1 /* $NetBSD: fgetln.c,v 1.3 1997/07/13 20:14:54 christos 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 1.3 1997/07/13 20:14:54 christos 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 53 int __slbexpand __P((FILE *, size_t)); 54 55 /* 56 * Expand the line buffer. Return -1 on error. 57 #ifdef notdef 58 * The `new size' does not account for a terminating '\0', 59 * so we add 1 here. 60 #endif 61 */ 62 int 63 __slbexpand(fp, newsize) 64 FILE *fp; 65 size_t newsize; 66 { 67 void *p; 68 69 #ifdef notdef 70 ++newsize; 71 #endif 72 if (fp->_lb._size >= newsize) 73 return (0); 74 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 75 return (-1); 76 fp->_lb._base = p; 77 fp->_lb._size = newsize; 78 return (0); 79 } 80 81 /* 82 * Get an input line. The returned pointer often (but not always) 83 * points into a stdio buffer. Fgetline does not alter the text of 84 * the returned line (which is thus not a C string because it will 85 * not necessarily end with '\0'), but does allow callers to modify 86 * it if they wish. Thus, we set __SMOD in case the caller does. 87 */ 88 char * 89 fgetln(fp, lenp) 90 register FILE *fp; 91 size_t *lenp; 92 { 93 register unsigned char *p; 94 register size_t len; 95 size_t off; 96 97 /* make sure there is input */ 98 if (fp->_r <= 0 && __srefill(fp)) { 99 *lenp = 0; 100 return (NULL); 101 } 102 103 /* look for a newline in the input */ 104 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) != NULL) { 105 register char *ret; 106 107 /* 108 * Found one. Flag buffer as modified to keep fseek from 109 * `optimising' a backward seek, in case the user stomps on 110 * the text. 111 */ 112 p++; /* advance over it */ 113 ret = (char *)fp->_p; 114 *lenp = len = p - fp->_p; 115 fp->_flags |= __SMOD; 116 fp->_r -= len; 117 fp->_p = p; 118 return (ret); 119 } 120 121 /* 122 * We have to copy the current buffered data to the line buffer. 123 * As a bonus, though, we can leave off the __SMOD. 124 * 125 * OPTIMISTIC is length that we (optimistically) expect will 126 * accomodate the `rest' of the string, on each trip through the 127 * loop below. 128 */ 129 #define OPTIMISTIC 80 130 131 for (len = fp->_r, off = 0;; len += fp->_r) { 132 register size_t diff; 133 134 /* 135 * Make sure there is room for more bytes. Copy data from 136 * file buffer to line buffer, refill file and look for 137 * newline. The loop stops only when we find a newline. 138 */ 139 if (__slbexpand(fp, len + OPTIMISTIC)) 140 goto error; 141 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 142 len - off); 143 off = len; 144 if (__srefill(fp)) 145 break; /* EOF or error: return partial line */ 146 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) == NULL) 147 continue; 148 149 /* got it: finish up the line (like code above) */ 150 p++; 151 diff = p - fp->_p; 152 len += diff; 153 if (__slbexpand(fp, len)) 154 goto error; 155 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 156 diff); 157 fp->_r -= diff; 158 fp->_p = p; 159 break; 160 } 161 *lenp = len; 162 #ifdef notdef 163 fp->_lb._base[len] = 0; 164 #endif 165 return ((char *)fp->_lb._base); 166 167 error: 168 *lenp = 0; /* ??? */ 169 return (NULL); /* ??? */ 170 } 171