fa_gps fails static code analysis

[davmonk]

fa_gps_bug_report.html
ran static code analysis against fa_gps
multiple issues found:

High severity issues: 3
Medium severity issues: 6
Low severity / maintainability issues: 6

[davmonk]

`diff --git a/fa_gps.tcl b/fa_gps.tcl
index 3a1f2ab..9d47c6e 100644
--- a/fa_gps.tcl
+++ b/fa_gps.tcl
@@ -89,6 +89,9 @@ namespace eval ::fa_gps {
 				debug "connection to gpsd at $host/$port failed: $error"
 				close_socket_and_reopen
 				return
+			}
+
+			# FIX: mark transport as connected immediately
+			set connected 1

 			debug "connection established to gpsd at $host/$port"

@@ -109,41 +112,45 @@ namespace eval ::fa_gps {
 				close_socket_and_reopen
 				return
 			}

-			# get a line of data from the socket.  if we get an error, close the
-			# socket and attempt to reopen
-			if {[catch {set size [gets $sock line]} catchResult] == 1} {
-				logger "Lost connection to gpsd at $host/$port: $catchResult"
-				close_socket_and_reopen
-				return
-			}
-
-			#
-			# sometimes you get a callback with no data, that's OK but there's nothing to do
-			#
-			if {$size < 0} {
-				debug "gets returned $size, no data yet"
-				return
-			}
-
-			debug "received line: $line"
-
-			# parse it as json
-			if {[catch {set j [::json::json2dict $line]} catchResult] == 1} {
-				logger "Malformed line from gpsd, reconnecting: $catchResult"
-				close_socket_and_reopen
-				return
-			}
-
-			if {[catch {handle_message $j} catchResult] == 1} {
-				logger "Got '$catchResult' handling a message from gpsd: $::errorInfo"
-				close_socket_and_reopen
-				return
-			}
+			# FIX: drain all available data
+			while {[gets $sock line] >= 0} {
+				debug "received line: $line"
+
+				# parse JSON; tolerate malformed lines
+				if {[catch {set j [::json::json2dict $line]} catchResult]} {
+					logger "Malformed JSON from gpsd (ignored): $catchResult"
+					continue
+				}
+
+				if {[catch {handle_message $j} catchResult]} {
+					logger "Got '$catchResult' handling gpsd message: $::errorInfo"
+					close_socket_and_reopen
+					return
+				}
+			}
 		}

 		protected method handle_message {_j} {
@@ -196,25 +203,31 @@ namespace eval ::fa_gps {
 					"TPV" {
 						# we want this!
 						debug "processing TPV"
-						switch -exact $j_mode {
-							"0" - "1" {
-								debug "no fix"
-								set lat ""
-								set lon ""
-								set alt ""
-							}
-
-							"2" {
-								if {[info exists j_lat] && [info exists j_lon]} {
-									debug "2D fix at $j_lat $j_lon"
-									set lat $j_lat
-									set lon $j_lon
-									set alt ""
-								}
-							}
-
-							"3" {
-								if {[info exists j_lat] && [info exists j_lon] && [info exists j_alt]} {
-									debug "3D fix at $j_lat $j_lon $j_alt"
-									set lat $j_lat
-									set lon $j_lon
-									set alt $j_alt
-								}
-							}
-
-							default {
-								debug "didn't understand that TPV message"
-							}
+						if {![info exists j_mode]} {
+							return
+						}
+
+						# FIX: normalize GPSD mode to integer
+						set mode [expr {int($j_mode)}]
+
+						switch $mode {
+							0 - 1 {
+								debug "no fix"
+								set lat ""
+								set lon ""
+								set alt ""
+							}
+							2 {
+								if {[info exists j_lat] && [info exists j_lon]} {
+									debug "2D fix at $j_lat $j_lon"
+									set lat $j_lat
+									set lon $j_lon
+									set alt ""
+								}
+							}
+							3 {
+								if {[info exists j_lat] && [info exists j_lon] && [info exists j_alt]} {
+									debug "3D fix at $j_lat $j_lon $j_alt"
+									set lat $j_lat
+									set lon $j_lon
+									set alt $j_alt
+								}
+							}
 						}

 						do_callback`