIN32_LEAN_AND_MEAN
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#include <windows.h>
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#endif
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/*
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HAVE_MEMCPY should be defined if you are not otherwise using
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ANSI STD C, but still have memcpy and memset in your C library
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and want to use them in calloc and realloc. Otherwise simple
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macro versions are defined here.
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USE_MEMCPY should be defined as 1 if you actually want to
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have memset and memcpy called. People report that the macro
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versions are often enough faster than libc versions on many
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systems that it is better to use them.
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*/
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#define HAVE_MEMCPY
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#ifndef USE_MEMCPY
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#ifdef HAVE_MEMCPY
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#define USE_MEMCPY 1
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#else
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#define USE_MEMCPY 0
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#endif
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#endif
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#if (__STD_C || defined(HAVE_MEMCPY))
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#if __STD_C
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void* memset(void*, int, size_t);
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void* memcpy(void*, const void*, size_t);
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#else
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#ifdef WIN32
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/* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */
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/* 'windows.h' */
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#else
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Void_t* memset();
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Void_t* memcpy();
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#endif
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#endif
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#endif
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#if USE_MEMCPY
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/* The following macros are only invoked with (2n+1)-multiples of
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INTERNAL_SIZE_T units, with a positive integer n. This is exploited
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for fast inline execution when n is small. */
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#define MALLOC_ZERO(charp, nbytes) \
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do { \
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INTERNAL_SIZE_T mzsz = (nbytes); \
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if(mzsz <= 9*sizeof(mzsz)) { \
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INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
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if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
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*mz++ = 0; \
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if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
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*mz++ = 0; \
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if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
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*mz++ = 0; }}} \
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*mz++ = 0; \
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*mz++ = 0; \
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*mz = 0; \
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} else memset((charp), 0, mzsz); \
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} while(0)
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#define MALLOC_COPY(dest,src,nbytes) \
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do { \
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INTERNAL_SIZE_T mcsz = (nbytes); \
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if(mcsz <= 9*sizeof(mcsz)) { \
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INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
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INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
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if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
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*mcdst++ = *mcsrc++; \
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if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
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*mcdst++ = *mcsrc++; \
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if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
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*mcdst++ = *mcsrc++; }}} \
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*mcdst++ = *mcsrc++; \
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*mcdst++ = *mcsrc++; \
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*mcdst = *mcsrc ; \
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} else memcpy(dest, src, mcsz); \
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} while(0)
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#else /* !USE_MEMCPY */
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/* Use Duff's device for good zeroing/copying performance. */
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#define MALLOC_ZERO(charp, nbytes) \
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do { \
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INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
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long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
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if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
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switch (mctmp) { \
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case 0: for(;;) { *mzp++ = 0; \
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case 7: *mzp++ = 0; \
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case 6: *mzp++ = 0; \
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case 5: *mzp++ = 0; \
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case 4: *mzp++ = 0; \
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case 3: *mzp++ = 0; \
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case 2: *mzp++ = 0; \
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case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
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||
} \
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} while(0)
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#define MALLOC_COPY(dest,src,nbytes) \
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do { \
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INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
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INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
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long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
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if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
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switch (mctmp) { \
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case 0: for(;;) { *mcdst++ = *mcsrc++; \
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case 7: *mcdst++ = *mcsrc++; \
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case 6: *mcdst++ = *mcsrc++; \
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case 5: *mcdst++ = *mcsrc++; \
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case 4: *mcdst++ = *mcsrc++; \
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case 3: *mcdst++ = *mcsrc++; \
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case 2: *mcdst++ = *mcsrc++; \
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case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
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} \
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} while(0)
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#endif
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/*
|
||
Define HAVE_MMAP to optionally make malloc() use mmap() to
|
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allocate very large blocks. These will be returned to the
|
||
operating system immediately after a free().
|
||
*/
|
||
|
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#ifndef HAVE_MMAP
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#define HAVE_MMAP 1
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#endif
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/*
|
||
Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
|
||
large blocks. This is currently only possible on Linux with
|
||
kernel versions newer than 1.3.77.
|
||
*/
|
||
|
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#ifndef HAVE_MREMAP
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||
#ifdef INTERNAL_LINUX_C_LIB
|
||
#define HAVE_MREMAP 1
|
||
#else
|
||
#define HAVE_MREMAP 0
|
||
#endif
|
||
#endif
|
||
|
||
#if HAVE_MMAP
|
||
|
||
#include <unistd.h>
|
||
#include <fcntl.h>
|
||
#include <sys/mman.h>
|
||
|
||
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
|
||
#define MAP_ANONYMOUS MAP_ANON
|
||
#endif
|
||
|
||
#endif /* HAVE_MMAP */
|
||
|
||
/*
|
||
Access to system page size. To the extent possible, this malloc
|
||
manages memory from the system in page-size units.
|
||
|
||
The following mechanics for getpagesize were adapted from
|
||
bsd/gnu getpagesize.h
|
||
*/
|
||
|
||
#ifndef LACKS_UNISTD_H
|
||
# include <unistd.h>
|
||
#endif
|
||
|
||
#ifndef malloc_getpagesize
|
||
# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
|
||
# ifndef _SC_PAGE_SIZE
|
||
# define _SC_PAGE_SIZE _SC_PAGESIZE
|
||
# endif
|
||
# endif
|
||
# ifdef _SC_PAGE_SIZE
|
||
# define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
|
||
# else
|
||
# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
|
||
extern size_t getpagesize();
|
||
# define malloc_getpagesize getpagesize()
|
||
# else
|
||
# ifdef WIN32
|
||
# define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
|
||
# else
|
||
# ifndef LACKS_SYS_PARAM_H
|
||
# include <sys/param.h>
|
||
# endif
|
||
# ifdef EXEC_PAGESIZE
|
||
# define malloc_getpagesize EXEC_PAGESIZE
|
||
# else
|
||
# ifdef NBPG
|
||
# ifndef CLSIZE
|
||
# define malloc_getpagesize NBPG
|
||
# else
|
||
# define malloc_getpagesize (NBPG * CLSIZE)
|
||
# endif
|
||
# else
|
||
# ifdef NBPC
|
||
# define malloc_getpagesize NBPC
|
||
# else
|
||
# ifdef PAGESIZE
|
||
# define malloc_getpagesize PAGESIZE
|
||
# else
|
||
# define malloc_getpagesize (4096) /* just guess */
|
||
# endif
|
||
# endif
|
||
# endif
|
||
# endif
|
||
# endif
|
||
# endif
|
||
# endif
|
||
#endif
|
||
|
||
|
||
/*
|
||
|
||
This version of malloc supports the standard SVID/XPG mallinfo
|
||
routine that returns a struct containing the same kind of
|
||
information you can get from malloc_stats. It should work on
|
||
any SVID/XPG compliant system that has a /usr/include/malloc.h
|
||
defining struct mallinfo. (If you'd like to install such a thing
|
||
yourself, cut out the preliminary declarations as described above
|
||
and below and save them in a malloc.h file. But there's no
|
||
compelling reason to bother to do this.)
|
||
|
||
The main declaration needed is the mallinfo struct that is returned
|
||
(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
|
||
bunch of fields, most of which are not even meaningful in this
|
||
version of malloc. Some of these fields are are instead filled by
|
||
mallinfo() with other numbers that might possibly be of interest.
|
||
|
||
HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
|
||
/usr/include/malloc.h file that includes a declaration of struct
|
||
mallinfo. If so, it is included; else an SVID2/XPG2 compliant
|
||
version is declared below. These must be precisely the same for
|
||
mallinfo() to work.
|
||
|
||
*/
|
||
|
||
/* #define HAVE_USR_INCLUDE_MALLOC_H */
|
||
|
||
#if HAVE_USR_INCLUDE_MALLOC_H
|
||
#include "/usr/include/malloc.h"
|
||
#else
|
||
|
||
/* SVID2/XPG mallinfo structure */
|
||
|
||
struct mallinfo {
|
||
int arena; /* total space allocated from system */
|
||
int ordblks; /* number of non-inuse chunks */
|
||
int smblks; /* unused -- always zero */
|
||
int hblks; /* number of mmapped regions */
|
||
int hblkhd; /* total space in mmapped regions */
|
||
int usmblks; /* unused -- always zero */
|
||
int fsmblks; /* unused -- always zero */
|
||
int uordblks; /* total allocated space */
|
||
int fordblks; /* total non-inuse space */
|
||
int keepcost; /* top-most, releasable (via malloc_trim) space */
|
||
};
|
||
|
||
/* SVID2/XPG mallopt options */
|
||
|
||
#define M_MXFAST 1 /* UNUSED in this malloc */
|
||
#define M_NLBLKS 2 /* UNUSED in this malloc */
|
||
#define M_GRAIN 3 /* UNUSED in this malloc */
|
||
#define M_KEEP 4 /* UNUSED in this malloc */
|
||
|
||
#endif
|
||
|
||
/* mallopt options that actually do something */
|
||
|
||
#define M_TRIM_THRESHOLD -1
|
||
#define M_TOP_PAD -2
|
||
#define M_MMAP_THRESHOLD -3
|
||
#define M_MMAP_MAX -4
|
||
|
||
|
||
#ifndef DEFAULT_TRIM_THRESHOLD
|
||
#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
|
||
#endif
|
||
|
||
/*
|
||
M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
|
||
to keep before releasing via malloc_trim in free().
|
||
|
||
Automatic trimming is mainly useful in long-lived programs.
|
||
Because trimming via sbrk can be slow on some systems, and can
|
||
sometimes be wasteful (in cases where programs immediately
|
||
afterward allocate more large chunks) the value should be high
|
||
enough so that your overall system performance would improve by
|
||
releasing.
|
||
|
||
The trim threshold and the mmap control parameters (see below)
|
||
can be traded off with one another. Trimming and mmapping are
|
||
two different ways of releasing unused memory back to the
|
||
system. Between these two, it is often possible to keep
|
||
system-level demands of a long-lived program down to a bare
|
||
minimum. For example, in one test suite of sessions measuring
|
||
the XF86 X server on Linux, using a trim threshold of 128K and a
|
||
mmap threshold of 192K led to near-minimal long term resource
|
||
consumption.
|
||
|
||
If you are using this malloc in a long-lived program, it should
|
||
pay to experiment with these values. As a rough guide, you
|
||
might set to a value close to the average size of a process
|
||
(program) running on your system. Releasing this much memory
|
||
would allow such a process to run in memory. Generally, it's
|
||
worth it to tune for trimming rather tham memory mapping when a
|
||
program undergoes phases where several large chunks are
|
||
allocated and released in ways that can reuse each other's
|
||
storage, perhaps mixed with phases where there are no such
|
||
chunks at all. And in well-behaved long-lived programs,
|
||
controlling release of large blocks via trimming versus mapping
|
||
is usually faster.
|
||
|
||
However, in most programs, these parameters serve mainly as
|
||
protection against the system-level effects of carrying around
|
||
massive amounts of unneeded memory. Since frequent calls to
|
||
sbrk, mmap, and munmap otherwise degrade performance, the default
|
||
parameters are set to relatively high values that serve only as
|
||
safeguards.
|
||
|
||
The default trim value is high enough to cause trimming only in
|
||
fairly extreme (by current memory consumption standards) cases.
|
||
It must be greater than page size to have any useful effect. To
|
||
disable trimming completely, you can set to (unsigned long)(-1);
|
||
|
||
|
||
*/
|
||
|
||
|
||
#ifndef DEFAULT_TOP_PAD
|
||
#define DEFAULT_TOP_PAD (0)
|
||
#endif
|
||
|
||
/*
|
||
M_TOP_PAD is the amount of extra `padding' space to allocate or
|
||
retain whenever sbrk is called. It is used in two ways internally:
|
||
|
||
* When sbrk is called to extend the top of the arena to satisfy
|
||
a new malloc request, this much padding is added to the sbrk
|
||
request.
|
||
|
||
* When malloc_trim is called automatically from free(),
|
||
it is used as the `pad' argument.
|
||
|
||
In both cases, the actual amount of padding is rounded
|
||
so that the end of the arena is always a system page boundary.
|
||
|
||
The main reason for using padding is to avoid calling sbrk so
|
||
often. Having even a small pad greatly reduces the likelihood
|
||
that nearly every malloc request during program start-up (or
|
||
after trimming) will invoke sbrk, which needlessly wastes
|
||
time.
|
||
|
||
Automatic rounding-up to page-size units is normally sufficient
|
||
to avoid measurable overhead, so the default is 0. However, in
|
||
systems where sbrk is relatively slow, it can pay to increase
|
||
this value, at the expense of carrying around more memory than
|
||
the program needs.
|
||
|
||
*/
|
||
|
||
|
||
#ifndef DEFAULT_MMAP_THRESHOLD
|
||
#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
|
||
#endif
|
||
|
||
/*
|
||
|
||
M_MMAP_THRESHOLD is the request size threshold for using mmap()
|
||
to service a request. Requests of at least this size that cannot
|
||
be allocated using already-existing space will be serviced via mmap.
|
||
(If enough normal freed space already exists it is used instead.)
|
||
|
||
Using mmap segregates relatively large chunks of memory so that
|
||
they can be individually obtained and released from the host
|
||
system. A request serviced through mmap is never reused by any
|
||
other request (at least not directly; the system may just so
|
||
happen to remap successive requests to the same locations).
|
||
|
||
Segregating space in this way has the benefit that mmapped space
|
||
can ALWAYS be individually released back to the system, which
|
||
helps keep the system level memory demands of a long-lived
|
||
program low. Mapped memory can never become `locked' between
|
||
other chunks, as can happen with normally allocated chunks, which
|
||
menas that even trimming via malloc_trim would not release them.
|
||
|
||
However, it has the disadvantages that:
|
||
|
||
1. The space cannot be reclaimed, consolidated, and then
|
||
used to service later requests, as happens with normal chunks.
|
||
2. It can lead to more wastage because of mmap page alignment
|
||
requirements
|
||
3. It causes malloc performance to be more dependent on host
|
||
system memory management support routines which may vary in
|
||
implementation quality and may impose arbitrary
|
||
limitations. Generally, servicing a request via normal
|
||
malloc steps is faster than going through a system's mmap.
|
||
|
||
All together, these considerations should lead you to use mmap
|
||
only for relatively large requests.
|
||
|
||
|
||
*/
|
||
|
||
|
||
#ifndef DEFAULT_MMAP_MAX
|
||
#if HAVE_MMAP
|
||
#define DEFAULT_MMAP_MAX (64)
|
||
#else
|
||
#define DEFAULT_MMAP_MAX (0)
|
||
#endif
|
||
#endif
|
||
|
||
/*
|
||
M_MMAP_MAX is the maximum number of requests to simultaneously
|
||
service using mmap. This parameter exists because:
|
||
|
||
1. Some systems have a limited number of internal tables for
|
||
use by mmap.
|
||
2. In most systems, overreliance on mmap can degrade overall
|
||
performance.
|
||
3. If a program allocates many large regions, it is probably
|
||
better off using normal sbrk-based allocation routines that
|
||
can reclaim and reallocate normal heap memory. Using a
|
||
small value allows transition into this mode after the
|
||
first few allocations.
|
||
|
||
Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
|
||
the default value is 0, and attempts to set it to non-zero values
|
||
in mallopt will fail.
|
||
*/
|
||
|
||
|
||
/*
|
||
USE_DL_PREFIX will prefix all public routines with the string 'dl'.
|
||
Useful to quickly avoid procedure declaration conflicts and linker
|
||
symbol conflicts with existing memory allocation routines.
|
||
|
||
*/
|
||
|
||
/* #define USE_DL_PREFIX */
|
||
|
||
|
||
/*
|
||
|
||
Special defines for linux libc
|
||
|
||
Except when compiled using these special defines for Linux libc
|
||
using weak aliases, this malloc is NOT designed to work in
|
||
multithreaded applications. No semaphores or other concurrency
|
||
control are provided to ensure that multiple malloc or free calls
|
||
don't run at the same time, which could be disasterous. A single
|
||
semaphore could be used across malloc, realloc, and free (which is
|
||
essentially the effect of the linux weak alias approach). It would
|
||
be hard to obtain finer granularity.
|
||
|
||
*/
|
||
|
||
|
||
#ifdef INTERNAL_LINUX_C_LIB
|
||
|
||
#if __STD_C
|
||
|
||
Void_t * __default_morecore_init (ptrdiff_t);
|
||
Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
|
||
|
||
#else
|
||
|
||
Void_t * __default_morecore_init ();
|
||
Void_t *(*__morecore)() = __default_morecore_init;
|
||
|
||
#endif
|
||
|
||
#define MORECORE (*__morecore)
|
||
#define MORECORE_FAILURE 0
|
||
#define MORECORE_CLEARS 1
|
||
|
||
#else /* INTERNAL_LINUX_C_LIB */
|
||
|
||
#if __STD_C
|
||
extern Void_t* sbrk(ptrdiff_t);
|
||
#else
|
||
extern Void_t* sbrk();
|
||
#endif
|
||
|
||
#ifndef MORECORE
|
||
#define MORECORE sbrk
|
||
#endif
|
||
|
||
#ifndef MORECORE_FAILURE
|
||
#define MORECORE_FAILURE -1
|
||
#endif
|
||
|
||
#ifndef MORECORE_CLEARS
|
||
#define MORECORE_CLEARS 1
|
||
#endif
|
||
|
||
#endif /* INTERNAL_LINUX_C_LIB */
|
||
|
||
#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
|
||
|
||
#define cALLOc __libc_calloc
|
||
#define fREe __libc_free
|
||
#define mALLOc __libc_malloc
|
||
#define mEMALIGn __libc_memalign
|
||
#define rEALLOc __libc_realloc
|
||
#define vALLOc __libc_valloc
|
||
#define pvALLOc __libc_pvalloc
|
||
#define mALLINFo __libc_mallinfo
|
||
#define mALLOPt __libc_mallopt
|
||
|
||
#pragma weak calloc = __libc_calloc
|
||
#pragma weak free = __libc_free
|
||
#pragma weak cfree = __libc_free
|
||
#pragma weak malloc = __libc_malloc
|
||
#pragma weak memalign = __libc_memalign
|
||
#pragma weak realloc = __libc_realloc
|
||
#pragma weak valloc = __libc_valloc
|
||
#pragma weak pvalloc = __libc_pvalloc
|
||
#pragma weak mallinfo = __libc_mallinfo
|
||
#pragma weak mallopt = __libc_mallopt
|
||
|
||
#else
|
||
|
||
#ifdef USE_DL_PREFIX
|
||
#define cALLOc dlcalloc
|
||
#define fREe dlfree
|
||
#define mALLOc dlmalloc
|
||
#define mEMALIGn dlmemalign
|
||
#define rEALLOc dlrealloc
|
||
#define vALLOc dlvalloc
|
||
#define pvALLOc dlpvalloc
|
||
#define mALLINFo dlmallinfo
|
||
#define mALLOPt dlmallopt
|
||
#else /* USE_DL_PREFIX */
|
||
#define cALLOc calloc
|
||
#define fREe free
|
||
#define mALLOc malloc
|
||
#define mEMALIGn memalign
|
||
#define rEALLOc realloc
|
||
#define vALLOc valloc
|
||
#define pvALLOc pvalloc
|
||
#define mALLINFo mallinfo
|
||
#define mALLOPt mallopt
|
||
#endif /* USE_DL_PREFIX */
|
||
|
||
#endif
|
||
|
||
/* Public routines */
|
||
|
||
#if __STD_C
|
||
|
||
Void_t* mALLOc(size_t);
|
||
void fREe(Void_t*);
|
||
Void_t* rEALLOc(Void_t*, size_t);
|
||
Void_t* mEMALIGn(size_t, size_t);
|
||
Void_t* vALLOc(size_t);
|
||
Void_t* pvALLOc(size_t);
|
||
Void_t* cALLOc(size_t, size_t);
|
||
void cfree(Void_t*);
|
||
int malloc_trim(size_t);
|
||
size_t malloc_usable_size(Void_t*);
|
||
void malloc_stats();
|
||
int mALLOPt(int, int);
|
||
struct mallinfo mALLINFo(void);
|
||
#else
|
||
Void_t* mALLOc();
|
||
void fREe();
|
||
Void_t* rEALLOc();
|
||
Void_t* mEMALIGn();
|
||
Void_t* vALLOc();
|
||
Void_t* pvALLOc();
|
||
Void_t* cALLOc();
|
||
void cfree();
|
||
int malloc_trim();
|
||
size_t malloc_usable_size();
|
||
void malloc_stats();
|
||
int mALLOPt();
|
||
struct mallinfo mALLINFo();
|
||
#endif
|
||
|
||
|
||
#ifdef __cplusplus
|
||
}; /* end of extern "C" */
|
||
#endif
|
||
|
||
/* ---------- To make a malloc.h, end cutting here ------------ */
|
||
|
||
|
||
/*
|
||
Emulation of sbrk for WIN32
|
||
All code within the ifdef WIN32 is untested by me.
|
||
|
||
Thanks to Martin Fong and others for supplying this.
|
||
*/
|
||
|
||
|
||
#ifdef WIN32
|
||
|
||
#define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \
|
||
~(malloc_getpagesize-1))
|
||
#define AlignPage64K(add) (((add) + (0x10000 - 1)) & ~(0x10000 - 1))
|
||
|
||
/* resrve 64MB to insure large contiguous space */
|
||
#define RESERVED_SIZE (1024*1024*64)
|
||
#define NEXT_SIZE (2048*1024)
|
||
#define TOP_MEMORY ((unsigned long)2*1024*1024*1024)
|
||
|
||
struct GmListElement;
|
||
typedef struct GmListElement GmListElement;
|
||
|
||
struct GmListElement
|
||
{
|
||
GmListElement* next;
|
||
void* base;
|
||
};
|
||
|
||
static GmListElement* head = 0;
|
||
static unsigned int gNextAddress = 0;
|
||
static unsigned int gAddressBase = 0;
|
||
static unsigned int gAllocatedSize = 0;
|
||
|
||
static
|
||
GmListElement* makeGmListElement (void* bas)
|
||
{
|
||
GmListElement* this;
|
||
this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement));
|
||
assert (this);
|
||
if (this)
|
||
{
|
||
this->base = bas;
|
||
this->next = head;
|
||
head = this;
|
||
}
|
||
return this;
|
||
}
|
||
|
||
void gcleanup ()
|
||
{
|
||
BOOL rval;
|
||
assert ( (head == NULL) || (head->base == (void*)gAddressBase));
|
||
if (gAddressBase && (gNextAddress - gAddressBase))
|
||
{
|
||
rval = VirtualFree ((void*)gAddressBase,
|
||
gNextAddress - gAddressBase,
|
||
MEM_DECOMMIT);
|
||
assert (rval);
|
||
}
|
||
while (head)
|
||
{
|
||
GmListElement* next = head->next;
|
||
rval = VirtualFree (head->base, 0, MEM_RELEASE);
|
||
assert (rval);
|
||
LocalFree (head);
|
||
head = next;
|
||
}
|
||
}
|
||
|
||
static
|
||
void* findRegion (void* start_address, unsigned long size)
|
||
{
|
||
MEMORY_BASIC_INFORMATION info;
|
||
if (size >= TOP_MEMORY) return NULL;
|
||
|
||
while ((unsigned long)start_address + size < TOP_MEMORY)
|
||
{
|
||
VirtualQuery (start_address, &info, sizeof (info));
|
||
if ((info.State == MEM_FREE) && (info.RegionSize >= size))
|
||
return start_address;
|
||
else
|
||
{
|
||
/* Requested region is not available so see if the */
|
||
/* next region is available. Set 'start_address' */
|
||
/* to the next region and call 'VirtualQuery()' */
|
||
/* again. */
|
||
|
||
start_address = (char*)info.BaseAddress + info.RegionSize;
|
||
|
||
/* Make sure we start looking for the next region */
|
||
/* on the *next* 64K boundary. Otherwise, even if */
|
||
/* the new region is free according to */
|
||
/* 'VirtualQuery()', the subsequent call to */
|
||
/* 'VirtualAlloc()' (which follows the call to */
|
||
/* this routine in 'wsbrk()') will round *down* */
|
||
/* the requested address to a 64K boundary which */
|
||
/* we already know is an address in the */
|
||
/* unavailable region. Thus, the subsequent call */
|
||
/* to 'VirtualAlloc()' will fail and bring us back */
|
||
/* here, causing us to go into an infinite loop. */
|
||
|
||
start_address =
|
||
(void *) AlignPage64K((unsigned long) start_address);
|
||
}
|
||
}
|
||
return NULL;
|
||
|
||
}
|
||
|
||
|
||
void* wsbrk (long size)
|
||
{
|
||
void* tmp;
|
||
if (size > 0)
|
||
{
|
||
if (gAddressBase == 0)
|
||
{
|
||
gAllocatedSize = max (RESERVED_SIZE, AlignPage (size));
|
||
gNextAddress = gAddressBase =
|
||
(unsigned int)VirtualAlloc (NULL, gAllocatedSize,
|
||
MEM_RESERVE, PAGE_NOACCESS);
|
||
} else if (AlignPage (gNextAddress + size) > (gAddressBase +
|
||
gAllocatedSize))
|
||
{
|
||
long new_size = max (NEXT_SIZE, AlignPage (size));
|
||
void* new_address = (void*)(gAddressBase+gAllocatedSize);
|
||
do
|
||
{
|
||
new_address = findRegion (new_address, new_size);
|
||
|
||
if (new_address == 0)
|
||
return (void*)-1;
|
||
|
||
gAddressBase = gNextAddress =
|
||
(unsigned int)VirtualAlloc (new_address, new_size,
|
||
MEM_RESERVE, PAGE_NOACCESS);
|
||
/* repeat in case of race condition */
|
||
/* The region that we found has been snagged */
|
||
/* by another thread */
|
||
}
|
||
while (gAddressBase == 0);
|
||
|
||
assert (new_address == (void*)gAddressBase);
|
||
|
||
gAllocatedSize = new_size;
|
||
|
||
if (!makeGmListElement ((void*)gAddressBase))
|
||
return (void*)-1;
|
||
}
|
||
if ((size + gNextAddress) > AlignPage (gNextAddress))
|
||
{
|
||
void* res;
|
||
res = VirtualAlloc ((void*)AlignPage (gNextAddress),
|
||
(size + gNextAddress -
|
||
AlignPage (gNextAddress)),
|
||
MEM_COMMIT, PAGE_READWRITE);
|
||
if (res == 0)
|
||
return (void*)-1;
|
||
}
|
||
tmp = (void*)gNextAddress;
|
||
gNextAddress = (unsigned int)tmp + size;
|
||
return tmp;
|
||
}
|
||
else if (size < 0)
|
||
{
|
||
unsigned int alignedGoal = AlignPage (gNextAddress + size);
|
||
/* Trim by releasing the virtual memory */
|
||
if (alignedGoal >= gAddressBase)
|
||
{
|
||
VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal,
|
||
MEM_DECOMMIT);
|
||
gNextAddress = gNextAddress + size;
|
||
return (void*)gNextAddress;
|
||
}
|
||
else
|
||
{
|
||
VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase,
|
||
MEM_DECOMMIT);
|
||
gNextAddress = gAddressBase;
|
||
return (void*)-1;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
return (void*)gNextAddress;
|
||
}
|
||
}
|
||
|
||
#endif
|
||
|
||
|
||
|
||
/*
|
||
Type declarations
|
||
*/
|
||
|
||
|
||
struct malloc_chunk
|
||
{
|
||
INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
|
||
INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */
|
||
struct malloc_chunk* fd; /* double links -- used only if free. */
|
||
struct malloc_chunk* bk;
|
||
};
|
||
|
||
typedef struct malloc_chunk* mchunkptr;
|
||
|
||
/*
|
||
|
||
malloc_chunk details:
|
||
|
||
(The following includes lightly edited explanations by Colin Plumb.)
|
||
|
||
Chunks of memory are maintained using a `boundary tag' method as
|
||
described in e.g., Knuth or Standish. (See the paper by Paul
|
||
Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
|
||
survey of such techniques.) Sizes of free chunks are stored both
|
||
in the front of each chunk and at the end. This makes
|
||
consolidating fragmented chunks into bigger chunks very fast. The
|
||
size fields also hold bits representing whether chunks are free or
|
||
in use.
|
||
|
||
An allocated chunk looks like this:
|
||
|
||
|
||
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
| Size of previous chunk, if allocated | |
|
||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
| Size of chunk, in bytes |P|
|
||
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
| User data starts here... .
|
||
. .
|
||
. (malloc_usable_space() bytes) .
|
||
. |
|
||
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
| Size of chunk |
|
||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
||
|
||
Where "chunk" is the front of the chunk for the purpose of most of
|
||
the malloc code, but "mem" is the pointer that is returned to the
|
||
user. "Nextchunk" is the beginning of the next contiguous chunk.
|
||
|
||
Chunks always begin on even word boundries, so the mem portion
|
||
(which is returned to the user) is also on an even word boundary, and
|
||
thus double-word aligned.
|
||
|
||
Free chunks are stored in circular doubly-linked lists, and look like this:
|
||
|
||
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
| Size of previous chunk |
|
||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
`head:' | Size of chunk, in bytes |P|
|
||
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
| Forward pointer to next chunk in list |
|
||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
| Back pointer to previous chunk in list |
|
||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
| Unused space (may be 0 bytes long) .
|
||
. .
|
||
. |
|
||
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
`foot:' | Size of chunk, in bytes |
|
||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
||
The P (PREV_INUSE) bit, stored in the unused low-order bit of the
|
||
chunk size (which is always a multiple of two words), is an in-use
|
||
bit for the *previous* chunk. If that bit is *clear*, then the
|
||
word before the current chunk size contains the previous chunk
|
||
size, and can be used to find the front of the previous chunk.
|
||
(The very first chunk allocated always has this bit set,
|
||
preventing access to non-existent (or non-owned) memory.)
|
||
|
||
Note that the `foot' of the current chunk is actually represented
|
||
as the prev_size of the NEXT chunk. (This makes it easier to
|
||
deal with alignments etc).
|
||
|
||
The two exceptions to all this are
|
||
|
||
1. The special chunk `top', which doesn't bother using the
|
||
trailing size field since there is no
|
||
next contiguous chunk that would have to index off it. (After
|
||
initialization, `top' is forced to always exist. If it would
|
||
become less than MINSIZE bytes long, it is replenished via
|
||
malloc_extend_top.)
|
||
|
||
2. Chunks allocated via mmap, which have the second-lowest-order
|
||
bit (IS_MMAPPED) set in their size fields. Because they are
|
||
never merged or traversed from any other chunk, they have no
|
||
foot size or inuse information.
|
||
|
||
Available chunks are kept in any of several places (all declared below):
|
||
|
||
* `av': An array of chunks serving as bin headers for consolidated
|
||
chunks. Each bin is doubly linked. The bins are approximately
|
||
proportionally (log) spaced. There are a lot of these bins
|
||
(128). This may look excessive, but works very well in
|
||
practice. All procedures maintain the invariant that no
|
||
consolidated chunk physically borders another one. Chunks in
|
||
bins are kept in size order, with ties going to the
|
||
approximately least recently used chunk.
|
||
|
||
The chunks in each bin are maintained in decreasing sorted order by
|
||
size. This is irrelevant for the small bins, which all contain
|
||
the same-sized chunks, but facilitates best-fit allocation for
|
||
larger chunks. (These lists are just sequential. Keeping them in
|
||
order almost never requires enough traversal to warrant using
|
||
fancier ordered data structures.) Chunks of the same size are
|
||
linked with the most recently freed at the front, and allocations
|
||
are taken from the back. This results in LRU or FIFO allocation
|
||
order, which tends to give each chunk an equal opportunity to be
|
||
consolidated with adjacent freed chunks, resulting in larger free
|
||
chunks and less fragmentation.
|
||
|
||
* `top': The top-most available chunk (i.e., the one bordering the
|
||
end of available memory) is treated specially. It is never
|
||
included in any bin, is used only if no other chunk is
|
||
available, and is released back to the system if it is very
|
||
large (see M_TRIM_THRESHOLD).
|
||
|
||
* `last_remainder': A bin holding only the remainder of the
|
||
most recently split (non-top) chunk. This bin is checked
|
||
before other non-fitting chunks, so as to provide better
|
||
locality for runs of sequentially allocated chunks.
|
||
|
||
* Implicitly, through the host system's memory mapping tables.
|
||
If supported, requests greater than a threshold are usually
|
||
serviced via calls to mmap, and then later released via munmap.
|
||
|
||
*/
|
||
|
||
|
||
|
||
|
||
|
||
/* sizes, alignments */
|
||
|
||
#define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
|
||
#define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ)
|
||
#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
|
||
#define MINSIZE (sizeof(struct malloc_chunk))
|
||
|
||
/* conversion from malloc headers to user pointers, and back */
|
||
|
||
#define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
|
||
#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
|
||
|
||
/* pad request bytes into a usable size */
|
||
|
||
#define request2size(req) \
|
||
(((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \
|
||
(long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \
|
||
(((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK)))
|
||
|
||
/* Check if m has acceptable alignment */
|
||
|
||
#define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
|
||
|
||
|
||
|
||
|
||
/*
|
||
Physical chunk operations
|
||
*/
|
||
|
||
|
||
/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
|
||
|
||
#define PREV_INUSE 0x1
|
||
|
||
/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
|
||
|
||
#define IS_MMAPPED 0x2
|
||
|
||
/* Bits to mask off when extracting size */
|
||
|
||
#define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
|
||
|
||
|
||
/* Ptr to next physical malloc_chunk. */
|
||
|
||
#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))
|
||
|
||
/* Ptr to previous physical malloc_chunk */
|
||
|
||
#define prev_chunk(p)\
|
||
((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
|
||
|
||
|
||
/* Treat space at ptr + offset as a chunk */
|
||
|
||
#define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
|
||
|
||
|
||
|
||
|
||
/*
|
||
Dealing with use bits
|
||
*/
|
||
|
||
/* extract p's inuse bit */
|
||
|
||
#define inuse(p)\
|
||
((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)
|
||
|
||
/* extract inuse bit of previous chunk */
|
||
|
||
#define prev_inuse(p) ((p)->size & PREV_INUSE)
|
||
|
||
/* check for mmap()'ed chunk */
|
||
|
||
#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
|
||
|
||
/* set/clear chunk as in use without otherwise disturbing */
|
||
|
||
#define set_inuse(p)\
|
||
((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE
|
||
|
||
#define clear_inuse(p)\
|
||
((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)
|
||
|
||
/* check/set/clear inuse bits in known places */
|
||
|
||
#define inuse_bit_at_offset(p, s)\
|
||
(((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
|
||
|
||
#define set_inuse_bit_at_offset(p, s)\
|
||
(((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
|
||
|
||
#define clear_inuse_bit_at_offset(p, s)\
|
||
(((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
|
||
|
||
|
||
|
||
|
||
/*
|
||
Dealing with size fields
|
||
*/
|
||
|
||
/* Get size, ignoring use bits */
|
||
|
||
#define chunksize(p) ((p)->size & ~(SIZE_BITS))
|
||
|
||
/* Set size at head, without disturbing its use bit */
|
||
|
||
#define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s)))
|
||
|
||
/* Set size/use ignoring previous bits in header */
|
||
|
||
#define set_head(p, s) ((p)->size = (s))
|
||
|
||
/* Set size at footer (only when chunk is not in use) */
|
||
|
||
#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
|
||
|
||
|
||
|
||
|
||
|
||
/*
|
||
Bins
|
||
|
||
The bins, `av_' are an array of pairs of pointers serving as the
|
||
heads of (initially empty) doubly-linked lists of chunks, laid out
|
||
in a way so that each pair can be treated as if it were in a
|
||
malloc_chunk. (This way, the fd/bk offsets for linking bin heads
|
||
and chunks are the same).
|
||
|
||
Bins for sizes < 512 bytes contain chunks of all the same size, spaced
|
||
8 bytes apart. Larger bins are approximately logarithmically
|
||
spaced. (See the table below.) The `av_' array is never mentioned
|
||
directly in the code, but instead via bin access macros.
|
||
|
||
Bin layout:
|
||
|
||
64 bins of size 8
|
||
32 bins of size 64
|
||
16 bins of size 512
|
||
8 bins of size 4096
|
||
4 bins of size 32768
|
||
2 bins of size 262144
|
||
1 bin of size what's left
|
||
|
||
There is actually a little bit of slop in the numbers in bin_index
|
||
for the sake of speed. This makes no difference elsewhere.
|
||
|
||
The special chunks `top' and `last_remainder' get their own bins,
|
||
(this is implemented via yet more trickery with the av_ array),
|
||
although `top' is never properly linked to its bin since it is
|
||
always handled specially.
