Prefer early exit/break to large conditional blocks.

Some of these are large and contain smaller unrelated refactors.

src/frontend/stmclient.cc

@@ -314,7 +314,9 @@ bool STMClient::process_user_input( int fd )
 
   NetworkType &net = *network;
 
-  if ( !net.shutdown_in_progress() ) {
+  if ( net.shutdown_in_progress() ) {
+    return true;
+  }
   overlays.get_prediction_engine().set_local_frame_sent( net.get_sent_state_last() );
 
   /* Don't predict for bulk data. */
@@ -336,9 +338,8 @@ bool STMClient::process_user_input( int fd )
 	  overlays.get_notification_engine().set_notification_string( wstring( L"Exiting on user request..." ), true );
 	  net.start_shutdown();
 	  return true;
-	  } else {
-	    return false;
 	}
+	return false;
       } else if ( the_byte == 0x1a ) { /* Suspend sequence is escape_key Ctrl-Z */
 	/* Restore terminal and terminal-driver state */
 	swrite( STDOUT_FILENO, display.close().c_str() );
@@ -390,7 +391,6 @@ bool STMClient::process_user_input( int fd )
 
     net.get_current_state().push_back( Parser::UserByte( the_byte ) );		
   }
-  }
 
   return true;
 }

src/frontend/terminaloverlay.cc

@@ -90,7 +90,10 @@ Validity ConditionalOverlayCell::get_validity( const Framebuffer &fb, int row,
   const Cell &current = *( fb.get_cell( row, col ) );
 
   /* see if it hasn't been updated yet */
-  if ( late_ack >= expiration_frame ) {
+  if ( late_ack < expiration_frame ) {
+    return Pending;
+  }
+
   if ( unknown ) {
     return CorrectNoCredit;
   }
@@ -107,15 +110,10 @@ Validity ConditionalOverlayCell::get_validity( const Framebuffer &fb, int row,
     }
     if ( it == original_contents.end() ) {
       return Correct;
-      } else {
+    }
     return CorrectNoCredit;
   }
-    } else {
   return IncorrectOrExpired;
-    }
-  }
-
-  return Pending;
 }
 
 Validity ConditionalCursorMove::get_validity( const Framebuffer &fb,

src/network/network.cc

@@ -523,7 +523,9 @@ string Connection::recv_one( int sock_to_recv, bool nonblocking )
 
   dos_assert( p.direction == (server ? TO_SERVER : TO_CLIENT) ); /* prevent malicious playback to sender */
 
-  if ( p.seq >= expected_receiver_seq ) { /* don't use out-of-order packets for timestamp or targeting */
+  if ( p.seq < expected_receiver_seq ) { /* don't use (but do return) out-of-order packets for timestamp or targeting */
+    return p.payload;
+  }
   expected_receiver_seq = p.seq + 1; /* this is security-sensitive because a replay attack could otherwise
 					screw up the timestamp and targeting */
 
@@ -564,9 +566,9 @@ string Connection::recv_one( int sock_to_recv, bool nonblocking )
   has_remote_addr = true;
   last_heard = timestamp();
 
-    if ( server ) { /* only client can roam */
-      if ( remote_addr_len != header.msg_namelen ||
-	   memcmp( &remote_addr, &packet_remote_addr, remote_addr_len ) != 0 ) {
+  if ( server && /* only client can roam */
+       ( remote_addr_len != header.msg_namelen ||
+	 memcmp( &remote_addr, &packet_remote_addr, remote_addr_len ) != 0 ) ) {
     remote_addr = packet_remote_addr;
     remote_addr_len = header.msg_namelen;
     char host[ NI_MAXHOST ], serv[ NI_MAXSERV ];
@@ -579,10 +581,7 @@ string Connection::recv_one( int sock_to_recv, bool nonblocking )
     fprintf( stderr, "Server now attached to client at %s:%s\n",
 	     host, serv );
   }
-    }
-  }
-
-  return p.payload; /* we do return out-of-order or duplicated packets to caller */
+  return p.payload;
 }
 
 std::string Connection::port( void ) const

src/terminal/terminaldisplay.cc

@@ -181,7 +181,9 @@ std::string Display::new_frame( bool initialized, const Framebuffer &last, const
     for ( int row = 0; row < f.ds.get_height(); row++ ) {
       const Row *new_row = f.get_row( 0 );
       const Row *old_row = &*rows.at( row );
-      if ( new_row == old_row || *new_row == *old_row ) {
+      if ( ! ( new_row == old_row || *new_row == *old_row ) ) {
+	continue;
+      }
       /* if row 0, we're looking at ourselves and probably didn't scroll */
       if ( row == 0 ) {
 	break;
@@ -204,7 +206,6 @@ std::string Display::new_frame( bool initialized, const Framebuffer &last, const
 
       break;
     }
-    }
 
     if ( scroll_height ) {
       frame_y = scroll_height;
@@ -458,8 +459,10 @@ bool Display::put_row( bool initialized, FrameState &frame, const Framebuffer &f
     }
   }
 
-  if ( wrote_last_cell
-       && (frame_y < f.ds.get_height() - 1) ) {
+  if ( ! ( wrote_last_cell
+	   && (frame_y < f.ds.get_height() - 1) ) ) {
+    return false;
+  }
   /* To hint that a word-select should group the end of one line
      with the beginning of the next, we let the real cursor
      actually wrap around in cases where it wrapped around for us. */
@@ -468,13 +471,11 @@ bool Display::put_row( bool initialized, FrameState &frame, const Framebuffer &f
     frame.cursor_x = 0;
     frame.cursor_y++;
     return true;
-    } else {
+  }
   /* Resort to CR/LF and update our cursor. */
   frame.append( "\r\n" );
   frame.cursor_x = 0;
   frame.cursor_y++;
-    }
-  }
   return false;
 }