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 1.7 2005/11/20 11:07:30 swildner 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 47 #include "libc_private.h" 48 #include "priv_stdio.h" 49 50 /* 51 * Read at most n-1 characters from the given file. 52 * Stop when a newline has been read, or the count runs out. 53 * Return first argument, or NULL if no characters were read. 54 */ 55 char * 56 fgets(char *buf, int n, FILE *fp) 57 { 58 size_t len; 59 char *s; 60 unsigned char *p, *t; 61 62 if (n <= 0) /* sanity check */ 63 return (NULL); 64 65 FLOCKFILE(fp); 66 s = buf; 67 n--; /* leave space for NUL */ 68 while (n != 0) { 69 /* 70 * If the buffer is empty, refill it. 71 */ 72 if ((len = fp->pub._r) <= 0) { 73 if (__srefill(fp)) { 74 /* EOF/error: stop with partial or no line */ 75 if (s == buf) { 76 FUNLOCKFILE(fp); 77 return (NULL); 78 } 79 break; 80 } 81 len = fp->pub._r; 82 } 83 p = fp->pub._p; 84 85 /* 86 * Scan through at most n bytes of the current buffer, 87 * looking for '\n'. If found, copy up to and including 88 * newline, and stop. Otherwise, copy entire chunk 89 * and loop. 90 */ 91 if (len > n) 92 len = n; 93 t = memchr((void *)p, '\n', len); 94 if (t != NULL) { 95 len = ++t - p; 96 fp->pub._r -= len; 97 fp->pub._p = t; 98 memcpy((void *)s, (void *)p, len); 99 s[len] = 0; 100 FUNLOCKFILE(fp); 101 return (buf); 102 } 103 fp->pub._r -= len; 104 fp->pub._p += len; 105 memcpy((void *)s, (void *)p, len); 106 s += len; 107 n -= len; 108 } 109 *s = 0; 110 FUNLOCKFILE(fp); 111 return (buf); 112 } 113