1 /* $NetBSD: fgets.c,v 1.27 2009/10/25 20:44:13 christos Exp $ */ 2 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 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)fgets.c 8.2 (Berkeley) 12/22/93"; 39 #else 40 __RCSID("$NetBSD: fgets.c,v 1.27 2009/10/25 20:44:13 christos Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <assert.h> 45 #include <stdio.h> 46 #include <errno.h> 47 #include <string.h> 48 #include "reentrant.h" 49 #include "local.h" 50 #ifdef _FORTIFY_SOURCE 51 #undef fgets 52 #endif 53 54 /* 55 * Read at most n-1 characters from the given file. 56 * Stop when a newline has been read, or the count runs out. 57 * Return first argument, or NULL if no characters were read. 58 */ 59 char * 60 fgets(buf, n, fp) 61 char *buf; 62 int n; 63 FILE *fp; 64 { 65 int len; 66 char *s; 67 unsigned char *p, *t; 68 69 _DIAGASSERT(buf != NULL); 70 _DIAGASSERT(fp != NULL); 71 72 FLOCKFILE(fp); 73 _SET_ORIENTATION(fp, -1); 74 s = buf; 75 n--; /* leave space for NUL */ 76 do { 77 /* 78 * If the buffer is empty, refill it. 79 */ 80 if (fp->_r <= 0) { 81 if (__srefill(fp)) { 82 /* EOF/error: stop with partial or no line */ 83 if (s == buf) { 84 FUNLOCKFILE(fp); 85 return (NULL); 86 } 87 break; 88 } 89 } 90 len = fp->_r; 91 p = fp->_p; 92 93 /* 94 * Scan through at most n bytes of the current buffer, 95 * looking for '\n'. If found, copy up to and including 96 * newline, and stop. Otherwise, copy entire chunk 97 * and loop. 98 */ 99 if (len > n) { 100 if (n < 0) { 101 /* 102 * Caller's length <= 0 103 * We can't write into the buffer, so cannot 104 * return a string, so must return NULL. 105 * Set errno and __SERR so it is consistent. 106 * TOG gives no indication of what to do here! 107 */ 108 errno = EINVAL; 109 fp->_flags |= __SERR; 110 FUNLOCKFILE(fp); 111 return NULL; 112 } 113 len = n; 114 } 115 t = memchr(p, '\n', (size_t)len); 116 if (t != NULL) { 117 len = (int)(++t - p); 118 fp->_r -= len; 119 fp->_p = t; 120 (void)memcpy(s, p, (size_t)len); 121 s[len] = 0; 122 FUNLOCKFILE(fp); 123 return (buf); 124 } 125 fp->_r -= len; 126 fp->_p += len; 127 (void)memcpy(s, p, (size_t)len); 128 s += len; 129 n -= len; 130 } while (n != 0); 131 *s = 0; 132 FUNLOCKFILE(fp); 133 return (buf); 134 } 135