[Lldb-commits] [lldb] Fix lldb crash while handling concurrent vfork() (PR #81564)

[Greg Clayton via lldb-commits]

================
@@ -0,0 +1,49 @@
+"""
+Make sure that the concurrent vfork() from multiple threads works correctly.
+"""
+
+
+import lldb
+import lldbsuite.test.lldbutil as lldbutil
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+
+
+class TestConcurrentVFork(TestBase):
+    NO_DEBUG_INFO_TESTCASE = True
+
+    def get_pid_from_variable(self):
+        target = self.dbg.GetTargetAtIndex(0)
+        return target.FindFirstGlobalVariable("g_pid").GetValueAsUnsigned()
+
+    @skipIfWindows
+    def test_vfork_follow_parent(self):
+        """
+        Make sure that debugging concurrent vfork() from multiple threads won't crash lldb during follow-parent.
+        And follow-parent successfully detach all child processes and exit debugger.
+        """
+
+        self.build()
----------------
clayborg wrote:

We need to add arguments to this to specify if we are calling `vfork` or `fork` and if we are calling exec. 

We should make a helper function that calls `lldbutil.run_to_source_breakpoint` so it can be used correctly with the right arguemnts getting to the program we launch:
```
def run_to_breakpoint(self, use_fork, call_exec):
    args = [self.getBuildArtifact("a.out")]
    if  use_fork:
        args.append("--fork");
    if call_exec:
        args.append("--exec");
    launch_info = lldb.SBLaunchInfo(args)
    launch_info.SetWorkingDirectory(self.getBuildDir())
    lldbutil.run_to_source_breakpoint(
        self, "// break here", lldb.SBFileSpec("main.cpp"), launch_info=launch_info
    )
```
Then we can call this function from each of the variations we need:
```
def test_vfork_follow_parent_no_exec(self):
def test_vfork_follow_parent_with_exec(self):
def test_vfork_follow_child_no_exec(self):
def test_vfork_follow_child_with_exec(self):
```

https://github.com/llvm/llvm-project/pull/81564