1 /* Open a descriptor to a file. 2 Copyright (C) 2007-2012 Free Software Foundation, Inc. 3 4 This program is free software: you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 3 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 16 17 /* Written by Bruno Haible <bruno (at) clisp.org>, 2007. */ 18 19 /* If the user's config.h happens to include <fcntl.h>, let it include only 20 the system's <fcntl.h> here, so that orig_open doesn't recurse to 21 rpl_open. */ 22 #define __need_system_fcntl_h 23 #include <config.h> 24 25 /* Get the original definition of open. It might be defined as a macro. */ 26 #include <fcntl.h> 27 #include <sys/types.h> 28 #undef __need_system_fcntl_h 29 30 static int 31 orig_open (const char *filename, int flags, mode_t mode) 32 { 33 return open (filename, flags, mode); 34 } 35 36 /* Specification. */ 37 /* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates 38 this include because of the preliminary #include <fcntl.h> above. */ 39 #include "fcntl.h" 40 41 #include <errno.h> 42 #include <stdarg.h> 43 #include <string.h> 44 #include <sys/types.h> 45 #include <sys/stat.h> 46 #include <unistd.h> 47 48 #ifndef REPLACE_OPEN_DIRECTORY 49 # define REPLACE_OPEN_DIRECTORY 0 50 #endif 51 52 int 53 open (const char *filename, int flags, ...) 54 { 55 mode_t mode; 56 int fd; 57 58 mode = 0; 59 if (flags & O_CREAT) 60 { 61 va_list arg; 62 va_start (arg, flags); 63 64 /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4 65 creates crashing code when 'mode_t' is smaller than 'int'. */ 66 mode = va_arg (arg, PROMOTED_MODE_T); 67 68 va_end (arg); 69 } 70 71 #if GNULIB_defined_O_NONBLOCK 72 /* The only known platform that lacks O_NONBLOCK is mingw, but it 73 also lacks named pipes and Unix sockets, which are the only two 74 file types that require non-blocking handling in open(). 75 Therefore, it is safe to ignore O_NONBLOCK here. It is handy 76 that mingw also lacks openat(), so that is also covered here. */ 77 flags &= ~O_NONBLOCK; 78 #endif 79 80 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ 81 if (strcmp (filename, "/dev/null") == 0) 82 filename = "NUL"; 83 #endif 84 85 #if OPEN_TRAILING_SLASH_BUG 86 /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR 87 is specified, then fail. 88 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html> 89 says that 90 "A pathname that contains at least one non-slash character and that 91 ends with one or more trailing slashes shall be resolved as if a 92 single dot character ( '.' ) were appended to the pathname." 93 and 94 "The special filename dot shall refer to the directory specified by 95 its predecessor." 96 If the named file already exists as a directory, then 97 - if O_CREAT is specified, open() must fail because of the semantics 98 of O_CREAT, 99 - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX 100 <http://www.opengroup.org/susv3/functions/open.html> says that it 101 fails with errno = EISDIR in this case. 102 If the named file does not exist or does not name a directory, then 103 - if O_CREAT is specified, open() must fail since open() cannot create 104 directories, 105 - if O_WRONLY or O_RDWR is specified, open() must fail because the 106 file does not contain a '.' directory. */ 107 if (flags & (O_CREAT | O_WRONLY | O_RDWR)) 108 { 109 size_t len = strlen (filename); 110 if (len > 0 && filename[len - 1] == '/') 111 { 112 errno = EISDIR; 113 return -1; 114 } 115 } 116 #endif 117 118 fd = orig_open (filename, flags, mode); 119 120 #if REPLACE_FCHDIR 121 /* Implementing fchdir and fdopendir requires the ability to open a 122 directory file descriptor. If open doesn't support that (as on 123 mingw), we use a dummy file that behaves the same as directories 124 on Linux (ie. always reports EOF on attempts to read()), and 125 override fstat() in fchdir.c to hide the fact that we have a 126 dummy. */ 127 if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES 128 && ((flags & O_ACCMODE) == O_RDONLY 129 || (O_SEARCH != O_RDONLY && (flags & O_ACCMODE) == O_SEARCH))) 130 { 131 struct stat statbuf; 132 if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode)) 133 { 134 /* Maximum recursion depth of 1. */ 135 fd = open ("/dev/null", flags, mode); 136 if (0 <= fd) 137 fd = _gl_register_fd (fd, filename); 138 } 139 else 140 errno = EACCES; 141 } 142 #endif 143 144 #if OPEN_TRAILING_SLASH_BUG 145 /* If the filename ends in a slash and fd does not refer to a directory, 146 then fail. 147 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html> 148 says that 149 "A pathname that contains at least one non-slash character and that 150 ends with one or more trailing slashes shall be resolved as if a 151 single dot character ( '.' ) were appended to the pathname." 152 and 153 "The special filename dot shall refer to the directory specified by 154 its predecessor." 155 If the named file without the slash is not a directory, open() must fail 156 with ENOTDIR. */ 157 if (fd >= 0) 158 { 159 /* We know len is positive, since open did not fail with ENOENT. */ 160 size_t len = strlen (filename); 161 if (filename[len - 1] == '/') 162 { 163 struct stat statbuf; 164 165 if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode)) 166 { 167 close (fd); 168 errno = ENOTDIR; 169 return -1; 170 } 171 } 172 } 173 #endif 174 175 #if REPLACE_FCHDIR 176 if (!REPLACE_OPEN_DIRECTORY && 0 <= fd) 177 fd = _gl_register_fd (fd, filename); 178 #endif 179 180 return fd; 181 } 182
