Re: [PATCH 1/1] merge-file: add an option to process object IDs

[Eric Sunshine <sunshine@sunshineco.com>]

On Tue, Oct 24, 2023 at 3:58 PM brian m. carlson
<sandals@crustytoothpaste.net> wrote:
> git merge-file knows how to merge files on the file system already.  It
> would be helpful, however, to allow it to also merge single blobs.
> Teach it an `--object-id` option which means that its arguments are
> object IDs and not files to allow it to do so.
>
> Since we obviously won't be writing the data to the first argument,
> either write to the object store and print the object ID, or honor the
> -p argument and print it to standard out.
>
> We handle the empty blob specially since read_mmblob doesn't read it
> directly, instead throwing an error, and otherwise users cannot specify
> an empty ancestor.
>
> Signed-off-by: brian m. carlson <bk2204@github.com>
> ---
> diff --git a/builtin/merge-file.c b/builtin/merge-file.c
> @@ -99,20 +116,29 @@ int cmd_merge_file(int argc, const char **argv, const char *prefix)
>         if (ret >= 0) {
> -               const char *filename = argv[0];
> -               char *fpath = prefix_filename(prefix, argv[0]);
> -               FILE *f = to_stdout ? stdout : fopen(fpath, "wb");
> +               if (object_id && !to_stdout) {
> +                       struct object_id oid;
> +                       if (result.size)
> +                               write_object_file(result.ptr, result.size, OBJ_BLOB, &oid);

Should this be caring about errors by checking the return value of
write_object_file()?

> +               } else {
> +                       const char *filename = argv[0];
> +                       char *fpath = prefix_filename(prefix, argv[0]);
> +                       FILE *f = to_stdout ? stdout : fopen(fpath, "wb");
> +                       if (!f)
> +                               ret = error_errno("Could not open %s for writing",
> +                                                 filename);
> +                       else if (result.size &&
> +                                fwrite(result.ptr, result.size, 1, f) != 1)
> +                               ret = error_errno("Could not write to %s", filename);
> +                       else if (fclose(f))
> +                               ret = error_errno("Could not close %s", filename);
> +                       free(fpath);

 The non-"object-id" case cares about errors.