1 /* $NetBSD: fopen.c,v 1.18 2018/01/05 19:01:36 kamil 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[] = "@(#)fopen.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 __RCSID("$NetBSD: fopen.c,v 1.18 2018/01/05 19:01:36 kamil Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <sys/types.h> 46 #include <sys/stat.h> 47 #include <assert.h> 48 #include <fcntl.h> 49 #include <unistd.h> 50 #include <stdio.h> 51 #include <errno.h> 52 #include <limits.h> 53 #include "reentrant.h" 54 #include "local.h" 55 56 FILE * 57 fopen(const char *file, const char *mode) 58 { 59 FILE *fp; 60 int f; 61 int flags, oflags; 62 63 _DIAGASSERT(file != NULL); 64 if ((flags = __sflags(mode, &oflags)) == 0) 65 return NULL; 66 if ((fp = __sfp()) == NULL) 67 return NULL; 68 if ((f = open(file, oflags, DEFFILEMODE)) < 0) 69 goto release; 70 /* 71 * File descriptors are a full int, but _file is only a short. 72 * If we get a valid file descriptor that is greater or equal to 73 * USHRT_MAX, then the fd will get sign-extended into an 74 * invalid file descriptor. Handle this case by failing the 75 * open. (We treat the short as unsigned, and special-case -1). 76 */ 77 if (f >= USHRT_MAX) { 78 (void)close(f); 79 errno = EMFILE; 80 goto release; 81 } 82 83 fp->_file = f; 84 fp->_flags = flags; 85 fp->_cookie = fp; 86 fp->_read = __sread; 87 fp->_write = __swrite; 88 fp->_seek = __sseek; 89 fp->_close = __sclose; 90 91 /* 92 * When opening in append mode, even though we use O_APPEND, 93 * we need to seek to the end so that ftell() gets the right 94 * answer. If the user then alters the seek pointer, or 95 * the file extends, this will fail, but there is not much 96 * we can do about this. (We could set __SAPP and check in 97 * fseek and ftell.) 98 */ 99 if (oflags & O_APPEND) 100 (void) __sseek((void *)fp, (off_t)0, SEEK_END); 101 return fp; 102 release: 103 fp->_flags = 0; /* release */ 104 return NULL; 105 } 106