* cygheap.h (enum fcwd_version_t): Move here from path.cc.

	(class fcwd_access_t): Ditto.  Only declare methods.
	(class cwdstuff): Move fast_cwd_ptr and fast_cwd_version from shared
	DLL section here.
	* path.cc: Keep fcwd_access_t method definitions.
	(fcwd_access_t::fast_cwd_version): New method.
	(find_fast_cwd_pointer): Change comment.  Mention test on W8CP.
	(cwdstuff::init): Initialize fast_cwd_ptr and fast_cwd_version.

1 files changed, 91 insertions, 1 deletions

diff --git a/winsup/cygwin/cygheap.h b/winsup/cygwin/cygheap.h
index 054297bd7..154ad6a84 100644
--- a/winsup/cygwin/cygheap.h
+++ b/winsup/cygwin/cygheap.h
@@ -204,7 +204,87 @@ public:
 
 /* cwd cache stuff.  */
 
-class muto;
+enum fcwd_version_t {
+  FCWD_OLD,
+  FCWD_W7,
+  FCWD_W8
+};
+
+/* This class is used to store the CWD starting with Windows Vista.
+   The CWD storage in the RTL_USER_PROCESS_PARAMETERS block is only
+   an afterthought now.  The actual CWD storage is a FAST_CWD structure
+   which is allocated on the process heap.  The new method only requires
+   minimal locking and it's much more multi-thread friendly.  Presumably
+   it minimizes contention when accessing the CWD.
+   The class fcwd_access_t is supposed to encapsulate the gory implementation
+   details depending on OS version from the calling functions. */
+class fcwd_access_t {
+  /* This is the layout used in Windows 8 developer preview. */
+  struct FAST_CWD_8 {
+    LONG           ReferenceCount;	/* Only release when this is 0. */
+    HANDLE         DirectoryHandle;
+    ULONG          OldDismountCount;	/* Reflects the system DismountCount
+					   at the time the CWD has been set. */
+    UNICODE_STRING Path;		/* Path's Buffer member always refers
+					   to the following Buffer array. */
+    LONG           FSCharacteristics;	/* Taken from FileFsDeviceInformation */
+    WCHAR          Buffer[MAX_PATH];
+  };
+  /* This is the layout used in Windows 7 and Vista. */
+  struct FAST_CWD_7 {
+    UNICODE_STRING Path;		/* Path's Buffer member always refers
+					   to the following Buffer array. */
+    HANDLE         DirectoryHandle;
+    LONG           FSCharacteristics;	/* Taken from FileFsDeviceInformation */
+    LONG           ReferenceCount;	/* Only release when this is 0. */
+    ULONG          OldDismountCount;	/* Reflects the system DismountCount
+					   at the time the CWD has been set. */
+    WCHAR          Buffer[MAX_PATH];
+  };
+  /* This is the old FAST_CWD structure up to the patch from KB 2393802,
+     release in February 2011. */
+  struct FAST_CWD_OLD {
+    LONG           ReferenceCount;	/* Only release when this is 0. */
+    HANDLE         DirectoryHandle;
+    ULONG          OldDismountCount;	/* Reflects the system DismountCount
+					   at the time the CWD has been set. */
+    UNICODE_STRING Path;		/* Path's Buffer member always refers
+					   to the following Buffer array. */
+    WCHAR          Buffer[MAX_PATH];
+  };
+  union {
+    FAST_CWD_OLD fold;
+    FAST_CWD_7   f7;
+    FAST_CWD_8   f8;
+  };
+
+#define IMPLEMENT(type, name) \
+  type name () { \
+    switch (fast_cwd_version ()) { \
+      case FCWD_OLD: \
+      default: \
+	return fold.name; \
+      case FCWD_W7: \
+	return f7.name; \
+      case FCWD_W8: \
+	return f8.name; \
+    } \
+  }
+  IMPLEMENT (LONG &, ReferenceCount)
+  IMPLEMENT (HANDLE &, DirectoryHandle)
+  IMPLEMENT (ULONG &, OldDismountCount)
+  IMPLEMENT (UNICODE_STRING &, Path)
+  IMPLEMENT (WCHAR *, Buffer)
+  void SetFSCharacteristics (LONG val);
+  static fcwd_version_t &fast_cwd_version (void);
+
+public:
+  void CopyPath (UNICODE_STRING &target);
+  void Free (PVOID heap);
+  void FillIn (HANDLE dir, PUNICODE_STRING name, ULONG old_dismount_count);
+  static void SetDirHandleFromBufferPointer (PWCHAR buf_p, HANDLE dir);
+  static void SetVersionFromPointer (PBYTE buf_p, bool is_buffer);
+};
 
 class cwdstuff
 {
@@ -217,6 +297,16 @@ private:
 			   a native Win32 application.  See cwdstuff::set for
 			   how it gets set.  See child_info_spawn::worker for how
 			   it's evaluated. */
+
+  friend class fcwd_access_t;
+  /* fast_cwd_ptr is a pointer to the global RtlpCurDirRef pointer in
+     ntdll.dll pointing to the FAST_CWD structure which constitutes the CWD.
+     Unfortunately RtlpCurDirRef is not exported from ntdll.dll. */
+  fcwd_access_t **fast_cwd_ptr;
+  /* Type of FAST_CWD used on this system.  Keeping this information
+     available in shared memory avoids to test for the version every time
+     around.  Default to new version. */
+  fcwd_version_t fast_cwd_version;
   void override_win32_cwd (bool, ULONG);
 
 public: