usr/src/lib/libc/port/print/asprintf.c

   1 /*
   2  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5
   6 /*
   7  * Copyright (c) 2004 Darren Tucker.
   8  *
   9  * Based originally on asprintf.c from OpenBSD:
  10  * Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
  11  *
  12  * Permission to use, copy, modify, and distribute this software for any
  13  * purpose with or without fee is hereby granted, provided that the above
  14  * copyright notice and this permission notice appear in all copies.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  17  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  18  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  19  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  20  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  21  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  22  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  23  */
  24
  25 #include <lint.h>
  26 #include <stdio.h>
  27 #include <stdarg.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <limits.h>
  31 #include <errno.h>
  32
  33 #define INIT_SZ 128
  34
  35 /* VARARGS2 */
  36 int
  37 vasprintf(char **str, const char *format, va_list ap)
  38 {
  39         char string[INIT_SZ];
  40         char *newstr;
  41         int ret;
  42         size_t len;
  43
  44         *str = NULL;
  45         ret = vsnprintf(string, INIT_SZ, format, ap);
  46         if (ret < 0)    /* retain the value of errno from vsnprintf() */
  47                 return (-1);
  48         if (ret < INIT_SZ) {
  49                 len = ret + 1;
  50                 if ((newstr = malloc(len)) == NULL)
  51                         return (-1);    /* retain errno from malloc() */
  52                 (void) memcpy(newstr, string, len);
  53                 *str = newstr;
  54                 return (ret);
  55         }
  56         /*
  57          * We will perform this loop more than once only if some other
  58          * thread modifies one of the vasprintf() arguments after our
  59          * previous call to vsnprintf().
  60          */
  61         for (;;) {
  62                 if (ret == INT_MAX) {   /* Bad length */
  63                         errno = ENOMEM;
  64                         return (-1);
  65                 }
  66                 len = ret + 1;
  67                 if ((newstr = malloc(len)) == NULL)
  68                         return (-1);    /* retain errno from malloc() */
  69                 ret = vsnprintf(newstr, len, format, ap);
  70                 if (ret < 0) {          /* retain errno from vsnprintf() */
  71                         free(newstr);
  72                         return (-1);
  73                 }
  74                 if (ret < len) {
  75                         *str = newstr;
  76                         return (ret);
  77                 }
  78                 free(newstr);
  79         }
  80 }
  81
  82 int
  83 asprintf(char **str, const char *format, ...)
  84 {
  85         va_list ap;
  86         int ret;
  87
  88         *str = NULL;
  89         va_start(ap, format);
  90         ret = vasprintf(str, format, ap);
  91         va_end(ap);
  92
  93         return (ret);
  94 }