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authorDaniel Barkalow <barkalow@iabervon.org>2005-06-06 20:31:29 (GMT)
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-07 00:09:45 (GMT)
commit95fc75129acf14d980bdd56b9b2ee74190f81d91 (patch)
treed3a6988ffe8b9ae0b554ddb4485ffb0f1cac0dc7 /refs.c
parent451322512f2f72fe07461a8aeae0df4cfce7fda1 (diff)
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[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>
Diffstat (limited to 'refs.c')
-rw-r--r--refs.c173
1 files changed, 173 insertions, 0 deletions
diff --git a/refs.c b/refs.c
new file mode 100644
index 0000000..9973d1f
--- /dev/null
+++ b/refs.c
@@ -0,0 +1,173 @@
+#include "refs.h"
+#include "cache.h"
+
+#include <errno.h>
+
+static char *ref_file_name(const char *ref)
+{
+ char *base = get_refs_directory();
+ int baselen = strlen(base);
+ int reflen = strlen(ref);
+ char *ret = xmalloc(baselen + 2 + reflen);
+ sprintf(ret, "%s/%s", base, ref);
+ return ret;
+}
+
+static char *ref_lock_file_name(const char *ref)
+{
+ char *base = get_refs_directory();
+ int baselen = strlen(base);
+ int reflen = strlen(ref);
+ char *ret = xmalloc(baselen + 7 + reflen);
+ sprintf(ret, "%s/%s.lock", base, ref);
+ return ret;
+}
+
+static int read_ref_file(const char *filename, unsigned char *sha1) {
+ int fd = open(filename, O_RDONLY);
+ char hex[41];
+ if (fd < 0) {
+ return error("Couldn't open %s\n", filename);
+ }
+ if ((read(fd, hex, 41) < 41) ||
+ (hex[40] != '\n') ||
+ get_sha1_hex(hex, sha1)) {
+ error("Couldn't read a hash from %s\n", filename);
+ close(fd);
+ return -1;
+ }
+ close(fd);
+ return 0;
+}
+
+int get_ref_sha1(const char *ref, unsigned char *sha1)
+{
+ char *filename;
+ int retval;
+ if (check_ref_format(ref))
+ return -1;
+ filename = ref_file_name(ref);
+ retval = read_ref_file(filename, sha1);
+ free(filename);
+ return retval;
+}
+
+static int lock_ref_file(const char *filename, const char *lock_filename,
+ const unsigned char *old_sha1)
+{
+ int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
+ unsigned char current_sha1[20];
+ int retval;
+ if (fd < 0) {
+ return error("Couldn't open lock file for %s: %s",
+ filename, strerror(errno));
+ }
+ retval = read_ref_file(filename, current_sha1);
+ if (old_sha1) {
+ if (retval) {
+ close(fd);
+ unlink(lock_filename);
+ return error("Could not read the current value of %s",
+ filename);
+ }
+ if (memcmp(current_sha1, old_sha1, 20)) {
+ close(fd);
+ unlink(lock_filename);
+ error("The current value of %s is %s",
+ filename, sha1_to_hex(current_sha1));
+ return error("Expected %s",
+ sha1_to_hex(old_sha1));
+ }
+ } else {
+ if (!retval) {
+ close(fd);
+ unlink(lock_filename);
+ return error("Unexpectedly found a value of %s for %s",
+ sha1_to_hex(current_sha1), filename);
+ }
+ }
+ return fd;
+}
+
+int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
+{
+ char *filename;
+ char *lock_filename;
+ int retval;
+ if (check_ref_format(ref))
+ return -1;
+ filename = ref_file_name(ref);
+ lock_filename = ref_lock_file_name(ref);
+ retval = lock_ref_file(filename, lock_filename, old_sha1);
+ free(filename);
+ free(lock_filename);
+ return retval;
+}
+
+static int write_ref_file(const char *filename,
+ const char *lock_filename, int fd,
+ const unsigned char *sha1)
+{
+ char *hex = sha1_to_hex(sha1);
+ char term = '\n';
+ if (write(fd, hex, 40) < 40 ||
+ write(fd, &term, 1) < 1) {
+ error("Couldn't write %s\n", filename);
+ close(fd);
+ return -1;
+ }
+ close(fd);
+ rename(lock_filename, filename);
+ return 0;
+}
+
+int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
+{
+ char *filename;
+ char *lock_filename;
+ int retval;
+ if (fd < 0)
+ return -1;
+ if (check_ref_format(ref))
+ return -1;
+ filename = ref_file_name(ref);
+ lock_filename = ref_lock_file_name(ref);
+ retval = write_ref_file(filename, lock_filename, fd, sha1);
+ free(filename);
+ free(lock_filename);
+ return retval;
+}
+
+int check_ref_format(const char *ref)
+{
+ char *middle;
+ if (ref[0] == '.' || ref[0] == '/')
+ return -1;
+ middle = strchr(ref, '/');
+ if (!middle || !middle[1])
+ return -1;
+ if (strchr(middle + 1, '/'))
+ return -1;
+ return 0;
+}
+
+int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
+{
+ char *filename;
+ char *lock_filename;
+ int fd;
+ int retval;
+ if (check_ref_format(ref))
+ return -1;
+ filename = ref_file_name(ref);
+ lock_filename = ref_lock_file_name(ref);
+ fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
+ if (fd < 0) {
+ error("Writing %s", lock_filename);
+ perror("Open");
+ }
+ retval = write_ref_file(filename, lock_filename, fd, sha1);
+ free(filename);
+ free(lock_filename);
+ return retval;
+}