Don't crash when a SBType is handed out through the API and later used after the module that owns the type is deleted.

The fix adds a std::weak_ptr<Module> into the TypeImpl and fills in the weak pointer when possible. It also checks to make sure the module is still alive prior to using it which should make our API safer to use.

<rdar://problem/15455145> 

llvm-svn: 212853

1 files changed, 193 insertions, 71 deletions

diff --git a/lldb/source/Symbol/Type.cpp b/lldb/source/Symbol/Type.cpp
index ce8666bc129..4eb538fb135 100644
--- a/lldb/source/Symbol/Type.cpp
+++ b/lldb/source/Symbol/Type.cpp
@@ -798,6 +798,13 @@ Type::GetTypeScopeAndBasename (const char* &name_cstr,
 }
 
 
+ModuleSP
+Type::GetModule()
+{
+    if (m_symbol_file)
+        return m_symbol_file->GetObjectFile()->GetModule();
+    return ModuleSP();
+}
 
 
 TypeAndOrName::TypeAndOrName () : m_type_pair(), m_type_name()
@@ -929,76 +936,95 @@ TypeAndOrName::HasClangASTType () const
 
 
 TypeImpl::TypeImpl() :
-m_static_type(),
-m_dynamic_type()
+    m_module_wp(),
+    m_static_type(),
+    m_dynamic_type()
 {
 }
 
 TypeImpl::TypeImpl(const TypeImpl& rhs) :
-m_static_type(rhs.m_static_type),
-m_dynamic_type(rhs.m_dynamic_type)
+    m_module_wp (rhs.m_module_wp),
+    m_static_type(rhs.m_static_type),
+    m_dynamic_type(rhs.m_dynamic_type)
 {
 }
 
-TypeImpl::TypeImpl (lldb::TypeSP type_sp) :
-m_static_type(type_sp),
-m_dynamic_type()
+TypeImpl::TypeImpl (const lldb::TypeSP &type_sp) :
+    m_module_wp (),
+    m_static_type(),
+    m_dynamic_type()
 {
+    SetType (type_sp);
 }
 
-TypeImpl::TypeImpl (ClangASTType clang_type) :
-m_static_type(clang_type),
-m_dynamic_type()
+TypeImpl::TypeImpl (const ClangASTType &clang_type) :
+    m_module_wp (),
+    m_static_type(),
+    m_dynamic_type()
 {
+    SetType (clang_type);
 }
 
-TypeImpl::TypeImpl (lldb::TypeSP type_sp, ClangASTType dynamic) :
-m_static_type (type_sp),
-m_dynamic_type(dynamic)
+TypeImpl::TypeImpl (const lldb::TypeSP &type_sp, const ClangASTType &dynamic) :
+    m_module_wp (),
+    m_static_type (type_sp),
+    m_dynamic_type(dynamic)
 {
+    SetType (type_sp, dynamic);
 }
 
-TypeImpl::TypeImpl (ClangASTType clang_type, ClangASTType dynamic) :
-m_static_type (clang_type),
-m_dynamic_type(dynamic)
+TypeImpl::TypeImpl (const ClangASTType &static_type, const ClangASTType &dynamic_type) :
+    m_module_wp (),
+    m_static_type (),
+    m_dynamic_type()
 {
+    SetType (static_type, dynamic_type);
 }
 
-TypeImpl::TypeImpl (TypePair pair, ClangASTType dynamic) :
-m_static_type (pair),
-m_dynamic_type(dynamic)
+TypeImpl::TypeImpl (const TypePair &pair, const ClangASTType &dynamic) :
+    m_module_wp (),
+    m_static_type (),
+    m_dynamic_type()
 {
+    SetType (pair, dynamic);
 }
 
 void
-TypeImpl::SetType (lldb::TypeSP type_sp)
+TypeImpl::SetType (const lldb::TypeSP &type_sp)
 {
     m_static_type.SetType(type_sp);
+    if (type_sp)
+        m_module_wp = type_sp->GetModule();
+    else
+        m_module_wp = lldb::ModuleWP();
 }
 
 void
-TypeImpl::SetType (ClangASTType clang_type)
+TypeImpl::SetType (const ClangASTType &clang_type)
 {
+    m_module_wp = lldb::ModuleWP();
     m_static_type.SetType (clang_type);
 }
 
 void
-TypeImpl::SetType (lldb::TypeSP type_sp, ClangASTType dynamic)
+TypeImpl::SetType (const lldb::TypeSP &type_sp, const ClangASTType &dynamic)
 {
-    m_static_type.SetType (type_sp);
+    SetType (type_sp);
     m_dynamic_type = dynamic;
 }
 
 void
-TypeImpl::SetType (ClangASTType clang_type, ClangASTType dynamic)
+TypeImpl::SetType (const ClangASTType &clang_type, const ClangASTType &dynamic)
 {
+    m_module_wp = lldb::ModuleWP();
     m_static_type.SetType (clang_type);
     m_dynamic_type = dynamic;
 }
 
