Subject: Re: `git bundle create -` may not write to `stdout`

From: Junio C Hamano <[email-masked]>
Date: Fri, 03 Mar 2023 15:05:14 -0800

Jeff King <[email-masked]> writes:

> This test looks good to me. Let's also not forget about the doc fixes. I
> don't think there's much urgency to get this into v2.40,

Doc?  Meaning 

	<file> can be "-" to mean the standard output (for writing)
	or the standard input (for reading)

or something?

Given that the other three subcommands also take <file>

    'git bundle' create [-q | --quiet | --progress | --all-progress] ...
                        [--version=<version>] <file> <git-rev-list-args>
    'git bundle' verify [-q | --quiet] <file>
    'git bundle' list-heads <file> [<refname>...]
    'git bundle' unbundle [--progress] <file> [<refname>...]

but read_bundle_header() function all three calls begins like so:

    int read_bundle_header(const char *path, struct bundle_header *header)
    {
            int fd = open(path, O_RDONLY);

            if (fd < 0)
                    return error(_("could not open '%s'"), path);
            return read_bundle_header_fd(fd, header, path);
    }

this function needs to be fixed first ;-)

Of course none of these is urgent for the upcoming 2.40 ;-).

> but I can put
> it together in the next day or three.

Thanks.  Just for reference, here is what I have (just a log
message, the patch is the same and does not support input yet).

----- >8 -----
Subject: [PATCH] bundle: don't blindly apply prefix_filename() to "-"

A user can specify a filename to a command from the command line,
either as the value given to a command line option, or a command
line argument.  When it is given as a relative filename, in the
user's mind, it is relative to the directory "git" was started from,
but by the time the filename is used, "git" would almost always have
chdir()'ed up to the root level of the working tree.

The given filename, if it is relative, needs to be prefixed with the
path to the current directory, and it typically is done by calling
prefix_filename() helper function.  For commands that can also take
"-" to use the standard input or the standard output, however, this
needs to be done with care.

"git bundle create" uses the next word on the command line as the
output filename, and can take "-" to mean "write to the standard
output".  It blindly called prefix_filename(), so running it in a
subdirectory did not quite work as expected.

Introduce a new helper, prefix_filename_except_for_dash(), and use
it to help "git bundle create" codepath.

Reported-by: Michael Henry
Helped-by: Jeff King <[email-masked]>
Signed-off-by: Junio C Hamano <[email-masked]>
---
 abspath.c              |  7 +++++++
 builtin/bundle.c       |  2 +-
 cache.h                |  3 +++
 parse-options.c        |  4 ++++
 t/t6020-bundle-misc.sh | 11 +++++++++++
 5 files changed, 26 insertions(+), 1 deletion(-)