Fix error creating directories during update when the app is installed to a drive other than C: on Windows.

FileUtils::dirname() did not include the drive letter under Windows and
the return value of dirname() was fed directly to mkpath().

When the drive letter is not specified, mkdir() assumes drive C: -
this either fails if the user does not have access rights to drive C:
or creates a directory in the wrong place.

This commit changes FileUtils::dirname() to include the drive letter
on Windows and adds a test.

src/FileUtils.cpp

@@ -335,7 +335,14 @@ std::string FileUtils::dirname(const char* path)
 	  0  /* extension length */
 	);
 
-	return std::string(dir);
+	std::string result;
+	if (drive[0])
+	{
+		result += std::string(drive);
+	}
+	result += dir;
+
+	return result;
 #endif
 }
 

src/FileUtils.h

@@ -84,7 +84,9 @@ class FileUtils
 		/** Returns the file name part of a file path, including the extension. */
 		static std::string fileName(const char* path);
 
-		/** Returns the directory part of a file path. */
+		/** Returns the directory part of a file path.
+		 * On Windows this includes the drive letter, if present in @p path.
+		 */
 		static std::string dirname(const char* path);
 
 		/** Remove a directory and all of its contents. */

src/tests/CMakeLists.txt

@@ -36,6 +36,12 @@ add_executable(TestUpdaterOptions
 target_link_libraries(TestUpdaterOptions
   updatershared
 )
+add_executable(TestFileUtils
+  TestFileUtils.cpp
+)
+target_link_libraries(TestFileUtils
+  updatershared
+)
   
 if (APPLE)
 	set_target_properties(TestUpdateScript PROPERTIES LINK_FLAGS "-framework Security -framework Cocoa")

src/tests/TestFileUtils.cpp

@@ -0,0 +1,19 @@
+#include "TestFileUtils.h"
+
+#include "FileUtils.h"
+#include "TestUtils.h"
+
+void TestFileUtils::testDirName()
+{
+#ifdef PLATFORM_WINDOWS
+	std::string dirName = FileUtils::dirname("E:/Some Dir/App.exe");
+	TEST_COMPARE(dirName,"E:/Some Dir/");
+#endif
+}
+
+int main(int,char**)
+{
+	TestList<TestFileUtils> tests;
+	tests.addTest(&TestFileUtils::testDirName);
+	return TestUtils::runTest(tests);
+}

src/tests/TestFileUtils.h

@@ -0,0 +1,7 @@
+#pragma once
+
+class TestFileUtils
+{
+	public:
+		void testDirName();
+};