Remove Process references from the Host module

The Process class was only being referenced because of the last-ditch
effort in the process launchers to set a process death callback in case
one isn't set already.

Although launching a process for debugging is the most important kind of
"launch" we are doing, it is by far not the only one, so assuming this
particular callback is the one to be used is not a good idea (besides
breaking layering). Instead of assuming a particular exit callback, I
change the launcher code to require the callback to be set by the user (and fix
up the two call sites which did not set the callback already).

Reviewers: jingham, davide

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D46395

llvm-svn: 332250

9 files changed, 37 insertions, 29 deletions

diff --git a/lldb/include/lldb/Host/Host.h b/lldb/include/lldb/Host/Host.h
index c6d5c3c4b67..459e9f563d1 100644
--- a/lldb/include/lldb/Host/Host.h
+++ b/lldb/include/lldb/Host/Host.h
@@ -199,6 +199,9 @@ public:
 
   static const lldb::UnixSignalsSP &GetUnixSignals();
 
+  /// Launch the process specified in launch_info. The monitoring callback in
+  /// launch_info must be set, and it will be called when the process
+  /// terminates.
   static Status LaunchProcess(ProcessLaunchInfo &launch_info);
 
   //------------------------------------------------------------------
diff --git a/lldb/include/lldb/Host/MonitoringProcessLauncher.h b/lldb/include/lldb/Host/MonitoringProcessLauncher.h
index 9ad36e90a77..341284800a4 100644
--- a/lldb/include/lldb/Host/MonitoringProcessLauncher.h
+++ b/lldb/include/lldb/Host/MonitoringProcessLauncher.h
@@ -24,6 +24,9 @@ public:
   explicit MonitoringProcessLauncher(
       std::unique_ptr<ProcessLauncher> delegate_launcher);
 
+  /// Launch the process specified in launch_info. The monitoring callback in
+  /// launch_info must be set, and it will be called when the process
+  /// terminates.
   HostProcess LaunchProcess(const ProcessLaunchInfo &launch_info,
                             Status &error) override;
 
diff --git a/lldb/include/lldb/Target/ProcessLaunchInfo.h b/lldb/include/lldb/Target/ProcessLaunchInfo.h
index fc7cdea04df..92c517a3e46 100644
--- a/lldb/include/lldb/Target/ProcessLaunchInfo.h
+++ b/lldb/include/lldb/Target/ProcessLaunchInfo.h
@@ -107,6 +107,12 @@ public:
     return m_monitor_callback;
   }
 
+  /// A Monitor callback which does not take any action on process events. Use
+  /// this if you don't need to take any particular action when the process
+  /// terminates, but you still need to reap it.
+  static bool NoOpMonitorCallback(lldb::pid_t pid, bool exited, int signal,
+                                  int status);
+
   bool GetMonitorSignals() const { return m_monitor_signals; }
 
   // If the LaunchInfo has a monitor callback, then arrange to monitor the
diff --git a/lldb/source/Host/common/MonitoringProcessLauncher.cpp b/lldb/source/Host/common/MonitoringProcessLauncher.cpp
index efc10004b5f..76c11454f57 100644
--- a/lldb/source/Host/common/MonitoringProcessLauncher.cpp
+++ b/lldb/source/Host/common/MonitoringProcessLauncher.cpp
@@ -9,7 +9,6 @@
 
 #include "lldb/Host/MonitoringProcessLauncher.h"
 #include "lldb/Host/HostProcess.h"
-#include "lldb/Target/Process.h"
 #include "lldb/Target/ProcessLaunchInfo.h"
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/Status.h"
@@ -58,18 +57,9 @@ MonitoringProcessLauncher::LaunchProcess(const ProcessLaunchInfo &launch_info,
   if (process.GetProcessId() != LLDB_INVALID_PROCESS_ID) {
     Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS));
 
-    Host::MonitorChildProcessCallback callback =
-        launch_info.GetMonitorProcessCallback();
-
-    bool monitor_signals = false;
-    if (callback) {
-      // If the ProcessLaunchInfo specified a callback, use that.
-      monitor_signals = launch_info.GetMonitorSignals();
-    } else {
-      callback = Process::SetProcessExitStatus;
-    }
-
-    process.StartMonitoring(callback, monitor_signals);
+    assert(launch_info.GetMonitorProcessCallback());
+    process.StartMonitoring(launch_info.GetMonitorProcessCallback(),
+                            launch_info.GetMonitorSignals());
     if (log)
       log->PutCString("started monitoring child process.");
   } else {
diff --git a/lldb/source/Host/common/NativeProcessProtocol.cpp b/lldb/source/Host/common/NativeProcessProtocol.cpp
index cc998e6da9f..3e8648f8147 100644
--- a/lldb/source/Host/common/NativeProcessProtocol.cpp
+++ b/lldb/source/Host/common/NativeProcessProtocol.cpp
@@ -13,7 +13,6 @@
 #include "lldb/Host/common/NativeRegisterContext.h"
 #include "lldb/Host/common/NativeThreadProtocol.h"
 #include "lldb/Host/common/SoftwareBreakpoint.h"
-#include "lldb/Target/Process.h"
 #include "lldb/Utility/LLDBAssert.h"
 #include "lldb/Utility/Log.h"
 #include "lldb/lldb-enumerations.h"
diff --git a/lldb/source/Host/macosx/Host.mm b/lldb/source/Host/macosx/Host.mm
index d87c6be915c..c2aea0afb88 100644
--- a/lldb/source/Host/macosx/Host.mm
+++ b/lldb/source/Host/macosx/Host.mm
@@ -57,7 +57,6 @@
 #include "lldb/Host/ConnectionFileDescriptor.h"
 #include "lldb/Host/HostInfo.h"
 #include "lldb/Host/ThreadLauncher.h"
-#include "lldb/Target/Process.h"
 #include "lldb/Utility/ArchSpec.h"
 #include "lldb/Utility/CleanUp.h"
 #include "lldb/Utility/DataBufferHeap.h"
@@ -68,6 +67,7 @@
 #include "lldb/Utility/NameMatches.h"
 #include "lldb/Utility/StreamString.h"
 #include "lldb/Utility/StructuredData.h"
+#include "lldb/lldb-defines.h"
 
