[Lldb-commits] [PATCH] D100208: [lldb] [Process/Linux] Report fork/vfork stop reason to client [WIP]

[Michał Górny via Phabricator via lldb-commits]

mgorny created this revision.
mgorny added reviewers: labath, emaste, krytarowski.
mgorny requested review of this revision.

Enable reporting fork/vfork events to the client when supported.  This
switches from implicit server-side handling to client-controlled
gdb-remote protocol exchange.


https://reviews.llvm.org/D100208

Files:
  lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
  lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
  lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp
  lldb/source/Plugins/Process/Linux/NativeThreadLinux.h


Index: lldb/source/Plugins/Process/Linux/NativeThreadLinux.h
===================================================================
--- lldb/source/Plugins/Process/Linux/NativeThreadLinux.h
+++ lldb/source/Plugins/Process/Linux/NativeThreadLinux.h
@@ -85,6 +85,10 @@
 
   void SetStoppedByTrace();
 
+  void SetStoppedByFork(lldb::pid_t child_pid);
+
+  void SetStoppedByVFork(lldb::pid_t child_pid);
+
   void SetStoppedWithNoReason();
 
   void SetStoppedByProcessorTrace(llvm::StringRef description);
Index: lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp
===================================================================
--- lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp
+++ lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp
@@ -394,6 +394,22 @@
   m_stop_info.details.signal.signo = SIGTRAP;
 }
 
+void NativeThreadLinux::SetStoppedByFork(lldb::pid_t child_pid) {
+  SetStopped();
+
+  m_stop_info.reason = StopReason::eStopReasonFork;
+  m_stop_info.details.fork.child_pid = child_pid;
+  m_stop_info.details.fork.child_tid = child_pid;
+}
+
+void NativeThreadLinux::SetStoppedByVFork(lldb::pid_t child_pid) {
+  SetStopped();
+
+  m_stop_info.reason = StopReason::eStopReasonVFork;
+  m_stop_info.details.fork.child_pid = child_pid;
+  m_stop_info.details.fork.child_tid = child_pid;
+}
+
 void NativeThreadLinux::SetStoppedWithNoReason() {
   SetStopped();
 
Index: lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
===================================================================
--- lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
+++ lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
@@ -142,6 +142,9 @@
 
   lldb::tid_t m_pending_notification_tid = LLDB_INVALID_THREAD_ID;
 
+  // Dummy loop for subprocess instances.
+  MainLoop m_subprocess_loop;
+
   /// Inferior memory (allocated by us) and its size.
   llvm::DenseMap<lldb::addr_t, lldb::addr_t> m_allocated_memory;
 
Index: lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
===================================================================
--- lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
+++ lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
@@ -914,16 +914,26 @@
     LLVM_FALLTHROUGH;
   case PTRACE_EVENT_FORK:
   case PTRACE_EVENT_VFORK: {
-    MainLoop unused_loop;
-    NativeProcessLinux child_process{static_cast<::pid_t>(child_pid),
-                                     m_terminal_fd,
-                                     *m_delegates[0],
-                                     m_arch,
-                                     unused_loop,
-                                     {static_cast<::pid_t>(child_pid)}};
-    child_process.Detach();
-    ResumeThread(*parent_thread, parent_thread->GetState(),
-                 LLDB_INVALID_SIGNAL_NUMBER);
+    std::unique_ptr<NativeProcessProtocol> child_process{new NativeProcessLinux(
+        static_cast<::pid_t>(child_pid), m_terminal_fd, *m_delegates[0], m_arch,
+        m_subprocess_loop, {static_cast<::pid_t>(child_pid)})};
+    Extension expected_ext = (clone_info->event != PTRACE_EVENT_VFORK)
+                                 ? Extension::fork
+                                 : Extension::vfork;
+    if ((m_enabled_extensions & expected_ext) == expected_ext) {
+      for (auto &x : m_delegates)
+        x->NewSubprocess(this, child_process);
+      // NB: non-vfork clone() is reported as fork
+      if (clone_info->event != PTRACE_EVENT_VFORK)
+        parent_thread->SetStoppedByFork(child_pid);
+      else
+        parent_thread->SetStoppedByVFork(child_pid);
+      StopRunningThreads(parent_thread->GetID());
+    } else {
+      child_process->Detach();
+      ResumeThread(*parent_thread, parent_thread->GetState(),
+                   LLDB_INVALID_SIGNAL_NUMBER);
+    }
     break;
   }
   default:


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