| 1 | /* Provide file descriptor control.
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| 2 |
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| 3 | Copyright (C) 2009-2012 Free Software Foundation, Inc.
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| 4 |
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| 5 | This program is free software: you can redistribute it and/or modify
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| 6 | it under the terms of the GNU General Public License as published by
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| 7 | the Free Software Foundation; either version 3 of the License, or
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| 8 | (at your option) any later version.
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| 9 |
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| 10 | This program is distributed in the hope that it will be useful,
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | GNU General Public License for more details.
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| 14 |
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| 15 | You should have received a copy of the GNU General Public License
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| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */
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| 17 |
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| 18 | /* Written by Eric Blake <ebb9@byu.net>. */
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| 19 |
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| 20 | #include <config.h>
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| 21 |
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| 22 | /* Specification. */
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| 23 | #include <fcntl.h>
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| 24 |
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| 25 | #include <errno.h>
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| 26 | #include <limits.h>
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| 27 | #include <stdarg.h>
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| 28 | #include <unistd.h>
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| 29 |
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| 30 | #if !HAVE_FCNTL
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| 31 | # define rpl_fcntl fcntl
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| 32 | #endif
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| 33 | #undef fcntl
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| 34 |
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| 35 | #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
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| 36 | /* Get declarations of the native Windows API functions. */
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| 37 | # define WIN32_LEAN_AND_MEAN
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| 38 | # include <windows.h>
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| 39 |
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| 40 | /* Get _get_osfhandle. */
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| 41 | # include "msvc-nothrow.h"
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| 42 |
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| 43 | /* Upper bound on getdtablesize(). See lib/getdtablesize.c. */
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| 44 | # define OPEN_MAX_MAX 0x10000
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| 45 |
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| 46 | /* Duplicate OLDFD into the first available slot of at least NEWFD,
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| 47 | which must be positive, with FLAGS determining whether the duplicate
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| 48 | will be inheritable. */
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| 49 | static int
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| 50 | dupfd (int oldfd, int newfd, int flags)
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| 51 | {
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| 52 | /* Mingw has no way to create an arbitrary fd. Iterate until all
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| 53 | file descriptors less than newfd are filled up. */
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| 54 | HANDLE curr_process = GetCurrentProcess ();
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| 55 | HANDLE old_handle = (HANDLE) _get_osfhandle (oldfd);
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| 56 | unsigned char fds_to_close[OPEN_MAX_MAX / CHAR_BIT];
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| 57 | unsigned int fds_to_close_bound = 0;
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| 58 | int result;
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| 59 | BOOL inherit = flags & O_CLOEXEC ? FALSE : TRUE;
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| 60 | int mode;
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| 61 |
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| 62 | if (newfd < 0 || getdtablesize () <= newfd)
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| 63 | {
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| 64 | errno = EINVAL;
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| 65 | return -1;
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| 66 | }
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| 67 | if (old_handle == INVALID_HANDLE_VALUE
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| 68 | || (mode = setmode (oldfd, O_BINARY)) == -1)
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| 69 | {
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| 70 | /* oldfd is not open, or is an unassigned standard file
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| 71 | descriptor. */
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| 72 | errno = EBADF;
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| 73 | return -1;
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| 74 | }
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| 75 | setmode (oldfd, mode);
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| 76 | flags |= mode;
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| 77 |
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| 78 | for (;;)
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| 79 | {
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| 80 | HANDLE new_handle;
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| 81 | int duplicated_fd;
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| 82 | unsigned int index;
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| 83 |
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| 84 | if (!DuplicateHandle (curr_process, /* SourceProcessHandle */
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| 85 | old_handle, /* SourceHandle */
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| 86 | curr_process, /* TargetProcessHandle */
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| 87 | (PHANDLE) &new_handle, /* TargetHandle */
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| 88 | (DWORD) 0, /* DesiredAccess */
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| 89 | inherit, /* InheritHandle */
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| 90 | DUPLICATE_SAME_ACCESS)) /* Options */
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| 91 | {
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| 92 | /* TODO: Translate GetLastError () into errno. */
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| 93 | errno = EMFILE;
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| 94 | result = -1;
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| 95 | break;
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| 96 | }
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| 97 | duplicated_fd = _open_osfhandle ((intptr_t) new_handle, flags);
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| 98 | if (duplicated_fd < 0)
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| 99 | {
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| 100 | CloseHandle (new_handle);
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| 101 | errno = EMFILE;
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| 102 | result = -1;
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| 103 | break;
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| 104 | }
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| 105 | if (newfd <= duplicated_fd)
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| 106 | {
