win: Save contents of TEBs allowing !teb and !gle to work in windbg

snapshot/win/process_reader_win.cc

Index: snapshot/win/process_reader_win.cc
diff --git a/snapshot/win/process_reader_win.cc b/snapshot/win/process_reader_win.cc
index bcdf448326941f20a1f455cb087b429bf4eec04b..084c823410d487eed05a4b80e3d6c4495f8d6dbb 100644
--- a/snapshot/win/process_reader_win.cc
+++ b/snapshot/win/process_reader_win.cc
@@ -176,7 +176,8 @@ bool FillThreadContextAndSuspendCount(HANDLE thread_handle,
 ProcessReaderWin::Thread::Thread()
     : context(),
       id(0),
-      teb(0),
+      teb_address(0),
+      teb_size(0),
       stack_region_address(0),
       stack_region_size(0),
       suspend_count(0),
@@ -331,8 +332,9 @@ void ProcessReaderWin::ReadThreadData(bool is_64_reading_32) {
     // Read the TIB (Thread Information Block) which is the first element of the
     // TEB, for its stack fields.
     process_types::NT_TIB<Traits> tib;
-    thread.teb = thread_basic_info.TebBaseAddress;
-    if (ReadMemory(thread.teb, sizeof(tib), &tib)) {
+    thread.teb_address = thread_basic_info.TebBaseAddress;
+    thread.teb_size = sizeof(process_types::TEB<Traits>);
+    if (ReadMemory(thread.teb_address, sizeof(tib), &tib)) {
       WinVMAddress base = 0;
       WinVMAddress limit = 0;
       // If we're reading a WOW64 process, then the TIB we just retrieved is the
@@ -340,8 +342,10 @@ void ProcessReaderWin::ReadThreadData(bool is_64_reading_32) {
       // https://msdn.microsoft.com/en-us/library/dn424783.aspx
       if (is_64_reading_32) {
         process_types::NT_TIB<process_types::internal::Traits32> tib32;
-        thread.teb = tib.Wow64Teb;
-        if (ReadMemory(thread.teb, sizeof(tib32), &tib32)) {
+        thread.teb_address = tib.Wow64Teb;
+        thread.teb_size =
+            sizeof(process_types::TEB<process_types::internal::Traits32>);
+        if (ReadMemory(thread.teb_address, sizeof(tib32), &tib32)) {
           base = tib32.StackBase;
           limit = tib32.StackLimit;
         }