user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/sysdeps/managarm/generic/mount.cpp

@@ -0,0 +1,44 @@
+#include <errno.h>
+#include <string.h>
+#include <sys/mount.h>
+
+#include <bits/ensure.h>
+#include <bits/errors.hpp>
+#include <bragi/helpers-frigg.hpp>
+#include <mlibc/all-sysdeps.hpp>
+#include <mlibc/allocator.hpp>
+#include <mlibc/posix-pipe.hpp>
+#include <posix.frigg_bragi.hpp>
+
+namespace mlibc {
+
+int
+sys_mount(const char *source, const char *target, const char *fstype, unsigned long, const void *) {
+	SignalGuard sguard;
+
+	managarm::posix::MountRequest<MemoryAllocator> req(getSysdepsAllocator());
+	req.set_path(frg::string<MemoryAllocator>(getSysdepsAllocator(), source ? source : ""));
+	req.set_target_path(frg::string<MemoryAllocator>(getSysdepsAllocator(), target ? target : ""));
+	req.set_fs_type(frg::string<MemoryAllocator>(getSysdepsAllocator(), fstype ? fstype : ""));
+
+	auto [offer, send_head, send_tail, recv_resp] = exchangeMsgsSync(
+	    getPosixLane(),
+	    helix_ng::offer(
+	        helix_ng::sendBragiHeadTail(req, getSysdepsAllocator()), helix_ng::recvInline()
+	    )
+	);
+
+	HEL_CHECK(offer.error());
+	HEL_CHECK(send_head.error());
+	HEL_CHECK(send_tail.error());
+	HEL_CHECK(recv_resp.error());
+
+	auto resp =
+	    *bragi::parse_head_only<managarm::posix::SvrResponse>(recv_resp, getSysdepsAllocator());
+	if (resp.error() != managarm::posix::Errors::SUCCESS)
+		return resp.error() | toErrno;
+
+	return 0;
+}
+
+} // namespace mlibc