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 1.7 2005/11/20 11:07:30 swildner Exp $ 39 */ 40 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include "local.h" 45 #include "priv_stdio.h" 46 47 /* 48 * Expand the line buffer. Return -1 on error. 49 #ifdef notdef 50 * The `new size' does not account for a terminating '\0', 51 * so we add 1 here. 52 #endif 53 */ 54 int 55 __slbexpand(FILE *fp, size_t newsize) 56 { 57 void *p; 58 59 #ifdef notdef 60 ++newsize; 61 #endif 62 if (fp->_lb._size >= newsize) 63 return (0); 64 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 65 return (-1); 66 fp->_lb._base = p; 67 fp->_lb._size = newsize; 68 return (0); 69 } 70 71 /* 72 * Get an input line. The returned pointer often (but not always) 73 * points into a stdio buffer. Fgetln does not alter the text of 74 * the returned line (which is thus not a C string because it will 75 * not necessarily end with '\0'), but does allow callers to modify 76 * it if they wish. Thus, we set __SMOD in case the caller does. 77 */ 78 char * 79 fgetln(FILE *fp, size_t *lenp) 80 { 81 unsigned char *p; 82 size_t len; 83 size_t off; 84 85 /* make sure there is input */ 86 if (fp->pub._r <= 0 && __srefill(fp)) { 87 *lenp = 0; 88 return (NULL); 89 } 90 91 /* look for a newline in the input */ 92 if ((p = memchr((void *)fp->pub._p, '\n', (size_t)fp->pub._r)) != NULL) { 93 char *ret; 94 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->pub._p; 102 *lenp = len = p - fp->pub._p; 103 fp->pub._flags |= __SMOD; 104 fp->pub._r -= len; 105 fp->pub._p = p; 106 return (ret); 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 * accomodate the `rest' of the string, on each trip through the 115 * loop below. 116 */ 117 #define OPTIMISTIC 80 118 119 for (len = fp->pub._r, off = 0;; len += fp->pub._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 memcpy((void *)(fp->_lb._base + off), (void *)fp->pub._p, 130 len - off); 131 off = len; 132 if (__srefill(fp)) 133 break; /* EOF or error: return partial line */ 134 if ((p = memchr((void *)fp->pub._p, '\n', (size_t)fp->pub._r)) 135 == NULL) 136 continue; 137 138 /* got it: finish up the line (like code above) */ 139 p++; 140 diff = p - fp->pub._p; 141 len += diff; 142 if (__slbexpand(fp, len)) 143 goto error; 144 memcpy((void *)(fp->_lb._base + off), (void *)fp->pub._p, 145 diff); 146 fp->pub._r -= diff; 147 fp->pub._p = p; 148 break; 149 } 150 *lenp = len; 151 #ifdef notdef 152 fp->_lb._base[len] = 0; 153 #endif 154 return ((char *)fp->_lb._base); 155 156 error: 157 *lenp = 0; /* ??? */ 158 return (NULL); /* ??? */ 159 } 160