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 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "namespace.h" 44 #include <sys/types.h> 45 #include <sys/stat.h> 46 #include <unistd.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include "un-namespace.h" 50 51 #include "libc_private.h" 52 #include "local.h" 53 54 /* 55 * Allocate a file buffer, or switch to unbuffered I/O. 56 * Per the ANSI C standard, ALL tty devices default to line buffered. 57 * 58 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 59 * optimisation) right after the _fstat() that finds the buffer size. 60 */ 61 void 62 __smakebuf(fp) 63 FILE *fp; 64 { 65 void *p; 66 int flags; 67 size_t size; 68 int couldbetty; 69 70 if (fp->_flags & __SNBF) { 71 fp->_bf._base = fp->_p = fp->_nbuf; 72 fp->_bf._size = 1; 73 return; 74 } 75 flags = __swhatbuf(fp, &size, &couldbetty); 76 if ((p = malloc(size)) == NULL) { 77 fp->_flags |= __SNBF; 78 fp->_bf._base = fp->_p = fp->_nbuf; 79 fp->_bf._size = 1; 80 return; 81 } 82 __cleanup = _cleanup; 83 flags |= __SMBF; 84 fp->_bf._base = fp->_p = p; 85 fp->_bf._size = size; 86 if (couldbetty && isatty(fp->_file)) 87 flags |= __SLBF; 88 fp->_flags |= flags; 89 } 90 91 /* 92 * Internal routine to determine `proper' buffering for a file. 93 */ 94 int 95 __swhatbuf(fp, bufsize, couldbetty) 96 FILE *fp; 97 size_t *bufsize; 98 int *couldbetty; 99 { 100 struct stat st; 101 102 if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) { 103 *couldbetty = 0; 104 *bufsize = BUFSIZ; 105 return (__SNPT); 106 } 107 108 /* could be a tty iff it is a character device */ 109 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 110 if (st.st_blksize <= 0) { 111 *bufsize = BUFSIZ; 112 return (__SNPT); 113 } 114 115 /* 116 * Optimise fseek() only if it is a regular file. (The test for 117 * __sseek is mainly paranoia.) It is safe to set _blksize 118 * unconditionally; it will only be used if __SOPT is also set. 119 */ 120 *bufsize = st.st_blksize; 121 fp->_blksize = st.st_blksize; 122 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 123 __SOPT : __SNPT); 124 } 125