1 /* $OpenBSD: fgets.c,v 1.10 2005/08/08 08:05:36 espie Exp $ */ 2 /*- 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Chris Torek. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <stdio.h> 35 #include <string.h> 36 #include "local.h" 37 38 /* 39 * Read at most n-1 characters from the given file. 40 * Stop when a newline has been read, or the count runs out. 41 * Return first argument, or NULL if no characters were read. 42 * Do not return NULL if n == 1. 43 */ 44 char * 45 fgets(char *buf, int n, FILE *fp) 46 { 47 size_t len; 48 char *s; 49 unsigned char *p, *t; 50 51 if (n <= 0) /* sanity check */ 52 return (NULL); 53 54 FLOCKFILE(fp); 55 _SET_ORIENTATION(fp, -1); 56 s = buf; 57 n--; /* leave space for NUL */ 58 while (n != 0) { 59 /* 60 * If the buffer is empty, refill it. 61 */ 62 if (fp->_r <= 0) { 63 if (__srefill(fp)) { 64 /* EOF/error: stop with partial or no line */ 65 if (s == buf) { 66 FUNLOCKFILE(fp); 67 return (NULL); 68 } 69 break; 70 } 71 } 72 len = fp->_r; 73 p = fp->_p; 74 75 /* 76 * Scan through at most n bytes of the current buffer, 77 * looking for '\n'. If found, copy up to and including 78 * newline, and stop. Otherwise, copy entire chunk 79 * and loop. 80 */ 81 if ((int)len > n) 82 len = n; 83 t = memchr((void *)p, '\n', len); 84 if (t != NULL) { 85 len = ++t - p; 86 fp->_r -= len; 87 fp->_p = t; 88 (void)memcpy((void *)s, (void *)p, len); 89 s[len] = '\0'; 90 FUNLOCKFILE(fp); 91 return (buf); 92 } 93 fp->_r -= len; 94 fp->_p += len; 95 (void)memcpy((void *)s, (void *)p, len); 96 s += len; 97 n -= len; 98 } 99 *s = '\0'; 100 FUNLOCKFILE(fp); 101 return (buf); 102 } 103
