Modify "platform connect" to connect to processes as well

The standard remote debugging workflow with gdb is to start the
application on the remote host under gdbserver (e.g.: gdbserver :5039
a.out) and then connect to it with gdb.

The same workflow is supported by debugserver/lldb-gdbserver with a very
similar syntax but to access all features of lldb we need to be
connected also to an lldb-platform instance running on the target.

Before this change this had to be done manually with starting a separate
lldb-platform on the target machine and then connecting to it with lldb
before connecting to the process.

This change modifies the behavior of "platform connect" with
automatically connecting to the process instance if it was started by
the remote platform. With this command replacing gdbserver in a gdb
based worflow is usually as simple as replacing the command to execute
gdbserver with executing lldb-platform.

Differential revision: http://reviews.llvm.org/D14952

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@255016 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Tamas Berghammer

docs/lldb-gdb-remote.txt

@@ -1597,3 +1597,29 @@ On MacOSX with debugserver, we expedite the frame pointer backchain for a thread
 (up to 256 entries) by reading 2 pointers worth of bytes at the frame pointer (for
 the previous FP and PC), and follow the backchain. Most backtraces on MacOSX and
 iOS now don't require us to read any memory!
+
+//----------------------------------------------------------------------
+// "qQueryGDBServer"
+//
+// BRIEF
+//  Ask the platform for the list of gdbservers we have to connect
+//
+// PRIORITY TO IMPLEMENT
+//  Low. The packet is required to support connecting to gdbserver started
+//  by the platform instance automatically.
+//----------------------------------------------------------------------
+
+If the remote platform automatically started one or more gdbserver instance (without
+lldb asking it) then it have to return the list of port number or socket name for
+each of them what can be used by lldb to connect to those instances.
+
+The data in this packet is a JSON array of JSON objects with the following keys:
+"port":        <the port number to connect>        (optional)
+"socket_name": <the name of the socket to connect> (optional)
+
+Example packet:
+[
+    { "port": 1234 },
+    { "port": 5432 },
+    { "socket_name": "foo" }
+]

include/lldb/Target/Platform.h

@@ -487,6 +487,13 @@ class ModuleCache;
                       Target *target,       // Can be nullptr, if nullptr create a new target, else use existing one
                       Error &error);
 
+        virtual lldb::ProcessSP
+        ConnectProcess (const char* connect_url,
+                        const char* plugin_name,
+                        lldb_private::Debugger &debugger,
+                        lldb_private::Target *target,
+                        lldb_private::Error &error);
+
         //------------------------------------------------------------------
         /// Attach to an existing process using a process ID.
         ///
@@ -1034,6 +1041,25 @@ class ModuleCache;
         virtual Error
         UnloadImage (lldb_private::Process* process, uint32_t image_token);
 
+        //------------------------------------------------------------------
+        /// Connect to all processes waiting for a debugger to attach
+        ///
+        /// If the platform have a list of processes waiting for a debugger
+        /// to connect to them then connect to all of these pending processes.
+        ///
+        /// @param[in] debugger
+        ///     The debugger used for the connect.
+        ///
+        /// @param[out] error
+        ///     If an error occurred during the connect then this object will
+        ///     contain the error message.
+        ///
+        /// @return
+        ///     The number of processes we are succesfully connected to.
+        //------------------------------------------------------------------
+        virtual size_t
+        ConnectToWaitingProcesses(lldb_private::Debugger& debugger, lldb_private::Error& error);
+
     protected:
         bool m_is_host;
         // Set to true when we are able to actually set the OS version while

packages/Python/lldbsuite/test/lldbtest.py

@@ -1115,21 +1115,23 @@ def wrapper(*args, **kwargs):
 # @skipIf(bugnumber, ["linux"], "gcc", ['>=', '4.9'], ['i386']), skip for gcc>=4.9 on linux with i386
 
 # TODO: refactor current code, to make skipIfxxx functions to call this function
-def skipIf(bugnumber=None, oslist=None, compiler=None, compiler_version=None, archs=None, debug_info=None, swig_version=None, py_version=None):
+def skipIf(bugnumber=None, oslist=None, compiler=None, compiler_version=None, archs=None, debug_info=None, swig_version=None, py_version=None, remote=None):
     def fn(self):
         oslist_passes = oslist is None or self.getPlatform() in oslist
         compiler_passes = compiler is None or (compiler in self.getCompiler() and self.expectedCompilerVersion(compiler_version))
         arch_passes = self.expectedArch(archs)
         debug_info_passes = debug_info is None or self.debug_info in debug_info
         swig_version_passes = (swig_version is None) or (not hasattr(lldb, 'swig_version')) or (check_expected_version(swig_version[0], swig_version[1], lldb.swig_version))
         py_version_passes = (py_version is None) or check_expected_version(py_version[0], py_version[1], sys.version_info)
+        remote_passes = (remote is None) or (remote == (lldb.remote_platform is not None))
 
