Merge pull request #616 from jasonmolenda/r29760580-launch-in-term-fix-bbranch

Fix an over-suspend bug with LaunchInNewTerminalWithAppleScript sessions

Author: jasonmolenda

lldb/source/Host/macosx/objcxx/Host.mm

@@ -153,33 +153,6 @@
   return NULL;
 }
 
-static bool WaitForProcessToSIGSTOP(const lldb::pid_t pid,
-                                    const int timeout_in_seconds) {
-  const int time_delta_usecs = 100000;
-  const int num_retries = timeout_in_seconds / time_delta_usecs;
-  for (int i = 0; i < num_retries; i++) {
-    struct proc_bsdinfo bsd_info;
-    int error = ::proc_pidinfo(pid, PROC_PIDTBSDINFO, (uint64_t)0, &bsd_info,
-                               PROC_PIDTBSDINFO_SIZE);
-
-    switch (error) {
-    case EINVAL:
-    case ENOTSUP:
-    case ESRCH:
-    case EPERM:
-      return false;
-
-    default:
-      break;
-
-    case 0:
-      if (bsd_info.pbi_status == SSTOP)
-        return true;
-    }
-    ::usleep(time_delta_usecs);
-  }
-  return false;
-}
 #if !defined(__arm__) && !defined(__arm64__) && !defined(__aarch64__)
 
 const char *applscript_in_new_tty = "tell application \"Terminal\"\n"
@@ -325,11 +298,6 @@ repeat with the_window in (get windows)\n\
   lldb_error = accept_thread->Join(&accept_thread_result);
   if (lldb_error.Success() && accept_thread_result) {
     pid = (intptr_t)accept_thread_result;
-
-    // Wait for process to be stopped at the entry point by watching
-    // for the process status to be set to SSTOP which indicates it it
-    // SIGSTOP'ed at the entry point
-    WaitForProcessToSIGSTOP(pid, 5);
   }
 
   llvm::sys::fs::remove(unix_socket_name);

lldb/tools/darwin-debug/CMakeLists.txt

@@ -1,3 +1,11 @@
+
+# Create an LC_SEGMENT with the special name ExecExtraSuspend which
+# debugserver can detect - it tells debugserver that it will exec a
+# process and that process will start suspended, so debugserver will
+# need to double-resume it to make it run.  A random file is copied
+# into the segment.
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-sectcreate,ExecExtraSuspend,ExecExtraSuspend,${CMAKE_CURRENT_SOURCE_DIR}/CMakeLists.txt")
+
 add_lldb_tool(darwin-debug ADD_TO_FRAMEWORK
   darwin-debug.cpp
 )

lldb/tools/debugserver/source/MacOSX/MachProcess.mm

@@ -734,6 +734,8 @@ static bool FBSAddEventDataToOptions(NSMutableDictionary *options,
       this_seg.nsects = seg.nsects;
       this_seg.flags = seg.flags;
       inf.segments.push_back(this_seg);
+      if (this_seg.name == "ExecExtraSuspend")
+        m_task.TaskWillExecProcessesSuspended();
     }
     if (lc.cmd == LC_SEGMENT_64) {
       struct segment_command_64 seg;
@@ -755,6 +757,8 @@ static bool FBSAddEventDataToOptions(NSMutableDictionary *options,
       this_seg.nsects = seg.nsects;
       this_seg.flags = seg.flags;
       inf.segments.push_back(this_seg);
+      if (this_seg.name == "ExecExtraSuspend")
+        m_task.TaskWillExecProcessesSuspended();
     }
     if (lc.cmd == LC_UUID) {
       struct uuid_command uuidcmd;

lldb/tools/debugserver/source/MacOSX/MachTask.h

@@ -85,6 +85,7 @@ class MachTask {
   const MachProcess *Process() const { return m_process; }
 
   nub_size_t PageSize();
+  void TaskWillExecProcessesSuspended() { m_exec_will_be_suspended = true; }
 
 protected:
   MachProcess *m_process; // The mach process that owns this MachTask
@@ -97,6 +98,12 @@ class MachTask {
                                 // need it
   mach_port_t m_exception_port; // Exception port on which we will receive child
                                 // exceptions
+  bool m_exec_will_be_suspended; // If this task exec's another process, that
+                                // process will be launched suspended and we will
+                                // need to execute one extra Resume to get it
+                                // to progress from dyld_start.
+  bool m_do_double_resume;      // next time we task_resume(), do it twice to
+                                // fix a too-high suspend count.
 
   typedef std::map<mach_vm_address_t, size_t> allocation_collection;
   allocation_collection m_allocations;

lldb/tools/debugserver/source/MacOSX/MachTask.mm

@@ -69,7 +69,8 @@
 //----------------------------------------------------------------------
 MachTask::MachTask(MachProcess *process)
     : m_process(process), m_task(TASK_NULL), m_vm_memory(),
-      m_exception_thread(0), m_exception_port(MACH_PORT_NULL) {
+      m_exception_thread(0), m_exception_port(MACH_PORT_NULL),
+      m_exec_will_be_suspended(false), m_do_double_resume(false) {
   memset(&m_exc_port_info, 0, sizeof(m_exc_port_info));
 }
 
@@ -103,6 +104,14 @@
   err = BasicInfo(task, &task_info);
 
   if (err.Success()) {
+    if (m_do_double_resume && task_info.suspend_count == 2) {
+      err = ::task_resume(task);
+      if (DNBLogCheckLogBit(LOG_TASK) || err.Fail())
+        err.LogThreaded("::task_resume double-resume after exec-start-stopped "
+                        "( target_task = 0x%4.4x )", task);
+    }
+    m_do_double_resume = false;
+      
     // task_resume isn't counted like task_suspend calls are, are, so if the
     // task is not suspended, don't try and resume it since it is already
     // running
@@ -135,6 +144,8 @@
   m_task = TASK_NULL;
   m_exception_thread = 0;
   m_exception_port = MACH_PORT_NULL;
+  m_exec_will_be_suspended = false;
+  m_do_double_resume = false;
 }
 
 //----------------------------------------------------------------------
@@ -651,6 +662,9 @@ static void get_threads_profile_data(DNBProfileDataScanType scanType,
     err.LogThreaded("::mach_port_deallocate ( task = 0x%4.4x, name = 0x%4.4x )",
                     task_self, exception_port);
 
+  m_exec_will_be_suspended = false;
+  m_do_double_resume = false;
+
   return err.Status();
 }
 
@@ -960,4 +974,14 @@ static void get_threads_profile_data(DNBProfileDataScanType scanType,
 void MachTask::TaskPortChanged(task_t task)
 {
   m_task = task;
+
+  // If we've just exec'd to a new process, and it
+  // is started suspended, we'll need to do two
+  // task_resume's to get the inferior process to
+  // continue.
+  if (m_exec_will_be_suspended)
+    m_do_double_resume = true;
+  else
+    m_do_double_resume = false;
+  m_exec_will_be_suspended = false;
 }