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git/list-objects-filter-options.h
Ævar Arnfjörð Bjarmason 5cb28270a1 pack-objects: lazily set up "struct rev_info", don't leak
In the preceding [1] (pack-objects: move revs out of
get_object_list(), 2022-03-22) the "repo_init_revisions()" was moved
to cmd_pack_objects() so that it unconditionally took place for all
invocations of "git pack-objects".

We'd thus start leaking memory, which is easily reproduced in
e.g. git.git by feeding e83c516331 (Initial revision of "git", the
information manager from hell, 2005-04-07) to "git pack-objects";

    $ echo e83c516331 | ./git pack-objects initial
    [...]
	==19130==ERROR: LeakSanitizer: detected memory leaks

	Direct leak of 7120 byte(s) in 1 object(s) allocated from:
	    #0 0x455308 in __interceptor_malloc (/home/avar/g/git/git+0x455308)
	    #1 0x75b399 in do_xmalloc /home/avar/g/git/wrapper.c:41:8
	    #2 0x75b356 in xmalloc /home/avar/g/git/wrapper.c:62:9
	    #3 0x5d7609 in prep_parse_options /home/avar/g/git/diff.c:5647:2
	    #4 0x5d415a in repo_diff_setup /home/avar/g/git/diff.c:4621:2
	    #5 0x6dffbb in repo_init_revisions /home/avar/g/git/revision.c:1853:2
	    #6 0x4f599d in cmd_pack_objects /home/avar/g/git/builtin/pack-objects.c:3980:2
	    #7 0x4592ca in run_builtin /home/avar/g/git/git.c:465:11
	    #8 0x457d81 in handle_builtin /home/avar/g/git/git.c:718:3
	    #9 0x458ca5 in run_argv /home/avar/g/git/git.c:785:4
	    #10 0x457b40 in cmd_main /home/avar/g/git/git.c:916:19
	    #11 0x562259 in main /home/avar/g/git/common-main.c:56:11
	    #12 0x7fce792ac7ec in __libc_start_main csu/../csu/libc-start.c:332:16
	    #13 0x4300f9 in _start (/home/avar/g/git/git+0x4300f9)

	SUMMARY: LeakSanitizer: 7120 byte(s) leaked in 1 allocation(s).
	Aborted

Narrowly fixing that commit would have been easy, just add call
repo_init_revisions() right before get_object_list(), which is
effectively what was done before that commit.

But an unstated constraint when setting it up early is that it was
needed for the subsequent [2] (pack-objects: parse --filter directly
into revs.filter, 2022-03-22), i.e. we might have a --filter
command-line option, and need to either have the "struct rev_info"
setup when we encounter that option, or later.

Let's just change the control flow so that we'll instead set up the
"struct rev_info" only when we need it. Doing so leads to a bit more
verbosity, but it's a lot clearer what we're doing and why.

An earlier version of this commit[3] went behind
opt_parse_list_objects_filter()'s back by faking up a "struct option"
before calling it. Let's avoid that and instead create a blessed API
for this pattern.

We could furthermore combine the two get_object_list() invocations
here by having repo_init_revisions() invoked on &pfd.revs, but I think
clearly separating the two makes the flow clearer. Likewise
redundantly but explicitly (i.e. redundant v.s. a "{ 0 }") "0" to
"have_revs" early in cmd_pack_objects().

While we're at it add parentheses around the arguments to the OPT_*
macros in in list-objects-filter-options.h, as we need to change those
lines anyway. It doesn't matter in this case, but is good general
practice.

1. https://lore.kernel.org/git/619b757d98465dbc4995bdc11a5282fbfcbd3daa.1647970119.git.gitgitgadget@gmail.com
2. https://lore.kernel.org/git/97de926904988b89b5663bd4c59c011a1723a8f5.1647970119.git.gitgitgadget@gmail.com
3. https://lore.kernel.org/git/patch-1.1-193534b0f07-20220325T121715Z-avarab@gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-28 09:57:21 -07:00

