ref: 94443daf8e248e65afc8d3f17f26efea22748b51
dir: /appl/cmd/mash/exec.b/
#
# Manage the execution of a command.
#
srv: string; # srv file proto
nsrv: int = 0; # srv file unique id
#
# Return error string.
#
errstr(): string
{
return sys->sprint("%r");
}
#
# Server thread for servefd.
#
server(c: ref Sys->FileIO, fd: ref Sys->FD, write: int)
{
a: array of byte;
if (!write)
a = array[Sys->ATOMICIO] of byte;
for (;;) {
alt {
(nil, b, nil, wc) := <- c.write =>
if (wc == nil)
return;
if (!write) {
wc <- = (0, EPIPE);
return;
}
r := sys->write(fd, b, len b);
if (r < 0) {
wc <- = (0, errstr());
return;
}
wc <- = (r, nil);
(nil, n, nil, rc) := <- c.read =>
if (rc == nil)
return;
if (write) {
rc <- = (array[0] of byte, nil);
return;
}
if (n > Sys->ATOMICIO)
n = Sys->ATOMICIO;
r := sys->read(fd, a, n);
if (r < 0) {
rc <- = (nil, errstr());
return;
}
rc <- = (a[0:r], nil);
}
}
}
#
# Serve FD as a #s file. Used to implement generators.
#
Env.servefd(e: self ref Env, fd: ref Sys->FD, write: int): string
{
(s, c) := e.servefile(nil);
spawn server(c, fd, write);
return s;
}
#
# Generate name and FileIO adt for a served filed.
#
Env.servefile(e: self ref Env, n: string): (string, ref Sys->FileIO)
{
c: ref Sys->FileIO;
s: string;
if (srv == nil) {
(ok, d) := sys->stat(CHAN);
if (ok < 0)
e.couldnot("stat", CHAN);
if (d.dtype != 's') {
if (sys->bind("#s", CHAN, Sys->MBEFORE) < 0)
e.couldnot("bind", CHAN);
}
srv = "mash." + string sys->pctl(0, nil);
}
retry := 0;
for (;;) {
if (retry || n == nil)
s = srv + "." + string nsrv++;
else
s = n;
c = sys->file2chan(CHAN, s);
s = CHAN + "/" + s;
if (c == nil) {
if (retry || n == nil || errstr() != EEXISTS)
e.couldnot("file2chan", s);
retry = 1;
continue;
}
break;
}
if (n != nil)
n = CHAN + "/" + n;
else
n = s;
if (retry && sys->bind(s, n, Sys->MREPL) < 0)
e.couldnot("bind", n);
return (n, c);
}
#
# Shorthand for string output.
#
Env.output(e: self ref Env, s: string)
{
if (s == nil)
return;
out := e.outfile();
if (out == nil)
return;
out.puts(s);
out.close();
}
#
# Return Iobuf for stdout.
#
Env.outfile(e: self ref Env): ref Bufio->Iobuf
{
fd := e.out;
if (fd == nil)
fd = sys->fildes(1);
out := bufio->fopen(fd, Bufio->OWRITE);
if (out == nil)
e.report(sys->sprint("fopen failed: %r"));
return out;
}
#
# Return FD for /dev/null.
#
Env.devnull(e: self ref Env): ref Sys->FD
{
fd := sys->open(DEVNULL, Sys->OREAD);
if (fd == nil)
e.couldnot("open", DEVNULL);
return fd;
}
#
# Make a pipe.
#
Env.pipe(e: self ref Env): array of ref Sys->FD
{
fds := array[2] of ref Sys->FD;
if (sys->pipe(fds) < 0) {
e.report(sys->sprint("pipe failed: %r"));
return nil;
}
return fds;
}
#
# Open wait file for an env.
#
waitfd(e: ref Env)
{
w := "#p/" + string sys->pctl(0, nil) + "/wait";
fd := sys->open(w, sys->OREAD);
if (fd == nil)
e.couldnot("open", w);
e.wait = fd;
}
#
# Wait for a thread. Perhaps propagate exception or exit.
#
waitfor(e: ref Env, pid: int, wc: chan of int, ec, xc: chan of string)
{
if (ec != nil || xc != nil) {
spawn waiter(e, pid, wc);
if (ec == nil)
ec = chan of string;
if (xc == nil)
xc = chan of string;
alt {
<-wc =>
return;
x := <-ec =>
<-wc;
exitmash();
x := <-xc =>
<-wc;
s := x;
if (len s < FAILLEN || s[0:FAILLEN] != FAIL)
s = FAIL + s;
raise s;
}
} else
waiter(e, pid, nil);
