Check if snprintf understands %zu.

If the platforms snprintf and friends don't understand %zu, use the
compat replacement.  Prevents segfaults on those platforms.

1 files changed, 23 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index c0e120fe9..9dacccb2d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2110,6 +2110,29 @@ if test "x$ac_cv_func_snprintf" = "xyes" ; then
         )
 fi
 
+if test "x$ac_cv_func_snprintf" = "xyes" ; then
+        AC_MSG_CHECKING([whether snprintf understands %zu])
+        AC_RUN_IFELSE(
+                [AC_LANG_PROGRAM([[
+#include <sys/types.h>
+#include <stdio.h>
+                ]],
+                [[
+        size_t a = 1, b = 2;
+        char z[128];
+        snprintf(z, sizeof z, "%zu%zu", a, b);
+        exit(strcmp(z, "12"));
+                ]])],
+                [AC_MSG_RESULT([yes])],
+                [
+                        AC_MSG_RESULT([no])
+                        AC_DEFINE([BROKEN_SNPRINTF], [1],
+                                [snprintf does not understand %zu])
+                ],
+                [ AC_MSG_WARN([cross compiling: Assuming working snprintf()]) ]
+        )
+fi
+
 # We depend on vsnprintf returning the right thing on overflow: the
 # number of characters it tried to create (as per SUSv3)
 if test "x$ac_cv_func_vsnprintf" = "xyes" ; then