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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)setvbuf.c   8.2 (Berkeley) 11/16/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdio/setvbuf.c,v 1.14 2007/01/09 00:28:07 imp Exp $");
  38
  39 #include "namespace.h"
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include "un-namespace.h"
  43 #include "local.h"
  44 #include "libc_private.h"
  45
  46 /*
  47  * Set one of the three kinds of buffering, optionally including
  48  * a buffer.
  49  */
  50 int
  51 setvbuf(FILE * __restrict fp, char * __restrict buf, int mode, size_t size)
  52 {
  53         int ret, flags;
  54         size_t iosize;
  55         int ttyflag;
  56
  57         /*
  58          * Verify arguments.  The `int' limit on `size' is due to this
  59          * particular implementation.  Note, buf and size are ignored
  60          * when setting _IONBF.
  61          */
  62         if (mode != _IONBF)
  63                 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
  64                         return (EOF);
  65
  66         FLOCKFILE(fp);
  67         /*
  68          * Write current buffer, if any.  Discard unread input (including
  69          * ungetc data), cancel line buffering, and free old buffer if
  70          * malloc()ed.  We also clear any eof condition, as if this were
  71          * a seek.
  72          */
  73         ret = 0;
  74         (void)__sflush(fp);
  75         if (HASUB(fp))
  76                 FREEUB(fp);
  77         fp->_r = fp->_lbfsize = 0;
  78         flags = fp->_flags;
  79         if (flags & __SMBF)
  80                 free((void *)fp->_bf._base);
  81         flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SOFF | __SNPT | __SEOF);
  82
  83         /* If setting unbuffered mode, skip all the hard work. */
  84         if (mode == _IONBF)
  85                 goto nbf;
  86
  87         /*
  88          * Find optimal I/O size for seek optimization.  This also returns
  89          * a `tty flag' to suggest that we check isatty(fd), but we do not
  90          * care since our caller told us how to buffer.
  91          */
  92         flags |= __swhatbuf(fp, &iosize, &ttyflag);
  93         if (size == 0) {
  94                 buf = NULL;     /* force local allocation */
  95                 size = iosize;
  96         }
  97
  98         /* Allocate buffer if needed. */
  99         if (buf == NULL) {
 100                 if ((buf = malloc(size)) == NULL) {
 101                         /*
 102                          * Unable to honor user's request.  We will return
 103                          * failure, but try again with file system size.
 104                          */
 105                         ret = EOF;
 106                         if (size != iosize) {
 107                                 size = iosize;
 108                                 buf = malloc(size);
 109                         }
 110                 }
 111                 if (buf == NULL) {
 112                         /* No luck; switch to unbuffered I/O. */
 113 nbf:
 114                         fp->_flags = flags | __SNBF;
 115                         fp->_w = 0;
 116                         fp->_bf._base = fp->_p = fp->_nbuf;
 117                         fp->_bf._size = 1;
 118                         FUNLOCKFILE(fp);
 119                         return (ret);
 120                 }
 121                 flags |= __SMBF;
 122         }
 123
 124         /*
 125          * Kill any seek optimization if the buffer is not the
 126          * right size.
 127          *
 128          * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
 129          */
 130         if (size != iosize)
 131                 flags |= __SNPT;
 132
 133         /*
 134          * Fix up the FILE fields, and set __cleanup for output flush on
 135          * exit (since we are buffered in some way).
 136          */
 137         if (mode == _IOLBF)
 138                 flags |= __SLBF;
 139         fp->_flags = flags;
 140         fp->_bf._base = fp->_p = (unsigned char *)buf;
 141         fp->_bf._size = size;
 142         /* fp->_lbfsize is still 0 */
 143         if (flags & __SWR) {
 144                 /*
 145                  * Begin or continue writing: see __swsetup().  Note
 146                  * that __SNBF is impossible (it was handled earlier).
 147                  */
 148                 if (flags & __SLBF) {
 149                         fp->_w = 0;
 150                         fp->_lbfsize = -fp->_bf._size;
 151                 } else
 152                         fp->_w = size;
 153         } else {
 154                 /* begin/continue reading, or stay in intermediate state */
 155                 fp->_w = 0;
 156         }
 157         __cleanup = _cleanup;
 158
 159         FUNLOCKFILE(fp);
 160         return (ret);
 161 }