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