1 /* Provide file descriptor control.
3 Copyright (C) 2009, 2010 Free Software Foundation, Inc.
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 /* Written by Eric Blake <ebb9@byu.net>. */
31 # define rpl_fcntl fcntl
35 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
36 /* Get declarations of the Win32 API functions. */
37 # define WIN32_LEAN_AND_MEAN
40 /* Upper bound on getdtablesize(). See lib/getdtablesize.c. */
41 # define OPEN_MAX_MAX 0x10000
43 /* Duplicate OLDFD into the first available slot of at least NEWFD,
44 which must be positive, with FLAGS determining whether the duplicate
45 will be inheritable. */
47 dupfd (int oldfd, int newfd, int flags)
49 /* Mingw has no way to create an arbitrary fd. Iterate until all
50 file descriptors less than newfd are filled up. */
51 HANDLE curr_process = GetCurrentProcess ();
52 HANDLE old_handle = (HANDLE) _get_osfhandle (oldfd);
53 unsigned char fds_to_close[OPEN_MAX_MAX / CHAR_BIT];
54 unsigned int fds_to_close_bound = 0;
56 BOOL inherit = flags & O_CLOEXEC ? FALSE : TRUE;
59 if (newfd < 0 || getdtablesize () <= newfd)
64 if (old_handle == INVALID_HANDLE_VALUE
65 || (mode = setmode (oldfd, O_BINARY)) == -1)
67 /* oldfd is not open, or is an unassigned standard file
72 setmode (oldfd, mode);
81 if (!DuplicateHandle (curr_process, /* SourceProcessHandle */
82 old_handle, /* SourceHandle */
83 curr_process, /* TargetProcessHandle */
84 (PHANDLE) &new_handle, /* TargetHandle */
85 (DWORD) 0, /* DesiredAccess */
86 inherit, /* InheritHandle */
87 DUPLICATE_SAME_ACCESS)) /* Options */
89 /* TODO: Translate GetLastError () into errno. */
94 duplicated_fd = _open_osfhandle ((long) new_handle, flags);
95 if (duplicated_fd < 0)
97 CloseHandle (new_handle);
102 if (newfd <= duplicated_fd)
104 result = duplicated_fd;
108 /* Set the bit duplicated_fd in fds_to_close[]. */
109 index = (unsigned int) duplicated_fd / CHAR_BIT;
110 if (fds_to_close_bound <= index)
112 if (sizeof fds_to_close <= index)
113 /* Need to increase OPEN_MAX_MAX. */
115 memset (fds_to_close + fds_to_close_bound, '\0',
116 index + 1 - fds_to_close_bound);
117 fds_to_close_bound = index + 1;
119 fds_to_close[index] |= 1 << ((unsigned int) duplicated_fd % CHAR_BIT);
122 /* Close the previous fds that turned out to be too small. */
124 int saved_errno = errno;
125 unsigned int duplicated_fd;
127 for (duplicated_fd = 0;
128 duplicated_fd < fds_to_close_bound * CHAR_BIT;
130 if ((fds_to_close[duplicated_fd / CHAR_BIT]
131 >> (duplicated_fd % CHAR_BIT))
133 close (duplicated_fd);
140 result = _gl_register_dup (oldfd, result);
146 /* Perform the specified ACTION on the file descriptor FD, possibly
147 using the argument ARG further described below. This replacement
148 handles the following actions, and forwards all others on to the
149 native fcntl. An unrecognized ACTION returns -1 with errno set to
152 F_DUPFD - duplicate FD, with int ARG being the minimum target fd.
153 If successful, return the duplicate, which will be inheritable;
154 otherwise return -1 and set errno.
156 F_DUPFD_CLOEXEC - duplicate FD, with int ARG being the minimum
157 target fd. If successful, return the duplicate, which will not be
158 inheritable; otherwise return -1 and set errno.
160 F_GETFD - ARG need not be present. If successful, return a
161 non-negative value containing the descriptor flags of FD (only
162 FD_CLOEXEC is portable, but other flags may be present); otherwise
163 return -1 and set errno. */
166 rpl_fcntl (int fd, int action, /* arg */...)
170 va_start (arg, action);
177 int target = va_arg (arg, int);
178 result = dupfd (fd, target, 0);
181 #elif FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR
184 int target = va_arg (arg, int);
185 /* Detect invalid target; needed for cygwin 1.5.x. */
186 if (target < 0 || getdtablesize () <= target)
190 result = fcntl (fd, action, target);
193 result = _gl_register_dup (fd, result);
198 #endif /* FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR */
200 case F_DUPFD_CLOEXEC:
202 int target = va_arg (arg, int);
205 result = dupfd (fd, target, O_CLOEXEC);
207 #else /* HAVE_FCNTL */
208 /* Try the system call first, if the headers claim it exists
209 (that is, if GNULIB_defined_F_DUPFD_CLOEXEC is 0), since we
210 may be running with a glibc that has the macro but with an
211 older kernel that does not support it. Cache the
212 information on whether the system call really works, but
213 avoid caching failure if the corresponding F_DUPFD fails
214 for any reason. 0 = unknown, 1 = yes, -1 = no. */
215 static int have_dupfd_cloexec = GNULIB_defined_F_DUPFD_CLOEXEC ? -1 : 0;
216 if (0 <= have_dupfd_cloexec)
218 result = fcntl (fd, action, target);
219 if (0 <= result || errno != EINVAL)
221 have_dupfd_cloexec = 1;
224 result = _gl_register_dup (fd, result);
229 result = rpl_fcntl (fd, F_DUPFD, target);
232 have_dupfd_cloexec = -1;
236 result = rpl_fcntl (fd, F_DUPFD, target);
237 if (0 <= result && have_dupfd_cloexec == -1)
239 int flags = fcntl (result, F_GETFD);
240 if (flags < 0 || fcntl (result, F_SETFD, flags | FD_CLOEXEC) == -1)
242 int saved_errno = errno;
249 #endif /* HAVE_FCNTL */
250 } /* F_DUPFD_CLOEXEC */
255 # if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
256 HANDLE handle = (HANDLE) _get_osfhandle (fd);
258 if (handle == INVALID_HANDLE_VALUE
259 || GetHandleInformation (handle, &flags) == 0)
262 result = (flags & HANDLE_FLAG_INHERIT) ? 0 : FD_CLOEXEC;
264 /* Use dup2 to reject invalid file descriptors. No way to
265 access this information, so punt. */
266 if (0 <= dup2 (fd, fd))
271 #endif /* !HAVE_FCNTL */
273 /* Implementing F_SETFD on mingw is not trivial - there is no
274 API for changing the O_NOINHERIT bit on an fd, and merely
275 changing the HANDLE_FLAG_INHERIT bit on the underlying handle
276 can lead to odd state. It may be possible by duplicating the
277 handle, using _open_osfhandle with the right flags, then
278 using dup2 to move the duplicate onto the original, but that
279 is not supported for now. */
284 void *p = va_arg (arg, void *);
285 result = fcntl (fd, action, p);