Add write_or_die(), a helper function
[git] / builtin-update-ref.c
1 #include "cache.h"
2 #include "refs.h"
3 #include "builtin.h"
4
5 static const char git_update_ref_usage[] =
6 "git-update-ref <refname> <value> [<oldval>] [-m <reason>]";
7
8 int cmd_update_ref(int argc, const char **argv, const char *prefix)
9 {
10         const char *refname=NULL, *value=NULL, *oldval=NULL, *msg=NULL;
11         struct ref_lock *lock;
12         unsigned char sha1[20], oldsha1[20];
13         int i;
14
15         setup_ident();
16         git_config(git_default_config);
17
18         for (i = 1; i < argc; i++) {
19                 if (!strcmp("-m", argv[i])) {
20                         if (i+1 >= argc)
21                                 usage(git_update_ref_usage);
22                         msg = argv[++i];
23                         if (!*msg)
24                                 die("Refusing to perform update with empty message.");
25                         if (strchr(msg, '\n'))
26                                 die("Refusing to perform update with \\n in message.");
27                         continue;
28                 }
29                 if (!refname) {
30                         refname = argv[i];
31                         continue;
32                 }
33                 if (!value) {
34                         value = argv[i];
35                         continue;
36                 }
37                 if (!oldval) {
38                         oldval = argv[i];
39                         continue;
40                 }
41         }
42         if (!refname || !value)
43                 usage(git_update_ref_usage);
44
45         if (get_sha1(value, sha1))
46                 die("%s: not a valid SHA1", value);
47         memset(oldsha1, 0, 20);
48         if (oldval && get_sha1(oldval, oldsha1))
49                 die("%s: not a valid old SHA1", oldval);
50
51         lock = lock_any_ref_for_update(refname, oldval ? oldsha1 : NULL, 0);
52         if (!lock)
53                 return 1;
54         if (write_ref_sha1(lock, sha1, msg) < 0)
55                 return 1;
56
57         /* write_ref_sha1 always unlocks the ref, no need to do it explicitly */
58         return 0;
59 }