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/* test-snprintf - Check whether snprintf allows doubly used strings.
Copyright (C) 2020-2025 Free Software Foundation, Inc.
This file is part of GNU Inetutils.
GNU Inetutils 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 3 of the License, or (at
your option) any later version.
GNU Inetutils 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.
You should have received a copy of the GNU General Public License
along with this program. If not, see `http://www.gnu.org/licenses/'. */
/* Written by Mats Erik Andersson. */
/*
* It is not in violation of POSIX, but implementations of snprintf()
* differ in their ability to handle a situation where the target string
* to be produced by snprintf() is at the same time providing data, which
* are to be passed through the format string, and to be part of the new
* resulting string. The different BSD unices, as well as OpenSolaris,
* are known to correctly handle this, whereas glibc is known to fail.
*
* This test issues a warning that non-portable behaviour is possible,
* should the program detect a discrepancy on this system. If the
* program detects the macro PACKAGE to have value "inetutils", then
* get attention with the exit value 77, to fit with our testing
* frame work.
*
* When the environment variable VERBOSE is defined, an encouraging
* message is issued also in the presence of an enhanced implementation
* of snprintf().
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MESSAGE "try a fool"
#define WRONG_MESSAGE "fool"
int
main (void)
{
int err = 0;
char msg[sizeof (MESSAGE)] = "try a ";
snprintf (msg, sizeof (msg), "%s%s", msg, WRONG_MESSAGE);
if (!strcmp (msg, WRONG_MESSAGE))
{
printf ("Warning! This implementation of snprintf() is not able\n"
"to handle string variables that appear as target and at the\n"
"same time as source. This might be a portability issue!\n");
#ifdef PACKAGE
if (!strcmp (PACKAGE, "inetutils"))
err = 77;
#endif
}
else if (getenv ("VERBOSE"))
{
printf ("The present implementation of snprintf() allows the same\n"
"string to act as target as well as source. Good news!\n");
}
/* Always return successfully, as we are only producing a reminder,
rather than a show stopper. */
return err;
}
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