Merge bitcoin#2516: [GUI][BUG] Console: allow empty arguments

47607df [Qt] Console: don't allow empty arguments when using the comma-syntax (random-zebra)
af215ef [Qt] Console: allow empty arguments (random-zebra)

Pull request description:

  bitcoin#2372 broke the support for empty arguments `""` (which is required as first argument of `sendmany`).
  Backport the fix from bitcoin#9329

  Thanks to @NoobieDev12 for reporting this bug.

ACKs for top commit:
  furszy:
    Nice catch👌, ACK 47607df
  Fuzzbawls:
    ACK 47607df

Tree-SHA512: 9ebcce3fbcb10856fc0a586365a9f0c4a3bbed5df571f21b37a143a882ab937b0fdf0502d1ba39e015cc0f745b07ed78fa8eb547110d0e53401f0d88af89cba1

Author: furszy

src/qt/rpcexecutor.cpp

@@ -112,6 +112,8 @@ bool RPCExecutor::ExecuteCommandLine(std::string& strResult, const std::string&
     enum CmdParseState
     {
         STATE_EATING_SPACES,
+        STATE_EATING_SPACES_IN_ARG,
+        STATE_EATING_SPACES_IN_BRACKETS,
         STATE_ARGUMENT,
         STATE_SINGLEQUOTED,
         STATE_DOUBLEQUOTED,
@@ -195,26 +197,29 @@ bool RPCExecutor::ExecuteCommandLine(std::string& strResult, const std::string&
                     break;
             }
             case STATE_ARGUMENT: // In or after argument
+            case STATE_EATING_SPACES_IN_ARG:
+            case STATE_EATING_SPACES_IN_BRACKETS:
             case STATE_EATING_SPACES: // Handle runs of whitespace
                 switch(ch)
             {
                 case '"': state = STATE_DOUBLEQUOTED; break;
                 case '\'': state = STATE_SINGLEQUOTED; break;
                 case '\\': state = STATE_ESCAPE_OUTER; break;
                 case '(': case ')': case '\n':
+                    if (state == STATE_EATING_SPACES_IN_ARG)
+                        throw std::runtime_error("Invalid Syntax");
                     if (state == STATE_ARGUMENT)
                     {
                         if (ch == '(' && stack.size() && stack.back().size() > 0)
                             stack.push_back(std::vector<std::string>());
-                        if (curarg.size())
-                        {
-                            // don't allow commands after executed commands on baselevel
-                            if (!stack.size())
-                                throw std::runtime_error("Invalid Syntax");
-                            stack.back().push_back(curarg);
-                        }
+
+                        // don't allow commands after executed commands on baselevel
+                        if (!stack.size())
+                            throw std::runtime_error("Invalid Syntax");
+
+                        stack.back().push_back(curarg);
                         curarg.clear();
-                        state = STATE_EATING_SPACES;
+                        state = STATE_EATING_SPACES_IN_BRACKETS;
                     }
                     if ((ch == ')' || ch == '\n') && stack.size() > 0)
                     {
@@ -238,12 +243,19 @@ bool RPCExecutor::ExecuteCommandLine(std::string& strResult, const std::string&
                     }
                     break;
                 case ' ': case ',': case '\t':
-                    if(state == STATE_ARGUMENT) // Space ends argument
+                    if(state == STATE_EATING_SPACES_IN_ARG && curarg.empty() && ch == ',')
+                        throw std::runtime_error("Invalid Syntax");
+
+                    else if(state == STATE_ARGUMENT) // Space ends argument
                     {
-                        if (curarg.size())
-                            stack.back().push_back(curarg);
+                        stack.back().push_back(curarg);
                         curarg.clear();
                     }
+                    if ((state == STATE_EATING_SPACES_IN_BRACKETS || state == STATE_ARGUMENT) && ch == ',')
+                    {
+                        state = STATE_EATING_SPACES_IN_ARG;
+                        break;
+                    }
                     state = STATE_EATING_SPACES;
                     break;
                 default: curarg += ch; state = STATE_ARGUMENT;