Re: [RFC/PATCH 4/4] replace: add --edit option

> This allows you to run:
>
>     git replace --edit SHA1
>
> to get dumped in an editor with the contents of the object
> for SHA1. The result is then read back in and used as a
> "replace" object for SHA1. The writing/reading is
> type-aware, so you get to edit "ls-tree" output rather than
> the binary tree format.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> diff --git a/builtin/replace.c b/builtin/replace.c
> index a090302..3ed5f75 100644
> --- a/builtin/replace.c
> +++ b/builtin/replace.c
> @@ -176,6 +177,105 @@ static int replace_object(const char *object_ref, const char *replace_ref, int f
>         return replace_object_sha1(object_ref, object, replace_ref, repl, force);
>  }
>
> +/*
> + * Read a previously-exported (and possibly edited) object back from "filename",
> + * interpreting it as "type", and writing the result to the object database.
> + * The sha1 of the written object is returned via sha1.
> + */
> +static void import_object(unsigned char *sha1, enum object_type type,
> +                         const char *filename)
> +{
> +       int fd;
> +
> +       fd = open(filename, O_RDONLY);
> +       if (fd < 0)
> +               die_errno("unable to open %s for reading", filename);
> +
> +       if (type == OBJ_TREE) {
> +               const char *argv[] = { "mktree", NULL };
> +               struct child_process cmd = { argv };
> +               struct strbuf result = STRBUF_INIT;
> +
> +               cmd.argv = argv;
> +               cmd.git_cmd = 1;
> +               cmd.in = fd;
> +               cmd.out = -1;
> +
> +               if (start_command(&cmd))
> +                       die("unable to spawn mktree");
> +
> +               if (strbuf_read(&result, cmd.out, 41) < 0)
> +                       die_errno("unable to read from mktree");
> +               close(cmd.out);
> +
> +               if (finish_command(&cmd))
> +                       die("mktree reported failure");
> +               if (get_sha1_hex(result.buf, sha1) < 0)
> +                       die("mktree did not return an object name");

> +       } else {
> +               struct stat st;
> +               int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
> +
> +               if (fstat(fd, &st) < 0)
> +                       die_errno("unable to fstat %s", filename);
> +               if (index_fd(sha1, fd, &st, type, NULL, flags) < 0)
> +                       die("unable to write object to database");
> +               /* index_fd close()s fd for us */
> +       }
> +
> +       /*
> +        * No need to close(fd) here; both run-command and index-fd
> +        * will have done it for us.
> +        */
> +}
> --
> 1.8.5.2.500.g8060133