|
||
|
||
*/
|
||
|
||
#define NAV 128 /* number of bins */
|
||
|
||
typedef struct malloc_chunk* mbinptr;
|
||
|
||
/* access macros */
|
||
|
||
#define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ))
|
||
#define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr)))
|
||
#define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr)))
|
||
|
||
/*
|
||
The first 2 bins are never indexed. The corresponding av_ cells are instead
|
||
used for bookkeeping. This is not to save space, but to simplify
|
||
indexing, maintain locality, and avoid some initialization tests.
|
||
*/
|
||
|
||
#define top (bin_at(0)->fd) /* The topmost chunk */
|
||
#define last_remainder (bin_at(1)) /* remainder from last split */
|
||
|
||
|
||
/*
|
||
Because top initially points to its own bin with initial
|
||
zero size, thus forcing extension on the first malloc request,
|
||
we avoid having any special code in malloc to check whether
|
||
it even exists yet. But we still need to in malloc_extend_top.
|
||
*/
|
||
|
||
#define initial_top ((mchunkptr)(bin_at(0)))
|
||
|
||
/* Helper macro to initialize bins */
|
||
|
||
#define IAV(i) bin_at(i), bin_at(i)
|
||
|
||
static mbinptr av_[NAV * 2 + 2] = {
|
||
0, 0,
|
||
IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7),
|
||
IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15),
|
||
IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23),
|
||
IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31),
|
||
IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39),
|
||
IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47),
|
||
IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55),
|
||
IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63),
|
||
IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71),
|
||
IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79),
|
||
IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87),
|
||
IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95),
|
||
IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103),
|
||
IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),
|
||
IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),
|
||
IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
|
||
};
|
||
|
||
|
||
|
||
/* field-extraction macros */
|
||
|
||
#define first(b) ((b)->fd)
|
||
#define last(b) ((b)->bk)
|
||
|
||
/*
|
||
Indexing into bins
|
||
*/
|
||
|
||
#define bin_index(sz) \
|
||
(((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \
|
||
((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \
|
||
((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \
|
||
((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \
|
||
((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \
|
||
((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \
|
||
126)
|
||
/*
|
||
bins for chunks < 512 are all spaced 8 bytes apart, and hold
|
||
identically sized chunks. This is exploited in malloc.
|
||
*/
|
||
|
||
#define MAX_SMALLBIN 63
|
||
#define MAX_SMALLBIN_SIZE 512
|
||
#define SMALLBIN_WIDTH 8
|
||
|
||
#define smallbin_index(sz) (((unsigned long)(sz)) >> 3)
|
||
|
||
/*
|
||
Requests are `small' if both the corresponding and the next bin are small
|
||
*/
|
||
|
||
#define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)
|
||
|
||
|
||
|
||
/*
|
||
To help compensate for the large number of bins, a one-level index
|
||
structure is used for bin-by-bin searching. `binblocks' is a
|
||
one-word bitvector recording whether groups of BINBLOCKWIDTH bins
|
||
have any (possibly) non-empty bins, so they can be skipped over
|
||
all at once during during traversals. The bits are NOT always
|
||
cleared as soon as all bins in a block are empty, but instead only
|
||
when all are noticed to be empty during traversal in malloc.
|
||
*/
|
||
|
||
#define BINBLOCKWIDTH 4 /* bins per block */
|
||
|
||
#define binblocks (bin_at(0)->size) /* bitvector of nonempty blocks */
|
||
|
||
/* bin<->block macros */
|
||
|
||
#define idx2binblock(ix) ((unsigned)1 << (ix / BINBLOCKWIDTH))
|
||
#define mark_binblock(ii) (binblocks |= idx2binblock(ii))
|
||
#define clear_binblock(ii) (binblocks &= ~(idx2binblock(ii)))
|
||
|
||
|
||
|
||
|
||
|
||
/* Other static bookkeeping data */
|
||
|
||
/* variables holding tunable values */
|
||
|
||
static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
|
||
static unsigned long top_pad = DEFAULT_TOP_PAD;
|
||
static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
|
||
static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;
|
||
|
||
/* The first value returned from sbrk */
|
||
static char* sbrk_base = (char*)(-1);
|
||
|
||
/* The maximum memory obtained from system via sbrk */
|
||
static unsigned long max_sbrked_mem = 0;
|
||
|
||
/* The maximum via either sbrk or mmap */
|
||
static unsigned long max_total_mem = 0;
|
||
|
||
/* internal working copy of mallinfo */
|
||
static struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
|
||
|
||
/* The total memory obtained from system via sbrk */
|
||
#define sbrked_mem (current_mallinfo.arena)
|
||
|
||
/* Tracking mmaps */
|
||
|
||
static unsigned int n_mmaps = 0;
|
||
static unsigned int max_n_mmaps = 0;
|
||
static unsigned long mmapped_mem = 0;
|
||
static unsigned long max_mmapped_mem = 0;
|
||
|
||
|
||
|
||
/*
|
||
Debugging support
|
||
*/
|
||
|
||
#if DEBUG
|
||
|
||
|
||
/*
|
||
These routines make a number of assertions about the states
|
||
of data structures that should be true at all times. If any
|
||
are not true, it's very likely that a user program has somehow
|
||
trashed memory. (It's also possible that there is a coding error
|
||
in malloc. In which case, please report it!)
|
||
*/
|
||
|
||
#if __STD_C
|
||
static void do_check_chunk(mchunkptr p)
|
||
#else
|
||
static void do_check_chunk(p) mchunkptr p;
|
||
#endif
|
||
{
|
||
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
|
||
|
||
/* No checkable chunk is mmapped */
|
||
assert(!chunk_is_mmapped(p));
|
||
|
||
/* Check for legal address ... */
|
||
assert((char*)p >= sbrk_base);
|
||
if (p != top)
|
||
assert((char*)p + sz <= (char*)top);
|
||
else
|
||
assert((char*)p + sz <= sbrk_base + sbrked_mem);
|
||
|
||
}
|
||
|
||
|
||
#if __STD_C
|
||
static void do_check_free_chunk(mchunkptr p)
|
||
#else
|
||
static void do_check_free_chunk(p) mchunkptr p;
|
||
#endif
|
||
{
|
||
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
|
||
mchunkptr next = chunk_at_offset(p, sz);
|
||
|
||
do_check_chunk(p);
|
||
|
||
/* Check whether it claims to be free ... */
|
||
assert(!inuse(p));
|
||
|
||
/* Unless a special marker, must have OK fields */
|
||
if ((long)sz >= (long)MINSIZE)
|
||
{
|
||
assert((sz & MALLOC_ALIGN_MASK) == 0);
|
||
assert(aligned_OK(chunk2mem(p)));
|
||
/* ... matching footer field */
|
||
assert(next->prev_size == sz);
|
||
/* ... and is fully consolidated */
|
||
assert(prev_inuse(p));
|
||
assert (next == top || inuse(next));
|
||
|
||
/* ... and has minimally sane links */
|
||
assert(p->fd->bk == p);
|
||
assert(p->bk->fd == p);
|
||
}
|
||
else /* markers are always of size SIZE_SZ */
|
||
assert(sz == SIZE_SZ);
|
||
}
|
||
|
||
#if __STD_C
|
||
static void do_check_inuse_chunk(mchunkptr p)
|
||
#else
|
||
static void do_check_inuse_chunk(p) mchunkptr p;
|
||
#endif
|
||
{
|
||
mchunkptr next = next_chunk(p);
|
||
do_check_chunk(p);
|
||
|
||
/* Check whether it claims to be in use ... */
|
||
assert(inuse(p));
|
||
|
||
/* ... and is surrounded by OK chunks.
|
||
Since more things can be checked with free chunks than inuse ones,
|
||
if an inuse chunk borders them and debug is on, it's worth doing them.
|
||
*/
|
||
if (!prev_inuse(p))
|
||
{
|
||
mchunkptr prv = prev_chunk(p);
|
||
assert(next_chunk(prv) == p);
|
||
do_check_free_chunk(prv);
|
||
}
|
||
if (next == top)
|
||
{
|
||
assert(prev_inuse(next));
|
||
assert(chunksize(next) >= MINSIZE);
|
||
}
|
||
else if (!inuse(next))
|
||
do_check_free_chunk(next);
|
||
|
||
}
|
||
|
||
#if __STD_C
|
||
static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
|
||
#else
|
||
static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
|
||
#endif
|
||
{
|
||
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
|
||
long room = sz - s;
|
||
|
||
do_check_inuse_chunk(p);
|
||
|
||
/* Legal size ... */
|
||
assert((long)sz >= (long)MINSIZE);
|
||
assert((sz & MALLOC_ALIGN_MASK) == 0);
|
||
assert(room >= 0);
|
||
assert(room < (long)MINSIZE);
|
||
|
||
/* ... and alignment */
|
||
assert(aligned_OK(chunk2mem(p)));
|
||
|
||
|
||
/* ... and was allocated at front of an available chunk */
|
||
assert(prev_inuse(p));
|
||
|
||
}
|
||
|
||
|
||
#define check_free_chunk(P) do_check_free_chunk(P)
|
||
#define check_inuse_chunk(P) do_check_inuse_chunk(P)
|
||
#define check_chunk(P) do_check_chunk(P)
|
||
#define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N)
|
||
#else
|
||
#define check_free_chunk(P)
|
||
#define check_inuse_chunk(P)
|
||
#define check_chunk(P)
|
||
#define check_malloced_chunk(P,N)
|
||
#endif
|
||
|
||
|
||
|
||
/*
|
||
Macro-based internal utilities
|
||
*/
|
||
|
||
|
||
/*
|
||
Linking chunks in bin lists.
|
||
Call these only with variables, not arbitrary expressions, as arguments.
|
||
*/
|
||
|
||
/*
|
||
Place chunk p of size s in its bin, in size order,
|
||
putting it ahead of others of same size.
|
||
*/
|
||
|
||
|
||
#define frontlink(P, S, IDX, BK, FD) \
|
||
{ \
|
||
if (S < MAX_SMALLBIN_SIZE) \
|
||
{ \
|
||
IDX = smallbin_index(S); \
|
||
mark_binblock(IDX); \
|
||
BK = bin_at(IDX); \
|
||
FD = BK->fd; \
|
||
P->bk = BK; \
|
||
P->fd = FD; \
|
||
FD->bk = BK->fd = P; \
|
||
} \
|
||
else \
|
||
{ \
|
||
IDX = bin_index(S); \
|
||
BK = bin_at(IDX); \
|
||
FD = BK->fd; \
|
||
if (FD == BK) mark_binblock(IDX); \
|
||
else \
|
||
{ \
|
||
while (FD != BK && S < chunksize(FD)) FD = FD->fd; \
|
||
BK = FD->bk; \
|
||
} \
|
||
P->bk = BK; \
|
||
P->fd = FD; \
|
||
FD->bk = BK->fd = P; \
|
||
} \
|
||
}
|
||
|
||
|
||
/* take a chunk off a list */
|
||
|
||
#define unlink(P, BK, FD) \
|
||
{ \
|
||
BK = P->bk; \
|
||
FD = P->fd; \
|
||
FD->bk = BK; \
|
||
BK->fd = FD; \
|
||
} \
|
||
|
||
/* Place p as the last remainder */
|
||
|
||
#define link_last_remainder(P) \
|
||
{ \
|
||
last_remainder->fd = last_remainder->bk = P; \
|
||
P->fd = P->bk = last_remainder; \
|
||
}
|
||
|
||
/* Clear the last_remainder bin */
|
||
|
||
#define clear_last_remainder \
|
||
(last_remainder->fd = last_remainder->bk = last_remainder)
|
||
|
||
|
||
|
||
|
||
|
||
/* Routines dealing with mmap(). */
|
||
|
||
#if HAVE_MMAP
|
||
|
||
#if __STD_C
|
||
static mchunkptr mmap_chunk(size_t size)
|
||
#else
|
||
static mchunkptr mmap_chunk(size) size_t size;
|
||
#endif
|
||
{
|
||
size_t page_mask = malloc_getpagesize - 1;
|
||
mchunkptr p;
|
||
|
||
#ifndef MAP_ANONYMOUS
|
||
static int fd = -1;
|
||
#endif
|
||
|
||
if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */
|
||
|
||
/* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because
|
||
* there is no following chunk whose prev_size field could be used.
