stdio/FreeBSD/setvbuf.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)setvbuf.c   8.2 (Berkeley) 11/16/93";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/stdio/setvbuf.c,v 1.13 2002/09/06 11:23:55 tjr Exp $");
  42
  43 #include "namespace.h"
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include "un-namespace.h"
  47 #include "local.h"
  48 #include "libc_private.h"
  49
  50 /*
  51  * Set one of the three kinds of buffering, optionally including
  52  * a buffer.
  53  */
  54 int
  55 setvbuf(FILE * __restrict fp, char * __restrict buf, int mode, size_t size)
  56 {
  57         int ret, flags;
  58         size_t iosize;
  59         int ttyflag;
  60
  61         /*
  62          * Verify arguments.  The `int' limit on `size' is due to this
  63          * particular implementation.  Note, buf and size are ignored
  64          * when setting _IONBF.
  65          */
  66         if (mode != _IONBF)
  67                 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
  68                         return (EOF);
  69
  70         FLOCKFILE(fp);
  71         /*
  72          * Write current buffer, if any.  Discard unread input (including
  73          * ungetc data), cancel line buffering, and free old buffer if
  74          * malloc()ed.  We also clear any eof condition, as if this were
  75          * a seek.
  76          */
  77         ret = 0;
  78         (void)__sflush(fp);
  79         if (HASUB(fp))
  80                 FREEUB(fp);
  81         fp->_r = fp->_lbfsize = 0;
  82         flags = fp->_flags;
  83         if (flags & __SMBF)
  84                 free((void *)fp->_bf._base);
  85         flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SOFF | __SNPT | __SEOF);
  86
  87         /* If setting unbuffered mode, skip all the hard work. */
  88         if (mode == _IONBF)
  89                 goto nbf;
  90
  91         /*
  92          * Find optimal I/O size for seek optimization.  This also returns
  93          * a `tty flag' to suggest that we check isatty(fd), but we do not
  94          * care since our caller told us how to buffer.
  95          */
  96         flags |= __swhatbuf(fp, &iosize, &ttyflag);
  97         if (size == 0) {
  98                 buf = NULL;     /* force local allocation */
  99                 size = iosize;
 100         }
 101
 102         /* Allocate buffer if needed. */
 103         if (buf == NULL) {
 104                 if ((buf = malloc(size)) == NULL) {
 105                         /*
 106                          * Unable to honor user's request.  We will return
 107                          * failure, but try again with file system size.
 108                          */
 109                         ret = EOF;
 110                         if (size != iosize) {
 111                                 size = iosize;
 112                                 buf = malloc(size);
 113                         }
 114                 }
 115                 if (buf == NULL) {
 116                         /* No luck; switch to unbuffered I/O. */
 117 nbf:
 118                         fp->_flags = flags | __SNBF;
 119                         fp->_w = 0;
 120                         fp->_bf._base = fp->_p = fp->_nbuf;
 121                         fp->_bf._size = 1;
 122                         FUNLOCKFILE(fp);
 123                         return (ret);
 124                 }
 125                 flags |= __SMBF;
 126         }
 127
 128         /*
 129          * Kill any seek optimization if the buffer is not the
 130          * right size.
 131          *
 132          * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
 133          */
 134         if (size != iosize)
 135                 flags |= __SNPT;
 136
 137         /*
 138          * Fix up the FILE fields, and set __cleanup for output flush on
 139          * exit (since we are buffered in some way).
 140          */
 141         if (mode == _IOLBF)
 142                 flags |= __SLBF;
 143         fp->_flags = flags;
 144         fp->_bf._base = fp->_p = (unsigned char *)buf;
 145         fp->_bf._size = size;
 146         /* fp->_lbfsize is still 0 */
 147         if (flags & __SWR) {
 148                 /*
 149                  * Begin or continue writing: see __swsetup().  Note
 150                  * that __SNBF is impossible (it was handled earlier).
 151                  */
 152                 if (flags & __SLBF) {
 153                         fp->_w = 0;
 154                         fp->_lbfsize = -fp->_bf._size;
 155                 } else
 156                         fp->_w = size;
 157         } else {
 158                 /* begin/continue reading, or stay in intermediate state */
 159                 fp->_w = 0;
 160         }
 161         __cleanup = _cleanup;
 162
 163         FUNLOCKFILE(fp);
 164         return (ret);
 165 }