1 /* $OpenBSD: fgetln.c,v 1.11 2009/11/21 09:53:44 guenther Exp $ */ 2 /*- 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Chris Torek. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include "local.h" 38 39 /* 40 * Expand the line buffer. Return -1 on error. 41 #ifdef notdef 42 * The `new size' does not account for a terminating '\0', 43 * so we add 1 here. 44 #endif 45 */ 46 int 47 __slbexpand(FILE *fp, size_t newsize) 48 { 49 void *p; 50 51 #ifdef notdef 52 ++newsize; 53 #endif 54 if (fp->_lb._size >= newsize) 55 return (0); 56 if ((p = realloc(fp->_lb._base, newsize)) == NULL) 57 return (-1); 58 fp->_lb._base = p; 59 fp->_lb._size = newsize; 60 return (0); 61 } 62 63 /* 64 * Get an input line. The returned pointer often (but not always) 65 * points into a stdio buffer. Fgetline does not alter the text of 66 * the returned line (which is thus not a C string because it will 67 * not necessarily end with '\0'), but does allow callers to modify 68 * it if they wish. Thus, we set __SMOD in case the caller does. 69 */ 70 char * 71 fgetln(FILE *fp, size_t *lenp) 72 { 73 unsigned char *p; 74 char *ret; 75 size_t len; 76 size_t off; 77 78 FLOCKFILE(fp); 79 _SET_ORIENTATION(fp, -1); 80 81 /* make sure there is input */ 82 if (fp->_r <= 0 && __srefill(fp)) 83 goto error; 84 85 /* look for a newline in the input */ 86 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) != NULL) { 87 /* 88 * Found one. Flag buffer as modified to keep fseek from 89 * `optimising' a backward seek, in case the user stomps on 90 * the text. 91 */ 92 p++; /* advance over it */ 93 ret = (char *)fp->_p; 94 *lenp = len = p - fp->_p; 95 fp->_flags |= __SMOD; 96 fp->_r -= len; 97 fp->_p = p; 98 FUNLOCKFILE(fp); 99 return (ret); 100 } 101 102 /* 103 * We have to copy the current buffered data to the line buffer. 104 * As a bonus, though, we can leave off the __SMOD. 105 * 106 * OPTIMISTIC is length that we (optimistically) expect will 107 * accommodate the `rest' of the string, on each trip through the 108 * loop below. 109 */ 110 #define OPTIMISTIC 80 111 112 for (len = fp->_r, off = 0;; len += fp->_r) { 113 size_t diff; 114 115 /* 116 * Make sure there is room for more bytes. Copy data from 117 * file buffer to line buffer, refill file and look for 118 * newline. The loop stops only when we find a newline. 119 */ 120 if (__slbexpand(fp, len + OPTIMISTIC)) 121 goto error; 122 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 123 len - off); 124 off = len; 125 if (__srefill(fp)) 126 break; /* EOF or error: return partial line */ 127 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) == NULL) 128 continue; 129 130 /* got it: finish up the line (like code above) */ 131 p++; 132 diff = p - fp->_p; 133 len += diff; 134 if (__slbexpand(fp, len)) 135 goto error; 136 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p, 137 diff); 138 fp->_r -= diff; 139 fp->_p = p; 140 break; 141 } 142 *lenp = len; 143 ret = (char *)fp->_lb._base; 144 #ifdef notdef 145 ret[len] = '\0'; 146 #endif 147 FUNLOCKFILE(fp); 148 return (ret); 149 150 error: 151 *lenp = 0; /* ??? */ 152 FUNLOCKFILE(fp); 153 return (NULL); /* ??? */ 154 } 155