Merge pull request #417 from vibe-d/fix_gc_filesteam_crash

Fix InvalidMemoryOperationError caused by leaking an open FileStream to the GC

source/vibe/core/file.d

@@ -699,9 +699,19 @@ scope:
 
 	~this()
 	nothrow {
+		import core.memory : GC;
+		import core.stdc.stdio : fprintf, stderr;
+
 		static if (is(typeof(&eventDriver.files.isUnique))) {
 			if (this.isOpen) {
-				if (m_ctx.driver is (() @trusted => cast(shared)eventDriver)()) {
+				if (GC.inFinalizer) {
+					() @trusted {
+						auto path = m_ctx.path.toString();
+						fprintf(stderr, "Warning: Leaking open FileStream handle because the instance was leaked to the GC (%.*s)\n",
+							cast(int)path.length, path.ptr);
+					} ();
+					m_fd = FileFD.invalid;
+				} else if (m_ctx.driver is (() @trusted => cast(shared)eventDriver)()) {
 					if (eventDriver.files.isUnique(m_fd)) {
 						try close();
 						catch (Exception e) logException(e, "Closing unclosed FileStream during destruction failed");

tests/vibe.core.file.gcleak.d

@@ -0,0 +1,20 @@
+/+ dub.sdl:
+	dependency "vibe-core" path=".."
++/
+module test;
+
+import vibe.core.file;
+
+
+// this test ensures that leaking an open FileStream will not crash the
+// application
+void main()
+{
+	auto fil = new FileStream;
+	*fil = openFile("test.tmp", FileMode.createTrunc);
+	fil = null;
+
+	ubyte[] arr;
+	foreach (i; 0 .. 1000)
+		arr ~= "1234567890";
+}