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 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include "namespace.h" 39 #include <sys/types.h> 40 #include <sys/stat.h> 41 #include <unistd.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include "un-namespace.h" 45 46 #include "libc_private.h" 47 #include "local.h" 48 49 /* 50 * Allocate a file buffer, or switch to unbuffered I/O. 51 * Per the ANSI C standard, ALL tty devices default to line buffered. 52 * 53 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 54 * optimisation) right after the _fstat() that finds the buffer size. 55 */ 56 void 57 __smakebuf(FILE *fp) 58 { 59 void *p; 60 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(FILE *fp, size_t *bufsize, int *couldbetty) 90 { 91 struct stat st; 92 93 if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) { 94 *couldbetty = 0; 95 *bufsize = BUFSIZ; 96 return (__SNPT); 97 } 98 99 /* could be a tty iff it is a character device */ 100 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 101 if (st.st_blksize <= 0) { 102 *bufsize = BUFSIZ; 103 return (__SNPT); 104 } 105 106 /* 107 * Optimise fseek() only if it is a regular file. (The test for 108 * __sseek is mainly paranoia.) It is safe to set _blksize 109 * unconditionally; it will only be used if __SOPT is also set. 110 */ 111 *bufsize = st.st_blksize; 112 fp->_blksize = st.st_blksize; 113 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 114 __SOPT : __SNPT); 115 } 116