gfapi: warn when glfs_realpath() returned malloc'd memory

glfs_realpath() may return memory allocated with malloc(). Depending on
the memory allocator that the application uses, calling free() on the
returned string can cause segmentation faults or other problems.

Functions that allocate memory, need to match the free'ing of the same
memory allocator and memory accounting. glibc/malloc and jemalloc/free
do not match together (other allocators could probably trigger these
problems as well).

Applications need to provide a pre-allocated buffer, or in case
glfs_realpath() allocates the memory, glfs_free() should be used to free
it.

Cherry picked from commit 85e959052148ec481823d55c8b91cdee36da2b43:
> Change-Id: I5d721a7425674aa700db8a7a436cbedb95a5927f
> BUG: 1370931
> Signed-off-by: Niels de Vos <ndevos@redhat.com>
> Reviewed-on: http://review.gluster.org/15332
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

Change-Id: I5d721a7425674aa700db8a7a436cbedb95a5927f
BUG: 1383591
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/15621
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

0 files changed, 0 insertions, 0 deletions