Not scanning local directory symlinks pointing to network drives

Source commit: 19baa413392caabbb7afea6eb2b925cc98ca5076

source/components/DriveView.cpp

@@ -3,9 +3,16 @@
 #pragma hdrstop
 
 #include <Common.h>
+#include <System.DateUtils.hpp>
+#include <System.IOUtils.hpp>
+#include "CoreMain.h"
 #include "DriveView.h"
 #include "IEDriveInfo.h"
 #include "DirView.h"
+#ifdef DESIGN_ONLY
+#undef AppLogFmt
+#define AppLogFmt(S, F)
+#endif
 //---------------------------------------------------------------------------
 #pragma package(smart_init)
 //---------------------------------------------------------------------------
@@ -73,10 +80,16 @@ void __fastcall TDriveView::CreateWnd()
 void __fastcall TDriveView::ReadSubDirs(TTreeNode * Node)
 {
   auto NodeData = static_cast<TNodeData *>(Node->Data);
+  TDateTime Start = Now();
   UnicodeString Path = NodePath(Node);
   TSearchRec SRec;
   if (!FindFirstSubDir(IncludeTrailingBackslash(Path) + L"*.*", SRec))
   {
+    int Sec = static_cast<int>(SecondsBetween(Now(), Start));
+    if (Sec > 2)
+    {
+      AppLogFmt(L"Took %d s to find that '%s' cannot be read", (Sec, Path));
+    }
     Node->HasChildren = false;
   }
   else
@@ -88,7 +101,7 @@ void __fastcall TDriveView::ReadSubDirs(TTreeNode * Node)
       Limit /= 10;
       CheckInterval /= 10;
     }
-    if (!ReadSubDirsBatch(Node, SRec, CheckInterval, Limit))
+    if (!ReadSubDirsBatch(Node, SRec, CheckInterval, Limit, Start))
     {
       NodeData->DelayedSrec = SRec;
       NodeData->DelayedExclude = new TStringList();
@@ -108,7 +121,8 @@ void __fastcall TDriveView::ReadSubDirs(TTreeNode * Node)
 //---------------------------------------------------------------------------
 bool __fastcall TDriveView::DoScanDir(TTreeNode * FromNode)
 {
-  return !static_cast<TNodeData *>(FromNode->Data)->IsRecycleBin;
+  auto NodeData = static_cast<TNodeData *>(FromNode->Data);
+  return !NodeData->IsRecycleBin && !NodeData->IsRemote;
 }
 //---------------------------------------------------------------------------
 void __fastcall TDriveView::AddChildNode(TTreeNode * ParentNode, UnicodeString ParentPath, const TSearchRec & SRec)
@@ -116,19 +130,32 @@ void __fastcall TDriveView::AddChildNode(TTreeNode * ParentNode, UnicodeString P
   auto NodeData = new TNodeData();
   NodeData->Attr = SRec.Attr;
   NodeData->DirName = SRec.Name;
+  UnicodeString Path = IncludeTrailingBackslash(ParentPath) + SRec.Name;
   NodeData->IsRecycleBin =
     FLAGSET(SRec.Attr, faSysFile) &&
     (ParentNode->Parent == nullptr) &&
     (SameText(SRec.Name, L"RECYCLED") ||
      SameText(SRec.Name, L"RECYCLER") ||
      SameText(SRec.Name, L"$RECYCLE.BIN"));
+
+  #ifndef DESIGN_ONLY
+  if (FLAGSET(SRec.Attr, faSymLink))
+  {
+    String Target;
+    NodeData->IsRemote =
+      FileGetSymLinkTargetSafe(Path, Target) &&
+      TPath::IsUNCRooted(Target);
+  }
+  #endif
+
   NodeData->Scanned = false;
 
   TTreeNode * NewNode = Items->AddChildObject(ParentNode, EmptyStr, NodeData);
   NewNode->Text = GetDisplayName(NewNode);
   NewNode->HasChildren = true;
-  if (GetDriveTypetoNode(ParentNode) != DRIVE_REMOTE)
+  if ((GetDriveTypetoNode(ParentNode) != DRIVE_REMOTE) &&
+      !NodeData->IsRemote)
   {
-    FSubDirReaderThread->Add(NewNode, IncludeTrailingBackslash(ParentPath) + SRec.Name);
+    FSubDirReaderThread->Add(NewNode, Path);
   }
 }

