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 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include "namespace.h" 40 #include <sys/types.h> 41 #include <sys/stat.h> 42 #include <unistd.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include "un-namespace.h" 46 47 #include "libc_private.h" 48 #include "local.h" 49 50 /* 51 * Allocate a file buffer, or switch to unbuffered I/O. 52 * Per the ANSI C standard, ALL tty devices default to line buffered. 53 * 54 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 55 * optimisation) right after the _fstat() that finds the buffer size. 56 */ 57 void 58 __smakebuf(FILE *fp) 59 { 60 void *p; 61 int flags; 62 size_t size; 63 int couldbetty; 64 65 if (fp->_flags & __SNBF) { 66 fp->_bf._base = fp->_p = fp->_nbuf; 67 fp->_bf._size = 1; 68 return; 69 } 70 flags = __swhatbuf(fp, &size, &couldbetty); 71 if ((p = malloc(size)) == NULL) { 72 fp->_flags |= __SNBF; 73 fp->_bf._base = fp->_p = fp->_nbuf; 74 fp->_bf._size = 1; 75 return; 76 } 77 __cleanup = _cleanup; 78 flags |= __SMBF; 79 fp->_bf._base = fp->_p = p; 80 fp->_bf._size = size; 81 if (couldbetty && isatty(fp->_file)) 82 flags |= __SLBF; 83 fp->_flags |= flags; 84 } 85 86 /* 87 * Internal routine to determine `proper' buffering for a file. 88 */ 89 int 90 __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty) 91 { 92 struct stat st; 93 94 if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) { 95 *couldbetty = 0; 96 *bufsize = BUFSIZ; 97 return (__SNPT); 98 } 99 100 /* could be a tty iff it is a character device */ 101 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 102 if (st.st_blksize <= 0) { 103 *bufsize = BUFSIZ; 104 return (__SNPT); 105 } 106 107 /* 108 * Optimise fseek() only if it is a regular file. (The test for 109 * __sseek is mainly paranoia.) It is safe to set _blksize 110 * unconditionally; it will only be used if __SOPT is also set. 111 */ 112 *bufsize = st.st_blksize; 113 fp->_blksize = st.st_blksize; 114 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 115 __SOPT : __SNPT); 116 } 117
