Bug 1550 – D DLLs close standard input/output streams when unloading

=== loader.d === import std.stdio; import std.string; import std.c.windows.windows; void main() { writefln("Loading DLL..."); HANDLE h = LoadLibraryA("library.dll"); if(!h) return writefln("Failed to load DLL."); writefln("DLL loaded. Unloading..."); if(!FreeLibrary(h)) return writefln("Failed to unload DLL."); writefln("DLL unloaded."); } === library.d === (standard DLL template copied from the documentation) import std.c.windows.windows; HINSTANCE g_hInst; extern (C) { void gc_init(); void gc_term(); void _minit(); void _moduleCtor(); void _moduleUnitTests(); } extern (Windows) BOOL DllMain(HINSTANCE hInstance, ULONG ulReason, LPVOID pvReserved) { switch (ulReason) { case DLL_PROCESS_ATTACH: gc_init(); // initialize GC _minit(); // initialize module list _moduleCtor(); // run module constructors _moduleUnitTests(); // run module unit tests break; case DLL_PROCESS_DETACH: gc_term(); // shut down GC break; case DLL_THREAD_ATTACH: case DLL_THREAD_DETACH: // Multiple threads not supported yet return false; } g_hInst=hInstance; return true; } === output === Loading DLL... DLL loaded. Unloading... === comments === D's runtime (DMC libc) closes the standard streams when the DLL is unloaded. Call stack: DllEntryPoint __cexit _exit ___fcloseall _fclose _close Needless to say, that shouldn't happen with DLLs. Workaround: import std.stdio and add _fcloseallp = null; somewhere in your DllMain.

I just noticed that this is somewhat documented at http://digitalmars.com/d/dll.html#Dcode . However, this applies not only when a program in D is the one loading the DLL. Thus, it should be moved outside the "D code calling D code in DLLs" section, and also into the "DLLs with a C Interface" source code template.

The workaround (setting _fcloseallp = null) also prevents any other open file from being closed. I think it should be fixed in the C-runtime library, where the handle for stdin/out/err is taken from a call to GetStdHandle(), and probably should not be closed when terminating.

*** Issue 4996 has been marked as a duplicate of this issue. ***

Doesn't happen in D2.

Still happens with the example dclient/dserver in dmd/samples.

Does this issue still manifests?

The pull request for the dmc runtime has been merged https://github.com/DigitalMars/dmc/pull/3 , but there has never been an update to the released snn.lib AFAICT.

(In reply to Rainer Schuetze from comment #7) > The pull request for the dmc runtime has been merged > https://github.com/DigitalMars/dmc/pull/3 , but there has never been an > update to the released snn.lib AFAICT. Any ideas on what actions should be taken to update the snn.lib? This is the first time I hear about this.

(In reply to RazvanN from comment #8) > Any ideas on what actions should be taken to update the snn.lib? This is the > first time I hear about this. Walter has to build it and upload it to http://ftp.digitalmars.com/snn.lib That's where the release build program downloads it from.

I verified the reported example (after some updates) works with the new snn.lib in 2.089-rc1 (and still failed with 2.088.1).