configure: Check for broken snprintf().

We rely on a working snprintf implementation at several places, so abort early
of the system has no fully C99 compliant version.

diff --git a/configure.ac b/configure.ac
index 6e3ab366e4ad26ab2dd2bcb27d798e345ac81cc3..80eaf095372b8bcd1663254b380e5203085bf53c 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -156,6 +156,86 @@ fade_cmdline_objs="add_cmdline(fade)"
 fade_errlist_objs="fade exec string fd"
 
 
+########################################################################### snprintf
+# ===========================================================================
+#        http://www.nongnu.org/autoconf-archive/ax_func_snprintf.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_FUNC_SNPRINTF
+#
+# DESCRIPTION
+#
+#   Checks for a fully C99 compliant snprintf, in particular checks whether
+#   it does bounds checking and returns the correct string length; does the
+#   same check for vsnprintf. If no working snprintf or vsnprintf is found,
+#   it prints an error message and aborts.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Ruediger Kuhlmann <info@ruediger-kuhlmann.de>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.
+
+AU_ALIAS([AC_FUNC_SNPRINTF], [AX_FUNC_SNPRINTF])
+AC_DEFUN([AX_FUNC_SNPRINTF],
+[AC_CHECK_FUNCS(snprintf vsnprintf)
+AC_MSG_CHECKING(for working snprintf)
+AC_CACHE_VAL(ac_cv_have_working_snprintf,
+[AC_TRY_RUN(
+[#include <stdio.h>
+
+int main(void)
+{
+    char bufs[5] = { 'x', 'x', 'x', '\0', '\0' };
+    char bufd[5] = { 'x', 'x', 'x', '\0', '\0' };
+    int i;
+    i = snprintf (bufs, 2, "%s", "111");
+    if (strcmp (bufs, "1")) exit (1);
+    if (i != 3) exit (1);
+    i = snprintf (bufd, 2, "%d", 111);
+    if (strcmp (bufd, "1")) exit (1);
+    if (i != 3) exit (1);
+    exit(0);
+}], ac_cv_have_working_snprintf=yes, ac_cv_have_working_snprintf=no, ac_cv_have_working_snprintf=cross)])
+AC_MSG_RESULT([$ac_cv_have_working_snprintf])
+AC_MSG_CHECKING(for working vsnprintf)
+AC_CACHE_VAL(ac_cv_have_working_vsnprintf,
+[AC_TRY_RUN(
+[#include <stdio.h>
+#include <stdarg.h>
+
+int my_vsnprintf (char *buf, const char *tmpl, ...)
+{
+    int i;
+    va_list args;
+    va_start (args, tmpl);
+    i = vsnprintf (buf, 2, tmpl, args);
+    va_end (args);
+    return i;
+}
+
+int main(void)
+{
+    char bufs[5] = { 'x', 'x', 'x', '\0', '\0' };
+    char bufd[5] = { 'x', 'x', 'x', '\0', '\0' };
+    int i;
+    i = my_vsnprintf (bufs, "%s", "111");
+    if (strcmp (bufs, "1")) exit (1);
+    if (i != 3) exit (1);
+    i = my_vsnprintf (bufd, "%d", 111);
+    if (strcmp (bufd, "1")) exit (1);
+    if (i != 3) exit (1);
+    exit(0);
+}], ac_cv_have_working_vsnprintf=yes, ac_cv_have_working_vsnprintf=no, ac_cv_have_working_vsnprintf=cross)])
+AC_MSG_RESULT([$ac_cv_have_working_vsnprintf])
+if test x$ac_cv_have_working_snprintf$ac_cv_have_working_vsnprintf != "xyesyes"; then
+AC_MSG_ERROR([fatal: buggy snprintf() detected])
+fi])
+AX_FUNC_SNPRINTF()
 ########################################################################### osl
 have_osl=yes
 OLD_CPPFLAGS="$CPPFLAGS"