|
||
*/
|
||
size = (size + SIZE_SZ + page_mask) & ~page_mask;
|
||
|
||
#ifdef MAP_ANONYMOUS
|
||
p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE,
|
||
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
|
||
#else /* !MAP_ANONYMOUS */
|
||
if (fd < 0)
|
||
{
|
||
fd = open("/dev/zero", O_RDWR);
|
||
if(fd < 0) return 0;
|
||
}
|
||
p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
|
||
#endif
|
||
|
||
if(p == (mchunkptr)-1) return 0;
|
||
|
||
n_mmaps++;
|
||
if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;
|
||
|
||
/* We demand that eight bytes into a page must be 8-byte aligned. */
|
||
assert(aligned_OK(chunk2mem(p)));
|
||
|
||
/* The offset to the start of the mmapped region is stored
|
||
* in the prev_size field of the chunk; normally it is zero,
|
||
* but that can be changed in memalign().
|
||
*/
|
||
p->prev_size = 0;
|
||
set_head(p, size|IS_MMAPPED);
|
||
|
||
mmapped_mem += size;
|
||
if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
|
||
max_mmapped_mem = mmapped_mem;
|
||
if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
|
||
max_total_mem = mmapped_mem + sbrked_mem;
|
||
return p;
|
||
}
|
||
|
||
#if __STD_C
|
||
static void munmap_chunk(mchunkptr p)
|
||
#else
|
||
static void munmap_chunk(p) mchunkptr p;
|
||
#endif
|
||
{
|
||
INTERNAL_SIZE_T size = chunksize(p);
|
||
int ret;
|
||
|
||
assert (chunk_is_mmapped(p));
|
||
assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
|
||
assert((n_mmaps > 0));
|
||
assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);
|
||
|
||
n_mmaps--;
|
||
mmapped_mem -= (size + p->prev_size);
|
||
|
||
ret = munmap((char *)p - p->prev_size, size + p->prev_size);
|
||
|
||
/* munmap returns non-zero on failure */
|
||
assert(ret == 0);
|
||
}
|
||
|
||
#if HAVE_MREMAP
|
||
|
||
#if __STD_C
|
||
static mchunkptr mremap_chunk(mchunkptr p, size_t new_size)
|
||
#else
|
||
static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
|
||
#endif
|
||
{
|
||
size_t page_mask = malloc_getpagesize - 1;
|
||
INTERNAL_SIZE_T offset = p->prev_size;
|
||
INTERNAL_SIZE_T size = chunksize(p);
|
||
char *cp;
|
||
|
||
assert (chunk_is_mmapped(p));
|
||
assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
|
||
assert((n_mmaps > 0));
|
||
assert(((size + offset) & (malloc_getpagesize-1)) == 0);
|
||
|
||
/* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
|
||
new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
|
||
|
||
cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1);
|
||
|
||
if (cp == (char *)-1) return 0;
|
||
|
||
p = (mchunkptr)(cp + offset);
|
||
|
||
assert(aligned_OK(chunk2mem(p)));
|
||
|
||
assert((p->prev_size == offset));
|
||
set_head(p, (new_size - offset)|IS_MMAPPED);
|
||
|
||
mmapped_mem -= size + offset;
|
||
mmapped_mem += new_size;
|
||
if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
|
||
max_mmapped_mem = mmapped_mem;
|
||
if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
|
||
max_total_mem = mmapped_mem + sbrked_mem;
|
||
return p;
|
||
}
|
||
|
||
#endif /* HAVE_MREMAP */
|
||
|
||
#endif /* HAVE_MMAP */
|
||
|
||
|
||
|
||
|
||
/*
|
||
Extend the top-most chunk by obtaining memory from system.
|
||
Main interface to sbrk (but see also malloc_trim).
|
||
*/
|
||
|
||
#if __STD_C
|
||
static void malloc_extend_top(INTERNAL_SIZE_T nb)
|
||
#else
|
||
static void malloc_extend_top(nb) INTERNAL_SIZE_T nb;
|
||
#endif
|
||
{
|
||
char* brk; /* return value from sbrk */
|
||
INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */
|
||
INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */
|
||
char* new_brk; /* return of 2nd sbrk call */
|
||
INTERNAL_SIZE_T top_size; /* new size of top chunk */
|
||
|
||
mchunkptr old_top = top; /* Record state of old top */
|
||
INTERNAL_SIZE_T old_top_size = chunksize(old_top);
|
||
char* old_end = (char*)(chunk_at_offset(old_top, old_top_size));
|
||
|
||
/* Pad request with top_pad plus minimal overhead */
|
||
|
||
INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE;
|
||
unsigned long pagesz = malloc_getpagesize;
|
||
|
||
/* If not the first time through, round to preserve page boundary */
|
||
/* Otherwise, we need to correct to a page size below anyway. */
|
||
/* (We also correct below if an intervening foreign sbrk call.) */
|
||
|
||
if (sbrk_base != (char*)(-1))
|
||
sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);
|
||
|
||
brk = (char*)(MORECORE (sbrk_size));
|
||
|
||
/* Fail if sbrk failed or if a foreign sbrk call killed our space */
|
||
if (brk == (char*)(MORECORE_FAILURE) ||
|
||
(brk < old_end && old_top != initial_top))
|
||
return;
|
||
|
||
sbrked_mem += sbrk_size;
|
||
|
||
if (brk == old_end) /* can just add bytes to current top */
|
||
{
|
||
top_size = sbrk_size + old_top_size;
|
||
set_head(top, top_size | PREV_INUSE);
|
||
}
|
||
else
|
||
{
|
||
if (sbrk_base == (char*)(-1)) /* First time through. Record base */
|
||
sbrk_base = brk;
|
||
else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */
|
||
sbrked_mem += brk - (char*)old_end;
|
||
|
||
/* Guarantee alignment of first new chunk made from this space */
|
||
front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
|
||
if (front_misalign > 0)
|
||
{
|
||
correction = (MALLOC_ALIGNMENT) - front_misalign;
|
||
brk += correction;
|
||
}
|
||
else
|
||
correction = 0;
|
||
|
||
/* Guarantee the next brk will be at a page boundary */
|
||
|
||
correction += ((((unsigned long)(brk + sbrk_size))+(pagesz-1)) &
|
||
~(pagesz - 1)) - ((unsigned long)(brk + sbrk_size));
|
||
|
||
/* Allocate correction */
|
||
new_brk = (char*)(MORECORE (correction));
|
||
if (new_brk == (char*)(MORECORE_FAILURE)) return;
|
||
|
||
sbrked_mem += correction;
|
||
|
||
top = (mchunkptr)brk;
|
||
top_size = new_brk - brk + correction;
|
||
set_head(top, top_size | PREV_INUSE);
|
||
|
||
if (old_top != initial_top)
|
||
{
|
||
|
||
/* There must have been an intervening foreign sbrk call. */
|
||
/* A double fencepost is necessary to prevent consolidation */
|
||
|
||
/* If not enough space to do this, then user did something very wrong */
|
||
if (old_top_size < MINSIZE)
|
||
{
|
||
set_head(top, PREV_INUSE); /* will force null return from malloc */
|
||
return;
|
||
}
|
||
|
||
/* Also keep size a multiple of MALLOC_ALIGNMENT */
|
||
old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
|
||
set_head_size(old_top, old_top_size);
|
||
chunk_at_offset(old_top, old_top_size )->size =
|
||
SIZE_SZ|PREV_INUSE;
|
||
chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size =
|
||
SIZE_SZ|PREV_INUSE;
|
||
/* If possible, release the rest. */
|
||
if (old_top_size >= MINSIZE)
|
||
fREe(chunk2mem(old_top));
|
||
}
|
||
}
|
||
|
||
if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem)
|
||
max_sbrked_mem = sbrked_mem;
|
||
if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
|
||
max_total_mem = mmapped_mem + sbrked_mem;
|
||
|
||
/* We always land on a page boundary */
|
||
assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0);
|
||
}
|
||
|
||
|
||
|
||
|
||
/* Main public routines */
|
||
|
||
|
||
/*
|
||
Malloc Algorthim:
|
||
|
||
The requested size is first converted into a usable form, `nb'.
|
||
This currently means to add 4 bytes overhead plus possibly more to
|
||
obtain 8-byte alignment and/or to obtain a size of at least
|
||
MINSIZE (currently 16 bytes), the smallest allocatable size.
|
||
(All fits are considered `exact' if they are within MINSIZE bytes.)
|
||
|
||
From there, the first successful of the following steps is taken:
|
||
|
||
1. The bin corresponding to the request size is scanned, and if
|
||
a chunk of exactly the right size is found, it is taken.
|
||
|
||
2. The most recently remaindered chunk is used if it is big
|
||
enough. This is a form of (roving) first fit, used only in
|
||
the absence of exact fits. Runs of consecutive requests use
|
||
the remainder of the chunk used for the previous such request
|
||
whenever possible. This limited use of a first-fit style
|
||
allocation strategy tends to give contiguous chunks
|
||
coextensive lifetimes, which improves locality and can reduce
|
||
fragmentation in the long run.
|
||
|
||
3. Other bins are scanned in increasing size order, using a
|
||
chunk big enough to fulfill the request, and splitting off
|
||
any remainder. This search is strictly by best-fit; i.e.,
|
||
the smallest (with ties going to approximately the least
|
||
recently used) chunk that fits is selected.
|
||
|
||
4. If large enough, the chunk bordering the end of memory
|
||
(`top') is split off. (This use of `top' is in accord with
|
||
the best-fit search rule. In effect, `top' is treated as
|
||
larger (and thus less well fitting) than any other available
|
||
chunk since it can be extended to be as large as necessary
|
||
(up to system limitations).
|
||
|
||
5. If the request size meets the mmap threshold and the
|
||
system supports mmap, and there are few enough currently
|
||
allocated mmapped regions, and a call to mmap succeeds,
|
||
the request is allocated via direct memory mapping.
|
||
|
||
6. Otherwise, the top of memory is extended by
|
||
obtaining more space from the system (normally using sbrk,
|
||
but definable to anything else via the MORECORE macro).
|
||
Memory is gathered from the system (in system page-sized
|
||
units) in a way that allows chunks obtained across different
|
||
sbrk calls to be consolidated, but does not require
|
||
contiguous memory. Thus, it should be safe to intersperse
|
||
mallocs with other sbrk calls.
|
||
|
||
|
||
All allocations are made from the the `lowest' part of any found
|
||
chunk. (The implementation invariant is that prev_inuse is
|
||
always true of any allocated chunk; i.e., that each allocated
|
||
chunk borders either a previously allocated and still in-use chunk,
|
||
or the base of its memory arena.)
|
||
|
||
*/
|
||
|
||
#if __STD_C
|
||
Void_t* mALLOc(size_t bytes)
|
||
#else
|
||
Void_t* mALLOc(bytes) size_t bytes;
|
||
#endif
|
||
{
|
||
mchunkptr victim; /* inspected/selected chunk */
|
||
INTERNAL_SIZE_T victim_size; /* its size */
|
||
int idx; /* index for bin traversal */
|
||
mbinptr bin; /* associated bin */
|
||
mchunkptr remainder; /* remainder from a split */
|
||
long remainder_size; /* its size */
|
||
int remainder_index; /* its bin index */
|
||
unsigned long block; /* block traverser bit */
|
||
int startidx; /* first bin of a traversed block */
|
||
mchunkptr fwd; /* misc temp for linking */
|
||
mchunkptr bck; /* misc temp for linking */
|
||
mbinptr q; /* misc temp */
|
||
|
||
INTERNAL_SIZE_T nb;
|
||
|
||
if ((long)bytes < 0) return 0;
|
||
|
||
nb = request2size(bytes); /* padded request size; */
|
||
|
||
/* Check for exact match in a bin */
|
||
|
||
if (is_small_request(nb)) /* Faster version for small requests */
|
||
{
|
||
idx = smallbin_index(nb);
|
||
|
||
/* No traversal or size check necessary for small bins. */
|
||
|
||
q = bin_at(idx);
|
||
victim = last(q);
|
||
|
||
/* Also scan the next one, since it would have a remainder < MINSIZE */
|
||
if (victim == q)
|
||
{
|
||
q = next_bin(q);
|
||
victim = last(q);
|
||
}
|
||
if (victim != q)
|
||
{
|
||
victim_size = chunksize(victim);
|
||
unlink(victim, bck, fwd);
|
||
set_inuse_bit_at_offset(victim, victim_size);
|
||
check_malloced_chunk(victim, nb);
|
||
return chunk2mem(victim);
|
||
}
|
||
|
||
idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */
|
||
|
||
}
|
||
else
|
||
{
|
||
idx = bin_index(nb);
|
||
bin = bin_at(idx);
|
||
|
||
for (victim = last(bin); victim != bin; victim = victim->bk)
|
||
{
|
||
victim_size = chunksize(victim);
|
||
remainder_size = victim_size - nb;
|
||
|
||
if (remainder_size >= (long)MINSIZE) /* too big */
|
||
{
|
||
--idx; /* adjust to rescan below after checking last remainder */
|
||
break;
|
||
}
|
||
|
||
else if (remainder_size >= 0) /* exact fit */
|
||
{
|
||
unlink(victim, bck, fwd);
|
||
set_inuse_bit_at_offset(victim, victim_size);
|
||
check_malloced_chunk(victim, nb);
|
||
return chunk2mem(victim);
|
||
}
|
||
}
|
||
|
||
++idx;
|
||
|
||
}
|
||
|
||
/* Try to use the last split-off remainder */
|
||
|
||
if ( (victim = last_remainder->fd) != last_remainder)
|
||
{
|
||
victim_size = chunksize(victim);
|
||
remainder_size = victim_size - nb;
|
||
|
||
if (remainder_size >= (long)MINSIZE) /* re-split */
|
||
{
|
||
remainder = chunk_at_offset(victim, nb);
|
||
set_head(victim, nb | PREV_INUSE);
|
||
link_last_remainder(remainder);
|
||
set_head(remainder, remainder_size | PREV_INUSE);
|
||
set_foot(remainder, remainder_size);
|
||
check_malloced_chunk(victim, nb);
|
||
return chunk2mem(victim);
|
||
}
|
||
|
||
clear_last_remainder;
|
||
|
||
if (remainder_size >= 0) /* exhaust */
|
||
{
|
||
set_inuse_bit_at_offset(victim, victim_size);
|
||
check_malloced_chunk(victim, nb);
|
||
return chunk2mem(victim);
|
||
}
|
||
|
||
/* Else place in bin */
|
||
|
||
frontlink(victim, victim_size, remainder_index, bck, fwd);
|
||
}
|
||
|
||
/*
|
||
If there are any possibly nonempty big-enough blocks,
|
||
search for best fitting chunk by scanning bins in blockwidth units.