         return (oslist_passes and
                 compiler_passes and
                 arch_passes and
                 debug_info_passes and
                 swig_version_passes and
-                py_version_passes)
+                py_version_passes and
+                remote_passes)
 
     local_vars = locals()
     args = [x for x in inspect.getargspec(skipIf).args]

packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py

@@ -147,29 +147,30 @@ def get_stub_port_from_named_socket(self, read_timeout_seconds=5):
 
         return stub_port
 
+    def run_shell_cmd(self, cmd):
+        platform = self.dbg.GetSelectedPlatform()
+        shell_cmd = lldb.SBPlatformShellCommand(cmd)
+        err = platform.Run(shell_cmd)
+        if err.Fail() or shell_cmd.GetStatus():
+            m = "remote_platform.RunShellCommand('%s') failed:\n" % cmd
+            m += ">>> return code: %d\n" % shell_cmd.GetStatus()
+            if err.Fail():
+                m += ">>> %s\n" % str(err).strip()
+            m += ">>> %s\n" % (shell_cmd.GetOutput() or
+                               "Command generated no output.")
+            raise Exception(m)
+        return shell_cmd.GetOutput().strip()
+
     def init_llgs_test(self, use_named_pipe=True):
         if lldb.remote_platform:
-            def run_shell_cmd(cmd):
-                platform = self.dbg.GetSelectedPlatform()
-                shell_cmd = lldb.SBPlatformShellCommand(cmd)
-                err = platform.Run(shell_cmd)
-                if err.Fail() or shell_cmd.GetStatus():
-                    m = "remote_platform.RunShellCommand('%s') failed:\n" % cmd
-                    m += ">>> return code: %d\n" % shell_cmd.GetStatus()
-                    if err.Fail():
-                        m += ">>> %s\n" % str(err).strip()
-                    m += ">>> %s\n" % (shell_cmd.GetOutput() or
-                                       "Command generated no output.")
-                    raise Exception(m)
-                return shell_cmd.GetOutput().strip()
             # Remote platforms don't support named pipe based port negotiation
             use_named_pipe = False
 
             # Grab the ppid from /proc/[shell pid]/stat
-            shell_stat = run_shell_cmd("cat /proc/$$/stat")
+            shell_stat = self.run_shell_cmd("cat /proc/$$/stat")
             # [pid] ([executable]) [state] [*ppid*]
             pid = re.match(r"^\d+ \(.+\) . (\d+)", shell_stat).group(1)
-            ls_output = run_shell_cmd("ls -l /proc/%s/exe" % pid)
+            ls_output = self.run_shell_cmd("ls -l /proc/%s/exe" % pid)
             exe = ls_output.split()[-1]
 
             # If the binary has been deleted, the link name has " (deleted)" appended.

packages/Python/lldbsuite/test/tools/lldb-server/platform-process-connect/Makefile

@@ -0,0 +1,5 @@
+LEVEL = ../../../make
+
+CXX_SOURCES := main.cpp
+
+include $(LEVEL)/Makefile.rules

packages/Python/lldbsuite/test/tools/lldb-server/platform-process-connect/TestPlatformProcessConnect.py