 void
-TypeImpl::SetType (TypePair pair, ClangASTType dynamic)
+TypeImpl::SetType (const TypePair &pair, const ClangASTType &dynamic)
 {
+    m_module_wp = pair.GetModule();
     m_static_type = pair;
     m_dynamic_type = dynamic;
 }
@@ -1008,6 +1034,7 @@ TypeImpl::operator = (const TypeImpl& rhs)
 {
     if (rhs != *this)
     {
+        m_module_wp = rhs.m_module_wp;
         m_static_type = rhs.m_static_type;
         m_dynamic_type = rhs.m_dynamic_type;
     }
@@ -1015,24 +1042,55 @@ TypeImpl::operator = (const TypeImpl& rhs)
 }
 
 bool
+TypeImpl::CheckModule (lldb::ModuleSP &module_sp) const
+{
+    // Check if we have a module for this type. If we do and the shared pointer is
+    // can be successfully initialized with m_module_wp, return true. Else return false
+    // if we didn't have a module, or if we had a module and it has been deleted. Any
+    // functions doing anything with a TypeSP in this TypeImpl class should call this
+    // function and only do anything with the ivars if this function returns true. If
+    // we have a module, the "module_sp" will be filled in with a strong reference to the
+    // module so that the module will at least stay around long enough for the type
+    // query to succeed.
+    module_sp = m_module_wp.lock();
+    if (!module_sp)
+    {
+        lldb::ModuleWP empty_module_wp;
+        // If either call to "std::weak_ptr::owner_before(...) value returns true, this
+        // indicates that m_module_wp once contained (possibly still does) a reference
+        // to a valid shared pointer. This helps us know if we had a valid reference to
+        // a section which is now invalid because the module it was in was deleted
+        if (empty_module_wp.owner_before(m_module_wp) || m_module_wp.owner_before(empty_module_wp))
+        {
+            // m_module_wp had a valid reference to a module, but all strong references
+            // have been released and the module has been deleted
+            return false;
+        }
+    }
+    // We either successfully locked the module, or didn't have one to begin with
+    return true;
+}
+
+bool
 TypeImpl::operator == (const TypeImpl& rhs) const
 {
-    return m_static_type == rhs.m_static_type &&
-    m_dynamic_type == rhs.m_dynamic_type;
+    return m_static_type == rhs.m_static_type && m_dynamic_type == rhs.m_dynamic_type;
 }
 
 bool
 TypeImpl::operator != (const TypeImpl& rhs) const
 {
-    return m_static_type != rhs.m_static_type ||
-    m_dynamic_type != rhs.m_dynamic_type;
+    return m_static_type != rhs.m_static_type || m_dynamic_type != rhs.m_dynamic_type;
 }
 
 bool
 TypeImpl::IsValid() const
 {
     // just a name is not valid
-    return m_static_type.IsValid() || m_dynamic_type.IsValid();
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
+        return m_static_type.IsValid() || m_dynamic_type.IsValid();
+    return false;
 }
 
 TypeImpl::operator bool () const
@@ -1043,6 +1101,7 @@ TypeImpl::operator bool () const
 void
 TypeImpl::Clear()
 {
+    m_module_wp = lldb::ModuleWP();
     m_static_type.Clear();
     m_dynamic_type.Clear();
 }
@@ -1050,122 +1109,185 @@ TypeImpl::Clear()
 ConstString
 TypeImpl::GetName ()  const
 {
-    if (m_dynamic_type)
-        return m_dynamic_type.GetTypeName();
-    return m_static_type.GetName ();
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
+    {
+        if (m_dynamic_type)
+            return m_dynamic_type.GetTypeName();
+        return m_static_type.GetName ();
+    }
+    return ConstString();
 }
 
 ConstString
 TypeImpl::GetDisplayTypeName ()  const
 {
-    if (m_dynamic_type)
-        return m_dynamic_type.GetDisplayTypeName();
-    return m_static_type.GetDisplayTypeName();
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
+    {
+        if (m_dynamic_type)
+            return m_dynamic_type.GetDisplayTypeName();
+        return m_static_type.GetDisplayTypeName();
+    }
+    return ConstString();
 }
 
 TypeImpl
 TypeImpl::GetPointerType () const
 {
-    if (m_dynamic_type.IsValid())
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        return TypeImpl(m_static_type, m_dynamic_type.GetPointerType());
+        if (m_dynamic_type.IsValid())
+        {
+            return TypeImpl(m_static_type, m_dynamic_type.GetPointerType());
+        }
+        return TypeImpl(m_static_type.GetPointerType());
     }
-    return TypeImpl(m_static_type.GetPointerType());
+    return TypeImpl();
 }
 
 TypeImpl
 TypeImpl::GetPointeeType () const
 {
-    if (m_dynamic_type.IsValid())
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        return TypeImpl(m_static_type, m_dynamic_type.GetPointeeType());
+        if (m_dynamic_type.IsValid())
+        {
+            return TypeImpl(m_static_type, m_dynamic_type.GetPointeeType());
+        }
+        return TypeImpl(m_static_type.GetPointeeType());
     }
-    return TypeImpl(m_static_type.GetPointeeType());
+    return TypeImpl();
 }
 
