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fork_worker: use separate pipe for status messages

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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>
This commit is contained in:
Thomas Lamprecht 2017-12-15 17:00:30 +01:00 committed by Wolfgang Bumiller
parent 95109cc44e
commit ed52a8435a
1 changed files with 29 additions and 26 deletions
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55
src/PVE/RESTEnvironment.pm
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@ -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;