Support 'master@2 hours ago' syntax

[git.git] / refs.c

diff --git a/refs.c b/refs.c
index 4be75a5..4c99e37 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -429,3 +429,56 @@ int write_ref_sha1(struct ref_lock *lock,
        unlock_ref(lock);
        return 0;
 }
+
+int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
+{
+       const char *logfile, *logdata, *logend, *rec, *c;
+       char *tz_c;
+       int logfd, tz;
+       struct stat st;
+       unsigned long date;
+
+       logfile = git_path("logs/%s", ref);
+       logfd = open(logfile, O_RDONLY, 0);
+       if (logfd < 0)
+               die("Unable to read log %s: %s", logfile, strerror(errno));
+       fstat(logfd, &st);
+       if (!st.st_size)
+               die("Log %s is empty.", logfile);
+       logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
+       close(logfd);
+
+       rec = logend = logdata + st.st_size;
+       while (logdata < rec) {
+               if (logdata < rec && *(rec-1) == '\n')
+                       rec--;
+               while (logdata < rec && *(rec-1) != '\n')
+                       rec--;
+               c = rec;
+               while (c < logend && *c != '>' && *c != '\n')
+                       c++;
+               if (c == logend || *c == '\n')
+                       die("Log %s is corrupt.", logfile);
+               date = strtoul(c, NULL, 10);
+               if (date <= at_time) {
+                       if (get_sha1_hex(rec + 41, sha1))
+                               die("Log %s is corrupt.", logfile);
+                       munmap((void*)logdata, st.st_size);
+                       return 0;
+               }
+       }
+
+       c = logdata;
+       while (c < logend && *c != '>' && *c != '\n')
+               c++;
+       if (c == logend || *c == '\n')
+               die("Log %s is corrupt.", logfile);
+       date = strtoul(c, &tz_c, 10);
+       tz = strtoul(tz_c, NULL, 10);
+       if (get_sha1_hex(logdata, sha1))
+               die("Log %s is corrupt.", logfile);
+       munmap((void*)logdata, st.st_size);
+       fprintf(stderr, "warning: Log %s only goes back to %s.\n",
+               logfile, show_rfc2822_date(date, tz));
+       return 0;
+}