1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include "namespace.h" 36 #include <sys/types.h> 37 #include <sys/stat.h> 38 #include <unistd.h> 39 #include <stdio.h> 40 #include <stdlib.h> 41 #include "un-namespace.h" 42 43 #include "libc_private.h" 44 #include "local.h" 45 46 /* 47 * Allocate a file buffer, or switch to unbuffered I/O. 48 * Per the ANSI C standard, ALL tty devices default to line buffered. 49 * 50 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 51 * optimisation) right after the _fstat() that finds the buffer size. 52 */ 53 void 54 __smakebuf(FILE *fp) 55 { 56 void *p; 57 int flags; 58 size_t size; 59 int couldbetty; 60 61 if (fp->_flags & __SNBF) { 62 fp->_bf._base = fp->_p = fp->_nbuf; 63 fp->_bf._size = 1; 64 return; 65 } 66 flags = __swhatbuf(fp, &size, &couldbetty); 67 if ((p = malloc(size)) == NULL) { 68 fp->_flags |= __SNBF; 69 fp->_bf._base = fp->_p = fp->_nbuf; 70 fp->_bf._size = 1; 71 return; 72 } 73 __cleanup = _cleanup; 74 flags |= __SMBF; 75 fp->_bf._base = fp->_p = p; 76 fp->_bf._size = size; 77 if (couldbetty && isatty(fp->_file)) 78 flags |= __SLBF; 79 fp->_flags |= flags; 80 } 81 82 /* 83 * Internal routine to determine `proper' buffering for a file. 84 */ 85 int 86 __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty) 87 { 88 struct stat st; 89 90 if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) { 91 *couldbetty = 0; 92 *bufsize = BUFSIZ; 93 return (__SNPT); 94 } 95 96 /* could be a tty iff it is a character device */ 97 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 98 if (st.st_blksize <= 0) { 99 *bufsize = BUFSIZ; 100 return (__SNPT); 101 } 102 103 /* 104 * Optimise fseek() only if it is a regular file. (The test for 105 * __sseek is mainly paranoia.) It is safe to set _blksize 106 * unconditionally; it will only be used if __SOPT is also set. 107 */ 108 *bufsize = st.st_blksize; 109 fp->_blksize = st.st_blksize; 110 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 111 __SOPT : __SNPT); 112 } 113