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 * @(#)fgets.c 8.2 (Berkeley) 12/22/93 37 * $FreeBSD: src/lib/libc/stdio/fgets.c,v 1.9 1999/08/28 00:01:00 peter Exp $ 38 * $DragonFly: src/lib/libc/stdio/fgets.c,v 1.4 2004/06/07 20:35:41 hmp Exp $ 39 */ 40 41 #include <stdio.h> 42 #include <string.h> 43 #include "local.h" 44 #include "libc_private.h" 45 46 /* 47 * Read at most n-1 characters from the given file. 48 * Stop when a newline has been read, or the count runs out. 49 * Return first argument, or NULL if no characters were read. 50 */ 51 char * 52 fgets(char *buf, int n, FILE *fp) 53 { 54 size_t len; 55 char *s; 56 unsigned char *p, *t; 57 58 if (n <= 0) /* sanity check */ 59 return (NULL); 60 61 FLOCKFILE(fp); 62 s = buf; 63 n--; /* leave space for NUL */ 64 while (n != 0) { 65 /* 66 * If the buffer is empty, refill it. 67 */ 68 if ((len = fp->_r) <= 0) { 69 if (__srefill(fp)) { 70 /* EOF/error: stop with partial or no line */ 71 if (s == buf) { 72 FUNLOCKFILE(fp); 73 return (NULL); 74 } 75 break; 76 } 77 len = fp->_r; 78 } 79 p = fp->_p; 80 81 /* 82 * Scan through at most n bytes of the current buffer, 83 * looking for '\n'. If found, copy up to and including 84 * newline, and stop. Otherwise, copy entire chunk 85 * and loop. 86 */ 87 if (len > n) 88 len = n; 89 t = memchr((void *)p, '\n', len); 90 if (t != NULL) { 91 len = ++t - p; 92 fp->_r -= len; 93 fp->_p = t; 94 (void)memcpy((void *)s, (void *)p, len); 95 s[len] = 0; 96 FUNLOCKFILE(fp); 97 return (buf); 98 } 99 fp->_r -= len; 100 fp->_p += len; 101 (void)memcpy((void *)s, (void *)p, len); 102 s += len; 103 n -= len; 104 } 105 *s = 0; 106 FUNLOCKFILE(fp); 107 return (buf); 108 } 109