db.1.85/PORT/bsdi.1.0/local/setvbuf.c

   1 /*-
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * 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 5.5 (Berkeley) 5/6/93";
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include "local.h"
  44
  45 /*
  46  * Set one of the three kinds of buffering, optionally including
  47  * a buffer.
  48  */
  49 setvbuf(fp, buf, mode, size)
  50         register FILE *fp;
  51         char *buf;
  52         register int mode;
  53         register size_t size;
  54 {
  55         register int ret, flags;
  56         size_t iosize;
  57         int ttyflag;
  58
  59         /*
  60          * Verify arguments.  The `int' limit on `size' is due to this
  61          * particular implementation.  Note, buf and size are ignored
  62          * when setting _IONBF.
  63          */
  64         if (mode != _IONBF)
  65                 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
  66                         return (EOF);
  67
  68         /*
  69          * Write current buffer, if any.  Discard unread input, cancel
  70          * line buffering, and free old buffer if malloc()ed.
  71          */
  72         ret = 0;
  73         (void)__sflush(fp);
  74         fp->_r = fp->_lbfsize = 0;
  75         flags = fp->_flags;
  76         if (flags & __SMBF)
  77                 free((void *)fp->_bf._base);
  78         flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT);
  79
  80         /* If setting unbuffered mode, skip all the hard work. */
  81         if (mode == _IONBF)
  82                 goto nbf;
  83
  84         /*
  85          * Find optimal I/O size for seek optimization.  This also returns
  86          * a `tty flag' to suggest that we check isatty(fd), but we do not
  87          * care since our caller told us how to buffer.
  88          */
  89         flags |= __swhatbuf(fp, &iosize, &ttyflag);
  90         if (size == 0) {
  91                 buf = NULL;     /* force local allocation */
  92                 size = iosize;
  93         }
  94
  95         /* Allocate buffer if needed. */
  96         if (buf == NULL) {
  97                 if ((buf = malloc(size)) == NULL) {
  98                         /*
  99                          * Unable to honor user's request.  We will return
 100                          * failure, but try again with file system size.
 101                          */
 102                         ret = EOF;
 103                         if (size != iosize) {
 104                                 size = iosize;
 105                                 buf = malloc(size);
 106                         }
 107                 }
 108                 if (buf == NULL) {
 109                         /* No luck; switch to unbuffered I/O. */
 110 nbf:
 111                         fp->_flags = flags | __SNBF;
 112                         fp->_w = 0;
 113                         fp->_bf._base = fp->_p = fp->_nbuf;
 114                         fp->_bf._size = 1;
 115                         return (ret);
 116                 }
 117                 flags |= __SMBF;
 118         }
 119
 120         /*
 121          * Kill any seek optimization if the buffer is not the
 122          * right size.
 123          *
 124          * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
 125          */
 126         if (size != iosize)
 127                 flags |= __SNPT;
 128
 129         /*
 130          * Fix up the FILE fields, and set __cleanup for output flush on
 131          * exit (since we are buffered in some way).  If in r/w mode, go
 132          * to the intermediate state, so that everyone has to call
 133          * __srefill or __swsetup on the first operation -- it is more
 134          * trouble than it is worth to set things up correctly here.
 135          */
 136         if (mode == _IOLBF)
 137                 flags |= __SLBF;
 138         if (flags & __SRW)
 139                 flags &= ~(__SRD | __SWR);
 140         fp->_w = 0;
 141         fp->_flags = flags;
 142         fp->_bf._base = fp->_p = (unsigned char *)buf;
 143         fp->_bf._size = size;
 144         fp->_lbfsize = 0;
 145         __cleanup = _cleanup;
 146
 147         return (ret);
 148 }