libc/stdio/vasprintf.c

   1 /* Copyright (C) 2004       Manuel Novoa III    <mjn3@codepoet.org>
   2  *
   3  * GNU Library General Public License (LGPL) version 2 or later.
   4  *
   5  * Dedicated to Toni.  See uClibc/DEDICATION.mjn3 for details.
   6  */
   7
   8 #include <features.h>
   9
  10 #ifdef __USE_GNU
  11 #include "_stdio.h"
  12 #include <stdarg.h>
  13 #include <bits/uClibc_va_copy.h>
  14
  15 #ifndef __STDIO_HAS_VSNPRINTF
  16 #warning Skipping vasprintf since no vsnprintf!
  17 #else
  18
  19 int vasprintf(char **__restrict buf, const char * __restrict format,
  20                          va_list arg)
  21 {
  22 #ifdef __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__
  23
  24         FILE *f;
  25         size_t size;
  26         int rv = -1;
  27
  28         *buf = NULL;
  29
  30         if ((f = open_memstream(buf, &size)) != NULL) {
  31                 rv = vfprintf(f, format, arg);
  32                 fclose(f);
  33                 if (rv < 0) {
  34                         free(*buf);
  35                         *buf = NULL;
  36                 } else {
  37                         *buf = realloc(*buf, rv + 1);
  38                 }
  39         }
  40
  41         assert(rv >= -1);
  42
  43         return rv;
  44
  45 #else  /* __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__ */
  46
  47         /* This implementation actually calls the printf machinery twice, but
  48          * only does one malloc.  This can be a problem though when custom printf
  49          * specs or the %m specifier are involved because the results of the
  50          * second call might be different from the first. */
  51         va_list arg2;
  52         int rv;
  53
  54         va_copy(arg2, arg);
  55         rv = vsnprintf(NULL, 0, format, arg2);
  56         va_end(arg2);
  57
  58         *buf = NULL;
  59
  60         if (rv >= 0) {
  61                 if ((*buf = malloc(++rv)) != NULL) {
  62                         if ((rv = vsnprintf(*buf, rv, format, arg)) < 0) {
  63                                 free(*buf);
  64                                 *buf = NULL;
  65                         }
  66                 }
  67         }
  68
  69         assert(rv >= -1);
  70
  71         return rv;
  72
  73 #endif /* __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__ */
  74 }
  75 libc_hidden_def(vasprintf)
  76
  77 #endif
  78 #endif