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[] = "@(#)fgetln.c 8.2 (Berkeley) 1/2/94"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "namespace.h" 42 #include <errno.h> 43 #include <limits.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include "un-namespace.h" 48 #include "libc_private.h" 49 #include "local.h" 50 51 /* 52 * Expand the line buffer. Return -1 on error. 53 */ 54 int 55 __slbexpand(FILE *fp, size_t newsize) 56 { 57 void *p; 58 59 if (fp->_lb._size >= newsize) 60 return (0); 61 if (newsize > INT_MAX) { 62 errno = ENOMEM; 63 return (-1); 64 } 65 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 66 return (-1); 67 fp->_lb._base = p; 68 fp->_lb._size = newsize; 69 return (0); 70 } 71 72 /* 73 * Get an input line. The returned pointer often (but not always) 74 * points into a stdio buffer. Fgetln does not alter the text of 75 * the returned line (which is thus not a C string because it will 76 * not necessarily end with '\0'), but does allow callers to modify 77 * it if they wish. Thus, we set __SMOD in case the caller does. 78 */ 79 char * 80 fgetln(FILE *fp, size_t *lenp) 81 { 82 unsigned char *p; 83 char *ret; 84 size_t len; 85 size_t off; 86 87 FLOCKFILE_CANCELSAFE(fp); 88 ORIENT(fp, -1); 89 /* make sure there is input */ 90 if (fp->_r <= 0 && __srefill(fp)) { 91 *lenp = 0; 92 ret = NULL; 93 goto end; 94 } 95 96 /* look for a newline in the input */ 97 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) { 98 /* 99 * Found one. Flag buffer as modified to keep fseek from 100 * `optimising' a backward seek, in case the user stomps on 101 * the text. 102 */ 103 p++; /* advance over it */ 104 ret = (char *)fp->_p; 105 *lenp = len = p - fp->_p; 106 fp->_flags |= __SMOD; 107 fp->_r -= len; 108 fp->_p = p; 109 goto end; 110 } 111 112 /* 113 * We have to copy the current buffered data to the line buffer. 114 * As a bonus, though, we can leave off the __SMOD. 115 * 116 * OPTIMISTIC is length that we (optimistically) expect will 117 * accommodate the `rest' of the string, on each trip through the 118 * loop below. 119 */ 120 #define OPTIMISTIC 80 121 122 for (len = fp->_r, off = 0;; len += fp->_r) { 123 size_t diff; 124 125 /* 126 * Make sure there is room for more bytes. Copy data from 127 * file buffer to line buffer, refill file and look for 128 * newline. The loop stops only when we find a newline. 129 */ 130 if (__slbexpand(fp, len + OPTIMISTIC)) 131 goto error; 132 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 133 len - off); 134 off = len; 135 if (__srefill(fp)) { 136 if (__sfeof(fp)) 137 break; 138 goto error; 139 } 140 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL) 141 continue; 142 143 /* got it: finish up the line (like code above) */ 144 p++; 145 diff = p - fp->_p; 146 len += diff; 147 if (__slbexpand(fp, len)) 148 goto error; 149 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 150 diff); 151 fp->_r -= diff; 152 fp->_p = p; 153 break; 154 } 155 *lenp = len; 156 ret = (char *)fp->_lb._base; 157 end: 158 FUNLOCKFILE_CANCELSAFE(); 159 return (ret); 160 161 error: 162 *lenp = 0; /* ??? */ 163 fp->_flags |= __SERR; 164 ret = NULL; 165 goto end; 166 } 167