port/print/snprintf.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include "lint.h"
#include <mtlib.h>
#include <stdarg.h>
#include <values.h>
#include <thread.h>
#include <synch.h>
#include <errno.h>
#include <sys/types.h>
#include "print.h"
#include "libc.h"

/*VARARGS2*/
int
snprintf(char *string, size_t n, const char *format, ...)
{
    ssize_t count;
    FILE siop;
    va_list ap;
    size_t  max = MAXINT;
    unsigned char tmpbuf[1]; /* dummy buffer for _doprnt() if NULL string */

    siop._cnt = n - 1;
    siop._base = siop._ptr = (unsigned char *)string;
    siop._flag = _IOREAD;   /* distinguish dummy file descriptor */
#ifdef _LP64
    /*
     * _bufend() (_realbufend()) should return NULL for v/snprintf,
     * so PUT() macro in _doprnt() will bounds check.  For 32-bit,
     * there is no _end field, and _realbufend() will return NULL
     * since it cannot find the dummy FILE structure in the linked
     * list of FILE strucutres.  See bug 4274368.
     */
    siop._end = NULL;
#endif  /* _LP64 */

    if (n == 0) {
        /*
         * When n==0, string may be NULL, so always use tmpbuf to
         * guard for this case.  No bytes should be transmitted to
         * the buffer when n==0, so using tmpbuf instead of string
         * (ie, if string is not NULL) should not matter.
         */
        siop._base = siop._ptr = tmpbuf;
        siop._cnt = 0;
    } else if (n > max) {
        errno = EOVERFLOW;
        return (EOF);
    }

    va_start(ap, format);
    count = _ndoprnt(format, ap, &siop, 0);
    va_end(ap);

    *siop._ptr = '\0';   /* plant terminating null character */

    if (count == EOF)
        return (EOF);

    /* overflow check */
    if ((size_t)count > max) {
        errno = EOVERFLOW;
        return (EOF);
    } else {
        return ((int)count);
    }
}

#ifndef _LP64

/*
 * 32-bit shadow function of snprintf().
 * When using the c89 compiler to build 32-bit applications, the size
 * of intmax_t is 32-bits, otherwise the size of intmax_t is 64-bits.
 * The shadow function uses 32-bit size of intmax_t for %j conversion.
 * The #pragma redefine_extname in <stdio.h> selects the proper routine
 * at compile time for the user application.
 * NOTE: this function is only available in the 32-bit library.
 */

int
_snprintf_c89(char *string, size_t n, const char *format, ...)
{
    ssize_t count;
    va_list ap;

    va_start(ap, format);
    count = _vsnprintf_c89(string, n, format, ap);
    va_end(ap);
    return ((int)count);
}

#endif  /* _LP64 */