1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)fgetln.c 8.2 (Berkeley) 1/2/94 37 * $FreeBSD: src/lib/libc/stdio/fgetln.c,v 1.6 1999/08/28 00:00:59 peter Exp $ 38 * $DragonFly: src/lib/libc/stdio/fgetln.c,v 1.4 2004/06/07 20:35:41 hmp Exp $ 39 */ 40 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include "local.h" 45 46 /* 47 * Expand the line buffer. Return -1 on error. 48 #ifdef notdef 49 * The `new size' does not account for a terminating '\0', 50 * so we add 1 here. 51 #endif 52 */ 53 int 54 __slbexpand(FILE *fp, size_t newsize) 55 { 56 void *p; 57 58 #ifdef notdef 59 ++newsize; 60 #endif 61 if (fp->_lb._size >= newsize) 62 return (0); 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 size_t len; 82 size_t off; 83 84 /* make sure there is input */ 85 if (fp->_r <= 0 && __srefill(fp)) { 86 *lenp = 0; 87 return (NULL); 88 } 89 90 /* look for a newline in the input */ 91 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) { 92 char *ret; 93 94 /* 95 * Found one. Flag buffer as modified to keep fseek from 96 * `optimising' a backward seek, in case the user stomps on 97 * the text. 98 */ 99 p++; /* advance over it */ 100 ret = (char *)fp->_p; 101 *lenp = len = p - fp->_p; 102 fp->_flags |= __SMOD; 103 fp->_r -= len; 104 fp->_p = p; 105 return (ret); 106 } 107 108 /* 109 * We have to copy the current buffered data to the line buffer. 110 * As a bonus, though, we can leave off the __SMOD. 111 * 112 * OPTIMISTIC is length that we (optimistically) expect will 113 * accomodate the `rest' of the string, on each trip through the 114 * loop below. 115 */ 116 #define OPTIMISTIC 80 117 118 for (len = fp->_r, off = 0;; len += fp->_r) { 119 size_t diff; 120 121 /* 122 * Make sure there is room for more bytes. Copy data from 123 * file buffer to line buffer, refill file and look for 124 * newline. The loop stops only when we find a newline. 125 */ 126 if (__slbexpand(fp, len + OPTIMISTIC)) 127 goto error; 128 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 129 len - off); 130 off = len; 131 if (__srefill(fp)) 132 break; /* EOF or error: return partial line */ 133 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL) 134 continue; 135 136 /* got it: finish up the line (like code above) */ 137 p++; 138 diff = p - fp->_p; 139 len += diff; 140 if (__slbexpand(fp, len)) 141 goto error; 142 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 143 diff); 144 fp->_r -= diff; 145 fp->_p = p; 146 break; 147 } 148 *lenp = len; 149 #ifdef notdef 150 fp->_lb._base[len] = 0; 151 #endif 152 return ((char *)fp->_lb._base); 153 154 error: 155 *lenp = 0; /* ??? */ 156 return (NULL); /* ??? */ 157 } 158