/dev/zero is missing

[EvenOAndersen]

Please include the following in your bug report:

Version of emscripten/emsdk:
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.50 (047b825)
clang version 18.0.0 (https://github.com/llvm/llvm-project 14028ec0a62210d68a4dd7a046ac79c8c3b7727e)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: C:\emsdk\upstream\bin

int fd = open("/dev/zero", O_RDONLY);
assert(fd != -1);

[sbc100]

Emscripten doesn't have full support for the linux/unix /dev/ filesystem.

You can see the ones that we do support here:

emscripten/src/library_fs.js

Lines 1347 to 1365 in be8f1d1

	FS.mkdev('/dev/null', FS.makedev(1, 3));
	// setup /dev/tty and /dev/tty1
	// stderr needs to print output using err() rather than out()
	// so we register a second tty just for it.
	TTY.register(FS.makedev(5, 0), TTY.default_tty_ops);
	TTY.register(FS.makedev(6, 0), TTY.default_tty1_ops);
	FS.mkdev('/dev/tty', FS.makedev(5, 0));
	FS.mkdev('/dev/tty1', FS.makedev(6, 0));
	// setup /dev/[u]random
	// use a buffer to avoid overhead of individual crypto calls per byte
	var randomBuffer = new Uint8Array(1024), randomLeft = 0;
	var randomByte = () => {
	if (randomLeft === 0) {
	randomLeft = randomFill(randomBuffer).byteLength;
	}
	return randomBuffer[--randomLeft];
	};
	FS.createDevice('/dev', 'random', randomByte);
	FS.createDevice('/dev', 'urandom', randomByte);

It should be able to create it yourself using FS.createDevice. Howeever, it might be simpler and result if smaller code size if you modify your code to avoid using this file in the emscripten build. Its likely that something like memset(..., 0, ..) is going to be better in almost every way under emscripten.