StdLib/LibC/Stdio/setvbuf.c

   1 /** @file
   2     Implementation of setvbuf as declared in <stdio.h>.
   3
   4     Copyright (c) 2010, Intel Corporation. All rights reserved.<BR>
   5     This program and the accompanying materials are licensed and made available
   6     under the terms and conditions of the BSD License that accompanies this
   7     distribution.  The full text of the license may be found at
   8     http://opensource.org/licenses/bsd-license.php.
   9
  10     THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11     WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13     Copyright (c) 1990, 1993
  14     The Regents of the University of California.  All rights reserved.
  15
  16     This code is derived from software contributed to Berkeley by
  17     Chris Torek.
  18
  19     Redistribution and use in source and binary forms, with or without
  20     modification, are permitted provided that the following conditions
  21     are met:
  22       - Redistributions of source code must retain the above copyright
  23         notice, this list of conditions and the following disclaimer.
  24       - Redistributions in binary form must reproduce the above copyright
  25         notice, this list of conditions and the following disclaimer in the
  26         documentation and/or other materials provided with the distribution.
  27       - Neither the name of the University nor the names of its contributors
  28         may be used to endorse or promote products derived from this software
  29         without specific prior written permission.
  30
  31     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  32     AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  33     IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  34     ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
  35     LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  36     CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  37     SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  38     INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  39     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  40     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41     POSSIBILITY OF SUCH DAMAGE.
  42
  43     NetBSD: setvbuf.c,v 1.17 2003/08/07 16:43:31 agc Exp
  44     setvbuf.c 8.2 (Berkeley) 11/16/93
  45 **/
  46 #include  <LibConfig.h>
  47
  48 #include <assert.h>
  49 #include <errno.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <wchar.h>
  53 #include "reentrant.h"
  54 #include "local.h"
  55 #include  <MainData.h>
  56
  57 /*
  58  * Set one of the three kinds of buffering, optionally including
  59  * a buffer.
  60  */
  61 int
  62 setvbuf(FILE *fp, char *buf, int mode, size_t size)
  63 {
  64   int ret, flags;
  65   size_t iosize;
  66   int ttyflag;
  67
  68   _DIAGASSERT(fp != NULL);
  69   /* buf may be NULL */
  70
  71   /*
  72    * Verify arguments.  The `int' limit on `size' is due to this
  73    * particular implementation.  Note, buf and size are ignored
  74    * when setting _IONBF.
  75    */
  76   if (mode != _IONBF)
  77     if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
  78       return (-1);
  79
  80   FLOCKFILE(fp);
  81   /*
  82    * Write current buffer, if any.  Discard unread input (including
  83    * ungetc data), cancel line buffering, and free old buffer if
  84    * malloc()ed.  We also clear any eof condition, as if this were
  85    * a seek.
  86    */
  87   ret = 0;
  88   (void)__sflush(fp);
  89   if (HASUB(fp))
  90     FREEUB(fp);
  91   WCIO_FREE(fp);
  92   fp->_r = fp->_lbfsize = 0;
  93   flags = fp->_flags;
  94   if (flags & __SMBF)
  95     free((void *)fp->_bf._base);
  96   flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);
  97
  98   /* If setting unbuffered mode, skip all the hard work. */
  99   if (mode == _IONBF)
 100     goto nbf;
 101
 102   /*
 103    * Find optimal I/O size for seek optimization.  This also returns
 104    * a `tty flag' to suggest that we check isatty(fd), but we do not
 105    * care since our caller told us how to buffer.
 106    */
 107   flags |= __swhatbuf(fp, &iosize, &ttyflag);
 108   if (size == 0) {
 109     buf = NULL; /* force local allocation */
 110     size = iosize;
 111   }
 112
 113   /* Allocate buffer if needed. */
 114   if (buf == NULL) {
 115     if ((buf = malloc(size)) == NULL) {
 116       /*
 117        * Unable to honor user's request.  We will return
 118        * failure, but try again with file system size.
 119        */
 120       ret = -1;
 121       if (size != iosize) {
 122         size = iosize;
 123         buf = malloc(size);
 124       }
 125     }
 126     if (buf == NULL) {
 127       /* No luck; switch to unbuffered I/O. */
 128 nbf:
 129       fp->_flags = (unsigned short)(flags | __SNBF);
 130       fp->_w = 0;
 131       fp->_bf._base = fp->_p = fp->_nbuf;
 132       fp->_bf._size = 1;
 133       FUNLOCKFILE(fp);
 134       return (ret);
 135     }
 136     flags |= __SMBF;
 137   }
 138
 139   /*
 140    * Kill any seek optimization if the buffer is not the
 141    * right size.
 142    *
 143    * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
 144    */
 145   if (size != iosize)
 146     flags |= __SNPT;
 147
 148   /*
 149    * Fix up the FILE fields, and set gMD->cleanup for output flush on
 150    * exit (since we are buffered in some way).
 151    */
 152   if (mode == _IOLBF)
 153     flags |= __SLBF;
 154   fp->_flags = (unsigned short)flags;
 155   fp->_bf._base = fp->_p = (unsigned char *)buf;
 156   fp->_bf._size = (int)size;
 157   /* fp->_lbfsize is still 0 */
 158   if (flags & __SWR) {
 159     /*
 160      * Begin or continue writing: see __swsetup().  Note
 161      * that __SNBF is impossible (it was handled earlier).
 162      */
 163     if (flags & __SLBF) {
 164       fp->_w = 0;
 165       fp->_lbfsize = -fp->_bf._size;
 166     } else
 167       fp->_w = (int)size;
 168   } else {
 169     /* begin/continue reading, or stay in intermediate state */
 170     fp->_w = 0;
 171   }
 172   gMD->cleanup = _cleanup;
 173
 174   FUNLOCKFILE(fp);
 175   return (ret);
 176 }