[PATCH] Operations on refs
This patch adds code to read a hash out of a specified file under {GIT_DIR}/refs/, and to write such files atomically and optionally with an compare and lock. Signed-off-by: Daniel Barkalow <barkalow@iabervon.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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451322512f
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3
Makefile
3
Makefile
@ -40,7 +40,8 @@ install: $(PROG) $(SCRIPTS)
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$(INSTALL) $(PROG) $(SCRIPTS) $(dest)$(bin)
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LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o \
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tag.o delta.o date.o index.o diff-delta.o patch-delta.o entry.o epoch.o
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tag.o delta.o date.o index.o diff-delta.o patch-delta.o entry.o \
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epoch.o refs.o
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LIB_FILE=libgit.a
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LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h epoch.h
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1
cache.h
1
cache.h
@ -117,6 +117,7 @@ extern unsigned int active_nr, active_alloc, active_cache_changed;
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#define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
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extern char *get_object_directory(void);
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extern char *get_refs_directory(void);
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extern char *get_index_file(void);
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#define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
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173
refs.c
Normal file
173
refs.c
Normal file
@ -0,0 +1,173 @@
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#include "refs.h"
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#include "cache.h"
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#include <errno.h>
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static char *ref_file_name(const char *ref)
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{
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char *base = get_refs_directory();
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int baselen = strlen(base);
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int reflen = strlen(ref);
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char *ret = xmalloc(baselen + 2 + reflen);
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sprintf(ret, "%s/%s", base, ref);
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return ret;
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}
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static char *ref_lock_file_name(const char *ref)
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{
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char *base = get_refs_directory();
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int baselen = strlen(base);
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int reflen = strlen(ref);
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char *ret = xmalloc(baselen + 7 + reflen);
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sprintf(ret, "%s/%s.lock", base, ref);
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return ret;
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}
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static int read_ref_file(const char *filename, unsigned char *sha1) {
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int fd = open(filename, O_RDONLY);
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char hex[41];
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if (fd < 0) {
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return error("Couldn't open %s\n", filename);
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}
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if ((read(fd, hex, 41) < 41) ||
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(hex[40] != '\n') ||
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get_sha1_hex(hex, sha1)) {
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error("Couldn't read a hash from %s\n", filename);
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close(fd);
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return -1;
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}
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close(fd);
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return 0;
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}
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int get_ref_sha1(const char *ref, unsigned char *sha1)
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{
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char *filename;
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int retval;
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if (check_ref_format(ref))
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return -1;
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filename = ref_file_name(ref);
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retval = read_ref_file(filename, sha1);
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free(filename);
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return retval;
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}
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static int lock_ref_file(const char *filename, const char *lock_filename,
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const unsigned char *old_sha1)
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{
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int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
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unsigned char current_sha1[20];
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int retval;
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if (fd < 0) {
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return error("Couldn't open lock file for %s: %s",
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filename, strerror(errno));
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}
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retval = read_ref_file(filename, current_sha1);
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if (old_sha1) {
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if (retval) {
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close(fd);
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unlink(lock_filename);
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return error("Could not read the current value of %s",
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filename);
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}
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if (memcmp(current_sha1, old_sha1, 20)) {
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close(fd);
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unlink(lock_filename);
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error("The current value of %s is %s",
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filename, sha1_to_hex(current_sha1));
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return error("Expected %s",
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sha1_to_hex(old_sha1));
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}
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} else {
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if (!retval) {
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close(fd);
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unlink(lock_filename);
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return error("Unexpectedly found a value of %s for %s",
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sha1_to_hex(current_sha1), filename);
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}
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}
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return fd;
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}
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int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
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{
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char *filename;
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char *lock_filename;
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int retval;
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if (check_ref_format(ref))
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return -1;
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filename = ref_file_name(ref);
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lock_filename = ref_lock_file_name(ref);
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retval = lock_ref_file(filename, lock_filename, old_sha1);
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free(filename);
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free(lock_filename);
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return retval;
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}
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static int write_ref_file(const char *filename,
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const char *lock_filename, int fd,
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const unsigned char *sha1)
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{
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char *hex = sha1_to_hex(sha1);
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char term = '\n';
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if (write(fd, hex, 40) < 40 ||
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write(fd, &term, 1) < 1) {
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error("Couldn't write %s\n", filename);
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close(fd);
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return -1;
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}
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close(fd);
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rename(lock_filename, filename);
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return 0;
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}
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int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
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{
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char *filename;
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char *lock_filename;
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int retval;
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if (fd < 0)
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return -1;
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if (check_ref_format(ref))
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return -1;
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filename = ref_file_name(ref);
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lock_filename = ref_lock_file_name(ref);
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retval = write_ref_file(filename, lock_filename, fd, sha1);
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free(filename);
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free(lock_filename);
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return retval;
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}
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int check_ref_format(const char *ref)
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{
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char *middle;
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if (ref[0] == '.' || ref[0] == '/')
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return -1;
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middle = strchr(ref, '/');
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if (!middle || !middle[1])
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return -1;
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if (strchr(middle + 1, '/'))
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return -1;
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return 0;
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}
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int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
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{
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char *filename;
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char *lock_filename;
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int fd;
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int retval;
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if (check_ref_format(ref))
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return -1;
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filename = ref_file_name(ref);
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lock_filename = ref_lock_file_name(ref);
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fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
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if (fd < 0) {
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error("Writing %s", lock_filename);
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perror("Open");
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}
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retval = write_ref_file(filename, lock_filename, fd, sha1);
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free(filename);
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free(lock_filename);
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return retval;
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}
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21
refs.h
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21
refs.h
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@ -0,0 +1,21 @@
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#ifndef REFS_H
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#define REFS_H
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/** Reads the refs file specified into sha1 **/
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extern int get_ref_sha1(const char *ref, unsigned char *sha1);
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/** Locks ref and returns the fd to give to write_ref_sha1() if the ref
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* has the given value currently; otherwise, returns -1.
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**/
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extern int lock_ref_sha1(const char *ref, const unsigned char *old_sha1);
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/** Writes sha1 into the refs file specified, locked with the given fd. **/
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extern int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1);
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/** Writes sha1 into the refs file specified. **/
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extern int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1);
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/** Returns 0 if target has the right format for a ref. **/
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extern int check_ref_format(const char *target);
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#endif /* REFS_H */
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11
sha1_file.c
11
sha1_file.c
@ -58,7 +58,7 @@ static int get_sha1_file(const char *path, unsigned char *result)
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return get_sha1_hex(buffer, result);
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}
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static char *git_dir, *git_object_dir, *git_index_file;
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static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir;
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static void setup_git_env(void)
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{
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git_dir = gitenv(GIT_DIR_ENVIRONMENT);
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@ -69,6 +69,8 @@ static void setup_git_env(void)
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git_object_dir = xmalloc(strlen(git_dir) + 9);
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sprintf(git_object_dir, "%s/objects", git_dir);
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}
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git_refs_dir = xmalloc(strlen(git_dir) + 6);
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sprintf(git_refs_dir, "%s/refs", git_dir);
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git_index_file = gitenv(INDEX_ENVIRONMENT);
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if (!git_index_file) {
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git_index_file = xmalloc(strlen(git_dir) + 7);
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@ -83,6 +85,13 @@ char *get_object_directory(void)
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return git_object_dir;
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}
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char *get_refs_directory(void)
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{
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if (!git_refs_dir)
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setup_git_env();
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return git_refs_dir;
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}
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char *get_index_file(void)
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{
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if (!git_index_file)
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