Fix: Thread-local locale, fixes #244

Makes LT's threads robust against change of the process locale by system or other ill-behaving plugins

Include/LiveTraffic.h

@@ -42,6 +42,10 @@
 #include <cstring>
 #include <ctime>
 #include <cassert>
+#include <locale>
+#if APL
+#include <xlocale.h>
+#endif
 
 // Windows
 #if IBM
@@ -217,7 +221,11 @@ inline std::string strAtMost(const std::string s, size_t m) {
 }
 
 /// Replace all occurences of one string with another
-void str_replaceAll(std::string& str, const std::string& from, const std::string& to);
+void str_replaceAll(std::string& str, const std::string& from, const std::string& to, size_t start_pos = 0);
+
+/// @brief Replace a potentially wrong decimal point
+/// @returns if `true` if locale defines other decimal point than `.`
+bool str_correctDecimalPt (std::string& str, size_t start_pos = 0);
 
 // trimming of string
 // https://stackoverflow.com/questions/216823/whats-the-best-way-to-trim-stdstring
@@ -398,6 +406,26 @@ inline struct tm *localtime_s(struct tm * result, const time_t * time)
 
 #endif
 
+#if IBM
+#define locale_t         _locale_t
+#define freelocale       _free_locale
+
+#define LC_GLOBAL_LOCALE ((locale_t)-1)
+#define LC_ALL_MASK      LC_ALL
+#define LC_COLLATE_MASK  LC_COLLATE
+#define LC_CTYPE_MASK    LC_CTYPE
+#define LC_MONETARY_MASK LC_MONETARY
+#define LC_NUMERIC_MASK  LC_NUMERIC
+#define LC_TIME_MASK     LC_TIME
+
+// Base locale is ignored and mixing of masks is not supported
+#define newlocale(mask, locale, base) _create_locale(mask, locale)
+
+/// @brief Simulation of Linux' `uselocale()` function on Windows
+/// @see https://stackoverflow.com/a/17173977
+locale_t uselocale(locale_t new_locale);
+#endif
+
 /// Simpler access to strncpy_s if dest is a char array (not a pointer!)
 #define STRCPY_S(dest,src) strncpy_s(dest,sizeof(dest),src,sizeof(dest)-1)
 #define STRCPY_ATMOST(dest,src) strncpy_s(dest,sizeof(dest),strAtMost(src,sizeof(dest)-1).c_str(),sizeof(dest)-1)
@@ -411,18 +439,27 @@ inline int strerror_s( char *buf, size_t bufsz, int errnum )
 { strerror_r(errnum, buf, bufsz); return 0; }
 #endif
 
-// MARK: Thread names
-#ifdef DEBUG
-// This might not work on older Windows version, which is why we don't publish it in release builds
-#if IBM
-#define SET_THREAD_NAME(sName) SetThreadDescription(GetCurrentThread(), L##sName)
-#elif APL
-#define SET_THREAD_NAME(sName) pthread_setname_np(sName)
-#elif LIN
-#define SET_THREAD_NAME(sName) pthread_setname_np(pthread_self(),sName)
-#endif
-#else
-#define SET_THREAD_NAME(sName)
-#endif
+// MARK: Thread and Locale
+
+/// Begin a thread and set a thread-local locale
+/// @details In the communication with servers we must use internal standards,
+///          ie. C locale, so that for example the decimal point is `.`
+///          Hence we set a thread-local locale in all threads as they deal with communication.
+///          See https://stackoverflow.com/a/17173977
+class ThreadSettings {
+protected:
+    locale_t threadLocale = locale_t(0);
+    locale_t prevLocale = locale_t(0);
+public:
+    /// @brief Defines thread's name and sets the thread's locale
+    /// @param sThreadName Thread's name, max 16 chars
+    /// @param localeMask One of the LC_*_MASK constants. If `0` then locale is not changed.
+    /// @param sLocaleName New locale to set
+    ThreadSettings (const char* sThreadName,
+                    int localeMask = 0,
+                    const char* sLocaleName = "C");
+    /// Restores and cleans up locale
+    ~ThreadSettings();
+};
 
 #endif /* LiveTraffic_h */

Src/LTADSBEx.cpp

@@ -612,8 +612,8 @@ bool ADSBExchangeConnection::TestADSBExAPIKeyResult (bool& bIsKeyValid)
 // actual test, blocks, should by called via std::async
 bool ADSBExchangeConnection::DoTestADSBExAPIKey (const std::string newKey)
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_TestADSBEx");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_TestADSBEx", LC_ALL_MASK);
 
     bool bResult = false;
     char curl_errtxt[CURL_ERROR_SIZE];

