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* autoload.cc (CancelSynchronousIo): Define.

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* fcntl.cc (fcntl64): Drop handling of locking commands.
	* fhandler.h (class fhandler_disk_file): Add mandatory_locking.
	(fhandler_disk_file::fcntl): Declare.
	(fhandler_disk_file::mand_lock): Declare.
	* fhandler_disk_file.cc (fhandler_disk_file::fhandler_disk_file):
	Initialize mandatory_locking.
	(fhandler_disk_file::fcntl): New method.  Handle F_LCK_MANDATORY and
	locking commands.
	(fhandler_disk_file::dup): Duplicate mandatory_locking.  Fix a bug
	when duplicating prw_handle failed.
	(fhandler_disk_file::fixup_after_fork): Reset mandatory_locking.
	* flock.cc (fhandler_disk_file::lock): Add comment.
	(struct lock_parms): New struct to pass parameters to blocking_lock_thr
	thread function.
	(blocking_lock_thr): New thread function.
	(fhandler_disk_file::mand_lock): New methof implementing mandatory
	locking with Windows semantics.
	* ntdll.h (NtLockFile): Declare.
	(NtUnlockFile): Declare.
	* include/fcntl.h: Fix a comment.
	(F_LCK_MANDATORY): Define.  Add lengthy comment to explain.
This commit is contained in:
Corinna Vinschen
2013-06-02 10:22:14 +00:00
parent fa35814af1
commit a24ad2c346
9 changed files with 289 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

