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 * 4. 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(buf, n, fp) 53 char *buf; 54 int n; 55 FILE *fp; 56 { 57 size_t len; 58 char *s; 59 unsigned char *p, *t; 60 61 if (n <= 0) /* sanity check */ 62 return (NULL); 63 64 FLOCKFILE(fp); 65 ORIENT(fp, -1); 66 s = buf; 67 n--; /* leave space for NUL */ 68 while (n != 0) { 69 /* 70 * If the buffer is empty, refill it. 71 */ 72 if ((len = fp->_r) <= 0) { 73 if (__srefill(fp)) { 74 /* EOF/error: stop with partial or no line */ 75 if (s == buf) { 76 FUNLOCKFILE(fp); 77 return (NULL); 78 } 79 break; 80 } 81 len = fp->_r; 82 } 83 p = fp->_p; 84 85 /* 86 * Scan through at most n bytes of the current buffer, 87 * looking for '\n'. If found, copy up to and including 88 * newline, and stop. Otherwise, copy entire chunk 89 * and loop. 90 */ 91 if (len > n) 92 len = n; 93 t = memchr((void *)p, '\n', len); 94 if (t != NULL) { 95 len = ++t - p; 96 fp->_r -= len; 97 fp->_p = t; 98 (void)memcpy((void *)s, (void *)p, len); 99 s[len] = 0; 100 FUNLOCKFILE(fp); 101 return (buf); 102 } 103 fp->_r -= len; 104 fp->_p += len; 105 (void)memcpy((void *)s, (void *)p, len); 106 s += len; 107 n -= len; 108 } 109 *s = 0; 110 FUNLOCKFILE(fp); 111 return (buf); 112 } 113