lib: c: re-organise into separate static modules, plus a single shared library

lib/libc/io/unistd/mmap.c

@@ -0,0 +1,6 @@
+#include <sys/mman.h>
+
+void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
+{
+	return NULL;
+}

lib/libc/io/unistd/open.c

@@ -0,0 +1,40 @@
+#include <errno.h>
+#include <mango/handle.h>
+#include <mango/msg.h>
+#include <rosetta/fs.h>
+#include <sys/remote.h>
+
+int open(const char *path, int flags)
+{
+	tid_t remote_tid;
+	unsigned int remote_chid;
+	if (!sys_remote_get(SYS_REMOTE_NSD, &remote_tid, &remote_chid)) {
+		return __set_errno(ENXIO);
+	}
+
+	kern_handle_t port;
+	kern_status_t status = port_create(&port);
+	if (status != KERN_OK) {
+		return __set_errno(__errno_from_kern_status(status));
+	}
+
+	status = port_connect(port, remote_tid, remote_chid);
+	if (status != KERN_OK) {
+		kern_handle_close(port);
+		return __set_errno(__errno_from_kern_status(status));
+	}
+
+	int err = SUCCESS;
+	status = fs_open(port, path, flags, &err);
+	if (status != KERN_OK) {
+		kern_handle_close(port);
+		return __set_errno(__errno_from_kern_status(status));
+	}
+
+	if (err != SUCCESS) {
+		kern_handle_close(port);
+		return __set_errno(err);
+	}
+
+	return (int)port;
+}

lib/libc/io/unistd/read.c

@@ -0,0 +1,21 @@
+#include <errno.h>
+#include <mango/handle.h>
+#include <mango/msg.h>
+#include <rosetta/fs.h>
+#include <sys/remote.h>
+
+int read(int fd, void *buf, size_t count)
+{
+	int err;
+	size_t nr_read;
+	kern_status_t status = fs_read(fd, count, &err, &nr_read, buf, count);
+	if (status != KERN_OK) {
+		return __set_errno(__errno_from_kern_status(status));
+	}
+
+	if (err != SUCCESS) {
+		return __set_errno(err);
+	}
+
+	return nr_read;
+}