source/core/Common.cpp

@@ -8,6 +8,7 @@
 #include <shlwapi.h>
 #include <tlhelp32.h>
 #include <psapi.h>
+#include <winioctl.h>
 #include <SessionInfo.h>
 #include <Soap.EncdDecd.hpp>
 #pragma clang diagnostic push
@@ -1057,6 +1058,7 @@ bool __fastcall IsReservedName(UnicodeString FileName)
 // Inspired by
 // https://stackoverflow.com/q/18580945/850848
 // This can be reimplemented using PathCchCanonicalizeEx on Windows 8 and later
+// There's also TPath.GetPosAfterExtendedPrefix.
 enum PATH_PREFIX_TYPE
 {
   PPT_UNKNOWN,
@@ -1589,6 +1591,73 @@ void __fastcall ProcessLocalDirectory(UnicodeString DirName,
   }
 }
 //---------------------------------------------------------------------------
+// Similar structure might be a part of WINAPI eventually (VCLCOPY - sic)
+struct REPARSE_DATA_BUFFER
+{
+  ULONG  ReparseTag;
+  USHORT ReparseDataLength;
+  USHORT Reserved;
+  union
+  {
+    struct
+    {
+      USHORT SubstituteNameOffset;
+      USHORT SubstituteNameLength;
+      USHORT PrintNameOffset;
+      USHORT PrintNameLength;
+      ULONG  Flags;
+      WCHAR  PathBuffer[1];
+    } SymbolicLink;
+    struct
+    {
+      USHORT SubstituteNameOffset;
+      USHORT SubstituteNameLength;
+      USHORT PrintNameOffset;
+      USHORT PrintNameLength;
+      WCHAR  PathBuffer[1];
+    } MountPoint;
+  } ReparseBuffer;
+};
+//---------------------------------------------------------------------------
+// Contrary to VCL's FileGetSymLinkTarget, this does not try to open the target folder and does not throw an exception.
+// Also it would call CreateFile without FILE_FLAG_OPEN_REPARSE_POINT, what also tries to access the remote directory,
+// potentially stalling. And with FILE_FLAG_OPEN_REPARSE_POINT, the GetFinalPathNameByHandle does not work.
+bool FileGetSymLinkTargetSafe(const String & FileName, String & Target)
+{
+  bool Result = false;
+  HANDLE Handle =
+    CreateFile(
+      FileName.c_str(), 0, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_EXISTING,
+      FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT, NULL);
+  if (Handle != INVALID_HANDLE_VALUE)
+  {
+    DWORD bytesReturned = 0;
+    char Buffer[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
+    auto Reparse = reinterpret_cast<REPARSE_DATA_BUFFER *>(Buffer);
+    if (DeviceIoControl(Handle, FSCTL_GET_REPARSE_POINT, NULL, 0, Reparse, sizeof(Buffer), &bytesReturned, NULL))
+    {
+      BYTE * NamePtr = nullptr;
+      USHORT NameSize = 0;
+      if (Reparse->ReparseTag == IO_REPARSE_TAG_SYMLINK)
+      {
+        NamePtr = reinterpret_cast<BYTE*>(Reparse->ReparseBuffer.SymbolicLink.PathBuffer) + Reparse->ReparseBuffer.SymbolicLink.PrintNameOffset;
+        NameSize = Reparse->ReparseBuffer.SymbolicLink.PrintNameLength;
+      }
+      else if (Reparse->ReparseTag == IO_REPARSE_TAG_MOUNT_POINT)
+      {
+        NamePtr = reinterpret_cast<BYTE*>(Reparse->ReparseBuffer.MountPoint.PathBuffer) + Reparse->ReparseBuffer.MountPoint.PrintNameOffset;
+        NameSize = Reparse->ReparseBuffer.MountPoint.PrintNameLength;
+      }
+      if (NamePtr != nullptr)
+      {
+        Target = String(reinterpret_cast<wchar_t *>(NamePtr), NameSize / sizeof(wchar_t));
+        Result = true;
+      }
+    }
+  }
+  return Result;
+}
+//---------------------------------------------------------------------------
 int __fastcall FileGetAttrFix(const UnicodeString & FileName)
 {
   // Already called with ApiPath
@@ -1610,6 +1679,11 @@ int __fastcall FileGetAttrFix(const UnicodeString & FileName)
         // On Samba, InternalGetFileNameFromSymLink fails and returns true but empty target.
         // That confuses FileGetAttr, which returns attributes of the parent folder instead.
         // Using FileGetSymLinkTarget solves the problem, as it returns false.
+
+        // Might want to use FileGetSymLinkTargetSafe here for consistency,
+        // but flaws/limitations of VCL FileGetSymLinkTarget probably does not matter here.
+        // The FileGetSymLinkTarget does not return the target when it cannot open it.
+        // But then GetFileAttributes would fail anyway too, so we return -1 is either case.
         if (!FileGetSymLinkTarget(FileName, TargetName))
         {
           // FileGetAttr would return faInvalid (-1), but we want to allow an upload from Samba,