Src/LTApt.cpp

@@ -2390,11 +2390,11 @@ void PurgeApt (const boundingBoxTy& _box)
 /// @param radius Search radius around center position in meter
 void AsyncReadApt (positionTy ctr, double radius)
 {
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_ReadApt", LC_ALL_MASK);
+
     static size_t lenSceneryLnBegin = strlen(APTDAT_SCENERY_LN_BEGIN);
 
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_ReadApt");
-
     // To avoid costly distance calculations we define a bounding box
     // just by calculating lat/lon values north/east/south/west of given pos
     // and include all airports with coordinates falling into it

Src/LTChannel.cpp

@@ -694,8 +694,8 @@ void LTFlightDataStop()
 // and it runs in a loop until LTFlightDataHideAircraft stops it
 void LTFlightDataSelectAc ()
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_Channels");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_Channels", LC_ALL_MASK);
 
     while ( !bFDMainStop )
     {

Src/LTFlightData.cpp

@@ -1318,8 +1318,8 @@ dequeKeyTimeTy dequeKeyPosCalc;
 // the CalcNextPos function on the respective flight data objects
 void LTFlightData::CalcNextPosMain ()
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_CalcPos");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_CalcPos", LC_ALL_MASK);
 
     // loop till said to stop
     while ( !bFDMainStop ) {

Src/LTForeFlight.cpp

@@ -110,8 +110,8 @@ bool ForeFlightSender::StopConnection ()
 // thread main function
 void ForeFlightSender::udpSend()
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_ForeFlight");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_ForeFlight", LC_ALL_MASK);
 
     //
     // *** open the UDP socket ***

Src/LTMain.cpp

@@ -250,14 +250,16 @@ void LTOpenURL  (const std::string& _url, const std::string& addon)
 {
     // Transiently, we allow to add the current camera position into the URL
     std::string url(_url);
-    if (_url.find('%') != std::string::npos) {
+    const size_t posPrct = _url.find('%');
+    if (posPrct != std::string::npos) {
         char buf[256];
         const positionTy camPos = dataRefs.GetViewPos();
         snprintf (buf, sizeof(buf), _url.c_str(),
                   camPos.lat(), camPos.lon());
         url = buf;
+        str_correctDecimalPt(url, posPrct);
     }
-    
+
     // If an addon is sepcified it is just added to the end
     if (!addon.empty())
         url += addon;
@@ -311,17 +313,31 @@ bool str_isalnum(const std::string& s)
 }
 
 // Replace all occurences of one string with another
-void str_replaceAll(std::string& str, const std::string& from, const std::string& to)
+void str_replaceAll(std::string& str, const std::string& from, const std::string& to, size_t start_pos)
 {
     if (from.empty() || str.empty())
         return;
-    size_t start_pos = 0;
     while ((start_pos = str.find(from, start_pos)) != std::string::npos) {
         str.replace(start_pos, from.length(), to);
         start_pos += to.length(); // Continue search only _after_ the replacement position
     }
 }
 
+// @brief Replace a potentially wrong decimal point
+bool str_correctDecimalPt (std::string& str, size_t start_pos)
+{
+    // If the locale is not set to using a decimal point we might end up with a comma in the coordinates, which OpenSky doesn't like
+    // Setting the locale is no option due to immediate impact on all threads,
+    // so we retrospectively replace the wrong delimiter
+    const lconv* pL = localeconv();
+    if (pL && pL->decimal_point && std::strcmp(pL->decimal_point, "."))
+    {
+        str_replaceAll(str, pL->decimal_point, ".", start_pos);
+        return true;
+    }
+    return false;
+}
+
 // Cut off everything after `from` from `s`, `from` including
 std::string& cut_off(std::string& s, const std::string& from)
 {
@@ -663,6 +679,78 @@ bool dequal ( const double d1, const double d2 )
     ((d1 + epsilon) > d2);
 }
 
