Fix the communication in qPlatform_[mkdir,chmod]

[tberghammer]

Summary

With the previous implementation the protocol used by the client and the server for the response was different and worked only by an accident. With this change the communication is fixed and the return code from mkdir and chmod correctly captured by lldb. The change also add documentation for the qPlatform_[mkdir,chmod] packages.

[clayborg]

Looks good.

docs/lldb-gdb-remote.txt

 drwxrwxr-x 16 username groupname    4096 Aug 15 21:36 .
 drwxr-xr-x 17 username groupname    4096 Aug 10 16:39 ..
 -rw-rw-r--  1 username groupname   73875 Aug 12 16:46 notes.txt
 drwxrwxr-x  5 username groupname    4096 Aug 15 21:36 source.cpp
 -rw-r--r--  1 username groupname    2792 Aug 12 16:46 a.out
 -rw-r--r--  1 username groupname    3190 Aug 12 16:46 Makefile
 
 //----------------------------------------------------------------------
+// "qPlatform_mkdir"
+//
+// BRIEF
+//  Creates a new directory on the connected remote machine.
+//
+// PRIORITY TO IMPLEMENT
+//  Low. This command allows LLDB clients to create new directories on
+//  a remote host.
+//
+/----------------------------------------------------------------------
+
+Request:
+    qPlatform_mkdir:<hex-file-mode>,<ascii-hex-path>
+
+Reply:
+    F<mkdir-return-code>
+        mkdir called successfully and returned with the given return code
+    Exx
+        An error occurred
+
+//----------------------------------------------------------------------
+// "qPlatform_chmod"
+//
+// BRIEF
+//  Creates a new directory on the connected remote machine.
+//
+// PRIORITY TO IMPLEMENT
+//  Low. This command allows LLDB clients to change the permissions of
+//  a file on the remote host.
+//
+/----------------------------------------------------------------------
+
+Request:
+    qPlatform_chmod:<hex-file-mode>,<ascii-hex-path>
+
+Reply:
+    F<chmod-return-code>
+        chmod called successfully and returned with the given return code
+    Exx
+        An error occurred
+
+//----------------------------------------------------------------------
 // "qHostInfo"
 //
 // BRIEF
 //  Get information about the host we are remotely connected to.
 //
 // PRIORITY TO IMPLEMENT
 //  High. This packet is usually very easy to implement and can help
 //  LLDB select the correct plug-ins for the job based on the target

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

GDBRemoteCommunicationClient::MakeDirectory (const char *path,
     lldb_private::StreamString stream;
     stream.PutCString("qPlatform_mkdir:");
     stream.PutHex32(file_permissions);
     stream.PutChar(',');
     stream.PutBytesAsRawHex8(path, strlen(path));
     const char *packet = stream.GetData();
     int packet_len = stream.GetSize();
     StringExtractorGDBRemote response;
-    if (SendPacketAndWaitForResponse(packet, packet_len, response, false) == PacketResult::Success)
-    {
-        return Error(response.GetHexMaxU32(false, UINT32_MAX), eErrorTypePOSIX);
-    }
-    return Error();
 
+    if (SendPacketAndWaitForResponse(packet, packet_len, response, false) != PacketResult::Success)
+        return Error("failed to send '%s' packet", packet);
+
+    if (response.GetChar() != 'F')
+        return Error("invalid response to '%s' packet", packet);
+
+    return Error(response.GetU32(UINT32_MAX), eErrorTypePOSIX);
 }
 
 Error
 GDBRemoteCommunicationClient::SetFilePermissions (const char *path,
                                                   uint32_t file_permissions)
 {
     lldb_private::StreamString stream;
     stream.PutCString("qPlatform_chmod:");
     stream.PutHex32(file_permissions);
     stream.PutChar(',');
     stream.PutBytesAsRawHex8(path, strlen(path));
     const char *packet = stream.GetData();
     int packet_len = stream.GetSize();
     StringExtractorGDBRemote response;
-    if (SendPacketAndWaitForResponse(packet, packet_len, response, false) == PacketResult::Success)
-    {
-        return Error(response.GetHexMaxU32(false, UINT32_MAX), eErrorTypePOSIX);
-    }
-    return Error();
-    
+    if (SendPacketAndWaitForResponse(packet, packet_len, response, false) != PacketResult::Success)
+        return Error("failed to send '%s' packet", packet);
+
+    if (response.GetChar() != 'F')
+        return Error("invalid response to '%s' packet", packet);
+
+    return Error(response.GetU32(false, UINT32_MAX), eErrorTypePOSIX);
 }
 
 static uint64_t
 ParseHostIOPacketResponse (StringExtractorGDBRemote &response,
                            uint64_t fail_result,
                            Error &error)
 {
     response.SetFilePos(0);

source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerCommon.cpp

 {
     packet.SetFilePos(::strlen("qPlatform_mkdir:"));
     mode_t mode = packet.GetHexMaxU32(false, UINT32_MAX);
     if (packet.GetChar() == ',')
     {
         std::string path;
         packet.GetHexByteString(path);
         Error error = FileSystem::MakeDirectory(path.c_str(), mode);
-        if (error.Success())
-            return SendPacketNoLock ("OK", 2);
-        else
-            return SendErrorResponse(error.GetError());
+        
+        StreamGDBRemote response;
+        response.Printf("F%u", error.GetError());
+
+        return SendPacketNoLock(response.GetData(), response.GetSize());
     }
     return SendErrorResponse(20);
 }
 
 GDBRemoteCommunication::PacketResult
 GDBRemoteCommunicationServerCommon::Handle_qPlatform_chmod (StringExtractorGDBRemote &packet)
 {
     packet.SetFilePos(::strlen("qPlatform_chmod:"));
 
     mode_t mode = packet.GetHexMaxU32(false, UINT32_MAX);
     if (packet.GetChar() == ',')
     {
         std::string path;
         packet.GetHexByteString(path);
         Error error = FileSystem::SetFilePermissions(path.c_str(), mode);
-        if (error.Success())
-            return SendPacketNoLock ("OK", 2);
-        else
-            return SendErrorResponse(error.GetError());
+
+        StreamGDBRemote response;
+        response.Printf("F%u", error.GetError());
+
+        return SendPacketNoLock(response.GetData(), response.GetSize());
     }
     return SendErrorResponse(19);
 }
 
 GDBRemoteCommunication::PacketResult
 GDBRemoteCommunicationServerCommon::Handle_qSupported (StringExtractorGDBRemote &packet)
 {
     StreamGDBRemote response;