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