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. 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 */ 35 36 #include "namespace.h" 37 #include <stdio.h> 38 #include <string.h> 39 #include "un-namespace.h" 40 #include "local.h" 41 #include "libc_private.h" 42 43 /* 44 * Read at most n-1 characters from the given file. 45 * Stop when a newline has been read, or the count runs out. 46 * Return first argument, or NULL if no characters were read. 47 */ 48 char * 49 fgets(char *buf, int n, FILE *fp) 50 { 51 size_t len; 52 char *s; 53 unsigned char *p, *t; 54 55 if (n <= 0) /* sanity check */ 56 return (NULL); 57 58 FLOCKFILE(fp); 59 ORIENT(fp, -1); 60 s = buf; 61 n--; /* leave space for NUL */ 62 while (n != 0) { 63 /* 64 * If the buffer is empty, refill it. 65 */ 66 if ((len = fp->pub._r) <= 0) { 67 if (__srefill(fp)) { 68 /* EOF/error: stop with partial or no line */ 69 if (s == buf) { 70 FUNLOCKFILE(fp); 71 return (NULL); 72 } 73 break; 74 } 75 len = fp->pub._r; 76 } 77 p = fp->pub._p; 78 79 /* 80 * Scan through at most n bytes of the current buffer, 81 * looking for '\n'. If found, copy up to and including 82 * newline, and stop. Otherwise, copy entire chunk 83 * and loop. 84 */ 85 if (len > n) 86 len = n; 87 t = memchr((void *)p, '\n', len); 88 if (t != NULL) { 89 len = ++t - p; 90 fp->pub._r -= len; 91 fp->pub._p = t; 92 memcpy((void *)s, (void *)p, len); 93 s[len] = 0; 94 FUNLOCKFILE(fp); 95 return (buf); 96 } 97 fp->pub._r -= len; 98 fp->pub._p += len; 99 memcpy((void *)s, (void *)p, len); 100 s += len; 101 n -= len; 102 } 103 *s = 0; 104 FUNLOCKFILE(fp); 105 return (buf); 106 } 107