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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)fgets.c 8.2 (Berkeley) 12/22/93"; 40 #endif 41 static const char rcsid[] = 42 "$FreeBSD$"; 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <stdio.h> 46 #include <string.h> 47 #include "local.h" 48 #include "libc_private.h" 49 50 /* 51 * Read at most n-1 characters from the given file. 52 * Stop when a newline has been read, or the count runs out. 53 * Return first argument, or NULL if no characters were read. 54 */ 55 char * 56 fgets(buf, n, fp) 57 char *buf; 58 register int n; 59 register FILE *fp; 60 { 61 register size_t len; 62 register char *s; 63 register unsigned char *p, *t; 64 65 if (n <= 0) /* sanity check */ 66 return (NULL); 67 68 FLOCKFILE(fp); 69 s = buf; 70 n--; /* leave space for NUL */ 71 while (n != 0) { 72 /* 73 * If the buffer is empty, refill it. 74 */ 75 if ((len = fp->_r) <= 0) { 76 if (__srefill(fp)) { 77 /* EOF/error: stop with partial or no line */ 78 if (s == buf) { 79 FUNLOCKFILE(fp); 80 return (NULL); 81 } 82 break; 83 } 84 len = fp->_r; 85 } 86 p = fp->_p; 87 88 /* 89 * Scan through at most n bytes of the current buffer, 90 * looking for '\n'. If found, copy up to and including 91 * newline, and stop. Otherwise, copy entire chunk 92 * and loop. 93 */ 94 if (len > n) 95 len = n; 96 t = memchr((void *)p, '\n', len); 97 if (t != NULL) { 98 len = ++t - p; 99 fp->_r -= len; 100 fp->_p = t; 101 (void)memcpy((void *)s, (void *)p, len); 102 s[len] = 0; 103 FUNLOCKFILE(fp); 104 return (buf); 105 } 106 fp->_r -= len; 107 fp->_p += len; 108 (void)memcpy((void *)s, (void *)p, len); 109 s += len; 110 n -= len; 111 } 112 *s = 0; 113 FUNLOCKFILE(fp); 114 return (buf); 115 } 116