Cleanup some leaked file handles

[weirddan455]

Description

This allows Dunkle Schatten 2 to load and past the first couple of screens before it freezes. For some reason, it's very sensitive to extra files being created. It's kind of like a DOS Valgrind because it helped me clean up some leaks.

Once it gets past a certain number of files, it stomps on our device chain and then spins forever in this loop:

dosbox-staging/src/dos/dos_devices.cpp

Lines 238 to 257 in ffea16b

	// start walking the device chain of real pointers
	auto rp = dos_infoblock.GetDeviceChain();
	while (!DOS_IsEndPointer(rp)) {
	if (!is_a_driver(rp) || !DOS_DeviceHasName(rp, name)) {
	rp = DOS_GetNextDevice(rp);
	continue;
	}
	if (is_con_or_nul(rp)) {
	return 0;
	}
	if (skip_existing_drivers && is_existing_driver(rp)) {
	return 0;
	}
	// The device at the real pointer is a driver, has a name
	// matching the given name, is neither the CON nor NUL devices,
	// and (if requested) is not an existing device driver.
	return rp;
	}
	return 0;

I haven't fixed the root problem yet but it lead me to some buggy code I could fix regardless.

Related issues

#3668

Manual testing

• Output redirection works dir > test.txt
• Pipe works dir | more
• Input redirection works test.txt < more

Checklist

Please tick the items as you have addressed them. Don't remove items; leave the ones that are not applicable unchecked.

I have:

• followed the project's contributing guidelines and code of conduct.
• performed a self-review of my code.
• commented on the particularly hard-to-understand areas of my code.
• split my work into well-defined, bisectable commits, and I named my commits well.
• applied the appropriate labels (bug, enhancement, refactoring, documentation, etc.)
• checked that all my commits can be built.
• confirmed that my code does not cause performance regressions (e.g., by running the Quake benchmark).
• added unit tests where applicable to prove the correctness of my code and to avoid future regressions.
• made corresponding changes to the documentation or the website according to the documentation guidelines.
• locally verified my website or documentation changes.

[johnnovak]

Looks good, but I've only reviewed it superficially. I'm not familiar with this part of the codebase and I don't have time or willingness to investigate it more deeply, so I'll trust you on this one.

[weirddan455]

I've addressed your comments and tested redirection. I had a bug with pipes that I fixed.

PVS was throwing some false positive warnings so I did some #pragma pvs to disable it but now MSVC is throwing warnings about unknown pragmas. Stupid build systems man... don't worry about it MSVC that pragma is not meant for you.

[weirddan455]

CI all passes now finally. I think this is good to go but I'll give you a chance to look it over again if you want @johnnovak since I made some changes.

[johnnovak]

Still looking good 😄 A few minor comments, but good job otherwise @weirddan455 👍🏻

I found this amusing, btw:

It's kind of like a DOS Valgrind because it helped me clean up some leaks.