1 files changed, 112 insertions, 0 deletions
diff --git a/appl/alphabet/grid/rexec.b b/appl/alphabet/grid/rexec.b
new file mode 100644
index 00000000..02869659
--- /dev/null
+++ b/appl/alphabet/grid/rexec.b
@@ -0,0 +1,112 @@
+implement Rexec, Gridmodule;
+include "sys.m";
+	sys: Sys;
+include "draw.m";
+include "sh.m";
+	sh: Sh;
+include "string.m";
+	str: String;
+include "alphabet/reports.m";
+	reports: Reports;
+	report, Report, quit: import reports;
+include "alphabet/endpoints.m";
+	endpoints: Endpoints;
+	Endpoint: import endpoints;
+include "alphabet/grid.m";
+	grid: Grid;
+	Value: import grid;
+
+Rexec: module {};
+
+types(): string
+{
+	return "eesc-A";
+}
+
+init()
+{
+	sys = load Sys Sys->PATH;
+	reports = checkload(load Reports Reports->PATH, Reports->PATH);
+	endpoints = checkload(load Endpoints Endpoints->PATH, Endpoints->PATH);
+	endpoints->init();
+	grid = checkload(load Grid Grid->PATH, Grid->PATH);
+	grid->init();
+	sh = checkload(load Sh Sh->PATH, Sh->PATH);
+	sh->initialise();
+	str = checkload(load String String->PATH, String->PATH);
+}
+
+run(nil: chan of string, r: ref Reports->Report,
+		opts: list of (int, list of ref Grid->Value), args: list of ref Grid->Value): ref Grid->Value
+{
+	ec0 := (hd args).e().i;
+	addr := (hd tl args).s().i;
+	cmd := (hd tl tl args).c().i;
+
+	spawn rexecproc(sync := chan of int, addr, ec0, cmd, r.start("rexec"), opts != nil, ec1 := chan of Endpoint);
+	<-sync;
+	return ref Value.Ve(ec1);
+}
+
+rexecproc(sync: chan of int,
+		addr: string,
+		ec0: chan of Endpoint,
+		cmd: ref Sh->Cmd,
+		errorc: chan of string,
+		noauth: int,
+		ec1: chan of Endpoint
+	)
+{
+	sys->pctl(Sys->FORKNS, nil);
+	sync <-= 1;
+
+	ep0 := <-ec0;
+	if(ep0.addr == nil){
+		ec1 <-= ep0;
+		quit(errorc);
+	}
+
+	(ep1, err) := exec(addr, ep0, cmd, noauth);
+	if(err != nil){
+		endpoints->open(nil, ep0);	# discard 
+		report(errorc, err);
+	}
+	ec1 <-= ep1;
+	quit(errorc);
+}
+
+Nope: con Endpoint(nil, nil, nil);
+
+exec(addr: string, ep0: Endpoint, cmd: ref Sh->Cmd, noauth: int): (Endpoint, string)
+{
+	args := addr::"/n/remote"::nil;
+	if(noauth)
+		args = "-A"::args;
+	if((e := sh->run(nil, "mount"::args)) != nil)
+		return (Nope, sys->sprint("cannot mount rexec at %q: %s", addr, e));
+
+	fd := sys->open("/n/remote/exec", Sys->ORDWR);
+	if(fd == nil)
+		return (Nope, sys->sprint("cannot open exec at %q: %r", addr));
+	if(sys->fprint(fd, "%q %q", ep0.text(), sh->cmd2string(cmd)) == -1)
+		return (Nope, sys->sprint("exec write failed: %r"));
+	buf := array[1024] of byte;
+	n := sys->read(fd, buf, len buf);
+	if(n < 0)
+		return (Nope, sys->sprint("error reading endpoint: %r"));
+	if(n == 0)
+		return (Nope, "eof reading endpoint");
+	s := string buf[0:n];
+	ep1 := Endpoint.mk(s);
+	if(ep1.addr == nil)
+		return (Nope, sys->sprint("bad endpoint %#q: %s", s, ep1.about));
+	ep1.about = sys->sprint("%s | rexec %q %s", ep0.about, addr, sh->cmd2string(cmd));
+	return (ep1, nil);
+}
+
+checkload[T](m: T, path: string): T
+{
+	if(m != nil)
+		return m;
+	raise sys->sprint("fail:cannot load %s: %r", path);
+}