stdio/setvbuf.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1990, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * This code is derived from software contributed to Berkeley by
  27  * Chris Torek.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include "local.h"
  62
  63 /*
  64  * Set one of the three kinds of buffering, optionally including
  65  * a buffer.
  66  */
  67 int
  68 setvbuf(fp, buf, mode, size)
  69         register FILE *fp;
  70         char *buf;
  71         register int mode;
  72         register size_t size;
  73 {
  74         register int ret, flags;
  75         size_t iosize;
  76         int ttyflag;
  77
  78         /*
  79          * Verify arguments.  The `int' limit on `size' is due to this
  80          * particular implementation.  Note, buf and size are ignored
  81          * when setting _IONBF.
  82          */
  83         if (mode != _IONBF)
  84                 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
  85                         return (EOF);
  86
  87         /*
  88          * Write current buffer, if any.  Discard unread input (including
  89          * ungetc data), cancel line buffering, and free old buffer if
  90          * malloc()ed.  We also clear any eof condition, as if this were
  91          * a seek.
  92          */
  93         ret = 0;
  94         (void)__sflush(fp);
  95         if (HASUB(fp))
  96                 FREEUB(fp);
  97         fp->_r = fp->_lbfsize = 0;
  98         flags = fp->_flags;
  99         if (flags & __SMBF)
 100                 free((void *)fp->_bf._base);
 101         flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);
 102
 103         /* If setting unbuffered mode, skip all the hard work. */
 104         if (mode == _IONBF)
 105                 goto nbf;
 106
 107         /*
 108          * Find optimal I/O size for seek optimization.  This also returns
 109          * a `tty flag' to suggest that we check isatty(fd), but we do not
 110          * care since our caller told us how to buffer.
 111          */
 112         flags |= __swhatbuf(fp, &iosize, &ttyflag);
 113         if (size == 0) {
 114                 buf = NULL;     /* force local allocation */
 115                 size = iosize;
 116         }
 117
 118         /* Allocate buffer if needed. */
 119         if (buf == NULL) {
 120                 if ((buf = malloc(size)) == NULL) {
 121                         /*
 122                          * Unable to honor user's request.  We will return
 123                          * failure, but try again with file system size.
 124                          */
 125                         ret = EOF;
 126                         if (size != iosize) {
 127                                 size = iosize;
 128                                 buf = malloc(size);
 129                         }
 130                 }
 131                 if (buf == NULL) {
 132                         /* No luck; switch to unbuffered I/O. */
 133 nbf:
 134                         fp->_flags = flags | __SNBF;
 135                         fp->_w = 0;
 136                         fp->_bf._base = fp->_p = fp->_nbuf;
 137                         fp->_bf._size = 1;
 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 __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 = flags;
 159         fp->_bf._base = fp->_p = (unsigned char *)buf;
 160         fp->_bf._size = 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 = size;
 172         } else {
 173                 /* begin/continue reading, or stay in intermediate state */
 174                 fp->_w = 0;
 175         }
 176         __cleanup = _cleanup;
 177
 178         return (ret);
 179 }