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Errno.h"
@@ -1497,15 +1497,9 @@ Status Host::LaunchProcess(ProcessLaunchInfo &launch_info) {
     launch_info.SetProcessID(pid);
 
     // Make sure we reap any processes we spawn or we will have zombies.
-    if (!launch_info.MonitorProcess()) {
-      const bool monitor_signals = false;
-      Host::MonitorChildProcessCallback callback = nullptr;
-
-      if (!launch_info.GetFlags().Test(lldb::eLaunchFlagDontSetExitStatus))
-        callback = Process::SetProcessExitStatus;
-
-      StartMonitoringChildProcess(callback, pid, monitor_signals);
-    }
+    bool monitoring = launch_info.MonitorProcess());
+    UNUSED_IF_ASSERT_DISABLED(monitoring);
+    assert(monitoring);
   } else {
     // Invalid process ID, something didn't go well
     if (error.Success())
diff --git a/lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp b/lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
index 9b2c86a5f68..eeff8f3518a 100644
--- a/lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
+++ b/lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
@@ -868,11 +868,12 @@ PlatformPOSIX::DebugProcess(ProcessLaunchInfo &launch_info, Debugger &debugger,
 
   if (IsHost()) {
     // We are going to hand this process off to debugserver which will be in
-    // charge of setting the exit status. We still need to reap it from lldb
-    // but if we let the monitor thread also set the exit status, we set up a
-    // race between debugserver & us for who will find out about the debugged
-    // process's death.
-    launch_info.GetFlags().Set(eLaunchFlagDontSetExitStatus);
+    // charge of setting the exit status.  However, we still need to reap it
+    // from lldb. So, make sure we use a exit callback which does not set exit
+    // status.
+    const bool monitor_signals = false;
+    launch_info.SetMonitorProcessCallback(
+        &ProcessLaunchInfo::NoOpMonitorCallback, monitor_signals);
     process_sp = Platform::DebugProcess(launch_info, debugger, target, error);
   } else {
     if (m_remote_platform_sp)
diff --git a/lldb/source/Target/ProcessLaunchInfo.cpp b/lldb/source/Target/ProcessLaunchInfo.cpp
index 60fe26bb60d..9569750bc5f 100644
--- a/lldb/source/Target/ProcessLaunchInfo.cpp
+++ b/lldb/source/Target/ProcessLaunchInfo.cpp
@@ -189,6 +189,13 @@ void ProcessLaunchInfo::SetMonitorProcessCallback(
   m_monitor_signals = monitor_signals;
 }
 
+bool ProcessLaunchInfo::NoOpMonitorCallback(lldb::pid_t pid, bool exited, int signal, int status) {
+  Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS);
+  LLDB_LOG(log, "pid = {0}, exited = {1}, signal = {2}, status = {3}", pid,
+           exited, signal, status);
+  return true;
+}
+
 bool ProcessLaunchInfo::MonitorProcess() const {
   if (m_monitor_callback && ProcessIDIsValid()) {
     Host::StartMonitoringChildProcess(m_monitor_callback, GetProcessID(),
diff --git a/lldb/unittests/tools/lldb-server/tests/TestClient.cpp b/lldb/unittests/tools/lldb-server/tests/TestClient.cpp
index 2410b6270f2..3dd5be2c6e8 100644
--- a/lldb/unittests/tools/lldb-server/tests/TestClient.cpp
+++ b/lldb/unittests/tools/lldb-server/tests/TestClient.cpp
@@ -97,6 +97,11 @@ Expected<std::unique_ptr<TestClient>> TestClient::launchCustom(StringRef Log, Ar
   Info.SetArchitecture(arch_spec);
   Info.SetArguments(args, true);
   Info.GetEnvironment() = Host::GetEnvironment();
+  // TODO: Use this callback to detect botched launches. If lldb-server does not
+  // start, we can print a nice error message here instead of hanging in
+  // Accept().
+  Info.SetMonitorProcessCallback(&ProcessLaunchInfo::NoOpMonitorCallback,
+                                 false);
 
   status = Host::LaunchProcess(Info);
   if (status.Fail())