@@ -0,0 +1,55 @@
+from __future__ import print_function
+
+import gdbremote_testcase
+from lldbsuite.test.lldbtest import *
+import lldbsuite.test.lldbutil as lldbutil
+
+class TestPlatformProcessConnect(gdbremote_testcase.GdbRemoteTestCaseBase):
+    mydir = TestBase.compute_mydir(__file__)
+
+    @llgs_test
+    @no_debug_info_test
+    @skipIf(remote=False)
+    def test_platform_process_connect(self):
+        self.build()
+        self.init_llgs_test(False)
+
+        working_dir = lldb.remote_platform.GetWorkingDirectory()
+        err = lldb.remote_platform.Put(lldb.SBFileSpec(os.path.join(os.getcwd(), "a.out")),
+                                       lldb.SBFileSpec(os.path.join(working_dir, "a.out")))
+        if err.Fail():
+            raise RuntimeError("Unable copy '%s' to '%s'.\n>>> %s" % (f, wd, err.GetCString()))
+
+        port_file = "%s/port" % working_dir
+        commandline_args = ["platform", "--listen", "*:0", "--socket-file", port_file, "--", "%s/a.out" % working_dir, "foo"]
+        self.spawnSubprocess(self.debug_monitor_exe, commandline_args, install_remote=False)
+        self.addTearDownHook(self.cleanupSubprocesses)
+        new_port = self.run_shell_cmd("while [ ! -f %s ]; do sleep 0.25; done && cat %s" % (port_file, port_file))
+
+        new_debugger = lldb.SBDebugger.Create()
+        new_debugger.SetAsync(False)
+        def del_debugger():
+            del new_debugger
+        self.addTearDownHook(del_debugger)
+
+        new_platform = lldb.SBPlatform(lldb.remote_platform.GetName())
+        new_debugger.SetSelectedPlatform(new_platform)
+        new_interpreter = new_debugger.GetCommandInterpreter()
+
+        m = re.search("(.*):[0-9]+", configuration.lldb_platform_url)
+        command = "platform connect %s:%s" % (m.group(1), new_port)
+        result = lldb.SBCommandReturnObject()
+        new_interpreter.HandleCommand(command, result)
+        self.assertTrue(result.Succeeded(), "platform process connect failed: %s" % result.GetOutput())
+
+        target = new_debugger.GetSelectedTarget()
+        process = target.GetProcess()
+        thread = process.GetThreadAtIndex(0)
+
+        breakpoint = target.BreakpointCreateByName("main")
+        process.Continue()
+
+        frame = thread.GetFrameAtIndex(0)
+        self.assertEqual(frame.GetFunction().GetName(), "main")
+        self.assertEqual(frame.FindVariable("argc").GetValueAsSigned(), 2)
+        process.Continue()

packages/Python/lldbsuite/test/tools/lldb-server/platform-process-connect/main.cpp

@@ -0,0 +1,7 @@
+#include <cstdio>
+
+int main (int argc, char **argv)
+{
+    printf("argc: %d\n", argc);
+    return argv[0][0];
+}

source/Commands/CommandObjectPlatform.cpp

@@ -409,12 +409,19 @@ class CommandObjectPlatformConnect : public CommandObjectParsed
             if (error.Success())
             {
                 platform_sp->GetStatus (ostrm);
-                result.SetStatus (eReturnStatusSuccessFinishResult);            
+                result.SetStatus (eReturnStatusSuccessFinishResult);
+
+                platform_sp->ConnectToWaitingProcesses(m_interpreter.GetDebugger(), error);
+                if (error.Fail())
+                {
+                    result.AppendError (error.AsCString());
+                    result.SetStatus (eReturnStatusFailed);
+                }
             }
             else
             {
                 result.AppendErrorWithFormat ("%s\n", error.AsCString());
-                result.SetStatus (eReturnStatusFailed);            
+                result.SetStatus (eReturnStatusFailed);
             }
         }
         else

source/Commands/CommandObjectProcess.cpp

@@ -1051,78 +1051,46 @@ class CommandObjectProcessConnect : public CommandObjectParsed
     bool
     DoExecute (Args& command, CommandReturnObject &result) override
     {
-        
-        TargetSP target_sp (m_interpreter.GetDebugger().GetSelectedTarget());
-        Error error;        
-        Process *process = m_exe_ctx.GetProcessPtr();
-        if (process)
+        if (command.GetArgumentCount() != 1)
         {
-            if (process->IsAlive())
-            {
-                result.AppendErrorWithFormat ("Process %" PRIu64 " is currently being debugged, kill the process before connecting.\n",
-                                              process->GetID());
-                result.SetStatus (eReturnStatusFailed);
-                return false;
-            }
+            result.AppendErrorWithFormat ("'%s' takes exactly one argument:\nUsage: %s\n",
+                                          m_cmd_name.c_str(),
+                                          m_cmd_syntax.c_str());
+            result.SetStatus (eReturnStatusFailed);
+            return false;
         }
+
 
-        if (!target_sp)
+        Process *process = m_exe_ctx.GetProcessPtr();
+        if (process && process->IsAlive())
         {
-            // If there isn't a current target create one.
-            
-            error = m_interpreter.GetDebugger().GetTargetList().CreateTarget (m_interpreter.GetDebugger(), 
-                                                                              NULL,
-                                                                              NULL, 
-                                                                              false,
-                                                                              NULL, // No platform options
-                                                                              target_sp);
-            if (!target_sp || error.Fail())
-            {
-                result.AppendError(error.AsCString("Error creating target"));
-                result.SetStatus (eReturnStatusFailed);
-                return false;
-            }
-            m_interpreter.GetDebugger().GetTargetList().SetSelectedTarget(target_sp.get());
+            result.AppendErrorWithFormat ("Process %" PRIu64 " is currently being debugged, kill the process before connecting.\n",
+                                          process->GetID());
+            result.SetStatus (eReturnStatusFailed);
+            return false;
         }
-        
-        if (command.GetArgumentCount() == 1)
-        {
-            const char *plugin_name = NULL;
-            if (!m_options.plugin_name.empty())
-                plugin_name = m_options.plugin_name.c_str();
 