source/core/Common.h

@@ -269,6 +269,7 @@ int __fastcall FindNextChecked(TSearchRecChecked & F);
 int __fastcall FindNextUnchecked(TSearchRecChecked & F);
 void __fastcall ProcessLocalDirectory(UnicodeString DirName,
   TProcessLocalFileEvent CallBackFunc, void * Param = NULL, int FindAttrs = -1);
+bool FileGetSymLinkTargetSafe(const UnicodeString & FileName, UnicodeString & Target);
 int __fastcall FileGetAttrFix(const UnicodeString & FileName);
 //---------------------------------------------------------------------------
 extern const wchar_t * DSTModeNames;

source/packages/filemng/DriveViewInt.pas

@@ -80,6 +80,7 @@ type
     FScanned: Boolean;
     FData: Pointer;
     FIsRecycleBin: Boolean;
+    FIsRemote: Boolean;
     FIconEmpty: Boolean;
     FSchedule: TSubDirReaderSchedule;
 
@@ -95,6 +96,7 @@ type
     property Scanned: Boolean read FScanned write FScanned;
     property Data: Pointer read FData write FData;
     property IsRecycleBin: Boolean read FIsRecycleBin write FIsRecycleBin;
+    property IsRemote: Boolean read FIsRemote write FIsRemote;
     property IconEmpty: Boolean read FIconEmpty write FIconEmpty;
     property Schedule: TSubDirReaderSchedule read FSchedule write FSchedule;
   end;
@@ -183,7 +185,7 @@ type
     procedure ReadSubDirs(Node: TTreeNode); virtual; abstract;
     procedure CancelDelayedNode(Node: TTreeNode);
     procedure DelayedNodeTimer(Sender: TObject);
-    function ReadSubDirsBatch(Node: TTreeNode; var SRec: TSearchRec; CheckInterval, Limit: Integer): Boolean;
+    function ReadSubDirsBatch(Node: TTreeNode; var SRec: TSearchRec; CheckInterval, Limit: Integer; Start: TDateTime): Boolean;
     procedure UpdateDelayedNodeTimer;
     function DoSearchSubDirs(
       ParentNode: TTreeNode; Path: string; Level: Integer; ExistingOnly: Boolean;
@@ -436,6 +438,7 @@ begin
   FScanned := False;
   FDirName := '';
   FIsRecycleBin := False;
+  FIsRemote := False;
   FIconEmpty := True;
   FSchedule := nil;
   DelayedExclude := nil;
@@ -785,6 +788,7 @@ begin
     NewData.Scanned := SourceData.Scanned;
     NewData.Data := SourceData.Data;
     NewData.FIsRecycleBin := SourceData.FIsRecycleBin;
+    NewData.FIsRemote := SourceData.FIsRemote;
     NewData.IconEmpty := SourceData.IconEmpty;
     TTreeNode(Source).Data := NewData;
   end;
@@ -1853,15 +1857,13 @@ begin
   Result := (FindNext(SRec) = 0) and GetSubDir(SRec);
 end;
 
-function TDriveViewInt.ReadSubDirsBatch(Node: TTreeNode; var SRec: TSearchRec; CheckInterval, Limit: Integer): Boolean;
+function TDriveViewInt.ReadSubDirsBatch(Node: TTreeNode; var SRec: TSearchRec; CheckInterval, Limit: Integer; Start: TDateTime): Boolean;
 var
-  Start: TDateTime;
   Cont: Boolean;
   Path: string;
   Count: Integer;
   DelayedExclude: TStringList;
 begin
-  Start := Now;
   Path := NodePath(Node);
   Result := True;
   Count := 0;
@@ -1916,7 +1918,7 @@ begin
       else
     begin
       NodeData := TNodeData(Node.Data);
-      if ReadSubDirsBatch(Node, NodeData.DelayedSrec, 10, 50) then
+      if ReadSubDirsBatch(Node, NodeData.DelayedSrec, 10, 50, Now) then
       begin
         FreeAndNil(NodeData.DelayedExclude);
         FDelayedNodes.Delete(0);