have_varvs.c

/*
 * have_varvs - try <varargs.h> to see if it really works with vsnprintf()
 *
 * Copyright (C) 1999,2018,2021  Landon Curt Noll
 *
 * Calc is open software; you can redistribute it and/or modify it under
 * the terms of the version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * Calc 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 Lesser General
 * Public License for more details.
 *
 * A copy of version 2.1 of the GNU Lesser General Public License is
 * distributed with calc under the filename COPYING-LGPL.  You should have
 * received a copy with calc; if not, write to Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Under source code control:   1995/09/09 22:41:10
 * File existed as early as:    1995
 *
 * chongo <was here> /\oo/\     http://www.isthe.com/chongo/
 * Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/
 */

/*
 * Some systems have bugs in the <varargs.h> implementation that show up in
 * vsnprintf(), so we may have to try to use snprintf() as if it were
 * vsnprintf() and hope for the best.
 *
 * This program will output #defines and exits 0 if vsnprintf() (or snprintf())
 * produces the results that we expect.  This program exits 1 if vsnprintf()
 * (or snprintf()) produces unexpected results while using the <stdarg.h>
 * include file.
 */

#include <stdio.h>

#include "have_unistd.h"
#if defined(HAVE_UNISTD_H)
#include <unistd.h>
#endif

#include "have_string.h"
#ifdef HAVE_STRING_H
# include <string.h>
#endif

#undef VSNPRINTF_SIZE_T
#if defined(FORCE_STDC) || (defined(__STDC__) && __STDC__ != 0) || \
    defined(__cplusplus)
# define VSNPRINTF_SIZE_T size_t
#else
# define VSNPRINTF_SIZE_T long
#endif

#if !defined(STDARG) && !defined(SIMULATE_STDARG)
#include <varargs.h>
#endif


#include "banned.h"     /* include after system header <> includes */


char buf[BUFSIZ+1];

#if !defined(STDARG) && !defined(SIMULATE_STDARG)

void
try_nthis(char *fmt, VSNPRINTF_SIZE_T size, ...)
{
    va_list ap;

    va_start(ap);

#if !defined(DONT_HAVE_VSNPRINTF)
    vsnprintf(buf, size, fmt, ap);
#else
    snprintf(buf, size, fmt, ap);
#endif

    va_end(ap);
}

#else

void
try_nthis(char *a, VSNPRINTF_SIZE_T size, int b, char *c, int d)
{
    return;
}

#endif


int
main(void)
{
        /*
         * setup
         */
        buf[0] = '\0';

        /*
         * test variable args and vsnprintf/snprintf
         */
        try_nthis("@%d:%s:%d@", sizeof(buf)-1, 1, "hello", 5);
        if (strcmp(buf, "@1:hello:5@") != 0) {
#if !defined(DONT_HAVE_VSNPRINTF)
            /* <varargs.h> with vsnprintf() didn't work */
#else
            /* <varargs.h> with snprintf() simulating vsnprintf() didn't work */
#endif
            exit(1);
        }
        try_nthis("%s %d%s%d%d %s", sizeof(buf)-1,
            "Landon Noll 1st proved that", 2, "^", 23209, -1, "was prime");
        if (strcmp(buf,
                   "Landon Noll 1st proved that 2^23209-1 was prime") != 0) {
#if !defined(DONT_HAVE_VSNPRINTF)
            /* <varargs.h> with vsnprintf() didn't work */
#else
            /* <varargs.h> with snprintf() simulating vsnprintf() didn't work */
#endif
            exit(1);
        }

        /*
         * report the result
         */
        puts("/* what type of variable args do we have? */");
        puts("#define VARARGS /* use <varargs.h> */");
        puts("#include <varargs.h>");
        puts("\n/* should we use vsnprintf() and vsnprintf()? */");
#if !defined(DONT_HAVE_VSNPRINTF)
        puts("#define HAVE_VSNPRINTF /* yes */");
#else
        puts("/*");
        puts(" * Hack aleart!!!");
        puts(" *");
        puts(" * Systems that do not have vsnprintf() need something. In some");
        puts(" * cases the snprintf() function will deal correctly with the");
        puts(" * va_alist 4th arg.  Same goes for a lack of an vsnprintf()");
        puts(" * function.  In either case we use the #defines below and");
        puts(" * hope for the best!");
        puts(" */");
        puts("#define vsnprintf snprintf");
        puts("#undef HAVE_VSNPRINTF");
#endif
        /* exit(0); */
        return 0;
}