Re: Potential problem in git-add may corrupt the index file

Hi Junio,

Thanks for the fast reply! We've also discovered other similar programs in git, enclosed below so you may want to fix them in one patch.

Here is one example in refs.c:
1710:  lockpath = mkpath("%s.lock", git_HEAD);
        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
....
      written = write_in_full(fd, ref, len);
// We may add
// fsync_or_die(fd, ...);
// here
      if (close(fd) != 0 || written != len) {
              error("Unable to write to %s", lockpath);
              goto error_unlink_return;
      }
      if (rename(lockpath, git_HEAD) < 0) {
...

So there is a problem here, and the head file may be corrupted.

In server-info.c, there is a similar problem:
216:   namelen = sprintf(infofile, "%s/info/packs", get_object_directory());
         strcpy(name, infofile);
         strcpy(name + namelen, "+");

         init_pack_info(infofile, force);

         safe_create_leading_directories(name);
         fp = fopen(name, "w");
         if (!fp)
                 return error("cannot open %s", name);
         write_pack_info_file(fp);
// We may add
// fsync_or_die(fileno(fp), ...);
// here
         fclose(fp);
         adjust_shared_perm(name);
         rename(name, infofile);
Here, the packs file in the objects/info directory may be corrupted.

In the same file, the info/refs file may also be corrupted:
28:  char *path0 = git_pathdup("info/refs");
      int len = strlen(path0);
      char *path1 = xmalloc(len + 2);

      strcpy(path1, path0);
      strcpy(path1 + len, "+");

      safe_create_leading_directories(path0);
      info_ref_fp = fopen(path1, "w");
      if (!info_ref_fp)
              return error("unable to update %s", path1);
      for_each_ref(add_info_ref, NULL);
// We may add
// fsync_or_die(fileno(info_ref_fp), ...);
// here
      fclose(info_ref_fp);
      adjust_shared_perm(path1);
      rename(path1, path0);

On Mon, Apr 23, 2012 at 9:51 PM, Junio C Hamano <gitster@pobox.com> wrote: