Ticket #3617: 3617-mc_open-handle-varargs-mode_t-promotion-issue.patch

File 3617-mc_open-handle-varargs-mode_t-promotion-issue.patch, 1.5 KB (added by mooffie, 8 years ago)

  • lib/vfs/interface.c 

    From 2ca899c30deed86ff546fdc8f26c973c67696740 Mon Sep 17 00:00:00 2001
From: Mooffie <mooffie@gmail.com>
Date: Wed, 16 Mar 2016 00:22:27 +0200
Subject: [PATCH] Ticket #3617: (mc_open): handle varargs mode_t promotion
 issue.

On systems where 'mode_t' is smaller than 'int', doing 'va_arg (ap, mode_t)' is
wrong because of C's "default argument promotions". GCC 4 creates crashing code
in this case.

We pick the solution described in the "va_arg" page of Gnulib's manual:

    https://www.gnu.org/software/gnulib/manual/html_node/va_005farg.html

A slightly different solution is to define a PROMOTED_MODE_T macro in the
configuration stage, as demonstrated here:

    https://lists.gnu.org/archive/html/bug-gnulib/2009-05/msg00231.html

(If any of the URLs above no longer works, simply search the web for the
mentioned words.)
---
 lib/vfs/interface.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/vfs/interface.c b/lib/vfs/interface.c
index 64acb96..f1a4171 100644
    a b mc_open (const vfs_path_t * vpath, int flags, ...) 
    200200    { 
    201201        va_list ap; 
    202202        va_start (ap, flags); 
    203         mode = va_arg (ap, mode_t); 
     203        /* Handle varargs mode_t promotion issue. See the "va_arg" page of Gnulib's manual. */ 
     204        if (sizeof (mode_t) < sizeof (int)) 
     205            mode = va_arg (ap, int); 
     206        else 
     207            mode = va_arg (ap, mode_t); 
    204208        va_end (ap); 
    205209    } 
    206210