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https://github.com/git/git.git
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b5af910727
This one is about a million times simpler, and much more likely to be correct too. Instead of trying to match up a tree object against the index, we just read in the tree object side-by-side into the index, and just walk the resulting index file. This was what all the read-tree cleanups were all getting to.
146 lines
4.6 KiB
C
146 lines
4.6 KiB
C
#ifndef CACHE_H
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#define CACHE_H
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#include <unistd.h>
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#include <stdio.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/mman.h>
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#include <sys/param.h>
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#include <netinet/in.h>
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#include SHA1_HEADER
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#include <zlib.h>
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/*
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* Basic data structures for the directory cache
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*
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* NOTE NOTE NOTE! This is all in the native CPU byte format. It's
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* not even trying to be portable. It's trying to be efficient. It's
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* just a cache, after all.
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*/
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#define CACHE_SIGNATURE 0x44495243 /* "DIRC" */
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struct cache_header {
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unsigned int hdr_signature;
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unsigned int hdr_version;
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unsigned int hdr_entries;
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};
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/*
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* The "cache_time" is just the low 32 bits of the
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* time. It doesn't matter if it overflows - we only
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* check it for equality in the 32 bits we save.
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*/
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struct cache_time {
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unsigned int sec;
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unsigned int nsec;
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};
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/*
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* dev/ino/uid/gid/size are also just tracked to the low 32 bits
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* Again - this is just a (very strong in practice) heuristic that
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* the inode hasn't changed.
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*
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* We save the fields in big-endian order to allow using the
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* index file over NFS transparently.
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*/
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struct cache_entry {
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struct cache_time ce_ctime;
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struct cache_time ce_mtime;
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unsigned int ce_dev;
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unsigned int ce_ino;
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unsigned int ce_mode;
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unsigned int ce_uid;
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unsigned int ce_gid;
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unsigned int ce_size;
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unsigned char sha1[20];
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unsigned short ce_flags;
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char name[0];
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};
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#define CE_NAMEMASK (0x0fff)
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#define CE_STAGEMASK (0x3000)
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#define CE_STAGESHIFT 12
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#define create_ce_flags(len, stage) htons((len) | ((stage) << CE_STAGESHIFT))
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#define ce_namelen(ce) (CE_NAMEMASK & ntohs((ce)->ce_flags))
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#define ce_size(ce) cache_entry_size(ce_namelen(ce))
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#define ce_stage(ce) ((CE_STAGEMASK & ntohs((ce)->ce_flags)) >> CE_STAGESHIFT)
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#define ce_permissions(mode) (((mode) & 0100) ? 0755 : 0644)
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#define create_ce_mode(mode) htonl(S_IFREG | ce_permissions(mode))
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#define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
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const char *sha1_file_directory;
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struct cache_entry **active_cache;
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unsigned int active_nr, active_alloc;
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#define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
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#define DEFAULT_DB_ENVIRONMENT ".git/objects"
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#define get_object_directory() (getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT)
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#define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
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#define DEFAULT_INDEX_ENVIRONMENT ".git/index"
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#define get_index_file() (getenv(INDEX_ENVIRONMENT) ? : DEFAULT_INDEX_ENVIRONMENT)
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#define alloc_nr(x) (((x)+16)*3/2)
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/* Initialize and use the cache information */
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extern int read_cache(void);
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extern int write_cache(int newfd, struct cache_entry **cache, int entries);
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extern int cache_name_pos(const char *name, int namelen);
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extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
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extern int remove_entry_at(int pos);
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extern int remove_file_from_cache(char *path);
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extern int same_name(struct cache_entry *a, struct cache_entry *b);
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extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
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#define MTIME_CHANGED 0x0001
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#define CTIME_CHANGED 0x0002
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#define OWNER_CHANGED 0x0004
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#define MODE_CHANGED 0x0008
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#define INODE_CHANGED 0x0010
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#define DATA_CHANGED 0x0020
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/* Return a statically allocated filename matching the sha1 signature */
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extern char *sha1_file_name(const unsigned char *sha1);
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/* Write a memory buffer out to the sha file */
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extern int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size);
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/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
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extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
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extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
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extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
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extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
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extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size, const char *type);
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/* Read a tree into the cache */
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extern int read_tree(void *buffer, unsigned long size, int stage);
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/* Convert to/from hex/sha1 representation */
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extern int get_sha1_hex(const char *hex, unsigned char *sha1);
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extern char *sha1_to_hex(const unsigned char *sha1); /* static buffer result! */
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/* General helper functions */
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extern void usage(const char *err);
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extern void die(const char *err, ...);
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extern int error(const char *err, ...);
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extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
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extern void *read_tree_with_tree_or_commit_sha1(const unsigned char *sha1,
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unsigned long *size,
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unsigned char *tree_sha1_ret);
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#endif /* CACHE_H */
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