1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)fgetln.c 8.2 (Berkeley) 1/2/94"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include "local.h" 45 46 /* 47 * Expand the line buffer. Return -1 on error. 48 #ifdef notdef 49 * The `new size' does not account for a terminating '\0', 50 * so we add 1 here. 51 #endif 52 */ 53 __slbexpand(fp, newsize) 54 FILE *fp; 55 size_t newsize; 56 { 57 void *p; 58 59 #ifdef notdef 60 ++newsize; 61 #endif 62 if (fp->_lb._size >= newsize) 63 return (0); 64 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 65 return (-1); 66 fp->_lb._base = p; 67 fp->_lb._size = newsize; 68 return (0); 69 } 70 71 /* 72 * Get an input line. The returned pointer often (but not always) 73 * points into a stdio buffer. Fgetln does not alter the text of 74 * the returned line (which is thus not a C string because it will 75 * not necessarily end with '\0'), but does allow callers to modify 76 * it if they wish. Thus, we set __SMOD in case the caller does. 77 */ 78 char * 79 fgetln(fp, lenp) 80 register FILE *fp; 81 size_t *lenp; 82 { 83 register unsigned char *p; 84 register size_t len; 85 size_t off; 86 87 /* make sure there is input */ 88 if (fp->_r <= 0 && __srefill(fp)) { 89 *lenp = 0; 90 return (NULL); 91 } 92 93 /* look for a newline in the input */ 94 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) != NULL) { 95 register char *ret; 96 97 /* 98 * Found one. Flag buffer as modified to keep fseek from 99 * `optimising' a backward seek, in case the user stomps on 100 * the text. 101 */ 102 p++; /* advance over it */ 103 ret = (char *)fp->_p; 104 *lenp = len = p - fp->_p; 105 fp->_flags |= __SMOD; 106 fp->_r -= len; 107 fp->_p = p; 108 return (ret); 109 } 110 111 /* 112 * We have to copy the current buffered data to the line buffer. 113 * As a bonus, though, we can leave off the __SMOD. 114 * 115 * OPTIMISTIC is length that we (optimistically) expect will 116 * accomodate the `rest' of the string, on each trip through the 117 * loop below. 118 */ 119 #define OPTIMISTIC 80 120 121 for (len = fp->_r, off = 0;; len += fp->_r) { 122 register size_t diff; 123 124 /* 125 * Make sure there is room for more bytes. Copy data from 126 * file buffer to line buffer, refill file and look for 127 * newline. The loop stops only when we find a newline. 128 */ 129 if (__slbexpand(fp, len + OPTIMISTIC)) 130 goto error; 131 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 132 len - off); 133 off = len; 134 if (__srefill(fp)) 135 break; /* EOF or error: return partial line */ 136 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) == NULL) 137 continue; 138 139 /* got it: finish up the line (like code above) */ 140 p++; 141 diff = p - fp->_p; 142 len += diff; 143 if (__slbexpand(fp, len)) 144 goto error; 145 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 146 diff); 147 fp->_r -= diff; 148 fp->_p = p; 149 break; 150 } 151 *lenp = len; 152 #ifdef notdef 153 fp->_lb._base[len] = 0; 154 #endif 155 return ((char *)fp->_lb._base); 156 157 error: 158 *lenp = 0; /* ??? */ 159 return (NULL); /* ??? */ 160 } 161