* dtable.cc (dtable::dup_worker): Reset path_conv handle in duplicated

fhandler.
	* fhandler.cc (fhandler_base::fstatvfs): Keep handle in created
	path_conv.
	* fhandler.h (fhandler_base::get_stat_access): New method.
	(fhandler_base::get_stat_handle): New method.
	* fhandler_disk_file.cc (fhandler_base::fstat_by_handle): Use handle
	returned by get_stat_handle.  Only request inode from system if it
	isn't already set in the fhandler, and only for filesystems supporting
	them.
	(fhandler_base::fstat_fs): Use handle returned by get_stat_handle.
	Change the way open_fs is called.  Explain why.
	(fhandler_base::fstat_helper): Use handle returned by get_stat_handle.
	Never use 0 inode number.  Simplify executable recognition by re-using
	get_stat_handle if file could be opened with sufficient rights.
	(fhandler_disk_file::fstatvfs): Use handle returned by get_stat_handle.
	(fhandler_disk_file::facl): Use handle returned by get_stat_handle in
	GETACL and GETACLCNT cases.
	(fhandler_disk_file::link): Use handle returned by get_stat_handle
	instead of opening file here again.  Add comment.
	(readdir_get_ino): Keep handle in created path_conv and drop
	opening file.
	* ntdll.h (wait_pending): New helper function.
	* path.cc (symlink_info::check): Drop unused 'opt' parameter from
	declaration.  Add path_conv_handle argument.
	(path_conv::check): Make sure conv_handle is closed.  Keep
	PC_KEEP_HANDLE flag in pflags_or.  Accommodate call to sym.check to
	new args.
	(path_conv::~path_conv): Close conv_handle.
	(symlink_info::check_shortcut): Don't re-open file here, just use
	incoming handle.  Drop goto's and label out.
	(symlink_info::check_sysfile): Don't re-open file here, just use
	incoming handle.  Keep track of file position to accommodate the fact
	that file has been opened asynchronously in calling function.
	(symlink_info::check_nfs_symlink): Don't re-open file here, just use
	incoming handle.
	(symlink_info::check): Drop unused 'opt' parameter.  Add
	path_conv_handle argument.  Always try to open file with GENERIC_READ
	rights first to allow reading file content w/o having to re-open the
	file.  Drop back to READ_CONTROL | FILE_READ_ATTRIBUTES otherwise.
	Call symlink test functions (except for check_reparse_point) only if
	file could be opened with GENERIC_READ.  Keep file handle open if
	PC_KEEP_HANDLE is set in pflags.
	* path.h (enum pathconv_arg): Add PC_KEEP_HANDLE flag.
	(class path_conv_handle): New class.
	(class path_conv): Add conv_handle member.
	(path_conv::operator =): Duplicate conv_handle.
	(path_conv::handle): New method.
	(path_conv::access): New method.
	(path_conv::reset_conv_handle): New method.
	(path_conv::close_conv_handle): New method.

winsup/cygwin/fhandler.cc

@@ -1124,7 +1124,7 @@ fhandler_base::fstatvfs (struct statvfs *sfs)
 {
   /* If we hit this base implementation, it's some device in /dev.
      Just call statvfs on /dev for simplicity. */
-  path_conv pc ("/dev");
+  path_conv pc ("/dev", PC_KEEP_HANDLE);
   fhandler_disk_file fh (pc);
   return fh.fstatvfs (sfs);
 }