source: vendor/synergy/current/lib/arch/vsnprintf.cpp

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2002 Chris Schoeneman
 * 
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file COPYING that should have accompanied this file.
 * 
 * This package 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.
 */

#if HAVE_VSNPRINTF

#if !defined(ARCH_VSNPRINTF)
#       define ARCH_VSNPRINTF vsnprintf
#endif

int
ARCH_STRING::vsnprintf(char* str, int size, const char* fmt, va_list ap)
{
        int n = ::ARCH_VSNPRINTF(str, size, fmt, ap);
        if (n > size) {
                n = -1;
        }
        return n;
}

#elif SYSAPI_UNIX // !HAVE_VSNPRINTF

#include <stdio.h>

int
ARCH_STRING::vsnprintf(char* str, int size, const char* fmt, va_list ap)
{
        static FILE* bitbucket = fopen("/dev/null", "w");
        if (bitbucket == NULL) {
                // uh oh
                if (size > 0) {
                        str[0] = '\0';
                }
                return 0;
        }
        else {
                // count the characters using the bitbucket
                int n = vfprintf(bitbucket, fmt, ap);
                if (n + 1 <= size) {
                        // it'll fit so print it into str
                        vsprintf(str, fmt, ap);
                }
                return n;
        }
}

#else // !HAVE_VSNPRINTF && !SYSAPI_UNIX

#error vsnprintf not implemented

#endif // !HAVE_VSNPRINTF