201
winsup/cygwin/flock.cc
View File

@@ -1,6 +1,6 @@
/* flock.cc. NT specific implementation of advisory file locking.
Copyright 2003, 2008, 2009, 2010, 2011, 2012 Red Hat, Inc.
Copyright 2003, 2008, 2009, 2010, 2011, 2012, 2013 Red Hat, Inc.
This file is part of Cygwin.
@@ -915,6 +915,9 @@ static int lf_setlock (lockf_t *, inode_t *, lockf_t **, HANDLE);
static void lf_split (lockf_t *, lockf_t *, lockf_t **);
static void lf_wakelock (lockf_t *, HANDLE);
/* This is the fcntl advisory lock implementation. For the implementation
of mandatory locks using the Windows mandatory locking functions, see the
fhandler_disk_file::mand_lock method at the end of this file. */
int
fhandler_disk_file::lock (int a_op, struct flock *fl)
{
@@ -1805,3 +1808,199 @@ done:
syscall_printf ("%R = lockf(%d, %d, %D)", res, filedes, function, size);
return res;
}
/* This is the fcntl lock implementation for mandatory locks using the
Windows mandatory locking functions. For the UNIX-like advisory locking
implementation see the fhandler_disk_file::lock method earlier in this
file. */
struct lock_parms {
HANDLE h;
PIO_STATUS_BLOCK pio;
PLARGE_INTEGER poff;
PLARGE_INTEGER plen;
BOOL type;
NTSTATUS status;
};
static DWORD WINAPI
blocking_lock_thr (LPVOID param)
{
struct lock_parms *lp = (struct lock_parms *) param;
lp->status = NtLockFile (lp->h, NULL, NULL, NULL, lp->pio, lp->poff,
lp->plen, 0, FALSE, lp->type);
return 0;
}
int
fhandler_disk_file::mand_lock (int a_op, struct flock *fl)
{
NTSTATUS status;
IO_STATUS_BLOCK io;
FILE_POSITION_INFORMATION fpi;
FILE_STANDARD_INFORMATION fsi;
off_t startpos;
LARGE_INTEGER offset;
LARGE_INTEGER length;
/* Calculate where to start from, then adjust this by fl->l_start. */
switch (fl->l_whence)
{
case SEEK_SET:
startpos = 0;
break;
case SEEK_CUR:
status = NtQueryInformationFile (get_handle (), &io, &fpi, sizeof fpi,
FilePositionInformation);
if (!NT_SUCCESS (status))
{
__seterrno_from_nt_status (status);
return -1;
}
startpos = fpi.CurrentByteOffset.QuadPart;
break;
case SEEK_END:
status = NtQueryInformationFile (get_handle (), &io, &fsi, sizeof fsi,
FileStandardInformation);
if (!NT_SUCCESS (status))
{
__seterrno_from_nt_status (status);
return -1;
}
startpos = fsi.EndOfFile.QuadPart;
break;
default:
set_errno (EINVAL);
return -1;
}
/* Adjust start and length until they make sense. */
offset.QuadPart = startpos + fl->l_start;
if (fl->l_len < 0)
{
offset.QuadPart -= fl->l_len;
length.QuadPart = -fl->l_len;
}
else
length.QuadPart = fl->l_len;
if (offset.QuadPart < 0)
{
length.QuadPart -= -offset.QuadPart;
if (length.QuadPart <= 0)
{
set_errno (EINVAL);
return -1;
}
offset.QuadPart = 0;
}
/* Special case if len == 0. For POSIX this means lock to the end of
the entire file, even when file grows later. */
if (length.QuadPart == 0)
length.QuadPart = UINT64_MAX;
/* Action! */
if (fl->l_type == F_UNLCK)
{
status = NtUnlockFile (get_handle (), &io, &offset, &length, 0);
if (status == STATUS_RANGE_NOT_LOCKED) /* Not an error */
status = STATUS_SUCCESS;
}
else if (a_op == F_SETLKW)
{
/* We open file handles synchronously. To allow asynchronous operation
the file locking functions require a file handle opened in asynchronous
mode. Since Windows locks are per-process/per-file object, we can't
open another handle asynchrously and lock/unlock using that handle:
The original file handle would not have placed the lock and would be
restricted by the lock like any other file handle.
So, what we do here is to start a thread which calls the potentially
blocking NtLockFile call. Then we wait for thread completion in an
interruptible fashion. */
OBJECT_ATTRIBUTES attr;
HANDLE evt;
struct lock_parms lp = { get_handle (), &io, &offset, &length,
fl->l_type == F_WRLCK, 0 };
cygthread *thr = NULL;
InitializeObjectAttributes (&attr, NULL, 0, NULL, NULL);
status = NtCreateEvent (&evt, EVENT_ALL_ACCESS, &attr,
NotificationEvent, FALSE);
if (evt)
thr = new cygthread (blocking_lock_thr, &lp, "blk_lock", evt);
if (!thr)
{
/* Thread creation failed. Fall back to blocking lock call. */
if (evt)
NtClose (evt);
status = NtLockFile (get_handle (), NULL, NULL, NULL, &io, &offset,
&length, 0, FALSE, fl->l_type == F_WRLCK);
}
else
{
/* F_SETLKW and lock cannot be established. Wait until the lock can
be established, or a signal request arrived. We deliberately
don't handle thread cancel requests here. */
DWORD wait_res = cygwait (evt, INFINITE, cw_sig | cw_sig_eintr);
NtClose (evt);
switch (wait_res)
{
case WAIT_OBJECT_0:
/* Fetch completion status. */
status = lp.status;
thr->detach ();
break;
default:
/* Signal arrived. */
/* Starting with Vista, CancelSynchronousIo works, and we wait
for the thread to exit. lp.status will be either
STATUS_SUCCESS, or STATUS_CANCELLED. We only call
NtUnlockFile in the first case.
Prior to Vista, CancelSynchronousIo doesn't exist, so we
terminated the thread and always call NtUnlockFile since
lp.status was 0 to begin with. */
if (CancelSynchronousIo (thr->thread_handle ()))
thr->detach ();
else
thr->terminate_thread ();
if (NT_SUCCESS (lp.status))
NtUnlockFile (get_handle (), &io, &offset, &length, 0);
/* Per SUSv4: If a signal is received while fcntl is waiting,
fcntl shall be interrupted. Upon return from the signal
handler, fcntl shall return -1 with errno set to EINTR,
and the lock operation shall not be done. */
_my_tls.call_signal_handler ();
set_errno (EINTR);
return -1;
}
}
}
else
{
status = NtLockFile (get_handle (), NULL, NULL, NULL, &io, &offset,
&length, 0, TRUE, fl->l_type == F_WRLCK);
if (a_op == F_GETLK)
{
/* This is non-atomic, but there's no other way on Windows to detect
if another lock is blocking our lock, other than trying to place
the lock, and then having to unlock it again. */
if (NT_SUCCESS (status))
{
NtUnlockFile (get_handle (), &io, &offset, &length, 0);
fl->l_type = F_UNLCK;
}
else
{
/* FAKE! FAKE! FAKE! */
fl->l_type = F_WRLCK;
fl->l_whence = SEEK_SET;
fl->l_start = offset.QuadPart;
fl->l_len = length.QuadPart;
fl->l_pid = (pid_t) -1;
}
status = STATUS_SUCCESS;
}
}
if (!NT_SUCCESS (status))
{
__seterrno_from_nt_status (status);
return -1;
}
return 0;
}