[Lldb-commits] [PATCH] D141605: [lldb] Detach the child process when stepping over a fork

[Pavel Labath via Phabricator via lldb-commits]

labath created this revision.
labath added reviewers: jingham, mgorny.
Herald added a project: All.
labath requested review of this revision.
Herald added a project: LLDB.

Step over thread plans were claiming to explain the fork stop reasons,
which prevented the default fork logic (detaching from the child
process) from kicking in. This patch changes that.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D141605

Files:
  lldb/source/Target/ThreadPlan.cpp
  lldb/test/API/functionalities/fork/resumes-child/Makefile
  lldb/test/API/functionalities/fork/resumes-child/TestForkResumesChild.py
  lldb/test/API/functionalities/fork/resumes-child/main.cpp


Index: lldb/test/API/functionalities/fork/resumes-child/main.cpp
===================================================================
--- /dev/null
+++ lldb/test/API/functionalities/fork/resumes-child/main.cpp
@@ -0,0 +1,29 @@
+#include <cassert>
+#include <chrono>
+#include <cstdlib>
+#include <sys/wait.h>
+#include <thread>
+#include <unistd.h>
+
+int main() {
+  pid_t fork_result = fork(); // break here
+  assert(fork_result >= 0);
+  if (fork_result == 0) {
+    // child
+    _exit(47);
+  }
+  // parent
+  // Use polling to avoid blocking if the child is not actually resumed.
+  auto deadline = std::chrono::steady_clock::now() + std::chrono::seconds(10);
+  std::chrono::milliseconds poll_interval{10};
+  while (std::chrono::steady_clock::now() < deadline) {
+    int status;
+    pid_t waitpid_result = waitpid(fork_result, &status, WNOHANG);
+    if (waitpid_result == fork_result)
+      return 0;
+    assert(waitpid_result == 0);
+    std::this_thread::sleep_for(poll_interval);
+    poll_interval *= 2;
+  }
+  abort();
+}
Index: lldb/test/API/functionalities/fork/resumes-child/TestForkResumesChild.py
===================================================================
--- /dev/null
+++ lldb/test/API/functionalities/fork/resumes-child/TestForkResumesChild.py
@@ -0,0 +1,22 @@
+"""
+Make sure that the fork child keeps running.
+"""
+
+
+
+import lldb
+import lldbsuite.test.lldbutil as lldbutil
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+
+
+class TestForkResumesChild(TestBase):
+
+    NO_DEBUG_INFO_TESTCASE = True
+
+    @skipIfWindows
+    def test_step_over_fork(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self, "// break here", lldb.SBFileSpec("main.cpp"))
+        self.runCmd("next")
+        self.expect("continue", substrs = ["exited with status = 0"])
Index: lldb/test/API/functionalities/fork/resumes-child/Makefile
===================================================================
--- /dev/null
+++ lldb/test/API/functionalities/fork/resumes-child/Makefile
@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules
Index: lldb/source/Target/ThreadPlan.cpp
===================================================================
--- lldb/source/Target/ThreadPlan.cpp
+++ lldb/source/Target/ThreadPlan.cpp
@@ -171,6 +171,9 @@
   case eStopReasonExec:
   case eStopReasonThreadExiting:
   case eStopReasonInstrumentation:
+  case eStopReasonFork:
+  case eStopReasonVFork:
+  case eStopReasonVForkDone:
     return true;
   default:
     return false;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D141605.488610.patch
Type: text/x-patch
Size: 2558 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/lldb-commits/attachments/20230112/d3957051/attachment-0001.bin>