Mantis #5754: JclCreateThreadStackTrace fails unpredictably on Win7 6…

…4 bit
project-jedi · Jun 17, 2018 · bde4549 · bde4549 · PatrickvL · Jun 17, 2018
1 parent 267c312
commit bde4549
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Showing 2 changed files with 8 additions and 6 deletions.
diff --git a/jcl/experts/debug/simdview/JclSIMDUtils.pas b/jcl/experts/debug/simdview/JclSIMDUtils.pas
@@ -40,6 +40,7 @@ interface
   {$IFDEF UNITVERSIONING}
   JclUnitVersioning,
   {$ENDIF UNITVERSIONING}
+  JclBase,
   JclSysInfo,
   JclOtaResources;
 
@@ -938,8 +939,9 @@ function GetThreadJclContext(AThread: IOTAThread; out JclContext: TJclContext):
   begin
     GetMem(ContextMemory, SizeOf(TJclContext) + 15);
     try
-      if (Cardinal(ContextMemory) and 15) <> 0 then
-        AlignedContext := PJclContext((Cardinal(ContextMemory) + 16) and $FFFFFFF0)
+      if (TJclAddr(ContextMemory) and 15) <> 0 then
+        // PAnsiChar: TJclAddr is signed and would cause an int overflow for half the address space
+        AlignedContext := PContext(TJclAddr(PAnsiChar(ContextMemory) + 16) and -16)
       else
         AlignedContext := ContextMemory;
       AlignedContext^.ScalarContext.ContextFlags := CONTEXT_EXTENDED_REGISTERS;

diff --git a/jcl/source/windows/JclDebug.pas b/jcl/source/windows/JclDebug.pas
@@ -5292,13 +5292,13 @@ function JclCreateThreadStackTrace(Raw: Boolean; const ThreadHandle: THandle): T
   AlignedContext: PContext;
 begin
   Result := nil;
-  GetMem(ContextMemory, SizeOf(TContext) + 15);
+  ContextMemory := AllocMem(SizeOf(TContext) + 15);
   try
-    if (Cardinal(ContextMemory) and 15) <> 0 then
-      AlignedContext := PContext((Cardinal(ContextMemory) + 16) and $FFFFFFF0)
+    if (TJclAddr(ContextMemory) and 15) <> 0 then
+      // PAnsiChar: TJclAddr is signed and would cause an int overflow for half the address space
+      AlignedContext := PContext(TJclAddr(PAnsiChar(ContextMemory) + 16) and -16)
     else
       AlignedContext := ContextMemory;
-    ResetMemory(AlignedContext^, SizeOf(AlignedContext^));
     AlignedContext^.ContextFlags := CONTEXT_FULL;
     {$IFDEF CPU32}
     if GetThreadContext(ThreadHandle, AlignedContext^) then