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 1.7 2004/09/28 18:12:44 otto 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(char *buf, int n, FILE *fp) 49 { 50 size_t len; 51 char *s; 52 unsigned char *p, *t; 53 54 if (n <= 0) /* sanity check */ 55 return (NULL); 56 57 s = buf; 58 n--; /* leave space for NUL */ 59 while (n != 0) { 60 /* 61 * If the buffer is empty, refill it. 62 */ 63 if (fp->_r <= 0) { 64 if (__srefill(fp)) { 65 /* EOF/error: stop with partial or no line */ 66 if (s == buf) 67 return (NULL); 68 break; 69 } 70 } 71 len = fp->_r; 72 p = fp->_p; 73 74 /* 75 * Scan through at most n bytes of the current buffer, 76 * looking for '\n'. If found, copy up to and including 77 * newline, and stop. Otherwise, copy entire chunk 78 * and loop. 79 */ 80 if (len > n) 81 len = n; 82 t = memchr((void *)p, '\n', len); 83 if (t != NULL) { 84 len = ++t - p; 85 fp->_r -= len; 86 fp->_p = t; 87 (void)memcpy((void *)s, (void *)p, len); 88 s[len] = 0; 89 return (buf); 90 } 91 fp->_r -= len; 92 fp->_p += len; 93 (void)memcpy((void *)s, (void *)p, len); 94 s += len; 95 n -= len; 96 } 97 *s = 0; 98 return (buf); 99 } 100