|
||
*/
|
||
|
||
if ( (block = idx2binblock(idx)) <= binblocks)
|
||
{
|
||
|
||
/* Get to the first marked block */
|
||
|
||
if ( (block & binblocks) == 0)
|
||
{
|
||
/* force to an even block boundary */
|
||
idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;
|
||
block <<= 1;
|
||
while ((block & binblocks) == 0)
|
||
{
|
||
idx += BINBLOCKWIDTH;
|
||
block <<= 1;
|
||
}
|
||
}
|
||
|
||
/* For each possibly nonempty block ... */
|
||
for (;;)
|
||
{
|
||
startidx = idx; /* (track incomplete blocks) */
|
||
q = bin = bin_at(idx);
|
||
|
||
/* For each bin in this block ... */
|
||
do
|
||
{
|
||
/* Find and use first big enough chunk ... */
|
||
|
||
for (victim = last(bin); victim != bin; victim = victim->bk)
|
||
{
|
||
victim_size = chunksize(victim);
|
||
remainder_size = victim_size - nb;
|
||
|
||
if (remainder_size >= (long)MINSIZE) /* split */
|
||
{
|
||
remainder = chunk_at_offset(victim, nb);
|
||
set_head(victim, nb | PREV_INUSE);
|
||
unlink(victim, bck, fwd);
|
||
link_last_remainder(remainder);
|
||
set_head(remainder, remainder_size | PREV_INUSE);
|
||
set_foot(remainder, remainder_size);
|
||
check_malloced_chunk(victim, nb);
|
||
return chunk2mem(victim);
|
||
}
|
||
|
||
else if (remainder_size >= 0) /* take */
|
||
{
|
||
set_inuse_bit_at_offset(victim, victim_size);
|
||
unlink(victim, bck, fwd);
|
||
check_malloced_chunk(victim, nb);
|
||
return chunk2mem(victim);
|
||
}
|
||
|
||
}
|
||
|
||
bin = next_bin(bin);
|
||
|
||
} while ((++idx & (BINBLOCKWIDTH - 1)) != 0);
|
||
|
||
/* Clear out the block bit. */
|
||
|
||
do /* Possibly backtrack to try to clear a partial block */
|
||
{
|
||
if ((startidx & (BINBLOCKWIDTH - 1)) == 0)
|
||
{
|
||
binblocks &= ~block;
|
||
break;
|
||
}
|
||
--startidx;
|
||
q = prev_bin(q);
|
||
} while (first(q) == q);
|
||
|
||
/* Get to the next possibly nonempty block */
|
||
|
||
if ( (block <<= 1) <= binblocks && (block != 0) )
|
||
{
|
||
while ((block & binblocks) == 0)
|
||
{
|
||
idx += BINBLOCKWIDTH;
|
||
block <<= 1;
|
||
}
|
||
}
|
||
else
|
||
break;
|
||
}
|
||
}
|
||
|
||
|
||
/* Try to use top chunk */
|
||
|
||
/* Require that there be a remainder, ensuring top always exists */
|
||
if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)
|
||
{
|
||
|
||
#if HAVE_MMAP
|
||
/* If big and would otherwise need to extend, try to use mmap instead */
|
||
if ((unsigned long)nb >= (unsigned long)mmap_threshold &&
|
||
(victim = mmap_chunk(nb)) != 0)
|
||
return chunk2mem(victim);
|
||
#endif
|
||
|
||
/* Try to extend */
|
||
malloc_extend_top(nb);
|
||
if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)
|
||
return 0; /* propagate failure */
|
||
}
|
||
|
||
victim = top;
|
||
set_head(victim, nb | PREV_INUSE);
|
||
top = chunk_at_offset(victim, nb);
|
||
set_head(top, remainder_size | PREV_INUSE);
|
||
check_malloced_chunk(victim, nb);
|
||
return chunk2mem(victim);
|
||
|
||
}
|
||
|
||
|
||
|
||
|
||
/*
|
||
|
||
free() algorithm :
|
||
|
||
cases:
|
||
|
||
1. free(0) has no effect.
|
||
|
||
2. If the chunk was allocated via mmap, it is release via munmap().
|
||
|
||
3. If a returned chunk borders the current high end of memory,
|
||
it is consolidated into the top, and if the total unused
|
||
topmost memory exceeds the trim threshold, malloc_trim is
|
||
called.
|
||
|
||
4. Other chunks are consolidated as they arrive, and
|
||
placed in corresponding bins. (This includes the case of
|
||
consolidating with the current `last_remainder').
|
||
|
||
*/
|
||
|
||
|
||
#if __STD_C
|
||
void fREe(Void_t* mem)
|
||
#else
|
||
void fREe(mem) Void_t* mem;
|
||
#endif
|
||
{
|
||
mchunkptr p; /* chunk corresponding to mem */
|
||
INTERNAL_SIZE_T hd; /* its head field */
|
||
INTERNAL_SIZE_T sz; /* its size */
|
||
int idx; /* its bin index */
|
||
mchunkptr next; /* next contiguous chunk */
|
||
INTERNAL_SIZE_T nextsz; /* its size */
|
||
INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */
|
||
mchunkptr bck; /* misc temp for linking */
|
||
mchunkptr fwd; /* misc temp for linking */
|
||
int islr; /* track whether merging with last_remainder */
|
||
|
||
if (mem == 0) /* free(0) has no effect */
|
||
return;
|
||
|
||
p = mem2chunk(mem);
|
||
hd = p->size;
|
||
|
||
#if HAVE_MMAP
|
||
if (hd & IS_MMAPPED) /* release mmapped memory. */
|
||
{
|
||
munmap_chunk(p);
|
||
return;
|
||
}
|
||
#endif
|
||
|
||
check_inuse_chunk(p);
|
||
|
||
sz = hd & ~PREV_INUSE;
|
||
next = chunk_at_offset(p, sz);
|
||
nextsz = chunksize(next);
|
||
|
||
if (next == top) /* merge with top */
|
||
{
|
||
sz += nextsz;
|
||
|
||
if (!(hd & PREV_INUSE)) /* consolidate backward */
|
||
{
|
||
prevsz = p->prev_size;
|
||
p = chunk_at_offset(p, -((long) prevsz));
|
||
sz += prevsz;
|
||
unlink(p, bck, fwd);
|
||
}
|
||
|
||
set_head(p, sz | PREV_INUSE);
|
||
top = p;
|
||
if ((unsigned long)(sz) >= (unsigned long)trim_threshold)
|
||
malloc_trim(top_pad);
|
||
return;
|
||
}
|
||
|
||
set_head(next, nextsz); /* clear inuse bit */
|
||
|
||
islr = 0;
|
||
|
||
if (!(hd & PREV_INUSE)) /* consolidate backward */
|
||
{
|
||
prevsz = p->prev_size;
|
||
p = chunk_at_offset(p, -((long) prevsz));
|
||
sz += prevsz;
|
||
|
||
if (p->fd == last_remainder) /* keep as last_remainder */
|
||
islr = 1;
|
||
else
|
||
unlink(p, bck, fwd);
|
||
}
|
||
|
||
if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */
|
||
{
|
||
sz += nextsz;
|
||
|
||
if (!islr && next->fd == last_remainder) /* re-insert last_remainder */
|
||
{
|
||
islr = 1;
|
||
link_last_remainder(p);
|
||
}
|
||
else
|
||
unlink(next, bck, fwd);
|
||
}
|
||
|
||
|
||
set_head(p, sz | PREV_INUSE);
|
||
set_foot(p, sz);
|
||
if (!islr)
|
||
frontlink(p, sz, idx, bck, fwd);
|
||
}
|
||
|
||
|
||
|
||
|
||
|
||
/*
|
||
|
||
Realloc algorithm:
|
||
|
||
Chunks that were obtained via mmap cannot be extended or shrunk
|
||
unless HAVE_MREMAP is defined, in which case mremap is used.
|
||
Otherwise, if their reallocation is for additional space, they are
|
||
copied. If for less, they are just left alone.
|
||
|
||
Otherwise, if the reallocation is for additional space, and the
|
||
chunk can be extended, it is, else a malloc-copy-free sequence is
|
||
taken. There are several different ways that a chunk could be
|
||
extended. All are tried:
|
||
|
||
* Extending forward into following adjacent free chunk.
|
||
* Shifting backwards, joining preceding adjacent space
|
||
* Both shifting backwards and extending forward.
|
||
* Extending into newly sbrked space
|
||
|
||
Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a
|
||
size argument of zero (re)allocates a minimum-sized chunk.
|
||
|
||
If the reallocation is for less space, and the new request is for
|
||
a `small' (<512 bytes) size, then the newly unused space is lopped
|
||
off and freed.
|
||
|
||
The old unix realloc convention of allowing the last-free'd chunk
|
||
to be used as an argument to realloc is no longer supported.
|
||
I don't know of any programs still relying on this feature,
|
||
and allowing it would also allow too many other incorrect
|
||
usages of realloc to be sensible.
