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Autoconf Macro: ac_func_snprintf
</title>
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<hr>
<h1>
ac_func_snprintf
</h1>
<h2>
Synopsis
</h2>
<p class="indent" style="white-space:nowrap;">
<code>AC_FUNC_SNPRINTF</code>
</p>
<h2>
Description
</h2>
<div class="indent">
<p>
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, request
a replacement and warn the user about it. Note: the mentioned replacement
is freely available and may be used in any project regardless of it's
licence (just like the autoconf special exemption).
</p>
</div>
<h2>
Author
</h2>
<p class="indent">
Rüdiger Kuhlmann <info@ruediger-kuhlmann.de>
</p>
<h2>
Last Modified
</h2>
<p class="indent">
2002-09-26
</p>
<h2>
M4 Source Code
</h2>
<div class="indent">
<pre class="m4source">
AC_DEFUN([AC_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_LIBOBJ(snprintf)
AC_MSG_WARN([Replacing missing/broken (v)snprintf() with version from http://www.ijs.si/software/snprintf/.])
AC_DEFINE(PREFER_PORTABLE_SNPRINTF, 1, "enable replacement (v)snprintf if system (v)snprintf is broken")
fi])
</pre>
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