1 /* $NetBSD: fgetln.c,v 1.2 1995/02/02 02:09:10 jtc 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 #if defined(LIBC_SCCS) && !defined(lint) 40 /* from: static char sccsid[] = "@(#)fgetline.c 8.1 (Berkeley) 6/4/93"; */ 41 static char *rcsid = "$Id: fgetln.c,v 1.2 1995/02/02 02:09:10 jtc Exp $"; 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include "local.h" 48 49 /* 50 * Expand the line buffer. Return -1 on error. 51 #ifdef notdef 52 * The `new size' does not account for a terminating '\0', 53 * so we add 1 here. 54 #endif 55 */ 56 int 57 __slbexpand(fp, newsize) 58 FILE *fp; 59 size_t newsize; 60 { 61 void *p; 62 63 #ifdef notdef 64 ++newsize; 65 #endif 66 if (fp->_lb._size >= newsize) 67 return (0); 68 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 69 return (-1); 70 fp->_lb._base = p; 71 fp->_lb._size = newsize; 72 return (0); 73 } 74 75 /* 76 * Get an input line. The returned pointer often (but not always) 77 * points into a stdio buffer. Fgetline does not alter the text of 78 * the returned line (which is thus not a C string because it will 79 * not necessarily end with '\0'), but does allow callers to modify 80 * it if they wish. Thus, we set __SMOD in case the caller does. 81 */ 82 char * 83 fgetln(fp, lenp) 84 register FILE *fp; 85 size_t *lenp; 86 { 87 register unsigned char *p; 88 register size_t len; 89 size_t off; 90 91 /* make sure there is input */ 92 if (fp->_r <= 0 && __srefill(fp)) { 93 *lenp = 0; 94 return (NULL); 95 } 96 97 /* look for a newline in the input */ 98 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) != NULL) { 99 register char *ret; 100 101 /* 102 * Found one. Flag buffer as modified to keep fseek from 103 * `optimising' a backward seek, in case the user stomps on 104 * the text. 105 */ 106 p++; /* advance over it */ 107 ret = (char *)fp->_p; 108 *lenp = len = p - fp->_p; 109 fp->_flags |= __SMOD; 110 fp->_r -= len; 111 fp->_p = p; 112 return (ret); 113 } 114 115 /* 116 * We have to copy the current buffered data to the line buffer. 117 * As a bonus, though, we can leave off the __SMOD. 118 * 119 * OPTIMISTIC is length that we (optimistically) expect will 120 * accomodate the `rest' of the string, on each trip through the 121 * loop below. 122 */ 123 #define OPTIMISTIC 80 124 125 for (len = fp->_r, off = 0;; len += fp->_r) { 126 register size_t diff; 127 128 /* 129 * Make sure there is room for more bytes. Copy data from 130 * file buffer to line buffer, refill file and look for 131 * newline. The loop stops only when we find a newline. 132 */ 133 if (__slbexpand(fp, len + OPTIMISTIC)) 134 goto error; 135 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 136 len - off); 137 off = len; 138 if (__srefill(fp)) 139 break; /* EOF or error: return partial line */ 140 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) == NULL) 141 continue; 142 143 /* got it: finish up the line (like code above) */ 144 p++; 145 diff = p - fp->_p; 146 len += diff; 147 if (__slbexpand(fp, len)) 148 goto error; 149 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 150 diff); 151 fp->_r -= diff; 152 fp->_p = p; 153 break; 154 } 155 *lenp = len; 156 #ifdef notdef 157 fp->_lb._base[len] = 0; 158 #endif 159 return ((char *)fp->_lb._base); 160 161 error: 162 *lenp = 0; /* ??? */ 163 return (NULL); /* ??? */ 164 } 165