1 /* $NetBSD: fgets.c,v 1.5 1995/03/25 02:50:04 jtc Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 #if 0 41 static char sccsid[] = "@(#)fgets.c 8.2 (Berkeley) 12/22/93"; 42 #endif 43 static char rcsid[] = "$NetBSD: fgets.c,v 1.5 1995/03/25 02:50:04 jtc Exp $"; 44 #endif /* LIBC_SCCS and not lint */ 45 46 #include <stdio.h> 47 #include <string.h> 48 49 /* 50 * Read at most n-1 characters from the given file. 51 * Stop when a newline has been read, or the count runs out. 52 * Return first argument, or NULL if no characters were read. 53 */ 54 char * 55 fgets(buf, n, fp) 56 char *buf; 57 register int n; 58 register FILE *fp; 59 { 60 register size_t len; 61 register char *s; 62 register unsigned char *p, *t; 63 64 if (n <= 0) /* sanity check */ 65 return (NULL); 66 67 s = buf; 68 n--; /* leave space for NUL */ 69 while (n != 0) { 70 /* 71 * If the buffer is empty, refill it. 72 */ 73 if ((len = fp->_r) <= 0) { 74 if (__srefill(fp)) { 75 /* EOF/error: stop with partial or no line */ 76 if (s == buf) 77 return (NULL); 78 break; 79 } 80 len = fp->_r; 81 } 82 p = fp->_p; 83 84 /* 85 * Scan through at most n bytes of the current buffer, 86 * looking for '\n'. If found, copy up to and including 87 * newline, and stop. Otherwise, copy entire chunk 88 * and loop. 89 */ 90 if (len > n) 91 len = n; 92 t = memchr((void *)p, '\n', len); 93 if (t != NULL) { 94 len = ++t - p; 95 fp->_r -= len; 96 fp->_p = t; 97 (void)memcpy((void *)s, (void *)p, len); 98 s[len] = 0; 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 return (buf); 109 } 110