libc/stdio/setvbuf.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 "_stdio.h"
   9
  10 #if (_IOFBF != 0) || (_IOLBF != 1) || (_IONBF != 2)
  11 #error Assumption violated -- values of _IOFBF, _IOLBF, _IONBF
  12 #endif
  13 #if (__FLAG_FBF != 0) || (__FLAG_NBF != (2*__FLAG_LBF))
  14 #error Assumption violated for buffering mode flags
  15 #endif
  16
  17 int setvbuf(register FILE * __restrict stream, register char * __restrict buf,
  18                         int mode, size_t size)
  19 {
  20 #ifdef __STDIO_BUFFERS
  21
  22         int retval = EOF;
  23         int alloc_flag = 0;
  24         __STDIO_AUTO_THREADLOCK_VAR;
  25
  26         __STDIO_AUTO_THREADLOCK(stream);
  27         __STDIO_STREAM_VALIDATE(stream);
  28
  29         if (((unsigned int) mode) > 2) {
  30                 __set_errno(EINVAL);
  31                 goto ERROR;
  32         }
  33
  34         /* C99 states that setvbuf may only be used between a successful
  35          * open of the stream and before any other operation other than
  36          * an unsuccessful call to setvbuf. */
  37
  38 #ifdef __STDIO_FLEXIBLE_SETVBUF
  39         /* If we aren't currently reading (including ungots) or writing,
  40          * then allow the request to proceed. */
  41
  42         if (stream->__modeflags & (__MASK_READING|__FLAG_WRITING)) {
  43                 goto ERROR;
  44         }
  45 #else
  46         /* The following test isn't quite as strict as C99, as it will
  47          * not detect file positioning operations. */
  48
  49         if (stream->__modeflags & (__MASK_READING|__FLAG_WRITING
  50                                                          |__FLAG_NARROW|__FLAG_WIDE
  51                                                          |__FLAG_ERROR|__FLAG_EOF)
  52                 ) {
  53                 goto ERROR;
  54         }
  55 #endif
  56
  57         stream->__modeflags &= ~(__MASK_BUFMODE);       /* Clear current mode */
  58         stream->__modeflags |= mode * __FLAG_LBF;       /*   and set new one. */
  59
  60         if ((mode == _IONBF) || !size) {
  61                 size = 0;
  62                 buf = NULL;
  63         } else if (!buf) {
  64                 if ((__STDIO_STREAM_BUFFER_SIZE(stream) == size) /* Same size or */
  65                         || !(buf = malloc(size)) /* malloc failed, so don't change. */
  66                         ) {
  67                         goto DONE;
  68                 }
  69                 alloc_flag = __FLAG_FREEBUF;
  70         }
  71
  72         if (stream->__modeflags & __FLAG_FREEBUF) {
  73                 stream->__modeflags &= ~(__FLAG_FREEBUF);
  74                 free(stream->__bufstart);
  75         }
  76
  77         stream->__modeflags |= alloc_flag;
  78         stream->__bufstart = (unsigned char *) buf;
  79         stream->__bufend = (unsigned char *) buf + size;
  80         __STDIO_STREAM_INIT_BUFREAD_BUFPOS(stream);
  81         __STDIO_STREAM_DISABLE_GETC(stream);
  82         __STDIO_STREAM_DISABLE_PUTC(stream);
  83
  84  DONE:
  85         retval = 0;
  86
  87  ERROR:
  88         __STDIO_STREAM_VALIDATE(stream);
  89         __STDIO_AUTO_THREADUNLOCK(stream);
  90
  91         return retval;
  92
  93 #else  /* __STDIO_BUFFERS  */
  94
  95         if (mode == _IONBF) {
  96                 return 0;
  97         }
  98
  99         if (((unsigned int) mode) > 2) {
 100                 __set_errno(EINVAL);
 101         }
 102
 103         return EOF;
 104
 105 #endif
 106 }
 107 libc_hidden_def(setvbuf)