More files related to user-level file servers.

Also add acme!

src/libfs/ns.c

@@ -0,0 +1,36 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <fs.h>
+#include <ctype.h>
+
+Fsys*
+nsmount(char *name, char *aname)
+{
+	char *addr, *ns;
+	int fd;
+	Fsys *fs;
+
+	ns = getns();
+	if(ns == nil)
+		return nil;
+
+	addr = smprint("unix!%s/%s", ns, name);
+	free(ns);
+	if(addr == nil)
+		return nil;
+
+	fd = dial(addr, 0, 0, 0);
+	if(fd < 0){
+		werrstr("dial %s: %r", addr);
+		return nil;
+	}
+
+	fs = fsmount(fd, aname);
+	if(fs == nil){
+		close(fd);
+		return nil;
+	}
+
+	return fs;
+}

src/libfs/openfd.c

@@ -0,0 +1,26 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <fs.h>
+#include "fsimpl.h"
+
+int
+fsopenfd(Fsys *fs, char *name, int mode)
+{
+	Fid *fid;
+	Fcall tx, rx;
+
+	if((fid = fswalk(fs->root, name)) == nil)
+		return -1;
+	tx.type = Topenfd;
+	tx.fid = fid->fid;
+	tx.mode = mode&~OCEXEC;
+	if(fsrpc(fs, &tx, &rx, 0) < 0){
+		fsclose(fid);
+		return -1;
+	}
+	_fsputfid(fid);
+	if(mode&OCEXEC && rx.unixfd>=0)
+		fcntl(rx.unixfd, F_SETFL, FD_CLOEXEC);
+	return rx.unixfd;
+}