port/print/asprintf.c

	asprintf.c revision d09832051bb4b41ce2b3202c09fceedc089678af
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2004 Darren Tucker.
 *
 * Based originally on asprintf.c from OpenBSD:
 * Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <lint.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>

#define INIT_SZ 128

/* VARARGS2 */
int
vasprintf(char **str, const char *format, va_list ap)
{
    char string[INIT_SZ];
    char *newstr;
    int ret;
    size_t len;

    *str = NULL;
    ret = vsnprintf(string, INIT_SZ, format, ap);
    if (ret < 0)    /* retain the value of errno from vsnprintf() */
        return (-1);
    if (ret < INIT_SZ) {
        len = ret + 1;
        if ((newstr = malloc(len)) == NULL)
            return (-1);    /* retain errno from malloc() */
        (void) strlcpy(newstr, string, len);
        *str = newstr;
        return (ret);
    }
    /*
     * We will perform this loop more than once only if some other
     * thread modifies one of the vasprintf() arguments after our
     * previous call to vsnprintf().
     */
    for (;;) {
        if (ret == INT_MAX) {   /* Bad length */
            errno = ENOMEM;
            return (-1);
        }
        len = ret + 1;
        if ((newstr = malloc(len)) == NULL)
            return (-1);    /* retain errno from malloc() */
        ret = vsnprintf(newstr, len, format, ap);
        if (ret < 0) {      /* retain errno from vsnprintf() */
            free(newstr);
            return (-1);
        }
        if (ret < len) {
            *str = newstr;
            return (ret);
        }
        free(newstr);
    }
}

int
asprintf(char **str, const char *format, ...)
{
    va_list ap;
    int ret;

    *str = NULL;
    va_start(ap, format);
    ret = vasprintf(str, format, ap);
    va_end(ap);

    return (ret);
}