lib/libc/stdio/setvbuf.c

   1 /*      $NetBSD: setvbuf.c,v 1.19 2012/03/15 18:22:30 christos Exp $    */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)setvbuf.c   8.2 (Berkeley) 11/16/93";
  39 #else
  40 __RCSID("$NetBSD: setvbuf.c,v 1.19 2012/03/15 18:22:30 christos Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include <assert.h>
  45 #include <errno.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <wchar.h>
  49 #include "reentrant.h"
  50 #include "local.h"
  51
  52 /*
  53  * Set one of the three kinds of buffering, optionally including
  54  * a buffer.
  55  */
  56 int
  57 setvbuf(FILE *fp, char *buf, int mode, size_t size)
  58 {
  59         int ret, flags;
  60         size_t iosize;
  61         int ttyflag;
  62
  63         _DIAGASSERT(fp != NULL);
  64         /* buf may be NULL */
  65
  66         /*
  67          * Verify arguments.  The `int' limit on `size' is due to this
  68          * particular implementation.  Note, buf and size are ignored
  69          * when setting _IONBF.
  70          */
  71         if (mode != _IONBF)
  72                 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
  73                         return -1;
  74
  75         FLOCKFILE(fp);
  76         /*
  77          * Write current buffer, if any.  Discard unread input (including
  78          * ungetc data), cancel line buffering, and free old buffer if
  79          * malloc()ed.  We also clear any eof condition, as if this were
  80          * a seek.
  81          */
  82         ret = 0;
  83         (void)__sflush(fp);
  84         if (HASUB(fp))
  85                 FREEUB(fp);
  86         WCIO_FREE(fp);
  87         fp->_r = fp->_lbfsize = 0;
  88         flags = fp->_flags;
  89         if (flags & __SMBF)
  90                 free((void *)fp->_bf._base);
  91         flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);
  92
  93         /* If setting unbuffered mode, skip all the hard work. */
  94         if (mode == _IONBF)
  95                 goto nbf;
  96
  97         /*
  98          * Find optimal I/O size for seek optimization.  This also returns
  99          * a `tty flag' to suggest that we check isatty(fd), but we do not
 100          * care since our caller told us how to buffer.
 101          */
 102         flags |= __swhatbuf(fp, &iosize, &ttyflag);
 103         if (size == 0) {
 104                 buf = NULL;     /* force local allocation */
 105                 size = iosize;
 106         }
 107
 108         /* Allocate buffer if needed. */
 109         if (buf == NULL) {
 110                 if ((buf = malloc(size)) == NULL) {
 111                         /*
 112                          * Unable to honor user's request.  We will return
 113                          * failure, but try again with file system size.
 114                          */
 115                         ret = -1;
 116                         if (size != iosize) {
 117                                 size = iosize;
 118                                 buf = malloc(size);
 119                         }
 120                 }
 121                 if (buf == NULL) {
 122                         /* No luck; switch to unbuffered I/O. */
 123 nbf:
 124                         fp->_flags = flags | __SNBF;
 125                         fp->_w = 0;
 126                         fp->_bf._base = fp->_p = fp->_nbuf;
 127                         fp->_bf._size = 1;
 128                         FUNLOCKFILE(fp);
 129                         return ret;
 130                 }
 131                 flags |= __SMBF;
 132         }
 133
 134         /*
 135          * Kill any seek optimization if the buffer is not the
 136          * right size.
 137          *
 138          * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
 139          */
 140         if (size != iosize)
 141                 flags |= __SNPT;
 142
 143         /*
 144          * Fix up the FILE fields, and set __cleanup for output flush on
 145          * exit (since we are buffered in some way).
 146          */
 147         if (mode == _IOLBF)
 148                 flags |= __SLBF;
 149         fp->_flags = flags;
 150         fp->_bf._base = fp->_p = (unsigned char *)buf;
 151         _DIAGASSERT(__type_fit(int, size));
 152         fp->_bf._size = (int)size;
 153         /* fp->_lbfsize is still 0 */
 154         if (flags & __SWR) {
 155                 /*
 156                  * Begin or continue writing: see __swsetup().  Note
 157                  * that __SNBF is impossible (it was handled earlier).
 158                  */
 159                 if (flags & __SLBF) {
 160                         fp->_w = 0;
 161                         fp->_lbfsize = -fp->_bf._size;
 162                 } else {
 163                         _DIAGASSERT(__type_fit(int, size));
 164                         fp->_w = (int)size;
 165                 }
 166         } else {
 167                 /* begin/continue reading, or stay in intermediate state */
 168                 fp->_w = 0;
 169         }
 170         __cleanup = _cleanup;
 171
 172         FUNLOCKFILE(fp);
 173         return ret;
 174 }