[Lldb-commits] [lldb] 9a3f0cd - Fix crash in lldb-vscode when missing function name

[Tom Yang via lldb-commits]

Author: Tom Yang
Date: 2023-08-03T12:56:37-07:00
New Revision: 9a3f0cd717f68ccf9e348bce2d76a2372482f4f2

URL: https://github.com/llvm/llvm-project/commit/9a3f0cd717f68ccf9e348bce2d76a2372482f4f2
DIFF: https://github.com/llvm/llvm-project/commit/9a3f0cd717f68ccf9e348bce2d76a2372482f4f2.diff

LOG: Fix crash in lldb-vscode when missing function name

Summary:
In cases where the PC has no function name, lldb-vscode crashes.

`lldb::SBFrame::GetDisplayFunctionName()` returns a `nullptr`, and when we
attempt to construct an `std::string`, it raises an exception.

Test plan:
This can be observed with creating a test file (credit to @clayborg for
the example):
```
int main() {
  typedef void (*FooCallback)();
  FooCallback foo_callback = (FooCallback)0;
  foo_callback(); // Crash at zero!
  return 0;
}
```
and attempting to debug the file through VSCode.

I add a test case in D156732 which should cover this.

Differential Revision: https://reviews.llvm.org/D156970

Added: 
    

Modified: 
    lldb/tools/lldb-vscode/JSONUtils.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/tools/lldb-vscode/JSONUtils.cpp b/lldb/tools/lldb-vscode/JSONUtils.cpp
index 5ece7c01346b73..6acb07296da3be 100644
--- a/lldb/tools/lldb-vscode/JSONUtils.cpp
+++ b/lldb/tools/lldb-vscode/JSONUtils.cpp
@@ -696,7 +696,11 @@ llvm::json::Value CreateStackFrame(lldb::SBFrame &frame) {
   int64_t frame_id = MakeVSCodeFrameID(frame);
   object.try_emplace("id", frame_id);
 
-  std::string frame_name = frame.GetDisplayFunctionName();
+  // `function_name` can be a nullptr, which throws an error when assigned to an
+  // `std::string`.
+  const char *function_name = frame.GetDisplayFunctionName();
+  std::string frame_name =
+      function_name == nullptr ? std::string() : function_name;
   if (frame_name.empty())
     frame_name = "<unknown>";
   bool is_optimized = frame.GetFunction().GetIsOptimized();