vx32

Local 9vx git repository for patches.
git clone git://r-36.net/vx32
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makebuf.c (3860B)

      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 rcsid[] = "$OpenBSD: makebuf.c,v 1.2 1996/08/19 08:32:54 tholo Exp $";
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include <sys/types.h>
     42 #include <sys/stat.h>
     43 #include <unistd.h>
     44 #include <stdio.h>
     45 #include <stdlib.h>
     46 #include "local.h"
     47 
     48 /*
     49  * Allocate a file buffer, or switch to unbuffered I/O.
     50  * Per the ANSI C standard, ALL tty devices default to line buffered.
     51  *
     52  * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
     53  * optimisation) right after the fstat() that finds the buffer size.
     54  */
     55 void
     56 __smakebuf(fp)
     57 	register FILE *fp;
     58 {
     59 	register void *p;
     60 	register int flags;
     61 	size_t size;
     62 	int couldbetty;
     63 
     64 	if (fp->_flags & __SNBF) {
     65 		fp->_bf._base = fp->_p = fp->_nbuf;
     66 		fp->_bf._size = 1;
     67 		return;
     68 	}
     69 	flags = __swhatbuf(fp, &size, &couldbetty);
     70 	if ((p = malloc(size)) == NULL) {
     71 		fp->_flags |= __SNBF;
     72 		fp->_bf._base = fp->_p = fp->_nbuf;
     73 		fp->_bf._size = 1;
     74 		return;
     75 	}
     76 	__cleanup = _cleanup;
     77 	flags |= __SMBF;
     78 	fp->_bf._base = fp->_p = p;
     79 	fp->_bf._size = size;
     80 	if (couldbetty && isatty(fp->_file))
     81 		flags |= __SLBF;
     82 	fp->_flags |= flags;
     83 }
     84 
     85 /*
     86  * Internal routine to determine `proper' buffering for a file.
     87  */
     88 int
     89 __swhatbuf(fp, bufsize, couldbetty)
     90 	register FILE *fp;
     91 	size_t *bufsize;
     92 	int *couldbetty;
     93 {
     94 	struct stat st;
     95 
     96 	if (fp->_file < 0 || fstat(fp->_file, &st) < 0) {
     97 		*couldbetty = 0;
     98 		*bufsize = BUFSIZ;
     99 		return (__SNPT);
    100 	}
    101 
    102 	/* could be a tty iff it is a character device */
    103 	*couldbetty = (st.st_mode & S_IFMT) == S_IFCHR;
    104 	if (st.st_blksize <= 0) {
    105 		*bufsize = BUFSIZ;
    106 		return (__SNPT);
    107 	}
    108 
    109 	/*
    110 	 * Optimise fseek() only if it is a regular file.  (The test for
    111 	 * __sseek is mainly paranoia.)  It is safe to set _blksize
    112 	 * unconditionally; it will only be used if __SOPT is also set.
    113 	 */
    114 	*bufsize = st.st_blksize;
    115 	fp->_blksize = st.st_blksize;
    116 	return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ?
    117 	    __SOPT : __SNPT);
    118 }