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* path.cc (etc::dir_changed): Change `io' to a static NO_COPY 

variable.  Explain why.  Add a muto to guard overwriting the changed_h
	handle by multiple concurrent threads.
	* path.h (class etc): Drop unused changed_h member.
This commit is contained in:
Corinna Vinschen 2012-07-31 19:36:16 +00:00
parent 217618d3d6
commit 68e41cfcf4
3 changed files with 40 additions and 22 deletions
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7
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,10 @@
2012-07-31 Corinna Vinschen <corinna@vinschen.de>
* path.cc (etc::dir_changed): Change `io' to a static NO_COPY
variable. Explain why. Add a muto to guard overwriting the changed_h
handle by multiple concurrent threads.
* path.h (class etc): Drop unused changed_h member.
2012-07-30 Christopher Faylor <me.cygwin2012@cgf.cx>
* winlean.h: Define constant which will be needed eventually. Remove

54
winsup/cygwin/path.cc
View File

@ -4311,46 +4311,58 @@ etc::test_file_change (int n)
bool
etc::dir_changed (int n)
{
static muto lock NO_COPY;
static HANDLE changed_h NO_COPY;
/* io MUST be static because NtNotifyChangeDirectoryFile works asynchronously.
It may write into io after the function has left, which may result in all
sorts of stack corruption. */
static IO_STATUS_BLOCK io NO_COPY;
if (!change_possible[n])
{
static HANDLE changed_h NO_COPY;
NTSTATUS status;
IO_STATUS_BLOCK io;
if (!changed_h)
{
OBJECT_ATTRIBUTES attr;
path_conv dir ("/etc");
status = NtOpenFile (&changed_h, SYNCHRONIZE | FILE_LIST_DIRECTORY,
dir.get_object_attr (attr, sec_none_nih), &io,
FILE_SHARE_VALID_FLAGS, FILE_DIRECTORY_FILE);
if (!NT_SUCCESS (status))
lock.init ("etc_dir_changed_lock")->acquire ();
if (!changed_h)
{
path_conv dir ("/etc");
status = NtOpenFile (&changed_h,
SYNCHRONIZE | FILE_LIST_DIRECTORY,
dir.get_object_attr (attr, sec_none_nih),
&io, FILE_SHARE_VALID_FLAGS,
FILE_DIRECTORY_FILE);
if (!NT_SUCCESS (status))
{
#ifdef DEBUGGING
system_printf ("NtOpenFile (%S) failed, %p",
dir.get_nt_native_path (), status);
system_printf ("NtOpenFile (%S) failed, %p",
dir.get_nt_native_path (), status);
#endif
changed_h = INVALID_HANDLE_VALUE;
}
else
{
status = NtNotifyChangeDirectoryFile (changed_h, NULL, NULL,
changed_h = INVALID_HANDLE_VALUE;
}
else
{
status = NtNotifyChangeDirectoryFile (changed_h, NULL, NULL,
NULL, &io, NULL, 0,
FILE_NOTIFY_CHANGE_LAST_WRITE
| FILE_NOTIFY_CHANGE_FILE_NAME,
FALSE);
if (!NT_SUCCESS (status))
{
if (!NT_SUCCESS (status))
{
#ifdef DEBUGGING
system_printf ("NtNotifyChangeDirectoryFile (1) failed, %p",
status);
system_printf ("NtNotifyChangeDirectoryFile (1) failed, "
"%p", status);
#endif
NtClose (changed_h);
changed_h = INVALID_HANDLE_VALUE;
NtClose (changed_h);
changed_h = INVALID_HANDLE_VALUE;
}
}
memset (change_possible, true, sizeof (change_possible));
}
memset (change_possible, true, sizeof (change_possible));
lock.release ();
}
if (changed_h == INVALID_HANDLE_VALUE)

1
winsup/cygwin/path.h
View File

@ -438,7 +438,6 @@ class etc
{
friend class dtable;
static int curr_ix;
static HANDLE changed_h;
static bool change_possible[MAX_ETC_FILES + 1];
static OBJECT_ATTRIBUTES fn[MAX_ETC_FILES + 1];
static LARGE_INTEGER last_modified[MAX_ETC_FILES + 1];