From d4ab51beb6958d2282e2def1bdc5e35a973ffaf4 Mon Sep 17 00:00:00 2001
From: Ole Tange <ole@tange.dk>
Date: Thu, 5 Mar 2015 23:15:11 +0100
Subject: [PATCH] parallel: Some Perl versions do not support substr($buf,0,$i)
 with $i > 2GB, so do this in 2GB chunks.

---
 src/parallel | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/parallel b/src/parallel
index df6dc7d1..2fc1d90b 100755
--- a/src/parallel
+++ b/src/parallel
@@ -332,7 +332,7 @@ sub spreadstdin {
 	  $anything_written +=
 	      write_record_to_pipe($chunk_number++,\$header,\$buf,
 				   $recstart,$recend,$last_newline_pos+1);
-	  substr($buf,0,$last_newline_pos+1) = "";
+	  shorten(\$buf,$last_newline_pos+1);
       } elsif($opt::regexp) {
 	  if($Global::max_number_of_args) {
 	      # -N => (start..*?end){n}
@@ -365,7 +365,7 @@ sub spreadstdin {
 		  $anything_written +=
 		      write_record_to_pipe($chunk_number++,\$header,\$buf,
 					   $recstart,$recend,$i);
-		  substr($buf,0,$i) = "";
+		  shorten(\$buf,$i);
 	      }
 	  } else {
 	      # Find the last recend+recstart in $buf
@@ -375,7 +375,7 @@ sub spreadstdin {
 		  $anything_written +=
 		      write_record_to_pipe($chunk_number++,\$header,\$buf,
 					   $recstart,$recend,$i);
-		  substr($buf,0,$i) = "";
+		  shorten(\$buf,$i);
 	      }
 	  }
       }
@@ -393,7 +393,6 @@ sub spreadstdin {
     ::debug("init", "Done reading input\n");
 
     # If there is anything left in the buffer write it
-    substr($buf,0,0) = "";
     write_record_to_pipe($chunk_number++,\$header,\$buf,$recstart,$recend,length $buf);
 
     $Global::start_no_new_jobs ||= 1;
@@ -583,6 +582,22 @@ sub rindex64 {
     return -1;
 }
 
+sub shorten {
+    # Do: substr($buf,0,$i) = "";
+    # Some Perl versions do not support $i > 2GB, so do this in 2GB chunks
+    # Input:
+    #   $buf_ref = \$buf
+    #   $i = position to shorten to
+    # Returns: N/A
+    my ($buf_ref, $i) = @_;
+    my $two_gb = 2**31-1;
+    while($i > $two_gb) {
+        substr($$buf_ref,0,$two_gb) = "";
+        $i -= $two_gb;
+    }
+    substr($$buf_ref,0,$i) = "";
+}
+
 sub write_record_to_pipe {
     # Fork then
     # Write record from pos 0 .. $endpos to pipe
@@ -6055,7 +6070,6 @@ sub base64_zip_eval {
     return $script;
 }
 
-
 sub sshlogin_wrap {
     # Wrap the command with the commands needed to run remotely
     # Input: