Error in posix_spawn(3) man page

[Keith Thompson]

On Fri, Jan 7, 2022 at 4:01 PM Keith Thompson
<Keith.S.Thompson@gmail.com> wrote:
>
> On Fri, Jan 7, 2022 at 1:32 AM Corinna Vinschen <vinschen@redhat.com> wrote:
> >
> > Hi Keith,
> >
> > On Jan  5 13:39, Keith Thompson wrote:
> > > On Wed, Jan 5, 2022 at 3:47 AM Corinna Vinschen <vinschen@redhat.com> wrote:
> > > >
> > > > Hi Keith,
> > > >
> > > > On Dec 28 19:24, Keith Thompson wrote:
> > > > > The posix_spawn(3) man page has incorrect types for the argv and
> > > > > envp parameters for the posix_spawn and posix_spawnp functions.
> > > > >
> > > > > They're shown as
> > > > >     char *const argv, char *const envp
> > > > > when they should be
> > > > >     char *const argv[], char *const envp[]
> > > > >
> > > > > Suggested patch (though I'm not 100% sure how the square brackets
> > > > > are handled when generating the man page):
> > > >
> > > > Please send a git compatible patch in `git format-patch' format.
> > > >
> > > >
> > > > Thanks,
> > > > Corinna
> > >
> > > As requested. Given the way I copy-and-pasted the patch into my email,
> > > it might not have
> > > treated tabs correctly.
> >
> > It's not TABs, it's an incorrect patch format:
> >
> > $ git am 0001-Fix-documented-argv-and-envp-params-for-posix_spawn.patch
> > Applying: Fix documented argv and envp params for posix_spawn
> > error: libc/posix/posix_spawn.c: does not exist in index
> > Patch failed at 0001 Fix documented argv and envp params for posix_spawn
> > hint: Use 'git am --show-current-patch=diff' to see the failed patch
> > [...]
> >
> > Did you actually create the patch with `git format-patch'?
> >
> >
> > Thanks,
> > Corinna
>
> The problem was that I had diff.noprefix=true in my $HOME/.gitconfig.
> It caused `git format-patch` to omit the `a/` and `b/` prefixes, and `git am`
> doesn't appear to have any way to consume a patch with those prefixes missing.
>
> I've attached an updated patch that should apply cleanly.
>
> (I'd argue that this is a git bug, but of course this isn't the place
> to report it.)

I submitted a Git bug report. The response:
] The -p<num> flag controls how many segments `git am` or `git apply`
] removes. The default is -p1. `git am -p0` should apply the patch
] correctly.

The "-p<n>" option to "git am" is mentioned in the git-am(1) man page,
but explained only by reference to git-apply(1), so it's easy to miss
(I certainly did).

My original patch could have been applied with `git am -p0`. I hope
this is useful if you receive any future patches with the same issue.