fcntl doesn't implement O_NONBLOCK for wasi:socket handles

[pavelsavara]

fcntl doesn't implement O_NONBLOCK for wasi:socket handles

See

wasi-libc/libc-bottom-half/cloudlibc/src/libc/fcntl/fcntl.c

Lines 10 to 61 in 1b19fc6

	int fcntl(int fildes, int cmd, ...) {
	switch (cmd) {
	case F_GETFD:
	// Act as if the close-on-exec flag is always set.
	return FD_CLOEXEC;
	case F_SETFD:
	// The close-on-exec flag is ignored.
	return 0;
	case F_GETFL: {
	// Obtain the flags and the rights of the descriptor.
	__wasi_fdstat_t fds;
	__wasi_errno_t error = __wasi_fd_fdstat_get(fildes, &fds);
	if (error != 0) {
	errno = error;
	return -1;
	}
	// Roughly approximate the access mode by converting the rights.
	int oflags = fds.fs_flags;
	if ((fds.fs_rights_base &
	(__WASI_RIGHTS_FD_READ | __WASI_RIGHTS_FD_READDIR)) != 0) {
	if ((fds.fs_rights_base & __WASI_RIGHTS_FD_WRITE) != 0)
	oflags |= O_RDWR;
	else
	oflags |= O_RDONLY;
	} else if ((fds.fs_rights_base & __WASI_RIGHTS_FD_WRITE) != 0) {
	oflags |= O_WRONLY;
	} else {
	oflags |= O_SEARCH;
	}
	return oflags;
	}
	case F_SETFL: {
	// Set new file descriptor flags.
	va_list ap;
	va_start(ap, cmd);
	int flags = va_arg(ap, int);
	va_end(ap);
	__wasi_fdflags_t fs_flags = flags & 0xfff;
	__wasi_errno_t error =
	__wasi_fd_fdstat_set_flags(fildes, fs_flags);
	if (error != 0) {
	errno = error;
	return -1;
	}
	return 0;
	}
	default:
	errno = EINVAL;
	return -1;
	}

[dicej]

We do already support both blocking and non-blocking sockets (e.g.

wasi-libc/libc-bottom-half/headers/public/__header_sys_socket.h

Line 55 in 1b19fc6

#define SOCK_NONBLOCK (0x00004000)

and

wasi-libc/libc-bottom-half/sources/socket.c

Line 92 in 1b19fc6

bool blocking = (type & SOCK_NONBLOCK) == 0;

), so presumably adding O_NONBLOCK support for toggling that should be pretty trivial.

[dicej]

BTW, we do already support setting FIONBIO on sockets via ioctl. I don't think there's a way to read the current state yet, though.