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cache.h
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93 lines (76 loc) · 2.43 KB
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#ifndef CACHE_H
#define CACHE_H
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdarg.h>
#include <errno.h>
#include <sys/mman.h>
#include <openssl/sha.h>
#include <zlib.h>
/*
* Basic data structures for the directory cache
*
* NOTE NOTE NOTE! This is all in the native CPU byte format. It's
* not even trying to be portable. It's trying to be efficient. It's
* just a cache, after all.
*/
#define CACHE_SIGNATURE 0x44495243 /* "DIRC" */
struct cache_header {
unsigned int signature;
unsigned int version;
unsigned int entries;
unsigned char sha1[20];
};
/*
* The "cache_time" is just the low 32 bits of the
* time. It doesn't matter if it overflows - we only
* check it for equality in the 32 bits we save.
*/
struct cache_time {
unsigned int sec;
unsigned int nsec;
};
/*
* dev/ino/uid/gid/size are also just tracked to the low 32 bits
* Again - this is just a (very strong in practice) heuristic that
* the inode hasn't changed.
*/
struct cache_entry {
struct cache_time ctime;
struct cache_time mtime;
unsigned int st_dev;
unsigned int st_ino;
unsigned int st_mode;
unsigned int st_uid;
unsigned int st_gid;
unsigned int st_size;
unsigned char sha1[20];
unsigned short namelen;
unsigned char name[0];
};
const char *sha1_file_directory;
struct cache_entry **active_cache;
unsigned int active_nr, active_alloc;
#define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
#define DEFAULT_DB_ENVIRONMENT ".dircache/objects"
#define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
#define ce_size(ce) cache_entry_size((ce)->namelen)
#define alloc_nr(x) (((x)+16)*3/2)
/* Initialize the cache information */
extern int read_cache(void);
/* Return a statically allocated filename matching the sha1 signature */
extern char *sha1_file_name(unsigned char *sha1);
/* Write a memory buffer out to the sha file */
extern int write_sha1_buffer(unsigned char *sha1, void *buf, unsigned int size);
/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
extern void * read_sha1_file(unsigned char *sha1, char *type, unsigned long *size);
extern int write_sha1_file(char *buf, unsigned len);
/* Convert to/from hex/sha1 representation */
extern int get_sha1_hex(char *hex, unsigned char *sha1);
extern char *sha1_to_hex(unsigned char *sha1); /* static buffer! */
/* General helper functions */
extern void usage(const char *err);
#endif /* CACHE_H */