Andrew's git - gitweb.git/blob

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