Fix debugserver translation check

Currently, debugserver has a test to check if it was launched in
translation. The intent was to cover the case where an x86_64
debugserver attempts to control an arm64/arm64e process, returning
an error. However, this check also covers the case where users
are attaching to an x86_64 process, exiting out before attempting
to hand off control to the translated debugserver at
`/Library/Apple/usr/libexec/oah/debugserver`.

This diff delays the debugserver translation check until after
determining whether to hand off control to
`/Library/Apple/usr/libexec/oah/debugserver`. Only when the
process is not translated and thus has not been handed off do we
check if the debugserver is translated, erroring out in that case.

Reviewed By: jasonmolenda

Differential Revision: https://reviews.llvm.org/D124814

Author: aperez

lldb/tools/debugserver/source/DNB.cpp

@@ -477,6 +477,10 @@ nub_process_t DNBProcessAttach(nub_process_t attach_pid,
     }
   }
 
+  if (DNBDebugserverIsTranslated()) {
+    return INVALID_NUB_PROCESS_ARCH;
+  }
+
   pid_t pid = INVALID_NUB_PROCESS;
   MachProcessSP processSP(new MachProcess);
   if (processSP.get()) {

lldb/tools/debugserver/source/DNBDefs.h

@@ -54,6 +54,7 @@ typedef uint32_t nub_event_t;
 typedef uint32_t nub_bool_t;
 
 #define INVALID_NUB_PROCESS ((nub_process_t)0)
+#define INVALID_NUB_PROCESS_ARCH ((nub_process_t)-1)
 #define INVALID_NUB_THREAD ((nub_thread_t)0)
 #define INVALID_NUB_WATCH_ID ((nub_watch_t)0)
 #define INVALID_NUB_HW_INDEX UINT32_MAX

lldb/tools/debugserver/source/RNBRemote.cpp

@@ -3753,17 +3753,6 @@ rnb_err_t RNBRemote::HandlePacket_v(const char *p) {
     char err_str[1024] = {'\0'};
     std::string attach_name;
 
-    if (DNBDebugserverIsTranslated()) {
-      DNBLogError("debugserver is x86_64 binary running in translation, attach "
-                  "failed.");
-      std::string return_message = "E96;";
-      return_message +=
-          cstring_to_asciihex_string("debugserver is x86_64 binary running in "
-                                     "translation, attached failed.");
-      SendPacket(return_message);
-      return rnb_err;
-    }
-
     if (strstr(p, "vAttachWait;") == p) {
       p += strlen("vAttachWait;");
       if (!GetProcessNameFrom_vAttach(p, attach_name)) {
@@ -3823,6 +3812,17 @@ rnb_err_t RNBRemote::HandlePacket_v(const char *p) {
       return HandlePacket_UNIMPLEMENTED(p);
     }
 
+    if (attach_pid == INVALID_NUB_PROCESS_ARCH) {
+      DNBLogError("debugserver is x86_64 binary running in translation, attach "
+                  "failed.");
+      std::string return_message = "E96;";
+      return_message +=
+          cstring_to_asciihex_string("debugserver is x86_64 binary running in "
+                                     "translation, attach failed.");
+      SendPacket(return_message.c_str());
+      return rnb_err;
+    }
+
     if (attach_pid != INVALID_NUB_PROCESS) {
       if (m_ctx.ProcessID() != attach_pid)
         m_ctx.SetProcessID(attach_pid);