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![Daniel Barkalow](/assets/img/avatar_default.png)
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>
174 lines
3.9 KiB
C
174 lines
3.9 KiB
C
#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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