--- /dev/null
+/* Provide file descriptor control.
+
+ Copyright (C) 2009, 2010 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+/* Written by Eric Blake <ebb9@byu.net>. */
+
+#include <config.h>
+
+/* Specification. */
+#include <fcntl.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <unistd.h>
+
+#if !HAVE_FCNTL
+# define rpl_fcntl fcntl
+#endif
+#undef fcntl
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+/* Get declarations of the Win32 API functions. */
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+
+/* Upper bound on getdtablesize(). See lib/getdtablesize.c. */
+# define OPEN_MAX_MAX 0x10000
+
+/* Duplicate OLDFD into the first available slot of at least NEWFD,
+ which must be positive, with FLAGS determining whether the duplicate
+ will be inheritable. */
+static int
+dupfd (int oldfd, int newfd, int flags)
+{
+ /* Mingw has no way to create an arbitrary fd. Iterate until all
+ file descriptors less than newfd are filled up. */
+ HANDLE curr_process = GetCurrentProcess ();
+ HANDLE old_handle = (HANDLE) _get_osfhandle (oldfd);
+ unsigned char fds_to_close[OPEN_MAX_MAX / CHAR_BIT];
+ unsigned int fds_to_close_bound = 0;
+ int result;
+ BOOL inherit = flags & O_CLOEXEC ? FALSE : TRUE;
+ int mode;
+
+ if (newfd < 0 || getdtablesize () <= newfd)
+ {
+ errno = EINVAL;
+ return -1;
+ }
+ if (old_handle == INVALID_HANDLE_VALUE
+ || (mode = setmode (oldfd, O_BINARY)) == -1)
+ {
+ /* oldfd is not open, or is an unassigned standard file
+ descriptor. */
+ errno = EBADF;
+ return -1;
+ }
+ setmode (oldfd, mode);
+ flags |= mode;
+
+ for (;;)
+ {
+ HANDLE new_handle;
+ int duplicated_fd;
+ unsigned int index;
+
+ if (!DuplicateHandle (curr_process, /* SourceProcessHandle */
+ old_handle, /* SourceHandle */
+ curr_process, /* TargetProcessHandle */
+ (PHANDLE) &new_handle, /* TargetHandle */
+ (DWORD) 0, /* DesiredAccess */
+ inherit, /* InheritHandle */
+ DUPLICATE_SAME_ACCESS)) /* Options */
+ {
+ /* TODO: Translate GetLastError () into errno. */
+ errno = EMFILE;
+ result = -1;
+ break;
+ }
+ duplicated_fd = _open_osfhandle ((long) new_handle, flags);
+ if (duplicated_fd < 0)
+ {
+ CloseHandle (new_handle);
+ errno = EMFILE;
+ result = -1;
+ break;
+ }
+ if (newfd <= duplicated_fd)
+ {
+ result = duplicated_fd;
+ break;
+ }
+
+ /* Set the bit duplicated_fd in fds_to_close[]. */
+ index = (unsigned int) duplicated_fd / CHAR_BIT;
+ if (fds_to_close_bound <= index)
+ {
+ if (sizeof fds_to_close <= index)
+ /* Need to increase OPEN_MAX_MAX. */
+ abort ();
+ memset (fds_to_close + fds_to_close_bound, '\0',
+ index + 1 - fds_to_close_bound);
+ fds_to_close_bound = index + 1;
+ }
+ fds_to_close[index] |= 1 << ((unsigned int) duplicated_fd % CHAR_BIT);
+ }
+
+ /* Close the previous fds that turned out to be too small. */
+ {
+ int saved_errno = errno;
+ unsigned int duplicated_fd;
+
+ for (duplicated_fd = 0;
+ duplicated_fd < fds_to_close_bound * CHAR_BIT;
+ duplicated_fd++)
+ if ((fds_to_close[duplicated_fd / CHAR_BIT]
+ >> (duplicated_fd % CHAR_BIT))
+ & 1)
+ close (duplicated_fd);
+
+ errno = saved_errno;
+ }
+
+# if REPLACE_FCHDIR
+ if (0 <= result)
+ result = _gl_register_dup (oldfd, result);
+# endif
+ return result;
+}
+#endif /* W32 */
+
+/* Perform the specified ACTION on the file descriptor FD, possibly
+ using the argument ARG further described below. This replacement
+ handles the following actions, and forwards all others on to the
+ native fcntl. An unrecognized ACTION returns -1 with errno set to
+ EINVAL.
+
+ F_DUPFD - duplicate FD, with int ARG being the minimum target fd.
+ If successful, return the duplicate, which will be inheritable;
+ otherwise return -1 and set errno.
