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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)fgets.c 8.2 (Berkeley) 12/22/93"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <stdio.h> 42 #include <string.h> 43 #include "local.h" 44 #ifdef _THREAD_SAFE 45 #include <pthread.h> 46 #include "pthread_private.h" 47 #endif 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(buf, n, fp) 56 char *buf; 57 register size_t n; 58 register FILE *fp; 59 { 60 register size_t len; 61 register char *s; 62 register unsigned char *p, *t; 63 64 if (n == 0) /* sanity check */ 65 return (NULL); 66 67 #ifdef _THREAD_SAFE 68 _thread_flockfile(fp,__FILE__,__LINE__); 69 #endif 70 s = buf; 71 n--; /* leave space for NUL */ 72 while (n != 0) { 73 /* 74 * If the buffer is empty, refill it. 75 */ 76 if ((len = fp->_r) <= 0) { 77 if (__srefill(fp)) { 78 /* EOF/error: stop with partial or no line */ 79 if (s == buf) { 80 #ifdef _THREAD_SAFE 81 _thread_funlockfile(fp); 82 #endif 83 return (NULL); 84 } 85 break; 86 } 87 len = fp->_r; 88 } 89 p = fp->_p; 90 91 /* 92 * Scan through at most n bytes of the current buffer, 93 * looking for '\n'. If found, copy up to and including 94 * newline, and stop. Otherwise, copy entire chunk 95 * and loop. 96 */ 97 if (len > n) 98 len = n; 99 t = memchr((void *)p, '\n', len); 100 if (t != NULL) { 101 len = ++t - p; 102 fp->_r -= len; 103 fp->_p = t; 104 (void)memcpy((void *)s, (void *)p, len); 105 s[len] = 0; 106 #ifdef _THREAD_SAFE 107 _thread_funlockfile(fp); 108 #endif 109 return (buf); 110 } 111 fp->_r -= len; 112 fp->_p += len; 113 (void)memcpy((void *)s, (void *)p, len); 114 s += len; 115 n -= len; 116 } 117 *s = 0; 118 #ifdef _THREAD_SAFE 119 _thread_funlockfile(fp); 120 #endif 121 return (buf); 122 } 123