1 /* $NetBSD: fgetln.c,v 1.5 1998/02/03 18:41:08 perry 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 1.5 1998/02/03 18:41:08 perry Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include "local.h" 52 #include "reentrant.h" 53 54 int __slbexpand __P((FILE *, size_t)); 55 56 /* 57 * Expand the line buffer. Return -1 on error. 58 #ifdef notdef 59 * The `new size' does not account for a terminating '\0', 60 * so we add 1 here. 61 #endif 62 */ 63 int 64 __slbexpand(fp, newsize) 65 FILE *fp; 66 size_t newsize; 67 { 68 void *p; 69 70 #ifdef notdef 71 ++newsize; 72 #endif 73 if (fp->_lb._size >= newsize) 74 return (0); 75 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 76 return (-1); 77 fp->_lb._base = p; 78 fp->_lb._size = newsize; 79 return (0); 80 } 81 82 /* 83 * Get an input line. The returned pointer often (but not always) 84 * points into a stdio buffer. Fgetline does not alter the text of 85 * the returned line (which is thus not a C string because it will 86 * not necessarily end with '\0'), but does allow callers to modify 87 * it if they wish. Thus, we set __SMOD in case the caller does. 88 */ 89 char * 90 fgetln(fp, lenp) 91 FILE *fp; 92 size_t *lenp; 93 { 94 unsigned char *p; 95 size_t len; 96 size_t off; 97 98 FLOCKFILE(fp); 99 100 /* make sure there is input */ 101 if (fp->_r <= 0 && __srefill(fp)) { 102 *lenp = 0; 103 FUNLOCKFILE(fp); 104 return (NULL); 105 } 106 107 /* look for a newline in the input */ 108 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) != NULL) { 109 char *ret; 110 111 /* 112 * Found one. Flag buffer as modified to keep fseek from 113 * `optimising' a backward seek, in case the user stomps on 114 * the text. 115 */ 116 p++; /* advance over it */ 117 ret = (char *)fp->_p; 118 *lenp = len = p - fp->_p; 119 fp->_flags |= __SMOD; 120 fp->_r -= len; 121 fp->_p = p; 122 FUNLOCKFILE(fp); 123 return (ret); 124 } 125 126 /* 127 * We have to copy the current buffered data to the line buffer. 128 * As a bonus, though, we can leave off the __SMOD. 129 * 130 * OPTIMISTIC is length that we (optimistically) expect will 131 * accomodate the `rest' of the string, on each trip through the 132 * loop below. 133 */ 134 #define OPTIMISTIC 80 135 136 for (len = fp->_r, off = 0;; len += fp->_r) { 137 size_t diff; 138 139 /* 140 * Make sure there is room for more bytes. Copy data from 141 * file buffer to line buffer, refill file and look for 142 * newline. The loop stops only when we find a newline. 143 */ 144 if (__slbexpand(fp, len + OPTIMISTIC)) 145 goto error; 146 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 147 len - off); 148 off = len; 149 if (__srefill(fp)) 150 break; /* EOF or error: return partial line */ 151 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) == NULL) 152 continue; 153 154 /* got it: finish up the line (like code above) */ 155 p++; 156 diff = p - fp->_p; 157 len += diff; 158 if (__slbexpand(fp, len)) 159 goto error; 160 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 161 diff); 162 fp->_r -= diff; 163 fp->_p = p; 164 break; 165 } 166 *lenp = len; 167 #ifdef notdef 168 fp->_lb._base[len] = 0; 169 #endif 170 FUNLOCKFILE(fp); 171 return ((char *)fp->_lb._base); 172 173 error: 174 *lenp = 0; /* ??? */ 175 FUNLOCKFILE(fp); 176 return (NULL); /* ??? */ 177 } 178