Commit 6b39b063 authored by Eric Blake's avatar Eric Blake Committed by Peter Maydell
Browse files

build: Work around SIZE_MAX bug in OSX headers 

C99 requires SIZE_MAX to be declared with the same type as the
integral promotion of size_t, but OSX mistakenly defines it as
an 'unsigned long long' expression even though size_t is only
'unsigned long'.  Rather than futzing around with whether size_t
is 32- or 64-bits wide (which would be needed if we cared about
using SIZE_T in a #if expression), just hard-code it with a cast.
This is not a strict C99-compliant definition, because it doesn't
work in the preprocessor, but if we later need that, the build
will break on Mac to inform us to improve our replacement at that
time.

See also https://patchwork.ozlabs.org/patch/542327/

 for an
instance where the wrong type trips us up if we don't fix it
for good in osdep.h.

Some versions of glibc make a similar mistake with SSIZE_MAX; the
goal is that the approach of this patch could be copied to work
around that problem if it ever becomes important to us.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
Message-id: 1476200784-17210-1-git-send-email-eblake@redhat.com
Reviewed-by: default avatarJohn Arbuckle <programmingkidx@gmail.com>
Tested-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
parent 627eae7d

configure

+16 −0
Original line number Diff line number Diff line
@@ -1725,6 +1725,19 @@ if test "$cocoa" = "yes"; then 
    sdl=no

fi



# Some versions of Mac OS X incorrectly define SIZE_MAX

cat > $TMPC << EOF

#include <stdint.h>

#include <stdio.h>

int main(int argc, char *argv[]) {

    return printf("%zu", SIZE_MAX);

}

EOF

have_broken_size_max=no

if ! compile_object -Werror ; then

    have_broken_size_max=yes

fi



##########################################

# L2TPV3 probe
@@ -5245,6 +5258,9 @@ fi 
if test "$have_ifaddrs_h" = "yes" ; then

    echo "HAVE_IFADDRS_H=y" >> $config_host_mak

fi

if test "$have_broken_size_max" = "yes" ; then

    echo "HAVE_BROKEN_SIZE_MAX=y" >> $config_host_mak

fi



# Work around a system header bug with some kernel/XFS header

# versions where they both try to define 'struct fsxattr':

include/qemu/osdep.h

+8 −0
Original line number Diff line number Diff line
@@ -141,6 +141,14 @@ extern int daemon(int, int); 
# error Unknown pointer size

#endif



/* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with

 * the wrong type. Our replacement isn't usable in preprocessor

 * expressions, but it is sufficient for our needs. */

#if defined(HAVE_BROKEN_SIZE_MAX) && HAVE_BROKEN_SIZE_MAX

#undef SIZE_MAX

#define SIZE_MAX ((size_t)-1)

#endif



#ifndef MIN

#define MIN(a, b) (((a) < (b)) ? (a) : (b))

#endif