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root/usr/lib/libc/stdio/makebuf.c

DEFINITIONS

1. __swhatbuf
2. __smakebuf

   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. 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  */
  33 #include <sys/types.h>
  34 #include <sys/stat.h>
  35 #include <unistd.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include "local.h"
  40 /*
  41  * Internal routine to determine `proper' buffering for a file.
  42  */
  43 static int
__swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
  45 {
  46         struct stat st;
  48         *bufsize = BUFSIZ;
  49         *couldbetty = 0;
  50         if (fp->_file < 0 || fstat(fp->_file, &st) < 0)
  51                 return 0;
  53         /* could be a tty iff it is a character device */
  54         *couldbetty = S_ISCHR(st.st_mode);
  55         return 0;
  56 }
  58 /*
  59  * Allocate a file buffer, or switch to unbuffered I/O.
  60  * Per the ANSI C standard, ALL tty devices default to line buffered.
  61  *
  62  * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
  63  * optimisation) right after the fstat() that finds the buffer size.
  64  */
  65 void
__smakebuf(fp)
FILE *fp;
  68 {
  69         void *p;
  70         int flags;
size_t size;
  72         int couldbetty;
  74         if (fp->_flags & __SNBF) {
fp->_bf._base = fp->_p = fp->_nbuf;
fp->_bf._size = 1;
  77                 return;
  78         }
flags = __swhatbuf(fp, &size, &couldbetty);
  80         if ((p = malloc(size)) == NULL) {
fp->_flags |= __SNBF;
fp->_bf._base = fp->_p = fp->_nbuf;
fp->_bf._size = 1;
  84                 return;
  85         }
__cleanup = _cleanup;
flags |= __SMBF;
fp->_bf._base = fp->_p = p;
fp->_bf._size = size;
  90         if (couldbetty && isatty(fp->_file))
flags |= __SLBF;
fp->_flags |= flags;
  94 }