StdLib/LibC/Stdio/setvbuf.c

   1 /** @file
   2     Implementation of setvbuf as declared in <stdio.h>.
   3
   4     Copyright (c) 2010 - 2011, 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.
   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   if(fp == NULL) {
  71     errno = EINVAL;
  72     return (EOF);
  73   }
  74
  75   /*
  76    * Verify arguments.  The `int' limit on `size' is due to this
  77    * particular implementation.  Note, buf and size are ignored
  78    * when setting _IONBF.
  79    */
  80   if (mode != _IONBF)
  81     if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
  82       return (-1);
  83
  84   FLOCKFILE(fp);
  85   /*
  86    * Write current buffer, if any.  Discard unread input (including
  87    * ungetc data), cancel line buffering, and free old buffer if
  88    * malloc()ed.  We also clear any eof condition, as if this were
  89    * a seek.
  90    */
  91   ret = 0;
  92   (void)__sflush(fp);
  93   if (HASUB(fp))
  94     FREEUB(fp);
  95   WCIO_FREE(fp);
  96   fp->_r = fp->_lbfsize = 0;
  97   flags = fp->_flags;
  98   if (flags & __SMBF)
  99     free((void *)fp->_bf._base);
 100   flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);
 101
 102   /* If setting unbuffered mode, skip all the hard work. */
 103   if (mode == _IONBF)
 104     goto nbf;
 105
 106   /*
 107    * Find optimal I/O size for seek optimization.  This also returns
 108    * a `tty flag' to suggest that we check isatty(fd), but we do not
 109    * care since our caller told us how to buffer.
 110    */
 111   flags |= __swhatbuf(fp, &iosize, &ttyflag);
 112   if (size == 0) {
 113     buf = NULL; /* force local allocation */
 114     size = iosize;
 115   }
 116
 117   /* Allocate buffer if needed. */
 118   if (buf == NULL) {
 119     if ((buf = malloc(size)) == NULL) {
 120       /*
 121        * Unable to honor user's request.  We will return
 122        * failure, but try again with file system size.
 123        */
 124       ret = -1;
 125       if (size != iosize) {
 126         size = iosize;
 127         buf = malloc(size);
 128       }
 129     }
 130     if (buf == NULL) {
 131       /* No luck; switch to unbuffered I/O. */
 132 nbf:
 133       fp->_flags = (unsigned short)(flags | __SNBF);
 134       fp->_w = 0;
 135       fp->_bf._base = fp->_p = fp->_nbuf;
 136       fp->_bf._size = 1;
 137       FUNLOCKFILE(fp);
 138       return (ret);
 139     }
 140     flags |= __SMBF;
 141   }
 142
 143   /*
 144    * Kill any seek optimization if the buffer is not the
 145    * right size.
 146    *
 147    * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
 148    */
 149   if (size != iosize)
 150     flags |= __SNPT;
 151
 152   /*
 153    * Fix up the FILE fields, and set gMD->cleanup for output flush on
 154    * exit (since we are buffered in some way).
 155    */
 156   if (mode == _IOLBF)
 157     flags |= __SLBF;
 158   fp->_flags = (unsigned short)flags;
 159   fp->_bf._base = fp->_p = (unsigned char *)buf;
 160   fp->_bf._size = (int)size;
 161   /* fp->_lbfsize is still 0 */
 162   if (flags & __SWR) {
 163     /*
 164      * Begin or continue writing: see __swsetup().  Note
 165      * that __SNBF is impossible (it was handled earlier).
 166      */
 167     if (flags & __SLBF) {
 168       fp->_w = 0;
 169       fp->_lbfsize = -fp->_bf._size;
 170     } else
 171       fp->_w = (int)size;
 172   } else {
 173     /* begin/continue reading, or stay in intermediate state */
 174     fp->_w = 0;
 175   }
 176   gMD->cleanup = _cleanup;
 177
 178   FUNLOCKFILE(fp);
 179   return (ret);
 180 }