[lldb] [gdb-remote client] Support detaching by PID

[mgorny]

Merged into D100206.

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h

public:
   /// \return
   ///     Boolean for success
   bool GetWorkingDir(FileSpec &working_dir);
 
   lldb::addr_t AllocateMemory(size_t size, uint32_t permissions);
 
   bool DeallocateMemory(lldb::addr_t addr);
 
-  Status Detach(bool keep_stopped);
+  Status Detach(bool keep_stopped, lldb::pid_t pid = LLDB_INVALID_PROCESS_ID);
 
   Status GetMemoryRegionInfo(lldb::addr_t addr, MemoryRegionInfo &range_info);
 
   Status GetWatchpointSupportInfo(uint32_t &num);
 
   Status GetWatchpointSupportInfo(uint32_t &num, bool &after,
                                   const ArchSpec &arch);
 

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp

if (SendPacketAndWaitForResponse(packet, response, false) ==
         return true;
     } else {
       m_supports_alloc_dealloc_memory = eLazyBoolNo;
     }
   }
   return false;
 }
 
-Status GDBRemoteCommunicationClient::Detach(bool keep_stopped) {
+Status GDBRemoteCommunicationClient::Detach(bool keep_stopped,
+                                            lldb::pid_t pid) {
   Status error;
+  lldb_private::StreamString packet;
 
+  packet.PutChar('D');
   if (keep_stopped) {
     if (m_supports_detach_stay_stopped == eLazyBoolCalculate) {
       char packet[64];
       const int packet_len =
           ::snprintf(packet, sizeof(packet), "qSupportsDetachAndStayStopped:");
       assert(packet_len < (int)sizeof(packet));
       UNUSED_IF_ASSERT_DISABLED(packet_len);
       StringExtractorGDBRemote response;
       if (SendPacketAndWaitForResponse(packet, response, false) ==
               PacketResult::Success &&
           response.IsOKResponse()) {
         m_supports_detach_stay_stopped = eLazyBoolYes;
       } else {
         m_supports_detach_stay_stopped = eLazyBoolNo;
       }
     }
 
     if (m_supports_detach_stay_stopped == eLazyBoolNo) {
       error.SetErrorString("Stays stopped not supported by this target.");
       return error;
     } else {
-      StringExtractorGDBRemote response;
-      PacketResult packet_result =
-          SendPacketAndWaitForResponse("D1", response, false);
-      if (packet_result != PacketResult::Success)
-        error.SetErrorString("Sending extended disconnect packet failed.");
+      packet.PutChar('1');
     }
-  } else {
-    StringExtractorGDBRemote response;
-    PacketResult packet_result =
-        SendPacketAndWaitForResponse("D", response, false);
-    if (packet_result != PacketResult::Success)
-      error.SetErrorString("Sending disconnect packet failed.");
-  }
+  }
+
+  if (pid != LLDB_INVALID_PROCESS_ID) {
+    if (!m_supports_multiprocess) {
+      error.SetErrorString(
+          "Multiprocess extension not supported by the server.");
+      return error;
+    }
+    packet.PutChar(';');
+    packet.PutHex64(pid);
+  }
+
+      SendPacketAndWaitForResponse(packet.GetString(), response, false);
+    error.SetErrorString("Sending isconnect packet failed.");
   return error;
 }
 
 Status GDBRemoteCommunicationClient::GetMemoryRegionInfo(
     lldb::addr_t addr, lldb_private::MemoryRegionInfo &region_info) {
   Status error;
   region_info.Clear();