1 /* $NetBSD: fgetln.c,v 1.10 2000/01/22 22:19:19 mycroft 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)fgetline.c 8.1 (Berkeley) 6/4/93"; 43 #else 44 __RCSID("$NetBSD: fgetln.c,v 1.10 2000/01/22 22:19:19 mycroft Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include "namespace.h" 49 50 #include <assert.h> 51 #include <stdio.h> 52 #include <stdlib.h> 53 #include <string.h> 54 #include "local.h" 55 #include "reentrant.h" 56 57 #ifdef __weak_alias 58 __weak_alias(fgetln,_fgetln) 59 #endif 60 61 int __slbexpand __P((FILE *, size_t)); 62 63 /* 64 * Expand the line buffer. Return -1 on error. 65 #ifdef notdef 66 * The `new size' does not account for a terminating '\0', 67 * so we add 1 here. 68 #endif 69 */ 70 int 71 __slbexpand(fp, newsize) 72 FILE *fp; 73 size_t newsize; 74 { 75 void *p; 76 77 #ifdef notdef 78 ++newsize; 79 #endif 80 _DIAGASSERT(fp != NULL); 81 82 if (fp->_lb._size >= newsize) 83 return (0); 84 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 85 return (-1); 86 fp->_lb._base = p; 87 fp->_lb._size = newsize; 88 return (0); 89 } 90 91 /* 92 * Get an input line. The returned pointer often (but not always) 93 * points into a stdio buffer. Fgetline does not alter the text of 94 * the returned line (which is thus not a C string because it will 95 * not necessarily end with '\0'), but does allow callers to modify 96 * it if they wish. Thus, we set __SMOD in case the caller does. 97 */ 98 char * 99 fgetln(fp, lenp) 100 FILE *fp; 101 size_t *lenp; 102 { 103 unsigned char *p; 104 size_t len; 105 size_t off; 106 107 _DIAGASSERT(fp != NULL); 108 _DIAGASSERT(lenp != NULL); 109 110 FLOCKFILE(fp); 111 112 /* make sure there is input */ 113 if (fp->_r <= 0 && __srefill(fp)) { 114 *lenp = 0; 115 FUNLOCKFILE(fp); 116 return (NULL); 117 } 118 119 /* look for a newline in the input */ 120 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) { 121 char *ret; 122 123 /* 124 * Found one. Flag buffer as modified to keep fseek from 125 * `optimising' a backward seek, in case the user stomps on 126 * the text. 127 */ 128 p++; /* advance over it */ 129 ret = (char *)fp->_p; 130 *lenp = len = p - fp->_p; 131 fp->_flags |= __SMOD; 132 fp->_r -= len; 133 fp->_p = p; 134 FUNLOCKFILE(fp); 135 return (ret); 136 } 137 138 /* 139 * We have to copy the current buffered data to the line buffer. 140 * As a bonus, though, we can leave off the __SMOD. 141 * 142 * OPTIMISTIC is length that we (optimistically) expect will 143 * accomodate the `rest' of the string, on each trip through the 144 * loop below. 145 */ 146 #define OPTIMISTIC 80 147 148 for (len = fp->_r, off = 0;; len += fp->_r) { 149 size_t diff; 150 151 /* 152 * Make sure there is room for more bytes. Copy data from 153 * file buffer to line buffer, refill file and look for 154 * newline. The loop stops only when we find a newline. 155 */ 156 if (__slbexpand(fp, len + OPTIMISTIC)) 157 goto error; 158 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 159 len - off); 160 off = len; 161 if (__srefill(fp)) 162 break; /* EOF or error: return partial line */ 163 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL) 164 continue; 165 166 /* got it: finish up the line (like code above) */ 167 p++; 168 diff = p - fp->_p; 169 len += diff; 170 if (__slbexpand(fp, len)) 171 goto error; 172 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 173 diff); 174 fp->_r -= diff; 175 fp->_p = p; 176 break; 177 } 178 *lenp = len; 179 #ifdef notdef 180 fp->_lb._base[len] = 0; 181 #endif 182 FUNLOCKFILE(fp); 183 return ((char *)fp->_lb._base); 184 185 error: 186 *lenp = 0; /* ??? */ 187 FUNLOCKFILE(fp); 188 return (NULL); /* ??? */ 189 } 190