compat: add qsort_s()

The function qsort_s() was introduced with C11 Annex K; it provides the
ability to pass a context pointer to the comparison function, supports
the convention of using a NULL pointer for an empty array and performs a
few safety checks.

Add an implementation based on compat/qsort.c for platforms that lack a
native standards-compliant qsort_s() (i.e. basically everyone).  It
doesn't perform the full range of possible checks: It uses size_t
instead of rsize_t and doesn't check nmemb and size against RSIZE_MAX
because we probably don't have the restricted size type defined.  For
the same reason it returns int instead of errno_t.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index f53fcc9..8c549ce 100644
--- a/Makefile
+++ b/Makefile
@@ -279,6 +279,9 @@ all::
 # is a simplified version of the merge sort used in glibc. This is
 # recommended if Git triggers O(n^2) behavior in your platform's qsort().
 #
+# Define HAVE_ISO_QSORT_S if your platform provides a qsort_s() that's
+# compatible with the one described in C11 Annex K.
+#
 # Define UNRELIABLE_FSTAT if your system's fstat does not return the same
 # information on a not yet closed file that lstat would return for the same
 # file after it was closed.
@@ -1423,6 +1426,11 @@ ifdef INTERNAL_QSORT
 	COMPAT_CFLAGS += -DINTERNAL_QSORT
 	COMPAT_OBJS += compat/qsort.o
 endif
+ifdef HAVE_ISO_QSORT_S
+	COMPAT_CFLAGS += -DHAVE_ISO_QSORT_S
+else
+	COMPAT_OBJS += compat/qsort_s.o
+endif
 ifdef RUNTIME_PREFIX
 	COMPAT_CFLAGS += -DRUNTIME_PREFIX
 endif