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| 107 | result = duplicated_fd;
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| 108 | break;
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| 109 | }
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| 110 |
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| 111 | /* Set the bit duplicated_fd in fds_to_close[]. */
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| 112 | index = (unsigned int) duplicated_fd / CHAR_BIT;
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| 113 | if (fds_to_close_bound <= index)
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| 114 | {
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| 115 | if (sizeof fds_to_close <= index)
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| 116 | /* Need to increase OPEN_MAX_MAX. */
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| 117 | abort ();
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| 118 | memset (fds_to_close + fds_to_close_bound, '\0',
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| 119 | index + 1 - fds_to_close_bound);
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| 120 | fds_to_close_bound = index + 1;
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| 121 | }
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| 122 | fds_to_close[index] |= 1 << ((unsigned int) duplicated_fd % CHAR_BIT);
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| 123 | }
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| 124 |
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| 125 | /* Close the previous fds that turned out to be too small. */
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| 126 | {
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| 127 | int saved_errno = errno;
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| 128 | unsigned int duplicated_fd;
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| 129 |
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| 130 | for (duplicated_fd = 0;
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| 131 | duplicated_fd < fds_to_close_bound * CHAR_BIT;
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| 132 | duplicated_fd++)
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| 133 | if ((fds_to_close[duplicated_fd / CHAR_BIT]
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| 134 | >> (duplicated_fd % CHAR_BIT))
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| 135 | & 1)
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| 136 | close (duplicated_fd);
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| 137 |
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| 138 | errno = saved_errno;
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| 139 | }
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| 140 |
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| 141 | # if REPLACE_FCHDIR
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| 142 | if (0 <= result)
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| 143 | result = _gl_register_dup (oldfd, result);
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| 144 | # endif
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| 145 | return result;
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| 146 | }
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| 147 | #endif /* W32 */
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| 148 |
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| 149 | /* Perform the specified ACTION on the file descriptor FD, possibly
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| 150 | using the argument ARG further described below. This replacement
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| 151 | handles the following actions, and forwards all others on to the
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| 152 | native fcntl. An unrecognized ACTION returns -1 with errno set to
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| 153 | EINVAL.
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| 154 |
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| 155 | F_DUPFD - duplicate FD, with int ARG being the minimum target fd.
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| 156 | If successful, return the duplicate, which will be inheritable;
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| 157 | otherwise return -1 and set errno.
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| 158 |
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| 159 | F_DUPFD_CLOEXEC - duplicate FD, with int ARG being the minimum
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| 160 | target fd. If successful, return the duplicate, which will not be
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| 161 | inheritable; otherwise return -1 and set errno.
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| 162 |
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| 163 | F_GETFD - ARG need not be present. If successful, return a
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| 164 | non-negative value containing the descriptor flags of FD (only
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| 165 | FD_CLOEXEC is portable, but other flags may be present); otherwise
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| 166 | return -1 and set errno. */
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| 167 |
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| 168 | int
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| 169 | rpl_fcntl (int fd, int action, /* arg */...)
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| 170 | {
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| 171 | va_list arg;
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| 172 | int result = -1;
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| 173 | va_start (arg, action);
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| 174 | switch (action)
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| 175 | {
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| 176 |
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| 177 | #if !HAVE_FCNTL
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| 178 | case F_DUPFD:
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| 179 | {
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| 180 | int target = va_arg (arg, int);
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| 181 | result = dupfd (fd, target, 0);
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| 182 | break;
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| 183 | }
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| 184 | #elif FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR
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| 185 | case F_DUPFD:
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| 186 | {
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| 187 | int target = va_arg (arg, int);
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| 188 | /* Detect invalid target; needed for cygwin 1.5.x. */
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| 189 | if (target < 0 || getdtablesize () <= target)
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| 190 | errno = EINVAL;
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| 191 | else
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| 192 | {
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| 193 | /* Haiku alpha 2 loses fd flags on original. */
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| 194 | int flags = fcntl (fd, F_GETFD);
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| 195 | if (flags < 0)
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| 196 | {
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| 197 | result = -1;
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| 198 | break;
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| 199 | }
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| 200 | result = fcntl (fd, action, target);
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| 201 | if (0 <= result && fcntl (fd, F_SETFD, flags) == -1)
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| 202 | {
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| 203 | int saved_errno = errno;
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| 204 | close (result);
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| 205 | result = -1;
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| 206 | errno = saved_errno;
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| 207 | }
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| 208 | # if REPLACE_FCHDIR
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| 209 | if (0 <= result)
