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[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; 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 } 119