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

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Junio,

On Fri, 28 Aug 2020, Junio C Hamano wrote:

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

True. The test suite passes with this, though, which means we haven't
covered that case.

> 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(...);

Sure.

> 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?

Yes, it can deal with both. It calls `strip_extension()`, which on Windows
removes the `.exe` suffix, if found.

> 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.

Right, it does not _require_ the extension. I do not necessarily agree
that it is sloppy, but I do agree that it is convenient ;-)

Ciao,
Dscho

> >  		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
>