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 1.5 2005/01/31 22:29:40 dillon Exp $ 39 */ 40 41 #include "namespace.h" 42 #include <stdio.h> 43 #include <string.h> 44 #include "un-namespace.h" 45 #include "local.h" 46 #include "libc_private.h" 47 48 /* 49 * Read at most n-1 characters from the given file. 50 * Stop when a newline has been read, or the count runs out. 51 * Return first argument, or NULL if no characters were read. 52 */ 53 char * 54 fgets(char *buf, int n, FILE *fp) 55 { 56 size_t len; 57 char *s; 58 unsigned char *p, *t; 59 60 if (n <= 0) /* sanity check */ 61 return (NULL); 62 63 FLOCKFILE(fp); 64 s = buf; 65 n--; /* leave space for NUL */ 66 while (n != 0) { 67 /* 68 * If the buffer is empty, refill it. 69 */ 70 if ((len = fp->_r) <= 0) { 71 if (__srefill(fp)) { 72 /* EOF/error: stop with partial or no line */ 73 if (s == buf) { 74 FUNLOCKFILE(fp); 75 return (NULL); 76 } 77 break; 78 } 79 len = fp->_r; 80 } 81 p = fp->_p; 82 83 /* 84 * Scan through at most n bytes of the current buffer, 85 * looking for '\n'. If found, copy up to and including 86 * newline, and stop. Otherwise, copy entire chunk 87 * and loop. 88 */ 89 if (len > n) 90 len = n; 91 t = memchr((void *)p, '\n', len); 92 if (t != NULL) { 93 len = ++t - p; 94 fp->_r -= len; 95 fp->_p = t; 96 (void)memcpy((void *)s, (void *)p, len); 97 s[len] = 0; 98 FUNLOCKFILE(fp); 99 return (buf); 100 } 101 fp->_r -= len; 102 fp->_p += len; 103 (void)memcpy((void *)s, (void *)p, len); 104 s += len; 105 n -= len; 106 } 107 *s = 0; 108 FUNLOCKFILE(fp); 109 return (buf); 110 } 111