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
  16 #ifdef __UCLIBC_MJN3_ONLY__
  17 /* Do the memstream stuff inline to avoid fclose and the openlist? */
  18 #warning CONSIDER: avoid open_memstream call?
  19 #endif
  20
  21 #ifndef __STDIO_HAS_VSNPRINTF
  22 #warning Skipping vasprintf since no vsnprintf!
  23 #else
  24
  25 int vasprintf(char **__restrict buf, const char * __restrict format,
  26                          va_list arg)
  27 {
  28 #ifdef __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__
  29
  30         FILE *f;
  31         size_t size;
  32         int rv = -1;
  33
  34         *buf = NULL;
  35
  36         if ((f = open_memstream(buf, &size)) != NULL) {
  37                 rv = vfprintf(f, format, arg);
  38                 fclose(f);
  39                 if (rv < 0) {
  40                         free(*buf);
  41                         *buf = NULL;
  42                 }
  43         }
  44
  45         assert(rv >= -1);
  46
  47         return rv;
  48
  49 #else  /* __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__ */
  50
  51         /* This implementation actually calls the printf machinery twice, but
  52          * only does one malloc.  This can be a problem though when custom printf
  53          * specs or the %m specifier are involved because the results of the
  54          * second call might be different from the first. */
  55         va_list arg2;
  56         int rv;
  57
  58         va_copy(arg2, arg);
  59         rv = vsnprintf(NULL, 0, format, arg2);
  60         va_end(arg2);
  61
  62         *buf = NULL;
  63
  64         if (rv >= 0) {
  65                 if ((*buf = malloc(++rv)) != NULL) {
  66                         if ((rv = vsnprintf(*buf, rv, format, arg)) < 0) {
  67                                 free(*buf);
  68                                 *buf = NULL;
  69                         }
  70                 }
  71         }
  72
  73         assert(rv >= -1);
  74
  75         return rv;
  76
  77 #endif /* __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__ */
  78 }
  79 libc_hidden_def(vasprintf)
  80
  81 #endif
  82 #endif