1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)fgets.c 8.2 (Berkeley) 12/22/93"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "namespace.h" 42 #include <errno.h> 43 #include <stdio.h> 44 #include <string.h> 45 #include "un-namespace.h" 46 #include "local.h" 47 #include "libc_private.h" 48 49 /* 50 * Read at most n-1 characters from the given file. 51 * Stop when a newline has been read, or the count runs out. 52 * Return first argument, or NULL if no characters were read. 53 */ 54 char * 55 fgets(char * __restrict buf, int n, FILE * __restrict fp) 56 { 57 size_t len; 58 char *s, *ret; 59 unsigned char *p, *t; 60 61 FLOCKFILE_CANCELSAFE(fp); 62 ORIENT(fp, -1); 63 64 if (n <= 0) { /* sanity check */ 65 fp->_flags |= __SERR; 66 errno = EINVAL; 67 ret = NULL; 68 goto end; 69 } 70 71 s = buf; 72 n--; /* leave space for NUL */ 73 while (n != 0) { 74 /* 75 * If the buffer is empty, refill it. 76 */ 77 if ((len = fp->_r) <= 0) { 78 if (__srefill(fp)) { 79 /* EOF/error: stop with partial or no line */ 80 if (!__sfeof(fp) || s == buf) { 81 ret = NULL; 82 goto end; 83 } 84 break; 85 } 86 len = fp->_r; 87 } 88 p = fp->_p; 89 90 /* 91 * Scan through at most n bytes of the current buffer, 92 * looking for '\n'. If found, copy up to and including 93 * newline, and stop. Otherwise, copy entire chunk 94 * and loop. 95 */ 96 if (len > n) 97 len = n; 98 t = memchr((void *)p, '\n', len); 99 if (t != NULL) { 100 len = ++t - p; 101 fp->_r -= len; 102 fp->_p = t; 103 (void)memcpy((void *)s, (void *)p, len); 104 s[len] = 0; 105 ret = buf; 106 goto end; 107 } 108 fp->_r -= len; 109 fp->_p += len; 110 (void)memcpy((void *)s, (void *)p, len); 111 s += len; 112 n -= len; 113 } 114 *s = 0; 115 ret = buf; 116 end: 117 FUNLOCKFILE_CANCELSAFE(); 118 return (ret); 119 } 120