Add ScopedEnvVar class, use it to safely pass LV2_PATH to bridges

Closes #195

source/backend/plugin/CarlaPluginLV2.cpp

@@ -25,6 +25,7 @@
 #include "CarlaLv2Utils.hpp"
 
 #include "CarlaBase64Utils.hpp"
+#include "CarlaEngineUtils.hpp"
 #include "CarlaPipeUtils.hpp"
 #include "CarlaPluginUI.hpp"
 #include "Lv2AtomRingBuffer.hpp"
@@ -393,8 +394,9 @@ public:
         UiCrashed
     };
 
-    CarlaPipeServerLV2(CarlaPluginLV2* const plugin)
-        : kPlugin(plugin),
+    CarlaPipeServerLV2(CarlaEngine* const engine, CarlaPluginLV2* const plugin)
+        : kEngine(engine),
+          kPlugin(plugin),
           fFilename(),
           fPluginURI(),
           fUiURI(),
@@ -422,6 +424,12 @@ public:
 
     bool startPipeServer() noexcept
     {
+        const ScopedEngineEnvironmentLocker _seel(kEngine);
+        const ScopedEnvVar _sev1("LV2_PATH", kEngine->getOptions().pathLV2);
+#ifdef CARLA_OS_LINUX
+        const ScopedEnvVar _sev2("LD_PRELOAD", nullptr);
+#endif
+
         return CarlaPipeServer::startPipeServer(fFilename, fPluginURI, fUiURI);
     }
 
@@ -470,6 +478,7 @@ protected:
     bool msgReceived(const char* const msg) noexcept override;
 
 private:
+    CarlaEngine*    const kEngine;
     CarlaPluginLV2* const kPlugin;
 
     CarlaString fFilename;
@@ -506,7 +515,7 @@ public:
           fEventsIn(),
           fEventsOut(),
           fLv2Options(),
-          fPipeServer(this),
+          fPipeServer(engine, this),
           fCustomURIDs(),
           fFirstActive(true),
           fLastStateChunk(nullptr),

source/utils/CarlaPipeUtils.cpp

@@ -1558,6 +1558,53 @@ void CarlaPipeClient::closePipeClient() noexcept
 
 // -----------------------------------------------------------------------
 
+ScopedEnvVar::ScopedEnvVar(const char* const key, const char* const value) noexcept
+    : fKey(nullptr),
+      fOrigValue(nullptr)
+{
+    CARLA_SAFE_ASSERT_RETURN(key != nullptr && key[0] != '\0',);
+
+    fKey = carla_strdup_safe(key);
+    CARLA_SAFE_ASSERT_RETURN(fKey != nullptr,);
+
+    if (const char* const origValue = std::getenv(key))
+    {
+        fOrigValue = carla_strdup_safe(origValue);
+        CARLA_SAFE_ASSERT_RETURN(fOrigValue != nullptr,);
+    }
+
+    if (value != nullptr)
+        carla_setenv(key, value);
+    else if (fOrigValue != nullptr)
+        carla_unsetenv(key);
+}
+
+ScopedEnvVar::~ScopedEnvVar() noexcept
+{
+    bool hasOrigValue = false;
+
+    if (fOrigValue != nullptr)
+    {
+        hasOrigValue = true;
+
+        carla_setenv(fKey, fOrigValue);
+
+        delete[] fOrigValue;
+        fOrigValue = nullptr;
+    }
+
+    if (fKey != nullptr)
+    {
+        if (! hasOrigValue)
+            carla_unsetenv(fKey);
+
+        delete[] fKey;
+        fKey = nullptr;
+    }
+}
+
+// -----------------------------------------------------------------------
+
 ScopedLocale::ScopedLocale() noexcept
     : fLocale(carla_strdup_safe(::setlocale(LC_NUMERIC, nullptr)))
 {

source/utils/CarlaPipeUtils.hpp

@@ -319,6 +319,22 @@ public:
     CARLA_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(CarlaPipeClient)
 };
 
+// -----------------------------------------------------------------------
+// ScopedEnvVar class
+
+class ScopedEnvVar {
+public:
+    ScopedEnvVar(const char* const key, const char* const value) noexcept;
+    ~ScopedEnvVar() noexcept;
+
+private:
+    const char* fKey;
+    const char* fOrigValue;
+
+    CARLA_DECLARE_NON_COPY_CLASS(ScopedEnvVar)
+    CARLA_PREVENT_HEAP_ALLOCATION
+};
+
 // -----------------------------------------------------------------------
 // ScopedLocale class
 

source/utils/CarlaUtils.hpp

@@ -258,6 +258,23 @@ void carla_setenv(const char* const key, const char* const value) noexcept
 #endif
 }
 
+/*
+ * Unset environment variable 'key'.
+ */
+static inline
+void carla_unsetenv(const char* const key) noexcept
+{
+    CARLA_SAFE_ASSERT_RETURN(key != nullptr && key[0] != '\0',);
+
+#ifdef CARLA_OS_WIN
+    try {
+        ::SetEnvironmentVariableA(key, nullptr);
+    } CARLA_SAFE_EXCEPTION("carla_unsetenv");
+#else
+    ::unsetenv(key);
+#endif
+}
+
 // -----------------------------------------------------------------------
 // carla_strdup