 TypeImpl
 TypeImpl::GetReferenceType () const
 {
-    if (m_dynamic_type.IsValid())
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        return TypeImpl(m_static_type, m_dynamic_type.GetLValueReferenceType());
+        if (m_dynamic_type.IsValid())
+        {
+            return TypeImpl(m_static_type, m_dynamic_type.GetLValueReferenceType());
+        }
+        return TypeImpl(m_static_type.GetReferenceType());
     }
-    return TypeImpl(m_static_type.GetReferenceType());
+    return TypeImpl();
 }
 
 TypeImpl
 TypeImpl::GetTypedefedType () const
 {
-    if (m_dynamic_type.IsValid())
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        return TypeImpl(m_static_type, m_dynamic_type.GetTypedefedType());
+        if (m_dynamic_type.IsValid())
+        {
+            return TypeImpl(m_static_type, m_dynamic_type.GetTypedefedType());
+        }
+        return TypeImpl(m_static_type.GetTypedefedType());
     }
-    return TypeImpl(m_static_type.GetTypedefedType());
+    return TypeImpl();
 }
 
 TypeImpl
 TypeImpl::GetDereferencedType () const
 {
-    if (m_dynamic_type.IsValid())
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        return TypeImpl(m_static_type, m_dynamic_type.GetNonReferenceType());
+        if (m_dynamic_type.IsValid())
+        {
+            return TypeImpl(m_static_type, m_dynamic_type.GetNonReferenceType());
+        }
+        return TypeImpl(m_static_type.GetDereferencedType());
     }
-    return TypeImpl(m_static_type.GetDereferencedType());
+    return TypeImpl();
 }
 
 TypeImpl
 TypeImpl::GetUnqualifiedType() const
 {
-    if (m_dynamic_type.IsValid())
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        return TypeImpl(m_static_type, m_dynamic_type.GetFullyUnqualifiedType());
+        if (m_dynamic_type.IsValid())
+        {
+            return TypeImpl(m_static_type, m_dynamic_type.GetFullyUnqualifiedType());
+        }
+        return TypeImpl(m_static_type.GetUnqualifiedType());
     }
-    return TypeImpl(m_static_type.GetUnqualifiedType());
+    return TypeImpl();
 }
 
 TypeImpl
 TypeImpl::GetCanonicalType() const
 {
-    if (m_dynamic_type.IsValid())
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        return TypeImpl(m_static_type, m_dynamic_type.GetCanonicalType());
+        if (m_dynamic_type.IsValid())
+        {
+            return TypeImpl(m_static_type, m_dynamic_type.GetCanonicalType());
+        }
+        return TypeImpl(m_static_type.GetCanonicalType());
     }
-    return TypeImpl(m_static_type.GetCanonicalType());
+    return TypeImpl();
 }
 
 ClangASTType
 TypeImpl::GetClangASTType (bool prefer_dynamic)
 {
-    if (prefer_dynamic)
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        if (m_dynamic_type.IsValid())
-            return m_dynamic_type;
+        if (prefer_dynamic)
+        {
+            if (m_dynamic_type.IsValid())
+                return m_dynamic_type;
+        }
+        return m_static_type.GetClangASTType();
     }
-    return m_static_type.GetClangASTType();
+    return ClangASTType();
 }
 
 clang::ASTContext *
 TypeImpl::GetClangASTContext (bool prefer_dynamic)
 {
-    if (prefer_dynamic)
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
     {
-        if (m_dynamic_type.IsValid())
-            return m_dynamic_type.GetASTContext();
+        if (prefer_dynamic)
+        {
+            if (m_dynamic_type.IsValid())
+                return m_dynamic_type.GetASTContext();
+        }
+        return m_static_type.GetClangASTContext();
     }
-    return m_static_type.GetClangASTContext();
+    return NULL;
 }
 
 bool
 TypeImpl::GetDescription (lldb_private::Stream &strm,
-                lldb::DescriptionLevel description_level)
+                          lldb::DescriptionLevel description_level)
 {
-    if (m_dynamic_type.IsValid())
+    ModuleSP module_sp;
+    if (CheckModule (module_sp))
+    {
+        if (m_dynamic_type.IsValid())
+        {
+            strm.Printf("Dynamic:\n");
+            m_dynamic_type.DumpTypeDescription(&strm);
+            strm.Printf("\nStatic:\n");
+        }
+        m_static_type.GetClangASTType().DumpTypeDescription(&strm);
+    }
+    else
     {
-        strm.Printf("Dynamic:\n");
-        m_dynamic_type.DumpTypeDescription(&strm);
-        strm.Printf("\nStatic:\n");
+        strm.PutCString("Invalid TypeImpl module for type has been deleted\n");
     }
-    m_static_type.GetClangASTType().DumpTypeDescription(&strm);
     return true;
 }