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 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char rcsid[] = "$OpenBSD: fgets.c,v 1.6 2003/10/08 10:29:55 avsm Exp $"; 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include <stdio.h> 38 #include <string.h> 39 #include "local.h" 40 41 /* 42 * Read at most n-1 characters from the given file. 43 * Stop when a newline has been read, or the count runs out. 44 * Return first argument, or NULL if no characters were read. 45 * Do not return NULL if n == 1. 46 */ 47 char * 48 fgets(buf, n, fp) 49 char *buf; 50 register int n; 51 register 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 s = buf; 61 n--; /* leave space for NUL */ 62 while (n != 0) { 63 /* 64 * If the buffer is empty, refill it. 65 */ 66 if (fp->_r <= 0) { 67 if (__srefill(fp)) { 68 /* EOF/error: stop with partial or no line */ 69 if (s == buf) 70 return (NULL); 71 break; 72 } 73 } 74 len = fp->_r; 75 p = fp->_p; 76 77 /* 78 * Scan through at most n bytes of the current buffer, 79 * looking for '\n'. If found, copy up to and including 80 * newline, and stop. Otherwise, copy entire chunk 81 * and loop. 82 */ 83 if (len > n) 84 len = n; 85 t = memchr((void *)p, '\n', len); 86 if (t != NULL) { 87 len = ++t - p; 88 fp->_r -= len; 89 fp->_p = t; 90 (void)memcpy((void *)s, (void *)p, len); 91 s[len] = 0; 92 return (buf); 93 } 94 fp->_r -= len; 95 fp->_p += len; 96 (void)memcpy((void *)s, (void *)p, len); 97 s += len; 98 n -= len; 99 } 100 *s = 0; 101 return (buf); 102 } 103