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| 210 | result = _gl_register_dup (fd, result);
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| 211 | # endif
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| 212 | }
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| 213 | break;
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| 214 | } /* F_DUPFD */
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| 215 | #endif /* FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR */
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| 216 |
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| 217 | case F_DUPFD_CLOEXEC:
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| 218 | {
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| 219 | int target = va_arg (arg, int);
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| 220 |
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| 221 | #if !HAVE_FCNTL
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| 222 | result = dupfd (fd, target, O_CLOEXEC);
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| 223 | break;
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| 224 | #else /* HAVE_FCNTL */
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| 225 | /* Try the system call first, if the headers claim it exists
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| 226 | (that is, if GNULIB_defined_F_DUPFD_CLOEXEC is 0), since we
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| 227 | may be running with a glibc that has the macro but with an
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| 228 | older kernel that does not support it. Cache the
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| 229 | information on whether the system call really works, but
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| 230 | avoid caching failure if the corresponding F_DUPFD fails
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| 231 | for any reason. 0 = unknown, 1 = yes, -1 = no. */
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| 232 | static int have_dupfd_cloexec = GNULIB_defined_F_DUPFD_CLOEXEC ? -1 : 0;
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| 233 | if (0 <= have_dupfd_cloexec)
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| 234 | {
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| 235 | result = fcntl (fd, action, target);
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| 236 | if (0 <= result || errno != EINVAL)
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| 237 | {
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| 238 | have_dupfd_cloexec = 1;
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| 239 | # if REPLACE_FCHDIR
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| 240 | if (0 <= result)
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| 241 | result = _gl_register_dup (fd, result);
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| 242 | # endif
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| 243 | }
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| 244 | else
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| 245 | {
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| 246 | result = rpl_fcntl (fd, F_DUPFD, target);
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| 247 | if (result < 0)
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| 248 | break;
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| 249 | have_dupfd_cloexec = -1;
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| 250 | }
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| 251 | }
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| 252 | else
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| 253 | result = rpl_fcntl (fd, F_DUPFD, target);
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| 254 | if (0 <= result && have_dupfd_cloexec == -1)
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| 255 | {
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| 256 | int flags = fcntl (result, F_GETFD);
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| 257 | if (flags < 0 || fcntl (result, F_SETFD, flags | FD_CLOEXEC) == -1)
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| 258 | {
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| 259 | int saved_errno = errno;
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| 260 | close (result);
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| 261 | errno = saved_errno;
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| 262 | result = -1;
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| 263 | }
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| 264 | }
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| 265 | break;
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| 266 | #endif /* HAVE_FCNTL */
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| 267 | } /* F_DUPFD_CLOEXEC */
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| 268 |
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| 269 | #if !HAVE_FCNTL
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| 270 | case F_GETFD:
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| 271 | {
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| 272 | # if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
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| 273 | HANDLE handle = (HANDLE) _get_osfhandle (fd);
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| 274 | DWORD flags;
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| 275 | if (handle == INVALID_HANDLE_VALUE
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| 276 | || GetHandleInformation (handle, &flags) == 0)
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| 277 | errno = EBADF;
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| 278 | else
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| 279 | result = (flags & HANDLE_FLAG_INHERIT) ? 0 : FD_CLOEXEC;
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| 280 | # else /* !W32 */
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| 281 | /* Use dup2 to reject invalid file descriptors. No way to
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| 282 | access this information, so punt. */
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| 283 | if (0 <= dup2 (fd, fd))
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| 284 | result = 0;
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| 285 | # endif /* !W32 */
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| 286 | break;
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| 287 | } /* F_GETFD */
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| 288 | #endif /* !HAVE_FCNTL */
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| 289 |
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| 290 | /* Implementing F_SETFD on mingw is not trivial - there is no
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| 291 | API for changing the O_NOINHERIT bit on an fd, and merely
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| 292 | changing the HANDLE_FLAG_INHERIT bit on the underlying handle
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| 293 | can lead to odd state. It may be possible by duplicating the
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| 294 | handle, using _open_osfhandle with the right flags, then
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| 295 | using dup2 to move the duplicate onto the original, but that
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| 296 | is not supported for now. */
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| 297 |
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| 298 | default:
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| 299 | {
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| 300 | #if HAVE_FCNTL
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| 301 | void *p = va_arg (arg, void *);
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| 302 | result = fcntl (fd, action, p);
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| 303 | #else
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| 304 | errno = EINVAL;
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| 305 | #endif
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| 306 | break;
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| 307 | }
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| 308 | }
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| 309 | va_end (arg);
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| 310 | return result;
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| 311 | }
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