-            const char *remote_url = command.GetArgumentAtIndex(0);
-            process = target_sp->CreateProcess (m_interpreter.GetDebugger().GetListener(), plugin_name, NULL).get();
-            
-            if (process)
-            {
-                error = process->ConnectRemote (process->GetTarget().GetDebugger().GetOutputFile().get(), remote_url);
+        const char *plugin_name = nullptr;
+        if (!m_options.plugin_name.empty())
+            plugin_name = m_options.plugin_name.c_str();
 
-                if (error.Fail())
-                {
-                    result.AppendError(error.AsCString("Remote connect failed"));
-                    result.SetStatus (eReturnStatusFailed);
-                    target_sp->DeleteCurrentProcess();
-                    return false;
-                }
-            }
-            else
-            {
-                result.AppendErrorWithFormat ("Unable to find process plug-in for remote URL '%s'.\nPlease specify a process plug-in name with the --plugin option, or specify an object file using the \"file\" command.\n", 
-                                              remote_url);
-                result.SetStatus (eReturnStatusFailed);
-            }
-        }
-        else
+        Error error;
+        Debugger& debugger = m_interpreter.GetDebugger();
+        PlatformSP platform_sp = m_interpreter.GetPlatform(true);
+        ProcessSP process_sp = platform_sp->ConnectProcess(command.GetArgumentAtIndex(0),
+                                                           plugin_name,
+                                                           debugger,
+                                                           debugger.GetSelectedTarget().get(),
+                                                           error);
+        if (error.Fail() || process_sp == nullptr)
         {
-            result.AppendErrorWithFormat ("'%s' takes exactly one argument:\nUsage: %s\n", 
-                                          m_cmd_name.c_str(),
-                                          m_cmd_syntax.c_str());
+            result.AppendError(error.AsCString("Error connecting to the process"));
             result.SetStatus (eReturnStatusFailed);
+            return false;
         }
-        return result.Succeeded();
+        return true;
     }
-    
+
     CommandOptions m_options;
 };
 

source/Plugins/Platform/Android/PlatformAndroidRemoteGDBServer.cpp

@@ -223,3 +223,53 @@ PlatformAndroidRemoteGDBServer::MakeConnectURL(const lldb::pid_t pid,
 
     return error;
 }
+
+lldb::ProcessSP
+PlatformAndroidRemoteGDBServer::ConnectProcess(const char* connect_url,
+                                               const char* plugin_name,
+                                               lldb_private::Debugger &debugger,
+                                               lldb_private::Target *target,
+                                               lldb_private::Error &error)
+{
+    // We don't have the pid of the remote gdbserver when it isn't started by us but we still want
+    // to store the list of port forwards we set up in our port forward map. Generate a fake pid for
+    // these cases what won't collide with any other valid pid on android.
+    static lldb::pid_t s_remote_gdbserver_fake_pid = 0xffffffffffffffffULL;
+
+    int remote_port;
+    std::string scheme, host, path;
+    if (!UriParser::Parse(connect_url, scheme, host, remote_port, path))
+    {
+        error.SetErrorStringWithFormat("Invalid URL: %s", connect_url);
+        return nullptr;
+    }
+
+    std::string new_connect_url;
+    error = MakeConnectURL(s_remote_gdbserver_fake_pid--,
+                           (remote_port < 0) ? 0 : remote_port,
+                           path.c_str(),
+                           new_connect_url);
+    if (error.Fail())
+        return nullptr;
+
+    return PlatformRemoteGDBServer::ConnectProcess(new_connect_url.c_str(),
+                                                   plugin_name,
+                                                   debugger,
+                                                   target,
+                                                   error);
+}
+
+size_t
+PlatformAndroidRemoteGDBServer::ConnectToWaitingProcesses(Debugger& debugger, Error& error)
+{
+    std::vector<std::string> connection_urls;
+    GetPendingGdbServerList(connection_urls);
+
+    for (size_t i = 0; i < connection_urls.size(); ++i)
+    {
+        ConnectProcess(connection_urls[i].c_str(), nullptr, debugger, nullptr, error);
+        if (error.Fail())
+            return i; // We already connected to i process succsessfully
+    }
+    return connection_urls.size();
+}