prefork-interp: wip

[chiark-utils.git] / perl / Prefork.pm

diff --git a/perl/Prefork.pm b/perl/Prefork.pm
index 162d5e471f5161571bd992e27e25daca2f3833df..fa986c1c739045b9e15436fd13355eb70947e710 100644 (file)
--- a/perl/Prefork.pm
+++ b/perl/Prefork.pm
@@ -18,8 +18,83 @@ sub server_quit ($) {
   _exit(0);
 }
 
+# Returns in the executor process
 sub become_monitor () {
-  
+  my $child = fork // fail("fork executor: $!");or 
+  if (!$child) {
+    #---- executor ----
+    open ::STDIN , "<& $call_fds[0]" or fail("dup for fd0");
+    open ::STDOUT, ">& $call_fds[1]" or fail("dup for fd1");
+    open ::STDERR, ">& $call_fds[2]" or fail("dup for fd2");
+    POSIX::close($_) foreach @call_fds;
+    close CALL;
+    return;
+  }
+
+  #---- monitor [2] ----
+  my $got = waitpid $child, 0 // fail("wait for executor: $!");
+  $got == $child or fail("wait for esecutor gave $got, expected $child");
+
+  protocol_write(pack "L", $?);
+  _exit(0);
+}
+
+sub protocol_write ($) {
+  my ($d) = @_;
+  return if (print CALL $d and flush CALL);
+  _exit(0) if $!==EPIPE || $!==ECONNRESET;
+  fail("protocol write: $!");
+}
+
+sub eintr_retry ($) {
+  my ($f) = @_;
+  for (;;) {
+    my $r = $f->();
+    return $r if defined $r;
+    next if $!==EINTR;
+    return $r;
+  }
+}
+
+sub protocol_read_fail ($) {
+  my ($what) = @_;
+  _exit(0) if $!==ECONNRESET;
+  fail("recv $what: $!");
+}
+
+sub protocol_exchange () {
+  protocol_write('\n');
+
+  @call_fds = map {
+    my $r;
+    for (;;) {
+      $! = 0;
+      $r = IO::FDPass::recv(fileno(CALL));
+      last if $r >= 0;
+      _exit(0) if $!==0;
+      protocol_read_fail("fd $_");
+    }
+    $r;
+  } 0..2;
+
+  my $len;
+  $r = read(CALL, $len, 4) // protocol_read_fail("message length");
+  $r == 4 or _exit(0);
+
+  $len = unpack "L", $len;
+  my $data;
+  $r = read(CALL, $data, $len) // protocol_read_fail("message data ($len)");
+  $r == $len or _exit(0);
+
+  @ARGV = split /\0/, $data;
+  @ARGV >= 2 or fail("message data has too few strings");
+  length(pop(@ARGV)) and fail("message data missing trailing nul");
+  %ENV = ();
+  while (my $s = shift @ARGV) {
+    last if !length $s;
+    $s =~ m/=/ or fail("message data env var missing equals");
+    $ENV{$`} = $';
+  }
 }
 
 sub initialisation_complete {
@@ -61,7 +136,7 @@ sub initialisation_complete {
   $child = fork // croak "second fork failed: $!";
   if (!$child) {
     # we are the child, i.e. the one fa-monitor
-    become_monitor();
+    return become_monitor();
   }
 
   our %children;
@@ -111,7 +186,10 @@ sub initialisation_complete {
       if (accept(CALL, LISTEN)) {
        $child = fork // fail("fork for accepted call failed: $!");
        if (!$child) {
-         become_monitor();
+         #---- monitor [1] ----
+         close LISTEN;
+         protocol_exchange();
+         return become_monitor();
        }
        close(CALL);
        $errcount = 0;