* smallprint.cc (__small_vswprintf): Fix uninitialized usage of `w'.

Revamp advisory file locking to avoid cross reference pointers as well
	as to allow BSD flock semantics.  More agressively delete unused nodes
	and sync objects.
	* fhandler.h (fhandler_base::ino): Rename from namehash.  Fix comment.
	(fhandler_base::node): Remove.
	(fhandler_base::unique_id): Add.
	(fhandler_base::del_my_locks): New method.
	(get_ino): Rename from get_namehash.  Change usage throughout Cygwin.
	(get_unique_id): New method.
	* fhandler.cc (fhandler_base::close): Call own del_my_locks method.
	Fix comment.
	(fhandler_base::fhandler_base): Accommodate new and changed members.
	(fhandler_base::fixup_after_fork): Call del_my_locks.
	(fhandler_base::fixup_after_exec): Ditto for files with close-on-exec
	flag set.
	* fhandler_disk_file.cc (get_ino_by_handle): Rename from
	readdir_get_ino_by_handle.  Accommodate throughout.
	(fhandler_base::open_fs): Fill ino with inode number if FS has good
	inodes.  Allocate a LUID and store in unique_id to recognize file
	descriptors referencing the same file object.
	* flock.cc: Drop flock TODO comments.  Use explicit types __dev32_t
	and __ino64_t instead of dev_t and ino_t.
	(LOCK_OBJ_NAME_LEN): Change to reflect longer lf_id length.
	(get_obj_handle_count): New method.
	(lockf_t::lf_id): Change type to long long.
	(inode_t::get_lock_obj_handle_count): Drop in favor of static function
	get_obj_handle_count.
	(inode_t::del_locks): Remove.
	(inode_t::get): Add create_if_missing flag argument.
	(inode_t::del_my_locks): Reimplement to handle POSIX and BSD flock
	locks.  Return if node can be deleted or not.
	(inode_t::~inode_t): Ditto.  Close handles to i_dir and i_mtx.
	(fixup_lockf_after_fork): Remove.
	(fhandler_base::del_my_locks): New method.
	(fixup_lockf_after_exec): Check if node can be deleted.
	(inode_t::get): Only create node if create_if_missing is set.  Lock
	the returned node here before unlocking the node list.
	(inode_t::get_all_locks_list): Accommodate new lf_id length.
	(inode_t::create_lock_obj): Ditto.
	(lockf_t::open_lock_obj): Ditto.  Change return type to bool.  De-const.
	Set lf_obj instead of returning a handle.
	(lockf_t::del_lock_obj): Call SetEvent only if new incoming parameters
	allow it.  Explain how it's supposed to work.
	(fhandler_disk_file::lock): Only fetch file length in SEEK_END case.
	Use NtQueryInformationFile(FileStandardInformation) instead of
	calling fstat_by_handle.  Always unlock node before returning.
	Use fhandler's unique id to create lf_id for BSD flock locks.
	Rely on node lock from inode_t::get.  Call del_lock_obj on removed
	locks here to allow explicit unlocking.  Delete node if no lock exists
	on the file anymore.
	(lf_setlock): Get file handle as additional parameter.  Handle the fact
	that lf_getblock now always opens the attached event object.  Reactivate
	erroneously applied patch which deactivates setting thread priority.
	Additionally handle blocking on BSD flock locks.
	(lf_clearlock): Get file handle as additional parameter.
	(lf_getlock): Close event handle opened by lf_getblock.
	(lf_getblock): Open potentially blocking event object here and check
	its signal state if it's a BSD flock lock.
	(lf_wakelock): Get file handle as additional parameter.
	* fork.cc (frok::child): Drop call to fixup_lockf_after_fork.
	* ntdll.h (struct _EVENT_BASIC_INFORMATION): Define.
	(enum _EVENT_INFORMATION_CLASS): Define.
	(NtQueryEvent): Declare.

	* fhandler.h (fhandler_base::fs_flags): Remove.
	(fhandler_base::set_fs_flags): Remove.
	(fhandler_base::get_fs_flags): Remove.
	* fhandler.cc (fhandler_base::write): Check for sparse file using
	pc.fs_flags().
	* fhandler_disk_file.cc (fhandler_disk_file::ftruncate): Ditto.

	The return of the volume serial number in fs_info.
	* fhandler.h (get_dev): New method.
	* fhandler_disk_file.cc (fhandler_base::fstat_by_handle): Drop call to
	NtQueryVolumeInformationFile(FileFsVolumeInformation).  Just use
	get_dev() method.
	* fhandler_fifo.cc (fhandler_fifo::open) Use device ID and inode number
	to generate fifo name.
	* path.h (fs_info::sernum): New member.
	(fs_info::serial_number): New method.
	(path_conv::fs_serial_number): New method.
	* path.cc (fs_info::update): Fetch volume serial number and store in
	sernum.

winsup/cygwin/fhandler.h

@@ -125,7 +125,7 @@ class fhandler_base
   int access;
   HANDLE io_handle;
 
-  __ino64_t namehash;	/* hashed filename, used as inode num */
+  __ino64_t ino;	/* file ID or hashed filename, depends on FS. */
 
  protected:
   /* File open flags from open () and fcntl () calls */
@@ -137,9 +137,10 @@ class fhandler_base
   size_t raixput;
   size_t rabuflen;
 
-  inode_t *node;	/* Used for advisory file locking.  See flock.cc.  */
+  /* Used for advisory file locking.  See flock.cc.  */
+  long long unique_id;
+  void del_my_locks (bool);
 
-  DWORD fs_flags;
   HANDLE read_state;
   int wait_overlapped (bool&, bool, DWORD *) __attribute__ ((regparm (3)));
   bool setup_overlapped () __attribute__ ((regparm (1)));
@@ -231,10 +232,6 @@ class fhandler_base
     ReleaseSemaphore (read_state, n, NULL);
   }
 
-  void set_fs_flags (DWORD flags) { fs_flags = flags; }
-  bool get_fs_flags (DWORD flagval = UINT32_MAX)
-    { return (fs_flags & (flagval)); }
-
   bool get_readahead_valid () { return raixget < ralen; }
   int puts_readahead (const char *s, size_t len = (size_t) -1);
   int put_readahead (char value);
@@ -255,7 +252,9 @@ class fhandler_base
   bool has_attribute (DWORD x) const {return pc.has_attribute (x);}
   const char *get_name () const { return pc.normalized_path; }
   const char *get_win32_name () { return pc.get_win32 (); }
-  __ino64_t get_namehash () { return namehash ?: namehash = hash_path_name (0, pc.get_nt_native_path ()); }
+  __dev32_t get_dev () { return pc.fs_serial_number (); }
+  __ino64_t get_ino () { return ino ?: ino = hash_path_name (0, pc.get_nt_native_path ()); }
+  long long get_unique_id () const { return unique_id; }
   /* Returns name used for /proc/<pid>/fd in buf. */
   virtual char *get_proc_fd_name (char *buf);