Re: [PATCH v1 3/3] git: catch an attempt to run "git-foo"

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 28, 2020, 22:03 UTC
Message-ID: <xmqq1rjqo2bp.fsf@gitster.c.googlers.com>
In-Reply-To: <nycvar.QRO.7.76.6.2008280412030.56@tvgsbejvaqbjf.bet>

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

> This is needed to handle the case where `argv[0]` contains the full path
> (which is the case on Windows) and the suffix `.exe` (which is also the
> case on Windows).

Oy.  Yeah, I totally forgot about ".exe" thing.

Show 17 quoted lines

> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>  git.c  | 3 ++-
>  help.c | 5 ++++-
>  2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/git.c b/git.c
> index 71ef4835b20e..863fd0c58a66 100644
> --- a/git.c
> +++ b/git.c
> @@ -851,7 +851,8 @@ int cmd_main(int argc, const char **argv)
>  	 * that one cannot handle it.
>  	 */
>  	if (skip_prefix(cmd, "git-", &cmd)) {
> -		warn_on_dashed_git(argv[0]);
> +		strip_extension(&cmd);
> +		warn_on_dashed_git(cmd);

The argv[0] may have been NULL from the beginning of cmd_main(), and cmd would be "git-help" in such a case. We used to pass NULL to warn_on_dashed_git() in such a case because "git-help" is not what the user typed, but what we internally trigger, so we didn't want warn_on_dashed_git() to do anything based on that internal string.

As there is no special casing of "help" in warn_on_dashed_git() mechanism, it probably would start triggering a warning/die when "git<ENTER>" is typed, no?

+	if (argv[0]) {
		strip_extension(&cmd);
		warn_on_dashed_git(cmd);

may be the minimum fix, but I would strongly prefer to keep the interface into warn_on_dashed_git() (eh, the most important is the interface into find_cmdname_help() helper function, which is designed to be reused by other parts of help.c) to take the full command name, not without "git-" prefix. This is primarily because the entirety of the help.c API is driven by full command names, without removing "git-" prefix, and it has to, because the help.c API needs to handle "gitk", from which you cannot remove any "git-" prefix.

Perhaps

	if (starts_with(cmd, "git-")) {
               	strip_extension(&cmd);
		if (argv[0])
			warn_on_dashed_git(cmd);
		argv[0] = cmd + 4;
                handle_builtin(argc, argv);
		die(...);

How does your handle_builtin() work, by the way?

The original code (even before we added warn_on_dashed_git() in this codepath) did not do any strip_extension(), so handle_builtin() can take commands with ".exe" suffix, but now we are feeding the result of strip_extension() to it, so it can deal with both?

Sounds convenient and sloppy (not the handle_builtin's implementation, but its callers that sometimes feeds the full executable name, and feeds only the basename some other times) at the same time.

Show 22 quoted lines

>  		argv[0] = cmd;
>  		handle_builtin(argc, argv);
> diff --git a/help.c b/help.c
> index c93a76944b00..27b1b26890be 100644
> --- a/help.c
> +++ b/help.c
> @@ -724,9 +724,12 @@ NORETURN void help_unknown_ref(const char *ref, const char *cmd,
>  static struct cmdname_help *find_cmdname_help(const char *name)
>  {
>  	int i;
> +	const char *p;
>
> +	skip_prefix(name, "git-", &name);
>  	for (i = 0; i < ARRAY_SIZE(command_list); i++) {
> -		if (!strcmp(command_list[i].name, name))
> +		if (skip_prefix(command_list[i].name, "git-", &p) &&
> +		    !strcmp(p, name))
>  			return &command_list[i];
>  	}
>  	return NULL;
> --
> 2.28.0.windows.1