}
#
# Wait for a specific pid.
#
waiter(e: ref Env, pid: int, wc: chan of int)
{
buf := array[sys->WAITLEN] of byte;
for(;;) {
n := sys->read(e.wait, buf, len buf);
if (n < 0) {
e.report(sys->sprint("read wait: %r\n"));
break;
}
status := string buf[0:n];
if (status[len status - 1] != ':')
sys->fprint(e.stderr, "%s\n", status);
who := int status;
if (who != 0 && who == pid)
break;
}
if (wc != nil)
wc <-= 0;
}
#
# Preparse IO for a new thread.
# Make a new FD group and redirect stdin/stdout.
#
prepareio(in, out: ref sys->FD): (int, ref Sys->FD)
{
fds := list of { 0, 1, 2};
if (in != nil)
fds = in.fd :: fds;
if (out != nil)
fds = out.fd :: fds;
pid := sys->pctl(sys->NEWFD, fds);
console := sys->fildes(2);
if (in != nil) {
sys->dup(in.fd, 0);
in = nil;
}
if (out != nil) {
sys->dup(out.fd, 1);
out = nil;
}
return (pid, console);
}
#
# Add ".dis" to a command if missing.
#
dis(s: string): string
{
if (len s < 4 || s[len s - 4:] != ".dis")
return s + ".dis";
return s;
}
#
# Load a builtin.
#
Env.doload(e: self ref Env, s: string)
{
file := dis(s);
l := load Mashbuiltin file;
if (l == nil) {
err := errstr();
if (nonexistent(err) && file[0] != '/' && file[0:2] != "./") {
l = load Mashbuiltin LIB + file;
if (l == nil)
err = errstr();
}
if (l == nil) {
e.report(s + ": " + err);
return;
}
}
l->mashinit("load" :: s :: nil, lib, l, e);
}
#
# Execute a spawned thread (dis module or builtin).
#
mkprog(args: list of string, e: ref Env, in, out: ref Sys->FD, wc: chan of int, ec, xc: chan of string)
{
(pid, console) := prepareio(in, out);
wc <-= pid;
if (pid < 0)
return;
cmd := hd args;
{
b := e.builtin(cmd);
if (b != nil) {
e = e.copy();
e.in = in;
e.out = out;
e.stderr = console;
e.wait = nil;
b->mashcmd(e, args);
} else {
file := dis(cmd);
c := load Command file;
if (c == nil) {
err := errstr();
if (nonexistent(err) && file[0] != '/' && file[0:2] != "./") {
c = load Command "/dis/" + file;
if (c == nil)
err = errstr();
}
if (c == nil) {
sys->fprint(console, "%s: %s\n", file, err);
return;
}
}
c->init(gctxt, args);
}
}exception x{
FAILPAT =>
if (xc != nil)
xc <-= x;
# the command failure should be propagated silently to
# a higher level, where $status can be set.. - wrtp.
#else
# sys->fprint(console, "%s: %s\n", cmd, x.name);
exit;
EPIPE =>
if (xc != nil)
xc <-= x;
#else
# sys->fprint(console, "%s: %s\n", cmd, x.name);
exit;
EXIT =>
if (ec != nil)
ec <-= x;
exit;
}
}
#
# Open/create files for redirection.
#
redirect(e: ref Env, f: array of string, in, out: ref Sys->FD): (int, ref Sys->FD, ref Sys->FD)
{
s: string;
err := 0;
if (f[Rinout] != nil) {
s = f[Rinout];
in = sys->open(s, Sys->ORDWR);
if (in == nil) {
sys->fprint(e.stderr, "%s: %r\n", s);
err = 1;
}
out = in;
} else if (f[Rin] != nil) {
s = f[Rin];
in = sys->open(s, Sys->OREAD);
if (in == nil) {
sys->fprint(e.stderr, "%s: %r\n", s);
err = 1;
}
}
if (f[Rout] != nil || f[Rappend] != nil) {
if (f[Rappend] != nil) {
s = f[Rappend];
out = sys->open(s, Sys->OWRITE);
if (out != nil)
sys->seek(out, big 0, Sys->SEEKEND);
} else {
s = f[Rout];
out = nil;
}
if (out == nil) {
out = sys->create(s, Sys->OWRITE, 8r666);
if (out == nil) {
sys->fprint(e.stderr, "%s: %r\n", s);
err = 1;
}
}
}
if (err)
return (0, nil, nil);
return (1, in, out);
}
#
# Spawn a command and maybe wait for it.
#
exec(a: list of string, e: ref Env, infd, outfd: ref Sys->FD, wait: int)
{
if (wait && e.wait == nil)
waitfd(e);
wc := chan of int;
if (wait && (e.flags & ERaise))
xc := chan of string;
if (wait && (e.flags & ETop))
ec := chan of string;
spawn mkprog(a, e, infd, outfd, wc, ec, xc);
pid := <-wc;
if (wait)
waitfor(e, pid, wc, ec, xc);
}