[Mesa-dev] [PATCH] mesa: Drop PATH_MAX usage.

[Kenneth Graunke]

On Tuesday, November 15, 2016 10:28:11 PM PST Roland Mainz wrote:
> On Tue, Nov 15, 2016 at 9:56 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> > On 15 November 2016 at 20:04, Kenneth Graunke <kenneth at whitecape.org> wrote:
> >> GNU/Hurd does not define PATH_MAX since it doesn't have such arbitrary
> >> limitation, so this failed to compile.  Apparently glibc does not
> >> enforce PATH_MAX restrictions anyway, so it's kind of a hoax:
> >>
> >> https://www.gnu.org/software/libc/manual/html_node/Limits-for-Files.html
> >>
> >> MSVC uses a different name (_MAX_PATH) as well, which is annoying.
> >>
> >> We don't really need it.  We can simply asprintf() the filenames.
> >> If the filename exceeds an OS path limit, presumably fopen() will
> >> fail, and we already check that.  (We actually use ralloc_asprintf
> >> because Mesa provides that everywhere, and it doesn't look like we've
> >> provided an implementation of GNU's asprintf() for all platforms.)
> >>
> >> Fixes the build on GNU/Hurd.
> >>
> >> Cc: "13.0" <mesa-stable at lists.freedesktop.org>
> >> Signed-off-by: Samuel Thibault <samuel.thibault at ens-lyon.org>
> >> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98632
> >> ---
> >>  src/mesa/main/arbprogram.c | 12 ++++--------
> >>  src/mesa/main/shaderapi.c  | 37 +++++++++++--------------------------
> >>  2 files changed, 15 insertions(+), 34 deletions(-)
> >>
> >> Samuel, does this fix the build for you?
> >>
> >> Emil, I didn't add the Fixes: tag because this was broken long before
> >> that patch - MESA_SHADER_DUMP_PATH/MESA_SHADER_READ_PATH have existed
> >> for a while now.
> >>
> > Ack, makes sense. I've only looked at the latest instance which
> > introduces/uses the define.
> >
> > The patch is spot on afaict
> > Reviewed-by: Emil Velikov <emil.velikov at collabora.com>
> 
> -- snip --
> +   char *name = construct_name(stage, source, read_path);
>     f = fopen(name, "r");
> +   ralloc_free(name);
>     if (!f)
>        return NULL;
> -- snip --
> 
> You don't need |errno|, right ? Most variants of |*free()| don't
> preserve the |errno| value...
> 
> ----
> 
> Bye,
> Roland

Good catch!  But no, we don't need errno...if the file fails to open,
we just bail, without caring why.
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