1 /* $NetBSD: fgetln.c,v 1.12 2003/08/07 16:43:23 agc Exp $ */ 2 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 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)fgetline.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 __RCSID("$NetBSD: fgetln.c,v 1.12 2003/08/07 16:43:23 agc Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 46 #include <assert.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include "reentrant.h" 51 #include "local.h" 52 53 #ifdef __weak_alias 54 __weak_alias(fgetln,_fgetln) 55 #endif 56 57 int __slbexpand __P((FILE *, size_t)); 58 59 /* 60 * Expand the line buffer. Return -1 on error. 61 #ifdef notdef 62 * The `new size' does not account for a terminating '\0', 63 * so we add 1 here. 64 #endif 65 */ 66 int 67 __slbexpand(fp, newsize) 68 FILE *fp; 69 size_t newsize; 70 { 71 void *p; 72 73 #ifdef notdef 74 ++newsize; 75 #endif 76 _DIAGASSERT(fp != NULL); 77 78 if (fp->_lb._size >= newsize) 79 return (0); 80 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 81 return (-1); 82 fp->_lb._base = p; 83 fp->_lb._size = newsize; 84 return (0); 85 } 86 87 /* 88 * Get an input line. The returned pointer often (but not always) 89 * points into a stdio buffer. Fgetline does not alter the text of 90 * the returned line (which is thus not a C string because it will 91 * not necessarily end with '\0'), but does allow callers to modify 92 * it if they wish. Thus, we set __SMOD in case the caller does. 93 */ 94 char * 95 fgetln(fp, lenp) 96 FILE *fp; 97 size_t *lenp; 98 { 99 unsigned char *p; 100 size_t len; 101 size_t off; 102 103 _DIAGASSERT(fp != NULL); 104 _DIAGASSERT(lenp != NULL); 105 106 FLOCKFILE(fp); 107 108 /* make sure there is input */ 109 if (fp->_r <= 0 && __srefill(fp)) { 110 *lenp = 0; 111 FUNLOCKFILE(fp); 112 return (NULL); 113 } 114 115 /* look for a newline in the input */ 116 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) { 117 char *ret; 118 119 /* 120 * Found one. Flag buffer as modified to keep fseek from 121 * `optimising' a backward seek, in case the user stomps on 122 * the text. 123 */ 124 p++; /* advance over it */ 125 ret = (char *)fp->_p; 126 *lenp = len = p - fp->_p; 127 fp->_flags |= __SMOD; 128 fp->_r -= len; 129 fp->_p = p; 130 FUNLOCKFILE(fp); 131 return (ret); 132 } 133 134 /* 135 * We have to copy the current buffered data to the line buffer. 136 * As a bonus, though, we can leave off the __SMOD. 137 * 138 * OPTIMISTIC is length that we (optimistically) expect will 139 * accomodate the `rest' of the string, on each trip through the 140 * loop below. 141 */ 142 #define OPTIMISTIC 80 143 144 for (len = fp->_r, off = 0;; len += fp->_r) { 145 size_t diff; 146 147 /* 148 * Make sure there is room for more bytes. Copy data from 149 * file buffer to line buffer, refill file and look for 150 * newline. The loop stops only when we find a newline. 151 */ 152 if (__slbexpand(fp, len + OPTIMISTIC)) 153 goto error; 154 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 155 len - off); 156 off = len; 157 if (__srefill(fp)) 158 break; /* EOF or error: return partial line */ 159 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL) 160 continue; 161 162 /* got it: finish up the line (like code above) */ 163 p++; 164 diff = p - fp->_p; 165 len += diff; 166 if (__slbexpand(fp, len)) 167 goto error; 168 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 169 diff); 170 fp->_r -= diff; 171 fp->_p = p; 172 break; 173 } 174 *lenp = len; 175 #ifdef notdef 176 fp->_lb._base[len] = 0; 177 #endif 178 FUNLOCKFILE(fp); 179 return ((char *)fp->_lb._base); 180 181 error: 182 *lenp = 0; /* ??? */ 183 FUNLOCKFILE(fp); 184 return (NULL); /* ??? */ 185 } 186