[cli] allow executing the factoryreset command when running sync co…

…mmands

When running the sync command, such as `diag radio receive 10000`, the cli
doesn't allow running other commands before the sync command returns. Which
causes that the sync command may be blocked for a very long time and users
can't do anything to terminate the sync command. This will also cause the
test script to fail to run the second case after running first case fails.

This commit allows the cli to execute the `factoryreset` command when running
the sync command.

src/cli/cli.cpp

@@ -287,29 +287,42 @@ template <> otError Interpreter::Process<Cmd("reset")>(Arg aArgs[])
 
 void Interpreter::ProcessLine(char *aBuf)
 {
-    Arg     args[kMaxArgs + 1];
-    otError error = OT_ERROR_NONE;
+    static const char *const kCmdFactoryReset = "factoryreset";
+    Arg                      args[kMaxArgs + 1];
+    otError                  error = OT_ERROR_NONE;
 
     OT_ASSERT(aBuf != nullptr);
 
+    args[0].Clear();
+
     if (!mInternalDebugCommand)
     {
         // Ignore the command if another command is pending.
-        VerifyOrExit(!mCommandIsPending, args[0].Clear());
-        mCommandIsPending = true;
-
-        VerifyOrExit(StringLength(aBuf, kMaxLineLength) <= kMaxLineLength - 1, error = OT_ERROR_PARSE);
+        if (!mCommandIsPending)
+        {
+            mCommandIsPending = true;
+            VerifyOrExit(StringLength(aBuf, kMaxLineLength) <= kMaxLineLength - 1, error = OT_ERROR_PARSE);
+        }
+        else
+        {
+            VerifyOrExit(StringLength(aBuf, kMaxLineLength) <= kMaxLineLength - 1, args[0].Clear());
+            VerifyOrExit(ot::Utils::CmdLineParser::ParseCmd(aBuf, args, kMaxArgs) == OT_ERROR_NONE, args[0].Clear());
+            VerifyOrExit(((!args[0].IsEmpty()) && (args[0] == kCmdFactoryReset)), args[0].Clear());
+        }
     }
 
-    SuccessOrExit(error = ot::Utils::CmdLineParser::ParseCmd(aBuf, args, kMaxArgs));
-    VerifyOrExit(!args[0].IsEmpty(), mCommandIsPending = false);
+    if (args[0].IsEmpty())
+    {
+        SuccessOrExit(error = ot::Utils::CmdLineParser::ParseCmd(aBuf, args, kMaxArgs));
+        VerifyOrExit(!args[0].IsEmpty(), mCommandIsPending = false);
+    }
 
     if (!mInternalDebugCommand)
     {
         LogInput(args);
 
 #if OPENTHREAD_CONFIG_DIAG_ENABLE
-        if (otDiagIsEnabled(GetInstancePtr()) && (args[0] != "diag") && (args[0] != "factoryreset"))
+        if (otDiagIsEnabled(GetInstancePtr()) && (args[0] != "diag") && (args[0] != kCmdFactoryReset))
         {
             OutputLine("under diagnostics mode, execute 'diag stop' before running any other commands.");
             ExitNow(error = OT_ERROR_INVALID_STATE);