From 18d62fe4522132e1e3c179c3a91fcd9bd6ed0066 Mon Sep 17 00:00:00 2001
From: Ole Tange <ole@tange.dk>
Date: Sat, 11 Apr 2015 20:54:56 +0200
Subject: [PATCH] parallel: Fixed bug #44810: --compress leaves tmp file
 hanging.

---
 src/parallel | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/parallel b/src/parallel
index a8142623..02eae684 100755
--- a/src/parallel
+++ b/src/parallel
@@ -1051,7 +1051,7 @@ sub parse_options {
 
 sub init_globals {
     # Defaults:
-    $Global::version = 20150403;
+    $Global::version = 20150409;
     $Global::progname = 'parallel';
     $Global::infinity = 2**31;
     $Global::debug = 0;
@@ -5503,18 +5503,26 @@ sub slot {
 	#   $cattail = perl program for: cattail "decompress program" writerpid [file_to_decompress or stdin] [file_to_unlink]
 	if(not $cattail) {
 	    $cattail = q{
-		# cat followed by tail.
+		# cat followed by tail (possibly with rm as soon at the file is opened)
 		# If $writerpid dead: finish after this round
 		use Fcntl;
 
 		$|=1;
 
 		my ($cmd, $writerpid, $read_file, $unlink_file) = @ARGV;
+		while(defined $unlink_file and not -e $unlink_file) {
+		    # Writer has not opened file, so we cannot open it
+		    $sleep = ($sleep < 30) ? ($sleep * 1.001 + 0.01) : ($sleep);
+		    usleep($sleep);
+		}
+
 		if($read_file) {
 		    open(IN,"<",$read_file) || die("cattail: Cannot open $read_file");
 		} else {
 		    *IN = *STDIN;
 		}
+		# The writer and we have both opened the file, so it is safe to unlink it
+		unlink $unlink_file;
 
 		my $first_round = 1;
 		my $flags;
@@ -5528,11 +5536,8 @@ sub slot {
 		    my $writer_running = kill 0, $writerpid;
 		    $read = sysread(IN,$buf,32768);
 		    if($read) {
-			# We can unlink the file now: The writer has written something
-			-e $unlink_file and unlink $unlink_file;
-
 			if($first_round) {
-			    # Do not start command if there is no input
+			    # Only start the command if there any input to process
 			    $first_round = 0;
 			    open(OUT,"|-",$cmd) || die("cattail: Cannot run $cmd");
 			}
@@ -5548,7 +5553,6 @@ sub slot {
 		    } else {
 			if(eof(IN) and not $writer_running) {
 			    # Writer dead: There will never be more to read => exit
-			    -e $unlink_file and unlink $unlink_file;
 			    exit;
 			}
 			# TODO This could probably be done more efficiently using select(2)
@@ -5695,6 +5699,9 @@ sub filter_through_compress {
     my $cattail = cattail();
 
     for my $fdno (1,2) {
+	# The tmpfile is used to tell the reader that the writer has started,
+	# so unlink it to start with.
+	unlink $self->fh($fdno,'name');
 	my $wpid = open(my $fdw,"|-", empty_input_detector().
 			"| ($opt::compress_program) >>".
 			$self->fh($fdno,'name')) || die $?;