From 7ebbef2b303fc1c54950bd9047f79e353ee0129c Mon Sep 17 00:00:00 2001
From: Zequan Wu <zequanwu@google.com>
Date: Mon, 15 Aug 2022 19:34:13 -0700
Subject: [PATCH] [LLDB][NativePDB] Add nullptr checking.

---
 .../SymbolFile/NativePDB/PdbAstBuilder.cpp    |  8 ++++--
 .../NativePDB/SymbolFileNativePDB.cpp         | 27 ++++++++++++-------
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
index 25425f9140880..b8848839f24f7 100644
--- a/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
@@ -501,6 +501,8 @@ clang::Decl *PdbAstBuilder::GetOrCreateSymbolForId(PdbCompilandSymId id) {
 
   if (isLocalVariableType(cvs.kind())) {
     clang::DeclContext *scope = GetParentDeclContext(id);
+    if (!scope)
+      return nullptr;
     clang::Decl *scope_decl = clang::Decl::castFromDeclContext(scope);
     PdbCompilandSymId scope_id =
         PdbSymUid(m_decl_to_status[scope_decl].uid).asCompilandSym();
@@ -1010,7 +1012,7 @@ PdbAstBuilder::GetOrCreateTypedefDecl(PdbGlobalSymId id) {
 
   PdbTypeSymId real_type_id{udt.Type, false};
   clang::QualType qt = GetOrCreateType(real_type_id);
-  if (qt.isNull())
+  if (qt.isNull() || !scope)
     return nullptr;
 
   std::string uname = std::string(DropNameScope(udt.Name));
@@ -1265,7 +1267,7 @@ PdbAstBuilder::CreateFunctionDeclFromId(PdbTypeSymId func_tid,
     lldbassert(false && "Invalid function id type!");
   }
   clang::QualType func_qt = GetOrCreateType(func_ti);
-  if (func_qt.isNull())
+  if (func_qt.isNull() || !parent)
     return nullptr;
   CompilerType func_ct = ToCompilerType(func_qt);
   uint32_t param_count =
@@ -1280,6 +1282,8 @@ PdbAstBuilder::GetOrCreateFunctionDecl(PdbCompilandSymId func_id) {
     return llvm::dyn_cast<clang::FunctionDecl>(decl);
 
   clang::DeclContext *parent = GetParentDeclContext(PdbSymUid(func_id));
+  if (!parent)
+    return nullptr;
   std::string context_name;
   if (clang::NamespaceDecl *ns = llvm::dyn_cast<clang::NamespaceDecl>(parent)) {
     context_name = ns->getQualifiedNameAsString();
diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
index ada7a0f71fb55..c596d9c7a1ae7 100644
--- a/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
@@ -345,10 +345,13 @@ Block &SymbolFileNativePDB::CreateBlock(PdbCompilandSymId block_id) {
     // This is a function.  It must be global.  Creating the Function entry
     // for it automatically creates a block for it.
     FunctionSP func = GetOrCreateFunction(block_id, *comp_unit);
-    Block &block = func->GetBlock(false);
-    if (block.GetNumRanges() == 0)
-      block.AddRange(Block::Range(0, func->GetAddressRange().GetByteSize()));
-    return block;
+    if (func) {
+      Block &block = func->GetBlock(false);
+      if (block.GetNumRanges() == 0)
+        block.AddRange(Block::Range(0, func->GetAddressRange().GetByteSize()));
+      return block;
+    }
+    break;
   }
   case S_BLOCK32: {
     // This is a block.  Its parent is either a function or another block.  In
@@ -1024,11 +1027,13 @@ uint32_t SymbolFileNativePDB::ResolveSymbolContext(
         continue;
       if (type == PDB_SymType::Function) {
         sc.function = GetOrCreateFunction(csid, *sc.comp_unit).get();
-        Block &block = sc.function->GetBlock(true);
-        addr_t func_base =
-            sc.function->GetAddressRange().GetBaseAddress().GetFileAddress();
-        addr_t offset = file_addr - func_base;
-        sc.block = block.FindInnermostBlockByOffset(offset);
+        if (sc.function) {
+          Block &block = sc.function->GetBlock(true);
+          addr_t func_base =
+              sc.function->GetAddressRange().GetBaseAddress().GetFileAddress();
+          addr_t offset = file_addr - func_base;
+          sc.block = block.FindInnermostBlockByOffset(offset);
+        }
       }
 
       if (type == PDB_SymType::Block) {
@@ -1908,6 +1913,8 @@ SymbolFileNativePDB::GetDeclContextForUID(lldb::user_id_t uid) {
 CompilerDeclContext
 SymbolFileNativePDB::GetDeclContextContainingUID(lldb::user_id_t uid) {
   clang::DeclContext *context = m_ast->GetParentDeclContext(PdbSymUid(uid));
+  if (!context)
+    return CompilerDeclContext();
   return m_ast->ToCompilerDeclContext(*context);
 }
 
@@ -1929,6 +1936,8 @@ Type *SymbolFileNativePDB::ResolveTypeUID(lldb::user_id_t type_uid) {
     return nullptr;
 
   TypeSP type_sp = CreateAndCacheType(type_id);
+  if (!type_sp)
+    return nullptr;
   return &*type_sp;
 }