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 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)fgets.c 8.2 (Berkeley) 12/22/93 33 * $FreeBSD: src/lib/libc/stdio/fgets.c,v 1.14 2007/01/09 00:28:06 imp Exp $ 34 * $DragonFly: src/lib/libc/stdio/fgets.c,v 1.7 2005/11/20 11:07:30 swildner Exp $ 35 */ 36 37 #include "namespace.h" 38 #include <stdio.h> 39 #include <string.h> 40 #include "un-namespace.h" 41 #include "local.h" 42 #include "libc_private.h" 43 #include "priv_stdio.h" 44 45 /* 46 * Read at most n-1 characters from the given file. 47 * Stop when a newline has been read, or the count runs out. 48 * Return first argument, or NULL if no characters were read. 49 */ 50 char * 51 fgets(char *buf, int n, FILE *fp) 52 { 53 size_t len; 54 char *s; 55 unsigned char *p, *t; 56 57 if (n <= 0) /* sanity check */ 58 return (NULL); 59 60 FLOCKFILE(fp); 61 ORIENT(fp, -1); 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->pub._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->pub._r; 78 } 79 p = fp->pub._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->pub._r -= len; 93 fp->pub._p = t; 94 memcpy((void *)s, (void *)p, len); 95 s[len] = 0; 96 FUNLOCKFILE(fp); 97 return (buf); 98 } 99 fp->pub._r -= len; 100 fp->pub._p += len; 101 memcpy((void *)s, (void *)p, len); 102 s += len; 103 n -= len; 104 } 105 *s = 0; 106 FUNLOCKFILE(fp); 107 return (buf); 108 } 109