|
||
|
||
|
||
*/
|
||
|
||
|
||
#if __STD_C
|
||
Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
|
||
#else
|
||
Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
|
||
#endif
|
||
{
|
||
INTERNAL_SIZE_T nb; /* padded request size */
|
||
|
||
mchunkptr oldp; /* chunk corresponding to oldmem */
|
||
INTERNAL_SIZE_T oldsize; /* its size */
|
||
|
||
mchunkptr newp; /* chunk to return */
|
||
INTERNAL_SIZE_T newsize; /* its size */
|
||
Void_t* newmem; /* corresponding user mem */
|
||
|
||
mchunkptr next; /* next contiguous chunk after oldp */
|
||
INTERNAL_SIZE_T nextsize; /* its size */
|
||
|
||
mchunkptr prev; /* previous contiguous chunk before oldp */
|
||
INTERNAL_SIZE_T prevsize; /* its size */
|
||
|
||
mchunkptr remainder; /* holds split off extra space from newp */
|
||
INTERNAL_SIZE_T remainder_size; /* its size */
|
||
|
||
mchunkptr bck; /* misc temp for linking */
|
||
mchunkptr fwd; /* misc temp for linking */
|
||
|
||
#ifdef REALLOC_ZERO_BYTES_FREES
|
||
if (bytes == 0) { fREe(oldmem); return 0; }
|
||
#endif
|
||
|
||
if ((long)bytes < 0) return 0;
|
||
|
||
/* realloc of null is supposed to be same as malloc */
|
||
if (oldmem == 0) return mALLOc(bytes);
|
||
|
||
newp = oldp = mem2chunk(oldmem);
|
||
newsize = oldsize = chunksize(oldp);
|
||
|
||
|
||
nb = request2size(bytes);
|
||
|
||
#if HAVE_MMAP
|
||
if (chunk_is_mmapped(oldp))
|
||
{
|
||
#if HAVE_MREMAP
|
||
newp = mremap_chunk(oldp, nb);
|
||
if(newp) return chunk2mem(newp);
|
||
#endif
|
||
/* Note the extra SIZE_SZ overhead. */
|
||
if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */
|
||
/* Must alloc, copy, free. */
|
||
newmem = mALLOc(bytes);
|
||
if (newmem == 0) return 0; /* propagate failure */
|
||
MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
|
||
munmap_chunk(oldp);
|
||
return newmem;
|
||
}
|
||
#endif
|
||
|
||
check_inuse_chunk(oldp);
|
||
|
||
if ((long)(oldsize) < (long)(nb))
|
||
{
|
||
|
||
/* Try expanding forward */
|
||
|
||
next = chunk_at_offset(oldp, oldsize);
|
||
if (next == top || !inuse(next))
|
||
{
|
||
nextsize = chunksize(next);
|
||
|
||
/* Forward into top only if a remainder */
|
||
if (next == top)
|
||
{
|
||
if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE))
|
||
{
|
||
newsize += nextsize;
|
||
top = chunk_at_offset(oldp, nb);
|
||
set_head(top, (newsize - nb) | PREV_INUSE);
|
||
set_head_size(oldp, nb);
|
||
return chunk2mem(oldp);
|
||
}
|
||
}
|
||
|
||
/* Forward into next chunk */
|
||
else if (((long)(nextsize + newsize) >= (long)(nb)))
|
||
{
|
||
unlink(next, bck, fwd);
|
||
newsize += nextsize;
|
||
goto split;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
next = 0;
|
||
nextsize = 0;
|
||
}
|
||
|
||
/* Try shifting backwards. */
|
||
|
||
if (!prev_inuse(oldp))
|
||
{
|
||
prev = prev_chunk(oldp);
|
||
prevsize = chunksize(prev);
|
||
|
||
/* try forward + backward first to save a later consolidation */
|
||
|
||
if (next != 0)
|
||
{
|
||
/* into top */
|
||
if (next == top)
|
||
{
|
||
if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE))
|
||
{
|
||
unlink(prev, bck, fwd);
|
||
newp = prev;
|
||
newsize += prevsize + nextsize;
|
||
newmem = chunk2mem(newp);
|
||
MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
|
||
top = chunk_at_offset(newp, nb);
|
||
set_head(top, (newsize - nb) | PREV_INUSE);
|
||
set_head_size(newp, nb);
|
||
return newmem;
|
||
}
|
||
}
|
||
|
||
/* into next chunk */
|
||
else if (((long)(nextsize + prevsize + newsize) >= (long)(nb)))
|
||
{
|
||
unlink(next, bck, fwd);
|
||
unlink(prev, bck, fwd);
|
||
newp = prev;
|
||
newsize += nextsize + prevsize;
|
||
newmem = chunk2mem(newp);
|
||
MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
|
||
goto split;
|
||
}
|
||
}
|
||
|
||
/* backward only */
|
||
if (prev != 0 && (long)(prevsize + newsize) >= (long)nb)
|
||
{
|
||
unlink(prev, bck, fwd);
|
||
newp = prev;
|
||
newsize += prevsize;
|
||
newmem = chunk2mem(newp);
|
||
MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
|
||
goto split;
|
||
}
|
||
}
|
||
|
||
/* Must allocate */
|
||
|
||
newmem = mALLOc (bytes);
|
||
|
||
if (newmem == 0) /* propagate failure */
|
||
return 0;
|
||
|
||
/* Avoid copy if newp is next chunk after oldp. */
|
||
/* (This can only happen when new chunk is sbrk'ed.) */
|
||
|
||
if ( (newp = mem2chunk(newmem)) == next_chunk(oldp))
|
||
{
|
||
newsize += chunksize(newp);
|
||
newp = oldp;
|
||
goto split;
|
||
}
|
||
|
||
/* Otherwise copy, free, and exit */
|
||
MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
|
||
fREe(oldmem);
|
||
return newmem;
|
||
}
|
||
|
||
|
||
split: /* split off extra room in old or expanded chunk */
|
||
|
||
if (newsize - nb >= MINSIZE) /* split off remainder */
|
||
{
|
||
remainder = chunk_at_offset(newp, nb);
|
||
remainder_size = newsize - nb;
|
||
set_head_size(newp, nb);
|
||
set_head(remainder, remainder_size | PREV_INUSE);
|
||
set_inuse_bit_at_offset(remainder, remainder_size);
|
||
fREe(chunk2mem(remainder)); /* let free() deal with it */
|
||
}
|
||
else
|
||
{
|
||
set_head_size(newp, newsize);
|
||
set_inuse_bit_at_offset(newp, newsize);
|
||
}
|
||
|
||
check_inuse_chunk(newp);
|
||
return chunk2mem(newp);
|
||
}
|
||
|
||
|
||
|
||
|
||
/*
|
||
|
||
memalign algorithm:
|
||
|
||
memalign requests more than enough space from malloc, finds a spot
|
||
within that chunk that meets the alignment request, and then
|
||
possibly frees the leading and trailing space.
|
||
|
||
The alignment argument must be a power of two. This property is not
|
||
checked by memalign, so misuse may result in random runtime errors.
|
||
|
||
8-byte alignment is guaranteed by normal malloc calls, so don't
|
||
bother calling memalign with an argument of 8 or less.
|
||
|
||
Overreliance on memalign is a sure way to fragment space.
|
||
|
||
*/
|
||
|
||
|
||
#if __STD_C
|
||
Void_t* mEMALIGn(size_t alignment, size_t bytes)
|
||
#else
|
||
Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes;
|
||
#endif
|
||
{
|
||
INTERNAL_SIZE_T nb; /* padded request size */
|
||
char* m; /* memory returned by malloc call */
|
||
mchunkptr p; /* corresponding chunk */
|
||
char* brk; /* alignment point within p */
|
||
mchunkptr newp; /* chunk to return */
|
||
INTERNAL_SIZE_T newsize; /* its size */
|
||
INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */
|
||
mchunkptr remainder; /* spare room at end to split off */
|
||
long remainder_size; /* its size */
|
||
|
||
if ((long)bytes < 0) return 0;
|
||
|
||
/* If need less alignment than we give anyway, just relay to malloc */
|
||
|
||
if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);
|
||
|
||
/* Otherwise, ensure that it is at least a minimum chunk size */
|
||
|
||
if (alignment < MINSIZE) alignment = MINSIZE;
|
||
|
||
/* Call malloc with worst case padding to hit alignment. */
|
||
|
||
nb = request2size(bytes);
|
||
m = (char*)(mALLOc(nb + alignment + MINSIZE));
|
||
|
||
if (m == 0) return 0; /* propagate failure */
|
||
|
||
p = mem2chunk(m);
|
||
|
||
if ((((unsigned long)(m)) % alignment) == 0) /* aligned */
|
||
{
|
||
#if HAVE_MMAP
|
||
if(chunk_is_mmapped(p))
|
||
return chunk2mem(p); /* nothing more to do */
|
||
#endif
|
||
}
|
||
else /* misaligned */
|
||
{
|
||
/*
|
||
Find an aligned spot inside chunk.
|
||
Since we need to give back leading space in a chunk of at
|
||
least MINSIZE, if the first calculation places us at
|
||
a spot with less than MINSIZE leader, we can move to the
|
||
next aligned spot -- we've allocated enough total room so that
|
||
this is always possible.
|
||
*/
|
||
|
||
brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -((signed) alignment));
|
||
if ((long)(brk - (char*)(p)) < MINSIZE) brk = brk + alignment;
|
||
|
||
newp = (mchunkptr)brk;
|
||
leadsize = brk - (char*)(p);
|
||
newsize = chunksize(p) - leadsize;
|
||
|
||
#if HAVE_MMAP
|
||
if(chunk_is_mmapped(p))
|
||
{
|
||
newp->prev_size = p->prev_size + leadsize;
|
||
set_head(newp, newsize|IS_MMAPPED);
|
||
return chunk2mem(newp);
|
||
}
|
||
#endif
|
||
|
||
/* give back leader, use the rest */
|
||
|
||
set_head(newp, newsize | PREV_INUSE);
|
||
set_inuse_bit_at_offset(newp, newsize);
|
||
set_head_size(p, leadsize);
|
||
fREe(chunk2mem(p));
|
||
p = newp;
|
||
|
||
assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0);
|
||
}
|
||
|
||
/* Also give back spare room at the end */
|
||
|
||
remainder_size = chunksize(p) - nb;
|
||
|
||
if (remainder_size >= (long)MINSIZE)
|
||
{
|
||
remainder = chunk_at_offset(p, nb);
|
||
set_head(remainder, remainder_size | PREV_INUSE);
|
||
set_head_size(p, nb);
|
||
fREe(chunk2mem(remainder));
|
||
}
|
||
|
||
check_inuse_chunk(p);
|
||
return chunk2mem(p);
|
||
|
||
}
|
||
|
||
|
||
|
||
|
||
/*
|
||
valloc just invokes memalign with alignment argument equal
|
||
to the page size of the system (or as near to this as can
|
||
be figured out from all the includes/defines above.)
|
||
*/
|
||
|
||
#if __STD_C
|
||
Void_t* vALLOc(size_t bytes)
|
||
#else
|
||
Void_t* vALLOc(bytes) size_t bytes;
|
||
#endif
|
||
{
|
||
return mEMALIGn (malloc_getpagesize, bytes);
|
||
}
|
||
|
||
/*
|
||
pvalloc just invokes valloc for the nearest pagesize
|
||
that will accommodate request
|
||
*/
|
||
|
||
|
||
#if __STD_C
|
||
Void_t* pvALLOc(size_t bytes)
|
||
#else
|
||
Void_t* pvALLOc(bytes) size_t bytes;
|
||
#endif
|
||
{
|
||
size_t pagesize = malloc_getpagesize;
|
||
return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
|
||
}
|
||
|
||
/*
|
||
|
||
calloc calls malloc, then zeroes out the allocated chunk.
|
||
|
||
*/
|
||
|
||
#if __STD_C
|
||
Void_t* cALLOc(size_t n, size_t elem_size)
|
||
#else
|
||
Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
|
||
#endif
|
||
{
|
||
mchunkptr p;
|
||
INTERNAL_SIZE_T csz;
|
||
|
||
INTERNAL_SIZE_T sz = n * elem_size;
|
||
|
||
|
||
/* check if expand_top called, in which case don't need to clear */
|
||
#if MORECORE_CLEARS
|
||
mchunkptr oldtop = top;
|
||
INTERNAL_SIZE_T oldtopsize = chunksize(top);
|
||
#endif
|
||
Void_t* mem = mALLOc (sz);
|
||
|
||
if ((long)n < 0) return 0;
|
||
|
||
if (mem == 0)
|
||
return 0;
|
||
else
|
||
{
|
||
p = mem2chunk(mem);
|
||
|
||
/* Two optional cases in which clearing not necessary */
|
||
|
||
|
||
#if HAVE_MMAP
|
||
if (chunk_is_mmapped(p)) return mem;
|
||
#endif
|
||
|
||
csz = chunksize(p);
|
||
|
||
#if MORECORE_CLEARS
|
||
if (p == oldtop && csz > oldtopsize)
|
||
{
|
||
/* clear only the bytes from non-freshly-sbrked memory */
|
||
csz = oldtopsize;
|
||
}
|
||
#endif
|
||
|
||
MALLOC_ZERO(mem, csz - SIZE_SZ);
|
||
return mem;
|
||
}
|
||
}
|
||
|
||
/*
|
||
|
||
cfree just calls free. It is needed/defined on some systems
|
||
that pair it with calloc, presumably for odd historical reasons.
|
||
|
||
*/
|
||
|
||
#if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__)
|
||
#if __STD_C
|
||
void cfree(Void_t *mem)
|
||
#else
|
||
void cfree(mem) Void_t *mem;
|
||
#endif
|
||
{
|
||
fREe(mem);
|
||
}
|
||
#endif
|
||
|
||
|
||
|
||
/*
|
||
|
||
Malloc_trim gives memory back to the system (via negative
|
||
arguments to sbrk) if there is unused memory at the `high' end of
|
||
the malloc pool. You can call this after freeing large blocks of
|
||
memory to potentially reduce the system-level memory requirements
|
||
of a program. However, it cannot guarantee to reduce memory. Under
|
||
some allocation patterns, some large free blocks of memory will be
|
||
locked between two used chunks, so they cannot be given back to
|
||
the system.