+//
+// MARK: Thread Handling
+//
+
+#if IBM
+// Simulation of Linux' `uselocale()` function on Windows
+locale_t uselocale(locale_t new_locale)
+{
+    // Retrieve the current per thread locale setting
+    bool bIsPerThread = (_configthreadlocale(0) == _ENABLE_PER_THREAD_LOCALE);
+
+    // Retrieve the current thread-specific locale
+    locale_t old_locale = bIsPerThread ? _get_current_locale() : LC_GLOBAL_LOCALE;
+
+    if(new_locale == LC_GLOBAL_LOCALE)
+    {
+        // Restore the global locale
+        _configthreadlocale(_DISABLE_PER_THREAD_LOCALE);
+    }
+    else if(new_locale != NULL)
+    {
+        // Configure the thread to set the locale only for this thread
+        _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
+
+        // Set all locale categories
+        for(int i = LC_MIN; i <= LC_MAX; i++)
+            setlocale(i, new_locale->locinfo->lc_category[i].locale);
+    }
+
+    return old_locale;
+}
+#endif
+
+// Defines thread's name and sets the thread's locale
+ThreadSettings::ThreadSettings ([[maybe_unused]] const char* sThreadName,
+                                int localeMask,
+                                const char* sLocaleName)
+{
+    // --- Set thread's name ---
+#if IBM
+    // This might not work on older Windows version, which is why we don't publish it in release builds
+#ifdef DEBUG
+    wchar_t swThreadName[100];
+    std::mbstowcs(swThreadName, sThreadName, sizeof(swThreadName));
+    SetThreadDescription(GetCurrentThread(), swThreadName);
+#endif
+
+#elif APL
+    pthread_setname_np(sThreadName);
+#elif LIN
+    pthread_setname_np(pthread_self(),sThreadName);
+#endif
+
+    // --- Set thread's locale ---
+    if (localeMask && sLocaleName)
+    {
+        threadLocale = newlocale(localeMask, sLocaleName, NULL);
+        prevLocale = uselocale(threadLocale);
+    }
+}
+
+// Restores and cleans up locale
+ThreadSettings::~ThreadSettings()
+{
+    if (prevLocale)
+        uselocale(prevLocale);
+    if (threadLocale) {
+        freelocale(threadLocale);
+        threadLocale = locale_t(0);
+    }
+}
+
 //
 //MARK: Callbacks
 //

Src/LTOpenGlider.cpp

@@ -332,8 +332,8 @@ std::string OpenGliderConnection::GetStatusText () const
 // Main function for APRS connection, expected to be started in a thread
 void OpenGliderConnection::APRSMain (const positionTy& pos, unsigned dist_km)
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_OGN_APRS");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_OGN_APRS", LC_ALL_MASK);
 
     try {
         // open a TCP connection to APRS.glidernet.org
@@ -901,8 +901,8 @@ static size_t OGNAcListNetwCB(char *ptr, size_t, size_t nmemb, void* userdata)
 /// @see http://ddb.glidernet.org/download/
 static bool OGNAcListDoDownload ()
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_OGNAcList");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_OGNAcList", LC_ALL_MASK);
 
     bool bRet = false;
     try {

Src/LTRealTraffic.cpp

@@ -352,8 +352,8 @@ bool RealTrafficConnection::StopConnections()
 
 void RealTrafficConnection::tcpConnection ()
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_RT_TCP");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_RT_TCP", LC_ALL_MASK);
 
     // sanity check: return in case of wrong status
     if (!IsConnecting()) {
@@ -471,8 +471,8 @@ void RealTrafficConnection::SendUsersPlanePos()
 // forwards that to the flight data
 void RealTrafficConnection::udpListen ()
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_RT_UDP");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_RT_UDP", LC_ALL_MASK);
 
     // sanity check: return in case of wrong status
     if (!IsConnecting()) {

Src/LTVersion.cpp

@@ -183,8 +183,8 @@ size_t FetchVersionCB(char *ptr, size_t, size_t nmemb, void* userdata)
 // This function would block. Idea is to call it in a thread like with std::async
 bool FetchXPlaneOrgVersion ()
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_Version");
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_Version", LC_ALL_MASK);
 
     char curl_errtxt[CURL_ERROR_SIZE];
     std::string readBuf;

Src/LTWeather.cpp

@@ -187,9 +187,9 @@ size_t WeatherFetchCB(char *ptr, size_t, size_t nmemb, void* userdata)
 // This function would block. Idea is to call it in a thread like with std::async
 bool WeatherFetch (float _lat, float _lon, float _radius_nm)
 {
-    // This is a thread main function, set thread's name
-    SET_THREAD_NAME("LT_Weather");
-    
+    // This is a communication thread's main function, set thread's name and C locale
+    ThreadSettings TS ("LT_Weather", LC_ALL_MASK);
+
     bool bRet = false;
     try {
         char curl_errtxt[CURL_ERROR_SIZE];

docs/readme.html

@@ -155,6 +155,11 @@ <h3>v3.3.0</h3>
             <i>Note 2:</i> Looks like particles, hence contrails, don't show beyond a certain distance from the camera,
             probably some <a href="https://en.wikipedia.org/wiki/Level_of_detail_(computer_graphics)">LoD</a> optimization by X-Plane; in my tests around 13nm.
         </li>
+        <li>
+            Fixed <a href="https://github.com/TwinFan/LiveTraffic/issues/244">#244</a>:
+            URL formatting and JSON parsing robust against changes to
+            locale/formatting settings in system or by other plugins.
+        </li>
     </ul>
 
     <h3>v3.2.2</h3>