[Lldb-commits] [PATCH] D100206: [lldb] [llgs client] Support minimal fork/vfork handling

[Michał Górny via Phabricator via lldb-commits]

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

Add a support for handling fork/vfork stops in LLGS client.  At this
point, it only sends a detach packet for the newly forked child
(and implicitly resumes the parent).


https://reviews.llvm.org/D100206

Files:
  lldb/include/lldb/Target/Process.h
  lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
  lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
  lldb/source/Target/StopInfo.cpp


Index: lldb/source/Target/StopInfo.cpp
===================================================================
--- lldb/source/Target/StopInfo.cpp
+++ lldb/source/Target/StopInfo.cpp
@@ -1150,8 +1150,8 @@
 class StopInfoFork : public StopInfo {
 public:
   StopInfoFork(Thread &thread, lldb::pid_t child_pid, lldb::tid_t child_tid)
-      : StopInfo(thread, child_pid), m_child_pid(child_pid),
-        m_child_tid(child_tid) {}
+      : StopInfo(thread, child_pid), m_performed_action(false),
+        m_child_pid(child_pid), m_child_tid(child_tid) {}
 
   ~StopInfoFork() override = default;
 
@@ -1161,6 +1161,19 @@
 
   const char *GetDescription() override { return "fork"; }
 
+protected:
+  void PerformAction(Event *event_ptr) override {
+    // Only perform the action once
+    if (m_performed_action)
+      return;
+    m_performed_action = true;
+    ThreadSP thread_sp(m_thread_wp.lock());
+    if (thread_sp)
+      thread_sp->GetProcess()->DidFork(m_child_pid, m_child_tid);
+  }
+
+  bool m_performed_action;
+
 private:
   lldb::pid_t m_child_pid;
   lldb::tid_t m_child_tid;
@@ -1171,8 +1184,8 @@
 class StopInfoVFork : public StopInfo {
 public:
   StopInfoVFork(Thread &thread, lldb::pid_t child_pid, lldb::tid_t child_tid)
-      : StopInfo(thread, child_pid), m_child_pid(child_pid),
-        m_child_tid(child_tid) {}
+      : StopInfo(thread, child_pid), m_performed_action(false),
+        m_child_pid(child_pid), m_child_tid(child_tid) {}
 
   ~StopInfoVFork() override = default;
 
@@ -1182,6 +1195,19 @@
 
   const char *GetDescription() override { return "vfork"; }
 
+protected:
+  void PerformAction(Event *event_ptr) override {
+    // Only perform the action once
+    if (m_performed_action)
+      return;
+    m_performed_action = true;
+    ThreadSP thread_sp(m_thread_wp.lock());
+    if (thread_sp)
+      thread_sp->GetProcess()->DidVFork(m_child_pid, m_child_tid);
+  }
+
+  bool m_performed_action;
+
 private:
   lldb::pid_t m_child_pid;
   lldb::tid_t m_child_tid;
Index: lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
===================================================================
--- lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
+++ lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
@@ -230,6 +230,9 @@
   std::string HarmonizeThreadIdsForProfileData(
       StringExtractorGDBRemote &inputStringExtractor);
 
+  void DidFork(lldb::pid_t child_pid, lldb::tid_t child_tid) override;
+  void DidVFork(lldb::pid_t child_pid, lldb::tid_t child_tid) override;
+
 protected:
   friend class ThreadGDBRemote;
   friend class GDBRemoteCommunicationClient;
Index: lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
===================================================================
--- lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -5432,3 +5432,29 @@
         GetTarget().GetDebugger().GetCommandInterpreter());
   return m_command_sp.get();
 }
+
+void ProcessGDBRemote::DidFork(lldb::pid_t child_pid, lldb::tid_t child_tid) {
+  Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PROCESS));
+
+  LLDB_LOG(log, "Detaching forked child {0}", child_pid);
+  Status error = m_gdb_comm.Detach(false, child_pid);
+  if (error.Fail()) {
+      LLDB_LOG(log,
+               "ProcessGDBRemote::DidFork() detach packet send failed: {0}",
+                error.AsCString() ? error.AsCString() : "<unknown error>");
+      return;
+  }
+}
+
+void ProcessGDBRemote::DidVFork(lldb::pid_t child_pid, lldb::tid_t child_tid) {
+  Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PROCESS));
+
+  LLDB_LOG(log, "Detaching forked child {0}", child_pid);
+  Status error = m_gdb_comm.Detach(false, child_pid);
+  if (error.Fail()) {
+      LLDB_LOG(log,
+               "ProcessGDBRemote::DidFork() detach packet send failed: {0}",
+                error.AsCString() ? error.AsCString() : "<unknown error>");
+      return;
+  }
+}
Index: lldb/include/lldb/Target/Process.h
===================================================================
--- lldb/include/lldb/Target/Process.h
+++ lldb/include/lldb/Target/Process.h
@@ -978,6 +978,12 @@
   /// anything after a process exec's itself.
   virtual void DoDidExec() {}
 
+  /// Called after a reported fork.
+  virtual void DidFork(lldb::pid_t child_pid, lldb::tid_t child_tid) {}
+
+  /// Called after a reported vfork.
+  virtual void DidVFork(lldb::pid_t child_pid, lldb::tid_t child_tid) {}
+
   /// Called before launching to a process.
   ///
   /// Allow Process plug-ins to execute some code before launching a process.

_______________________________________________
lldb-commits mailing list
lldb-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits