newlib/libc/stdio/vasniprintf.c

   1 /* Copyright (C) 2007, 2008 Eric Blake
   2  * Permission to use, copy, modify, and distribute this software
   3  * is freely granted, provided that this notice is preserved.
   4  */
   5 /* This code was derived from asprintf.c */
   6 /* doc in viprintf.c */
   7
   8 #include <_ansi.h>
   9 #include <reent.h>
  10 #include <stdio.h>
  11 #include <stdarg.h>
  12 #include <limits.h>
  13 #include <errno.h>
  14 #include "local.h"
  15
  16 char *
  17 _vasniprintf_r (struct _reent *ptr,
  18        char *buf,
  19        size_t *lenp,
  20        const char *fmt,
  21        va_list ap)
  22 {
  23   int ret;
  24   FILE f;
  25   size_t len = *lenp;
  26
  27   if (buf && len)
  28     {
  29       /* mark an existing buffer, but allow allocation of larger string */
  30       f._flags = __SWR | __SSTR | __SOPT;
  31     }
  32   else
  33     {
  34       /* mark a zero-length reallocatable buffer */
  35       f._flags = __SWR | __SSTR | __SMBF;
  36       len = 0;
  37       buf = NULL;
  38     }
  39   f._flags2 = 0;
  40   f._bf._base = f._p = (unsigned char *) buf;
  41   /* For now, inherit the 32-bit signed limit of FILE._bf._size.
  42      FIXME - it would be nice to rewrite sys/reent.h to support size_t
  43      for _size.  */
  44   if (len > INT_MAX)
  45     {
  46       _REENT_ERRNO(ptr) = EOVERFLOW;
  47       return NULL;
  48     }
  49   f._bf._size = f._w = len;
  50   f._file = -1;  /* No file. */
  51   ret = _svfiprintf_r (ptr, &f, fmt, ap);
  52   if (ret < 0)
  53     return NULL;
  54   *lenp = ret;
  55   *f._p = '\0';
  56   return (char *) f._bf._base;
  57 }
  58
  59 #ifndef _REENT_ONLY
  60
  61 char *
  62 vasniprintf (char *buf,
  63        size_t *lenp,
  64        const char *fmt,
  65        va_list ap)
  66 {
  67   return _vasniprintf_r (_REENT, buf, lenp, fmt, ap);
  68 }
  69
  70 #endif /* ! _REENT_ONLY */