File: ac_func_vsnprintf.html

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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
 <head>
  <title>
   Autoconf Macro: ac_func_vsnprintf
  </title>
  <link rel="stylesheet" type="text/css" href="autoconf-archive.css">
 </head>
 <body>
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  <hr>
  <h1>
   ac_func_vsnprintf
  </h1>
  <h2>
   Obsolete Macro
  </h2>
  <p class="indent">
   Use <a href="ac_func_snprintf.html">AC_FUNC_SNPRINTF</a>.
  </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 &lt;gs234@cam.ac.uk&gt;
  </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 &lt;stdio.h&gt;
#include &lt;stdarg.h&gt;

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 &amp;&amp; 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>
  </div>
  <h2>
   License
  </h2>
  <div class="indent">
   <span style="white-space:nowrap;">Copyright &copy; 2005 Gaute Strokkenes
   &lt;gs234@cam.ac.uk&gt;</span>
   <p>
    This program is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the Free
    Software Foundation; either version 2 of the License, or (at your option)
    any later version.
   </p>
   <p>
    This program is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
    more details.
   </p>
   <p>
    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc., 59
    Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   </p>
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