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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
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<title>
Autoconf Macro: ac_func_vsnprintf
</title>
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M4 Source</a>
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<hr>
<h1>
ac_func_vsnprintf
</h1>
<h2>
Obsolete Macro
</h2>
<p class="indent">
Use AC_FUNC_SNPRINTF.
</p>
<h2>
Synopsis
</h2>
<p class="indent" style="white-space:nowrap;">
<code>AC_FUNC_VSNPRINTF</code>
</p>
<h2>
Description
</h2>
<div class="indent">
<p>
Check whether there is a reasonably sane vsnprintf() function installed.
"Reasonably sane" in this context means never clobbering memory beyond the
buffer supplied, and having a sensible return value. It is explicitly
allowed not to NUL-terminate the return value, however.
</p>
</div>
<h2>
Author
</h2>
<p class="indent">
Gaute Strokkenes <gs234@cam.ac.uk>
</p>
<h2>
Last Modified
</h2>
<p class="indent">
2005-01-25
</p>
<h2>
M4 Source Code
</h2>
<div class="indent">
<pre class="m4source">
AC_DEFUN([AC_FUNC_VSNPRINTF],
[AC_CACHE_CHECK(for working vsnprintf,
ac_cv_func_vsnprintf,
[AC_TRY_RUN(
[#include <stdio.h>
#include <stdarg.h>
int
doit(char * s, ...)
{
char buffer[32];
va_list args;
int r;
buffer[5] = 'X';
va_start(args, s);
r = vsnprintf(buffer, 5, s, args);
va_end(args);
/* -1 is pre-C99, 7 is C99. */
if (r != -1 && r != 7)
exit(1);
/* We deliberately do not care if the result is NUL-terminated or
not, since this is easy to work around like this. */
buffer[4] = 0;
/* Simple sanity check. */
if (strcmp(buffer, "1234"))
exit(1);
if (buffer[5] != 'X')
exit(1);
exit(0);
}
int
main(void)
{
doit("1234567");
exit(1);
}], ac_cv_func_vsnprintf=yes, ac_cv_func_vsnprintf=no, ac_cv_func_vsnprintf=no)])
dnl Note that the default is to be pessimistic in the case of cross compilation.
dnl If you know that the target has a sensible vsnprintf(), you can get around this
dnl by setting ac_func_vsnprintf to yes, as described in the Autoconf manual.
if test $ac_cv_func_vsnprintf = yes; then
AC_DEFINE(HAVE_WORKING_VSNPRINTF, 1,
[Define if you have a version of the `vsnprintf' function
that honours the size argument and has a proper return value.])
fi
])# AC_FUNC_VSNPRINTF
</pre>
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