fetch.c: do not call process_tree() from process_tree().
[git/git.git] / update-ref.c
1 #include "cache.h"
2 #include "refs.h"
3
4 static const char git_update_ref_usage[] = "git-update-ref <refname> <value> [<oldval>]";
5
6 static int re_verify(const char *path, unsigned char *oldsha1, unsigned char *currsha1)
7 {
8 char buf[40];
9 int fd = open(path, O_RDONLY), nr;
10 if (fd < 0)
11 return -1;
12 nr = read(fd, buf, 40);
13 close(fd);
14 if (nr != 40 || get_sha1_hex(buf, currsha1) < 0)
15 return -1;
16 return memcmp(oldsha1, currsha1, 20) ? -1 : 0;
17 }
18
19 int main(int argc, char **argv)
20 {
21 char *hex;
22 const char *refname, *value, *oldval, *path;
23 char *lockpath;
24 unsigned char sha1[20], oldsha1[20], currsha1[20];
25 int fd, written;
26
27 setup_git_directory();
28 git_config(git_default_config);
29 if (argc < 3 || argc > 4)
30 usage(git_update_ref_usage);
31
32 refname = argv[1];
33 value = argv[2];
34 oldval = argv[3];
35 if (get_sha1(value, sha1))
36 die("%s: not a valid SHA1", value);
37 memset(oldsha1, 0, 20);
38 if (oldval && get_sha1(oldval, oldsha1))
39 die("%s: not a valid old SHA1", oldval);
40
41 path = resolve_ref(git_path("%s", refname), currsha1, !!oldval);
42 if (!path)
43 die("No such ref: %s", refname);
44
45 if (oldval) {
46 if (memcmp(currsha1, oldsha1, 20))
47 die("Ref %s is at %s but expected %s", refname, sha1_to_hex(currsha1), sha1_to_hex(oldsha1));
48 /* Nothing to do? */
49 if (!memcmp(oldsha1, sha1, 20))
50 exit(0);
51 }
52 path = strdup(path);
53 lockpath = mkpath("%s.lock", path);
54 if (safe_create_leading_directories(lockpath) < 0)
55 die("Unable to create all of %s", lockpath);
56
57 fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
58 if (fd < 0)
59 die("Unable to create %s", lockpath);
60 hex = sha1_to_hex(sha1);
61 hex[40] = '\n';
62 written = write(fd, hex, 41);
63 close(fd);
64 if (written != 41) {
65 unlink(lockpath);
66 die("Unable to write to %s", lockpath);
67 }
68
69 /*
70 * Re-read the ref after getting the lock to verify
71 */
72 if (oldval && re_verify(path, oldsha1, currsha1) < 0) {
73 unlink(lockpath);
74 die("Ref lock failed");
75 }
76
77 /*
78 * Finally, replace the old ref with the new one
79 */
80 if (rename(lockpath, path) < 0) {
81 unlink(lockpath);
82 die("Unable to create %s", path);
83 }
84 return 0;
85 }