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