175 lines
5.6 KiB
C

#ifndef LIST_OBJECTS_FILTER_OPTIONS_H
#define LIST_OBJECTS_FILTER_OPTIONS_H
#include "cache.h"
#include "parse-options.h"
#include "string-list.h"
/*
* The list of defined filters for list-objects.
*/
enum list_objects_filter_choice {
LOFC_DISABLED = 0,
LOFC_BLOB_NONE,
LOFC_BLOB_LIMIT,
LOFC_TREE_DEPTH,
LOFC_SPARSE_OID,
LOFC_OBJECT_TYPE,
LOFC_COMBINE,
LOFC__COUNT /* must be last */
};
/*
* Returns a configuration key suitable for describing the given object filter,
* e.g.: "blob:none", "combine", etc.
*/
const char *list_object_filter_config_name(enum list_objects_filter_choice c);
struct list_objects_filter_options {
/*
* 'filter_spec' is the raw argument value given on the command line
* or protocol request. (The part after the "--keyword=".) For
* commands that launch filtering sub-processes, or for communication
* over the network, don't use this value; use the result of
* expand_list_objects_filter_spec() instead.
* To get the raw filter spec given by the user, use the result of
* list_objects_filter_spec().
*/
struct string_list filter_spec;
/*
* 'choice' is determined by parsing the filter-spec. This indicates
* the filtering algorithm to use.
*/
enum list_objects_filter_choice choice;
/*
* Choice is LOFC_DISABLED because "--no-filter" was requested.
*/
unsigned int no_filter : 1;
/*
* BEGIN choice-specific parsed values from within the filter-spec. Only
* some values will be defined for any given choice.
*/
char *sparse_oid_name;
unsigned long blob_limit_value;
unsigned long tree_exclude_depth;
enum object_type object_type;
/* LOFC_COMBINE values */
/* This array contains all the subfilters which this filter combines. */
size_t sub_nr, sub_alloc;
struct list_objects_filter_options *sub;
/*
* END choice-specific parsed values.
*/
};
/*
* Parse value of the argument to the "filter" keyword.
* On the command line this looks like:
* --filter=<arg>
* and in the pack protocol as:
* "filter" SP <arg>
*
* The filter keyword will be used by many commands.
* See Documentation/rev-list-options.txt for allowed values for <arg>.
*
* Capture the given arg as the "filter_spec". This can be forwarded to
* subordinate commands when necessary (although it's better to pass it through
* expand_list_objects_filter_spec() first). We also "intern" the arg for the
* convenience of the current command.
*/
int gently_parse_list_objects_filter(
struct list_objects_filter_options *filter_options,
const char *arg,
struct strbuf *errbuf);
void list_objects_filter_die_if_populated(
struct list_objects_filter_options *filter_options);
/*
* Parses the filter spec string given by arg and either (1) simply places the
* result in filter_options if it is not yet populated or (2) combines it with
* the filter already in filter_options if it is already populated. In the case
* of (2), the filter specs are combined as if specified with 'combine:'.
*
* Dies and prints a user-facing message if an error occurs.
*/
void parse_list_objects_filter(
struct list_objects_filter_options *filter_options,
const char *arg);
/**
* The opt->value to opt_parse_list_objects_filter() is either a
* "struct list_objects_filter_option *" when using
* OPT_PARSE_LIST_OBJECTS_FILTER().
*
* Or, if using no "struct option" field is used by the callback,
* except the "defval" which is expected to be an "opt_lof_init"
* function, which is called with the "opt->value" and must return a
* pointer to the ""struct list_objects_filter_option *" to be used.
*
* The OPT_PARSE_LIST_OBJECTS_FILTER_INIT() can be used e.g. the
* "struct list_objects_filter_option" is embedded in a "struct
* rev_info", which the "defval" could be tasked with lazily
* initializing. See cmd_pack_objects() for an example.
*/
int opt_parse_list_objects_filter(const struct option *opt,
const char *arg, int unset);
typedef struct list_objects_filter_options *(*opt_lof_init)(void *);
#define OPT_PARSE_LIST_OBJECTS_FILTER_INIT(fo, init) \
{ OPTION_CALLBACK, 0, "filter", (fo), N_("args"), \
N_("object filtering"), 0, opt_parse_list_objects_filter, \
(intptr_t)(init) }
#define OPT_PARSE_LIST_OBJECTS_FILTER(fo) \
OPT_PARSE_LIST_OBJECTS_FILTER_INIT((fo), NULL)
/*
* Translates abbreviated numbers in the filter's filter_spec into their
* fully-expanded forms (e.g., "limit:blob=1k" becomes "limit:blob=1024").
* Returns a string owned by the list_objects_filter_options object.
*
* This form should be used instead of the raw list_objects_filter_spec()
* value when communicating with a remote process or subprocess.
*/
const char *expand_list_objects_filter_spec(
struct list_objects_filter_options *filter);
/*
* Returns the filter spec string more or less in the form as the user
* entered it. This form of the filter_spec can be used in user-facing
* messages. Returns a string owned by the list_objects_filter_options
* object.
*/
const char *list_objects_filter_spec(
struct list_objects_filter_options *filter);
void list_objects_filter_release(
struct list_objects_filter_options *filter_options);
static inline void list_objects_filter_set_no_filter(
struct list_objects_filter_options *filter_options)
{
list_objects_filter_release(filter_options);
filter_options->no_filter = 1;
}
void partial_clone_register(
const char *remote,
struct list_objects_filter_options *filter_options);
void partial_clone_get_default_filter_spec(
struct list_objects_filter_options *filter_options,
const char *remote);
void list_objects_filter_copy(
struct list_objects_filter_options *dest,
const struct list_objects_filter_options *src);
#endif /* LIST_OBJECTS_FILTER_OPTIONS_H */