|
||
|
||
The `pad' argument to malloc_trim represents the amount of free
|
||
trailing space to leave untrimmed. If this argument is zero,
|
||
only the minimum amount of memory to maintain internal data
|
||
structures will be left (one page or less). Non-zero arguments
|
||
can be supplied to maintain enough trailing space to service
|
||
future expected allocations without having to re-obtain memory
|
||
from the system.
|
||
|
||
Malloc_trim returns 1 if it actually released any memory, else 0.
|
||
|
||
*/
|
||
|
||
#if __STD_C
|
||
int malloc_trim(size_t pad)
|
||
#else
|
||
int malloc_trim(pad) size_t pad;
|
||
#endif
|
||
{
|
||
long top_size; /* Amount of top-most memory */
|
||
long extra; /* Amount to release */
|
||
char* current_brk; /* address returned by pre-check sbrk call */
|
||
char* new_brk; /* address returned by negative sbrk call */
|
||
|
||
unsigned long pagesz = malloc_getpagesize;
|
||
|
||
top_size = chunksize(top);
|
||
extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
|
||
|
||
if (extra < (long)pagesz) /* Not enough memory to release */
|
||
return 0;
|
||
|
||
else
|
||
{
|
||
/* Test to make sure no one else called sbrk */
|
||
current_brk = (char*)(MORECORE (0));
|
||
if (current_brk != (char*)(top) + top_size)
|
||
return 0; /* Apparently we don't own memory; must fail */
|
||
|
||
else
|
||
{
|
||
new_brk = (char*)(MORECORE (-extra));
|
||
|
||
if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */
|
||
{
|
||
/* Try to figure out what we have */
|
||
current_brk = (char*)(MORECORE (0));
|
||
top_size = current_brk - (char*)top;
|
||
if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */
|
||
{
|
||
sbrked_mem = current_brk - sbrk_base;
|
||
set_head(top, top_size | PREV_INUSE);
|
||
}
|
||
check_chunk(top);
|
||
return 0;
|
||
}
|
||
|
||
else
|
||
{
|
||
/* Success. Adjust top accordingly. */
|
||
set_head(top, (top_size - extra) | PREV_INUSE);
|
||
sbrked_mem -= extra;
|
||
check_chunk(top);
|
||
return 1;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
|
||
|
||
/*
|
||
malloc_usable_size:
|
||
|
||
This routine tells you how many bytes you can actually use in an
|
||
allocated chunk, which may be more than you requested (although
|
||
often not). You can use this many bytes without worrying about
|
||
overwriting other allocated objects. Not a particularly great
|
||
programming practice, but still sometimes useful.
|
||
|
||
*/
|
||
|
||
#if __STD_C
|
||
size_t malloc_usable_size(Void_t* mem)
|
||
#else
|
||
size_t malloc_usable_size(mem) Void_t* mem;
|
||
#endif
|
||
{
|
||
mchunkptr p;
|
||
if (mem == 0)
|
||
return 0;
|
||
else
|
||
{
|
||
p = mem2chunk(mem);
|
||
if(!chunk_is_mmapped(p))
|
||
{
|
||
if (!inuse(p)) return 0;
|
||
check_inuse_chunk(p);
|
||
return chunksize(p) - SIZE_SZ;
|
||
}
|
||
return chunksize(p) - 2*SIZE_SZ;
|
||
}
|
||
}
|
||
|
||
|
||
|
||
|
||
/* Utility to update current_mallinfo for malloc_stats and mallinfo() */
|
||
|
||
static void malloc_update_mallinfo()
|
||
{
|
||
int i;
|
||
mbinptr b;
|
||
mchunkptr p;
|
||
#if DEBUG
|
||
mchunkptr q;
|
||
#endif
|
||
|
||
INTERNAL_SIZE_T avail = chunksize(top);
|
||
int navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0;
|
||
|
||
for (i = 1; i < NAV; ++i)
|
||
{
|
||
b = bin_at(i);
|
||
for (p = last(b); p != b; p = p->bk)
|
||
{
|
||
#if DEBUG
|
||
check_free_chunk(p);
|
||
for (q = next_chunk(p);
|
||
q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE;
|
||
q = next_chunk(q))
|
||
check_inuse_chunk(q);
|
||
#endif
|
||
avail += chunksize(p);
|
||
navail++;
|
||
}
|
||
}
|
||
|
||
current_mallinfo.ordblks = navail;
|
||
current_mallinfo.uordblks = sbrked_mem - avail;
|
||
current_mallinfo.fordblks = avail;
|
||
current_mallinfo.hblks = n_mmaps;
|
||
current_mallinfo.hblkhd = mmapped_mem;
|
||
current_mallinfo.keepcost = chunksize(top);
|
||
|
||
}
|
||
|
||
|
||
|
||
/*
|
||
|
||
malloc_stats:
|
||
|
||
Prints on stderr the amount of space obtain from the system (both
|
||
via sbrk and mmap), the maximum amount (which may be more than
|
||
current if malloc_trim and/or munmap got called), the maximum
|
||
number of simultaneous mmap regions used, and the current number
|
||
of bytes allocated via malloc (or realloc, etc) but not yet
|
||
freed. (Note that this is the number of bytes allocated, not the
|
||
number requested. It will be larger than the number requested
|
||
because of alignment and bookkeeping overhead.)
|
||
|
||
*/
|
||
|
||
void malloc_stats()
|
||
{
|
||
malloc_update_mallinfo();
|
||
fprintf(stderr, "max system bytes = %10u\n",
|
||
(unsigned int)(max_total_mem));
|
||
fprintf(stderr, "system bytes = %10u\n",
|
||
(unsigned int)(sbrked_mem + mmapped_mem));
|
||
fprintf(stderr, "in use bytes = %10u\n",
|
||
(unsigned int)(current_mallinfo.uordblks + mmapped_mem));
|
||
#if HAVE_MMAP
|
||
fprintf(stderr, "max mmap regions = %10u\n",
|
||
(unsigned int)max_n_mmaps);
|
||
#endif
|
||
}
|
||
|
||
/*
|
||
mallinfo returns a copy of updated current mallinfo.
|
||
*/
|
||
|
||
struct mallinfo mALLINFo()
|
||
{
|
||
malloc_update_mallinfo();
|
||
return current_mallinfo;
|
||
}
|
||
|
||
|
||
|
||
|
||
/*
|
||
mallopt:
|
||
|
||
mallopt is the general SVID/XPG interface to tunable parameters.
|
||
The format is to provide a (parameter-number, parameter-value) pair.
|
||
mallopt then sets the corresponding parameter to the argument
|
||
value if it can (i.e., so long as the value is meaningful),
|
||
and returns 1 if successful else 0.
|
||
|
||
See descriptions of tunable parameters above.
|
||
|
||
*/
|
||
|
||
#if __STD_C
|
||
int mALLOPt(int param_number, int value)
|
||
#else
|
||
int mALLOPt(param_number, value) int param_number; int value;
|
||
#endif
|
||
{
|
||
switch(param_number)
|
||
{
|
||
case M_TRIM_THRESHOLD:
|
||
trim_threshold = value; return 1;
|
||
case M_TOP_PAD:
|
||
top_pad = value; return 1;
|
||
case M_MMAP_THRESHOLD:
|
||
mmap_threshold = value; return 1;
|
||
case M_MMAP_MAX:
|
||
#if HAVE_MMAP
|
||
n_mmaps_max = value; return 1;
|
||
#else
|
||
if (value != 0) return 0; else n_mmaps_max = value; return 1;
|
||
#endif
|
||
|
||
default:
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
/*
|
||
|
||
History:
|
||
|
||
V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee)
|
||
* return null for negative arguments
|
||
* Added Several WIN32 cleanups from Martin C. Fong <mcfong@yahoo.com>
|
||
* Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'
|
||
(e.g. WIN32 platforms)
|
||
* Cleanup up header file inclusion for WIN32 platforms
|
||
* Cleanup code to avoid Microsoft Visual C++ compiler complaints
|
||
* Add 'USE_DL_PREFIX' to quickly allow co-existence with existing
|
||
memory allocation routines
|
||
* Set 'malloc_getpagesize' for WIN32 platforms (needs more work)
|
||
* Use 'assert' rather than 'ASSERT' in WIN32 code to conform to
|
||
usage of 'assert' in non-WIN32 code
|
||
* Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to
|
||
avoid infinite loop
|
||
* Always call 'fREe()' rather than 'free()'
|
||
|
||
V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee)
|
||
* Fixed ordering problem with boundary-stamping
|
||
|
||
V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)
|
||
* Added pvalloc, as recommended by H.J. Liu
|
||
* Added 64bit pointer support mainly from Wolfram Gloger
|
||
* Added anonymously donated WIN32 sbrk emulation
|
||
* Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
|
||
* malloc_extend_top: fix mask error that caused wastage after
|
||
foreign sbrks
|
||
* Add linux mremap support code from HJ Liu
|
||
|
||
V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)
|
||
* Integrated most documentation with the code.
|
||
* Add support for mmap, with help from
|
||
Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
|
||
* Use last_remainder in more cases.
|
||
* Pack bins using idea from colin@nyx10.cs.du.edu
|
||
* Use ordered bins instead of best-fit threshhold
|
||
* Eliminate block-local decls to simplify tracing and debugging.
|
||
* Support another case of realloc via move into top
|
||
* Fix error occuring when initial sbrk_base not word-aligned.
|
||
* Rely on page size for units instead of SBRK_UNIT to
|
||
avoid surprises about sbrk alignment conventions.
|
||
* Add mallinfo, mallopt. Thanks to Raymond Nijssen
|
||
(raymond@es.ele.tue.nl) for the suggestion.
|
||
* Add `pad' argument to malloc_trim and top_pad mallopt parameter.
|
||
* More precautions for cases where other routines call sbrk,
|
||
courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
|
||
* Added macros etc., allowing use in linux libc from
|
||
H.J. Lu (hjl@gnu.ai.mit.edu)
|
||
* Inverted this history list
|
||
|
||
V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)
|
||
* Re-tuned and fixed to behave more nicely with V2.6.0 changes.
|
||
* Removed all preallocation code since under current scheme
|
||
the work required to undo bad preallocations exceeds
|
||
the work saved in good cases for most test programs.
|
||
* No longer use return list or unconsolidated bins since
|
||
no scheme using them consistently outperforms those that don't
|
||
given above changes.
|
||
* Use best fit for very large chunks to prevent some worst-cases.
|
||
* Added some support for debugging
|
||
|
||
V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)
|
||
* Removed footers when chunks are in use. Thanks to
|
||
Paul Wilson (wilson@cs.texas.edu) for the suggestion.
|
||
|
||
V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)
|
||
* Added malloc_trim, with help from Wolfram Gloger
|
||
(wmglo@Dent.MED.Uni-Muenchen.DE).
|
||
|
||
V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)
|
||
|
||
V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)
|
||
* realloc: try to expand in both directions
|
||
* malloc: swap order of clean-bin strategy;
|
||
* realloc: only conditionally expand backwards
|
||
* Try not to scavenge used bins
|
||
* Use bin counts as a guide to preallocation
|
||
* Occasionally bin return list chunks in first scan
|
||
* Add a few optimizations from colin@nyx10.cs.du.edu
|
||
|
||
V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)
|
||
* faster bin computation & slightly different binning
|
||
* merged all consolidations to one part of malloc proper
|
||
(eliminating old malloc_find_space & malloc_clean_bin)
|
||
* Scan 2 returns chunks (not just 1)
|
||
* Propagate failure in realloc if malloc returns 0
|
||
* Add stuff to allow compilation on non-ANSI compilers
|
||
from kpv@research.att.com
|
||
|
||
V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)
|
||
* removed potential for odd address access in prev_chunk
|
||
* removed dependency on getpagesize.h
|
||
* misc cosmetics and a bit more internal documentation
|
||
* anticosmetics: mangled names in macros to evade debugger strangeness
|
||
* tested on sparc, hp-700, dec-mips, rs6000
|
||
with gcc & native cc (hp, dec only) allowing
|
||
Detlefs & Zorn comparison study (in SIGPLAN Notices.)
|
||
|
||
Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)
|
||
* Based loosely on libg++-1.2X malloc. (It retains some of the overall
|
||
structure of old version, but most details differ.)
|
||
|
||
*/
|