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 sccsid[] = "@(#)fgets.c 8.2 (Berkeley) 12/22/93"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include "namespace.h" 40 #include <stdio.h> 41 #include <string.h> 42 #include "un-namespace.h" 43 #include "local.h" 44 #include "libc_private.h" 45 46 /* 47 * Read at most n-1 characters from the given file. 48 * Stop when a newline has been read, or the count runs out. 49 * Return first argument, or NULL if no characters were read. 50 */ 51 char * 52 fgets(char * __restrict buf, int n, FILE * __restrict fp) 53 { 54 size_t len; 55 char *s; 56 unsigned char *p, *t; 57 58 if (n <= 0) /* sanity check */ 59 return (NULL); 60 61 FLOCKFILE(fp); 62 ORIENT(fp, -1); 63 s = buf; 64 n--; /* leave space for NUL */ 65 while (n != 0) { 66 /* 67 * If the buffer is empty, refill it. 68 */ 69 if ((len = fp->_r) <= 0) { 70 if (__srefill(fp)) { 71 /* EOF/error: stop with partial or no line */ 72 if (s == buf) { 73 FUNLOCKFILE(fp); 74 return (NULL); 75 } 76 break; 77 } 78 len = fp->_r; 79 } 80 p = fp->_p; 81 82 /* 83 * Scan through at most n bytes of the current buffer, 84 * looking for '\n'. If found, copy up to and including 85 * newline, and stop. Otherwise, copy entire chunk 86 * and loop. 87 */ 88 if (len > n) 89 len = n; 90 t = memchr((void *)p, '\n', len); 91 if (t != NULL) { 92 len = ++t - p; 93 fp->_r -= len; 94 fp->_p = t; 95 (void)memcpy((void *)s, (void *)p, len); 96 s[len] = 0; 97 FUNLOCKFILE(fp); 98 return (buf); 99 } 100 fp->_r -= len; 101 fp->_p += len; 102 (void)memcpy((void *)s, (void *)p, len); 103 s += len; 104 n -= len; 105 } 106 *s = 0; 107 FUNLOCKFILE(fp); 108 return (buf); 109 } 110