snprtf_s.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 101 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
*    Public License version 1.0 (the 'License'). You may not use this file
*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
*    ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
*    provided with the Original Code and Modifications, and is also
*    available at www.sybase.com/developer/opensource.
*
*    The Original Code and all software distributed under the License are
*    distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
*    EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
*    ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
*    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
*    NON-INFRINGEMENT. Please see the License for the specific language
*    governing rights and limitations under the License.
*
*  ========================================================================
*
* Description:  Implementation of snprintf_s() - safe string fmt'd output.
*
****************************************************************************/


#include "variety.h"
#include "saferlib.h"
#include "widechar.h"
#include <stdio.h>
#include <stdarg.h>
#include <wchar.h>
#include "printf.h"


struct buf_limit {
    CHAR_TYPE   *bufptr;
    rsize_t     chars_output;
    rsize_t     max_chars;
};

/*
 * buf_putc -- append a character to a string in memory
 */
static slib_callback_t buf_putc; // setup calling convention
static void __SLIB_CALLBACK buf_putc( SPECS __SLIB *specs, int op_char )
{
    struct buf_limit    *info;

    info = (struct buf_limit *)specs->_dest;
    if( specs->_output_count < info->max_chars ) {
        *( info->bufptr++ ) = op_char;
        info->chars_output++;
    }
    specs->_output_count++;
}


_WCRTLINK int __F_NAME(snprintf_s,snwprintf_s)( CHAR_TYPE * __restrict s, rsize_t n,
                                          const CHAR_TYPE * __restrict format, ... )
{
    va_list    arg;
    struct buf_limit    info;
    const char          *msg;

    /* First check the critical conditions; if any of those
     * is violated, return immediately and don't touch anything.
     */
    if( __check_constraint_nullptr_msg( msg, s )
     && __check_constraint_maxsize_msg( msg, n )
     && __check_constraint_zero_msg( msg, n ) ) {

        /* The buffer looks okay, try doing something useful */
        if( __check_constraint_nullptr_msg( msg, format ) ) {
            int                 len;

            info.bufptr       = s;
            info.chars_output = 0;
            info.max_chars    = n - 1;
            msg = NULL;
            va_start( arg, format );
            len = __F_NAME(__prtf_s,__wprtf_s)( &info, format, arg, &msg, buf_putc );
            va_end( arg );
            if( msg == NULL ) {
                /* No rt-constraint violation while formatting */
                s[info.chars_output] = NULLCHAR;
                return( len );
            }
        }
        /* Something went wrong, output buffer will contain empty string */
        *s = NULLCHAR;
    }
    __rtct_fail( __func__, msg, NULL );
    return( -1 );
}