[lldb] Get lldb-server platform's --socket-file working again

[teemperor]

Summary

lldb-server platform --socket-file /any/path currently always fails to create
the socket file. This stopped working after D67424 which changed the
input variables of writeFileAtomically slightly. We're expected to
pass in a temporary path template (/tmp/foo-%%%%%) and the final
path we want to write. Instead we currently pass in the never set
temp_file_path as the temporary path (which will make this function always
fail) and pass in the temp_file_spec's path as the final path (which is actually
the template path such as /tmp/foo-%%%%%) instead of the actual path
we want to write (e.g. /tmp/foo).

[teemperor]

From what I can see TestPlatformProcessConnect should actually test this parameter, but I assume we never run the test since the
breaking revision landed?

[labath]

In D85890#2215190, @teemperor wrote:

From what I can see TestPlatformProcessConnect should actually test this parameter, but I assume we never run the test since the
breaking revision landed?

That's quite possible given that it is limited to remote llgs tests (i.e. android) and android testing is very shoddy lately. Neither of the restrictions is really necessary, so I'll try to update the test to work everywhere. I presume this is also going to be used by the upcoming completion tests...

[teemperor]

Yeah this patch is actually just preparation for @MrHate's completion test (that technically tests this too, but having a dedicated test would be nice).

lldb/tools/lldb-server/lldb-platform.cpp

static Status save_socket_id_to_file(const std::string &socket_id,
   FileSpec temp_file_spec(file_spec.GetDirectory().GetStringRef());
   Status error(llvm::sys::fs::create_directory(temp_file_spec.GetPath()));
   if (error.Fail())
     return Status("Failed to create directory %s: %s",
                   temp_file_spec.GetCString(), error.AsCString());
 
   llvm::SmallString<64> temp_file_path;
   temp_file_spec.AppendPathComponent("port-file.%%%%%%");
+  temp_file_path = temp_file_spec.GetPath();
 
   Status status;
   if (auto Err =
           handleErrors(llvm::writeFileAtomically(
-                           temp_file_path, temp_file_spec.GetPath(), socket_id),
+                           temp_file_path, file_spec.GetPath(), socket_id),
                        [&status, &file_spec](const AtomicFileWriteError &E) {
                          std::string ErrorMsgBuffer;
                          llvm::raw_string_ostream S(ErrorMsgBuffer);
                          E.log(S);
 
                          switch (E.Error) {
                          case atomic_write_error::failed_to_create_uniq_file:
                            status = Status("Failed to create temp file: %s",