Subject: Re: [PATCH] Provide a dirname() function when NO_LIBGEN_H=YesPlease

From: Ramsay Jones <[email-masked]>
Date: Wed, 30 Sep 2015 19:57:53 +0100

Hi Johannes,

On 30/09/15 15:50, Johannes Schindelin wrote:
> When there is no `libgen.h` to our disposal, we miss the `dirname()`
> function.
> 
> So far, we only had one user of that function: credential-cache--daemon
> (which was only compiled when Unix sockets are available, anyway). But
> now we also have `builtin/am.c` as user, so we need it.

Yes, many moons ago (on my old 32-bit laptop) when I was still 'working'
with MinGW I noticed this same thing while looking into providing a win32
emulation of unix sockets. So, I had to look into this at the same time.
Since this didn't progress, I didn't mention the libgen issue.

Anyway, I still have a 'test-libgen.c' file (attached) from back then that
contains some tests. I don't quite recall what the final state of this
code was, but it was intended to test _existing_ libgen implementations
as well as provide a 'git' version which would work on MinGW, cygwin and
linux. Note that some of the existing implementations didn't all agree on
what the tests should report! I don't remember if I looked at the POSIX
spec or not.

So, I don't know how useful it will be - if nothing else, there are some
tests! :-D

HTH

Ramsay Jones

> 
> Since `dirname()` is a sibling of `basename()`, we simply put our very
> own `gitdirname()` implementation next to `gitbasename()` and use it
> if `NO_LIBGEN_H` has been set.
> 
> Signed-off-by: Johannes Schindelin <[email-masked]>
> ---
> 
> 	I stumbled over the compile warning when upgrading Git for Windows
> 	to 2.6.0. There was a left-over NO_LIBGEN_H=YesPlease (which we
> 	no longer need in Git for Windows 2.x), but it did point to the
> 	fact that we use `dirname()` in builtin/am.c now, so we better
> 	have a fall-back implementation for platforms without libgen.h.
> 
> 	I tested this implementation a bit, but I still would appreciate
> 	a few eye-balls to go over it.
> 
>  compat/basename.c | 26 ++++++++++++++++++++++++++
>  git-compat-util.h |  2 ++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/compat/basename.c b/compat/basename.c
> index d8f8a3c..10dba38 100644
> --- a/compat/basename.c
> +++ b/compat/basename.c
> @@ -13,3 +13,29 @@ char *gitbasename (char *path)
>  	}
>  	return (char *)base;
>  }
> +
> +char *gitdirname(char *path)
> +{
> +	char *p = path, *slash, c;
> +
> +	/* Skip over the disk name in MSDOS pathnames. */
> +	if (has_dos_drive_prefix(p))
> +		p += 2;
> +	/* POSIX.1-2001 says dirname("/") should return "/" */
> +	slash = is_dir_sep(*p) ? ++p : NULL;
> +	while ((c = *(p++)))
> +		if (is_dir_sep(c)) {
> +			char *tentative = p - 1;
> +
> +			/* POSIX.1-2001 says to ignore trailing slashes */
> +			while (is_dir_sep(*p))
> +				p++;
> +			if (*p)
> +				slash = tentative;
> +		}
> +
> +	if (!slash)
> +		return ".";
> +	*slash = '\0';
> +	return path;
> +}
> diff --git a/git-compat-util.h b/git-compat-util.h
> index f649e81..8b01aa5 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -253,6 +253,8 @@ struct itimerval {
>  #else
>  #define basename gitbasename
>  extern char *gitbasename(char *);
> +#define dirname gitdirname
> +extern char *gitdirname(char *);
>  #endif
>  
>  #ifndef NO_ICONV
>