+
+ F_DUPFD_CLOEXEC - duplicate FD, with int ARG being the minimum
+ target fd. If successful, return the duplicate, which will not be
+ inheritable; otherwise return -1 and set errno.
+
+ F_GETFD - ARG need not be present. If successful, return a
+ non-negative value containing the descriptor flags of FD (only
+ FD_CLOEXEC is portable, but other flags may be present); otherwise
+ return -1 and set errno. */
+
+int
+rpl_fcntl (int fd, int action, /* arg */...)
+{
+ va_list arg;
+ int result = -1;
+ va_start (arg, action);
+ switch (action)
+ {
+
+#if !HAVE_FCNTL
+ case F_DUPFD:
+ {
+ int target = va_arg (arg, int);
+ result = dupfd (fd, target, 0);
+ break;
+ }
+#elif FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR
+ case F_DUPFD:
+ {
+ int target = va_arg (arg, int);
+ /* Detect invalid target; needed for cygwin 1.5.x. */
+ if (target < 0 || getdtablesize () <= target)
+ errno = EINVAL;
+ else
+ {
+ result = fcntl (fd, action, target);
+# if REPLACE_FCHDIR
+ if (0 <= result)
+ result = _gl_register_dup (fd, result);
+# endif
+ }
+ break;
+ } /* F_DUPFD */
+#endif /* FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR */
+
+ case F_DUPFD_CLOEXEC:
+ {
+ int target = va_arg (arg, int);
+
+#if !HAVE_FCNTL
+ result = dupfd (fd, target, O_CLOEXEC);
+ break;
+#else /* HAVE_FCNTL */
+ /* Try the system call first, if the headers claim it exists
+ (that is, if GNULIB_defined_F_DUPFD_CLOEXEC is 0), since we
+ may be running with a glibc that has the macro but with an
+ older kernel that does not support it. Cache the
+ information on whether the system call really works, but
+ avoid caching failure if the corresponding F_DUPFD fails
+ for any reason. 0 = unknown, 1 = yes, -1 = no. */
+ static int have_dupfd_cloexec = GNULIB_defined_F_DUPFD_CLOEXEC ? -1 : 0;
+ if (0 <= have_dupfd_cloexec)
+ {
+ result = fcntl (fd, action, target);
+ if (0 <= result || errno != EINVAL)
+ {
+ have_dupfd_cloexec = 1;
+# if REPLACE_FCHDIR
+ if (0 <= result)
+ result = _gl_register_dup (fd, result);
+# endif
+ }
+ else
+ {
+ result = rpl_fcntl (fd, F_DUPFD, target);
+ if (result < 0)
+ break;
+ have_dupfd_cloexec = -1;
+ }
+ }
+ else
+ result = rpl_fcntl (fd, F_DUPFD, target);
+ if (0 <= result && have_dupfd_cloexec == -1)
+ {
+ int flags = fcntl (result, F_GETFD);
+ if (flags < 0 || fcntl (result, F_SETFD, flags | FD_CLOEXEC) == -1)
+ {
+ int saved_errno = errno;
+ close (result);
+ errno = saved_errno;
+ result = -1;
+ }
+ }
+ break;
+#endif /* HAVE_FCNTL */
+ } /* F_DUPFD_CLOEXEC */
+
+#if !HAVE_FCNTL
+ case F_GETFD:
+ {
+# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+ HANDLE handle = (HANDLE) _get_osfhandle (fd);
+ DWORD flags;
+ if (handle == INVALID_HANDLE_VALUE
+ || GetHandleInformation (handle, &flags) == 0)
+ errno = EBADF;
+ else
+ result = (flags & HANDLE_FLAG_INHERIT) ? 0 : FD_CLOEXEC;
+# else /* !W32 */
+ /* Use dup2 to reject invalid file descriptors. No way to
+ access this information, so punt. */
+ if (0 <= dup2 (fd, fd))
+ result = 0;
+# endif /* !W32 */
+ break;
+ } /* F_GETFD */
+#endif /* !HAVE_FCNTL */
+
+ /* Implementing F_SETFD on mingw is not trivial - there is no
+ API for changing the O_NOINHERIT bit on an fd, and merely
+ changing the HANDLE_FLAG_INHERIT bit on the underlying handle
+ can lead to odd state. It may be possible by duplicating the
+ handle, using _open_osfhandle with the right flags, then
+ using dup2 to move the duplicate onto the original, but that
+ is not supported for now. */
+
+ default:
+ {
+#if HAVE_FCNTL
+ void *p = va_arg (arg, void *);
+ result = fcntl (fd, action, p);
+#else
+ errno = EINVAL;
+#endif
+ break;
+ }
+ }
+ va_end (arg);
+ return result;
+}
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