fork_worker: use separate pipe for status messages

We forced line wise flushing of the workers STDOUT and STDERR to
capture the final status (TASK OK/TASK ERROR).
Thus, if the code executed in the worker wanted to flush explicitly,
e.g., when the last output wasn't new line terminated but needed to
reach the users eyes, the parent just ignored that.
This leads to confusing results in CLI handlers using fork_workers.

So remove the buffering logic completely and introduce a separate
pipe for sending the final status.
Said pipe gets once read after the child closes (EOF) its STDOUT.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

diff --git a/src/PVE/RESTEnvironment.pm b/src/PVE/RESTEnvironment.pm
index 0ad6dbaefc28c96067cae96901ebb845be570c9c..3b1142d9ea6eaeb0870db29e7353085aa5110ae6 100644 (file)
--- a/src/PVE/RESTEnvironment.pm
+++ b/src/PVE/RESTEnvironment.pm
@@ -396,6 +396,7 @@ sub fork_worker {
 
     my @psync = POSIX::pipe();
     my @csync = POSIX::pipe();
+    my @ctrlfd = POSIX::pipe() if $sync;
 
     my $node = $self->{nodename};
 
@@ -427,9 +428,11 @@ sub fork_worker {
        POSIX::setsid();
 
        POSIX::close ($psync[0]);
+       POSIX::close ($ctrlfd[0]) if $sync;
        POSIX::close ($csync[1]);
 
        $outfh = $sync ? $psync[1] : undef;
+       my $resfh = $sync ? $ctrlfd[1] : undef;
 
        eval {
            PVE::INotify::inotify_close();
@@ -450,6 +453,7 @@ sub fork_worker {
                    if !open(STDIN, "</dev/null");
 
                $outfh = PVE::Tools::upid_open($upid);
+               $resfh = $outfh;
            }
 
 
@@ -499,10 +503,14 @@ sub fork_worker {
            chomp $err;
            $err =~ s/\n/ /mg;
            syslog('err', $err);
-           print STDERR "TASK ERROR: $err\n";
+           my $msg = "TASK ERROR: $err\n";
+           POSIX::write($resfh, $msg, length($msg));
+           POSIX::close($resfh) if $sync;
            POSIX::_exit(-1);
        } else {
-           print STDERR "TASK OK\n";
+           my $msg = "TASK OK\n";
+           POSIX::write($resfh, $msg, length($msg));
+           POSIX::close($resfh) if $sync;
            POSIX::_exit(0);
        }
        kill(-9, $$);
@@ -511,6 +519,7 @@ sub fork_worker {
     # parent
 
     POSIX::close ($psync[1]);
+    POSIX::close ($ctrlfd[1]) if $sync;
     POSIX::close ($csync[0]);
 
     my $readbuf = '';
@@ -562,7 +571,6 @@ sub fork_worker {
 
     if ($sync) {
        my $count;
-       my $outbuf = '';
        my $int_count = 0;
        eval {
            local $SIG{INT} = local $SIG{QUIT} = local $SIG{TERM} = sub {
@@ -591,38 +599,33 @@ sub fork_worker {
                    }
                    last if $count == 0; # eof
 
-                   $outbuf .= $readbuf;
-                   while ($outbuf =~ s/^(([^\010\r\n]*)(\r|\n|(\010)+|\r\n))//s) {
-                       my $line = $1;
-                       my $data = $2;
-                       if ($data =~ m/^TASK OK$/) {
-                           # skip
-                       } elsif ($data =~ m/^TASK ERROR: (.+)$/) {
-                           print STDERR "$1\n";
-                       } else {
-                           print $line;
-                       }
-                       if ($outfh) {
-                           print $outfh $line;
-                           $outfh->flush();
-                       }
-                   }
+                   print $readbuf;
+                   select->flush();
+
+                   print $outfh $readbuf;
+                   $outfh->flush();
                } else {
                    # some commands daemonize without closing stdout
                    last if !PVE::ProcFSTools::check_process_running($cpid);
                }
            }
+
+           # get status (error or OK)
+           POSIX::read($ctrlfd[0], $readbuf, 4096);
+           if ($readbuf =~ m/^TASK OK\n?$/) {
+               print $outfh $readbuf;
+           } elsif ($readbuf =~ m/^TASK ERROR: (.*)\n?$/) {
+               print STDERR "$1\n";
+               print $outfh "\n$readbuf";
+           } else {
+               die "got unexpected control message: $readbuf\n";
+           }
+           $outfh->flush();
        };
        my $err = $@;
 
        POSIX::close($psync[0]);
-
-       if ($outbuf) { # just to be sure
-           print $outbuf;
-           if ($outfh) {
-               print $outfh $outbuf;
-           }
-       }
+       POSIX::close($ctrlfd[0]);
 
        if ($err) {
            $err =~ s/\n/ /mg;