Temporarily change the current directory to that of the main binary when re-launching the application.

This may be required on Windows so that the application can find libraries
that it depends upon.

src/FileUtils.cpp

@@ -516,3 +516,38 @@ std::string FileUtils::makeAbsolute(const char* path, const char* basePath)
 		return path;
 	}
 }
+
+void FileUtils::chdir(const char* path) throw (IOException)
+{
+#ifdef PLATFORM_UNIX
+	if (::chdir(path) != 0)
+	{
+		throw FileUtils::IOException("Unable to change directory");
+	}
+#else
+	if (!SetCurrentDirectory(path))
+	{
+		throw FileUtils::IOException("Unable to change directory");
+	}
+#endif
+}
+
+std::string FileUtils::getcwd() throw (IOException)
+{
+#ifdef PLATFORM_UNIX
+	char path[PATH_MAX];
+	if (!::getcwd(path,PATH_MAX))
+	{
+		throw FileUtils::IOException("Failed to get current directory");
+	}
+	return std::string(path);
+#else
+	char path[MAX_PATH];
+	if (GetCurrentDirectory(MAX_PATH,path) != 0)
+	{
+		throw FileUtils::IOException("Failed to get current directory");
+	}
+	return toUnixPathSeparators(std::string(path));
+#endif
+}
+

src/FileUtils.h

@@ -119,5 +119,11 @@ class FileUtils
 		static std::string makeAbsolute(const char* path, const char* basePath);
 
 		static void writeFile(const char* path, const char* data, int length) throw (IOException);
+
+		/** Changes the current working directory to @p path */
+		static void chdir(const char* path) throw (IOException);
+
+		/** Returns the current working directory of the application. */
+		static std::string getcwd() throw (IOException);
 };
 

src/UpdateInstaller.cpp

@@ -401,6 +401,8 @@ void UpdateInstaller::setObserver(UpdateObserver* observer)
 }
 
 void UpdateInstaller::restartMainApp()
+{
+	try
 	{
 		std::string command;
 		std::list<std::string> args;
@@ -418,13 +420,28 @@ void UpdateInstaller::restartMainApp()
 		if (!command.empty())
 		{
 			LOG(Info,"Starting main application " + command);
+
+			// change the current directory to that of the application binary,
+			// so that on Windows the application can find shared libraries
+			// that it depends on which are in the same directory
+			std::string appDir = FileUtils::dirname(command.c_str());
+			std::string currentDir = FileUtils::getcwd();
+			FileUtils::chdir(appDir.c_str());
+
 			ProcessUtils::runAsync(command,args);
+
+			FileUtils::chdir(currentDir.c_str());
 		}
 		else
 		{
 			LOG(Error,"No main binary specified in update script");
 		}
 	}
+	catch (const std::exception& ex)
+	{
+		LOG(Error,"Unable to restart main app " + std::string(ex.what()));
+	}
+}
 
 void UpdateInstaller::postInstallUpdate()
 {