stdio/setvbuf.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1990, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * This code is derived from software contributed to Berkeley by
  30  * Chris Torek.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include "local.h"
  65
  66 /*
  67  * Set one of the three kinds of buffering, optionally including
  68  * a buffer.
  69  */
  70 int
  71 setvbuf(fp, buf, mode, size)
  72         register FILE *fp;
  73         char *buf;
  74         register int mode;
  75         register size_t size;
  76 {
  77         register int ret, flags;
  78         size_t iosize;
  79         int ttyflag;
  80
  81         /*
  82          * Verify arguments.  The `int' limit on `size' is due to this
  83          * particular implementation.  Note, buf and size are ignored
  84          * when setting _IONBF.
  85          */
  86         if (mode != _IONBF)
  87                 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
  88                         return (EOF);
  89
  90         /*
  91          * Write current buffer, if any.  Discard unread input (including
  92          * ungetc data), cancel line buffering, and free old buffer if
  93          * malloc()ed.  We also clear any eof condition, as if this were
  94          * a seek.
  95          */
  96         ret = 0;
  97         (void)__sflush(fp);
  98         if (HASUB(fp))
  99                 FREEUB(fp);
 100         fp->_r = fp->_lbfsize = 0;
 101         flags = fp->_flags;
 102         if (flags & __SMBF)
 103                 free((void *)fp->_bf._base);
 104         flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);
 105
 106         /* If setting unbuffered mode, skip all the hard work. */
 107         if (mode == _IONBF)
 108                 goto nbf;
 109
 110         /*
 111          * Find optimal I/O size for seek optimization.  This also returns
 112          * a `tty flag' to suggest that we check isatty(fd), but we do not
 113          * care since our caller told us how to buffer.
 114          */
 115         flags |= __swhatbuf(fp, &iosize, &ttyflag);
 116         if (size == 0) {
 117                 buf = NULL;     /* force local allocation */
 118                 size = iosize;
 119         }
 120
 121         /* Allocate buffer if needed. */
 122         if (buf == NULL) {
 123                 if ((buf = malloc(size)) == NULL) {
 124                         /*
 125                          * Unable to honor user's request.  We will return
 126                          * failure, but try again with file system size.
 127                          */
 128                         ret = EOF;
 129                         if (size != iosize) {
 130                                 size = iosize;
 131                                 buf = malloc(size);
 132                         }
 133                 }
 134                 if (buf == NULL) {
 135                         /* No luck; switch to unbuffered I/O. */
 136 nbf:
 137                         fp->_flags = flags | __SNBF;
 138                         fp->_w = 0;
 139                         fp->_bf._base = fp->_p = fp->_nbuf;
 140                         fp->_bf._size = 1;
 141                         return (ret);
 142                 }
 143                 flags |= __SMBF;
 144         }
 145
 146         /*
 147          * Kill any seek optimization if the buffer is not the
 148          * right size.
 149          *
 150          * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
 151          */
 152         if (size != iosize)
 153                 flags |= __SNPT;
 154
 155         /*
 156          * Fix up the FILE fields, and set __cleanup for output flush on
 157          * exit (since we are buffered in some way).
 158          */
 159         if (mode == _IOLBF)
 160                 flags |= __SLBF;
 161         fp->_flags = flags;
 162         fp->_bf._base = fp->_p = (unsigned char *)buf;
 163         fp->_bf._size = size;
 164         /* fp->_lbfsize is still 0 */
 165         if (flags & __SWR) {
 166                 /*
 167                  * Begin or continue writing: see __swsetup().  Note
 168                  * that __SNBF is impossible (it was handled earlier).
 169                  */
 170                 if (flags & __SLBF) {
 171                         fp->_w = 0;
 172                         fp->_lbfsize = -fp->_bf._size;
 173                 } else
 174                         fp->_w = size;
 175         } else {
 176                 /* begin/continue reading, or stay in intermediate state */
 177                 fp->_w = 0;
 178         }
 179         __cleanup = _cleanup;
 180
 181         return (ret);
 182 }