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DEFINITIONS
This source file includes following definitions.
- dupfd
- rpl_fcntl
/* Provide file descriptor control.
Copyright (C) 2009-2011 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
{
/* Haiku alpha 2 loses fd flags on original. */
int flags = fcntl (fd, F_GETFD);
if (flags < 0)
{
result = -1;
break;
}
result = fcntl (fd, action, target);
if (0 <= result && fcntl (fd, F_SETFD, flags) == -1)
{
int saved_errno = errno;
close (result);
result = -1;
errno = saved_errno;
}
# 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;
}