Improve abstraction of ref lock/write.
Created 'struct ref_lock' to contain the data necessary to perform a ref update. This change improves writing a ref as the file names are generated only once (rather than twice) and supports following symrefs (up to the maximum depth). Further the ref_lock structure provides room to extend the update API with ref logging. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Shawn Pearce
Junio C Hamano
parent
70e1a880a3
commit
4bd18c43d9
32
fetch.c
32
fetch.c
@ -204,14 +204,14 @@ static int mark_complete(const char *path, const unsigned char *sha1)
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int pull(char *target)
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{
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struct ref_lock *lock;
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unsigned char sha1[20];
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int fd = -1;
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save_commit_buffer = 0;
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track_object_refs = 0;
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if (write_ref && current_ref) {
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fd = lock_ref_sha1(write_ref, current_ref);
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if (fd < 0)
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if (write_ref) {
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lock = lock_ref_sha1(write_ref, current_ref, 1);
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if (!lock)
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return -1;
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}
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@ -219,20 +219,22 @@ int pull(char *target)
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for_each_ref(mark_complete);
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}
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if (interpret_target(target, sha1))
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return error("Could not interpret %s as something to pull",
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target);
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if (process(lookup_unknown_object(sha1)))
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if (interpret_target(target, sha1)) {
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error("Could not interpret %s as something to pull", target);
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unlock_ref(lock);
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return -1;
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if (loop())
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}
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if (process(lookup_unknown_object(sha1))) {
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unlock_ref(lock);
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return -1;
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}
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if (loop()) {
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unlock_ref(lock);
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return -1;
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}
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if (write_ref) {
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if (current_ref) {
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write_ref_sha1(write_ref, fd, sha1);
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} else {
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write_ref_sha1_unlocked(write_ref, sha1);
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}
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return write_ref_sha1(lock, sha1, "git fetch");
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}
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return 0;
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}
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240
refs.c
240
refs.c
@ -198,26 +198,6 @@ int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
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return do_for_each_ref("refs/remotes", fn, 13);
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}
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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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int get_ref_sha1(const char *ref, unsigned char *sha1)
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{
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if (check_ref_format(ref))
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@ -225,94 +205,6 @@ int get_ref_sha1(const char *ref, unsigned char *sha1)
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return read_ref(git_path("refs/%s", ref), sha1);
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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(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", 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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if (safe_create_leading_directories(filename))
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die("unable to create leading directory for %s", filename);
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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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/*
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* Make sure "ref" is something reasonable to have under ".git/refs/";
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* We do not like it if:
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@ -365,25 +257,119 @@ int check_ref_format(const char *ref)
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}
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}
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int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
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static struct ref_lock* verify_lock(struct ref_lock *lock,
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const unsigned char *old_sha1, int mustexist)
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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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if (safe_create_leading_directories(filename))
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die("unable to create leading directory for %s", filename);
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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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char buf[40];
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int nr, fd = open(lock->ref_file, O_RDONLY);
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if (fd < 0 && (mustexist || errno != ENOENT)) {
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error("Can't verify ref %s", lock->ref_file);
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unlock_ref(lock);
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return NULL;
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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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nr = read(fd, buf, 40);
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close(fd);
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if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
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error("Can't verify ref %s", lock->ref_file);
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unlock_ref(lock);
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return NULL;
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}
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if (memcmp(lock->old_sha1, old_sha1, 20)) {
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error("Ref %s is at %s but expected %s", lock->ref_file,
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sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
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unlock_ref(lock);
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return NULL;
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}
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return lock;
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}
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static struct ref_lock* lock_ref_sha1_basic(const char *path,
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int plen,
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const unsigned char *old_sha1, int mustexist)
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{
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struct ref_lock *lock;
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lock = xcalloc(1, sizeof(struct ref_lock));
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lock->lock_fd = -1;
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plen = strlen(path) - plen;
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path = resolve_ref(path, lock->old_sha1, mustexist);
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if (!path) {
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error("Can't read ref %s", path);
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unlock_ref(lock);
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return NULL;
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}
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lock->ref_file = strdup(path);
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lock->lock_file = strdup(mkpath("%s.lock", lock->ref_file));
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if (safe_create_leading_directories(lock->lock_file))
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die("unable to create directory for %s", lock->lock_file);
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lock->lock_fd = open(lock->lock_file,
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O_WRONLY | O_CREAT | O_EXCL, 0666);
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if (lock->lock_fd < 0) {
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error("Couldn't open lock file %s: %s",
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lock->lock_file, strerror(errno));
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unlock_ref(lock);
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return NULL;
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}
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return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
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}
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struct ref_lock* lock_ref_sha1(const char *ref,
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const unsigned char *old_sha1, int mustexist)
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{
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if (check_ref_format(ref))
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return NULL;
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return lock_ref_sha1_basic(git_path("refs/%s", ref),
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strlen(ref), old_sha1, mustexist);
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}
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struct ref_lock* lock_any_ref_for_update(const char *ref,
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const unsigned char *old_sha1, int mustexist)
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{
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return lock_ref_sha1_basic(git_path("%s", ref),
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strlen(ref), old_sha1, mustexist);
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}
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void unlock_ref (struct ref_lock *lock)
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{
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if (lock->lock_fd >= 0) {
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close(lock->lock_fd);
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unlink(lock->lock_file);
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}
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if (lock->ref_file)
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free(lock->ref_file);
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if (lock->lock_file)
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free(lock->lock_file);
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free(lock);
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}
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int write_ref_sha1(struct ref_lock *lock,
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const unsigned char *sha1, const char *logmsg)
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{
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static char term = '\n';
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if (!lock)
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return -1;
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if (!memcmp(lock->old_sha1, sha1, 20)) {
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unlock_ref(lock);
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return 0;
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}
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if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
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write(lock->lock_fd, &term, 1) != 1
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|| close(lock->lock_fd) < 0) {
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error("Couldn't write %s", lock->lock_file);
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unlock_ref(lock);
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return -1;
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}
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if (rename(lock->lock_file, lock->ref_file) < 0) {
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error("Couldn't set %s", lock->ref_file);
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unlock_ref(lock);
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return -1;
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}
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lock->lock_fd = -1;
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unlock_ref(lock);
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return 0;
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}
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24
refs.h
24
refs.h
@ -1,6 +1,13 @@
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#ifndef REFS_H
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#define REFS_H
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struct ref_lock {
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char *ref_file;
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char *lock_file;
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unsigned char old_sha1[20];
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int lock_fd;
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};
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/*
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* Calls the specified function for each ref file until it returns nonzero,
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* and returns the value
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@ -14,16 +21,17 @@ extern int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *
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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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/** Locks a "refs/" ref returning the lock on success and NULL on failure. **/
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extern struct ref_lock* lock_ref_sha1(const char *ref, const unsigned char *old_sha1, int mustexist);
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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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/** Locks any ref (for 'HEAD' type refs). */
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extern struct ref_lock* lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int mustexist);
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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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/** Release any lock taken but not written. **/
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extern void unlock_ref (struct ref_lock *lock);
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/** Writes sha1 into the ref specified by the lock. **/
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extern int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1, const char *msg);
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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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