From 1338ad16b15d53c7b9b08242d34f3683b5e46d73 Mon Sep 17 00:00:00 2001
From: Lukas Straub <lukasstraub2@web.de>
Date: Thu, 24 Dec 2020 00:10:33 +0100
Subject: [PATCH] Add suport for zstd long distance matching

---
 btrbk                     | 14 +++++++++++++-
 doc/btrbk.conf.5.asciidoc |  8 ++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/btrbk b/btrbk
index 0efabf6..a03aa4c 100755
--- a/btrbk
+++ b/btrbk
@@ -54,7 +54,7 @@ my %compression = (
   xz     => { name => 'xz',     format => 'xz',  compress_cmd => [ 'xz',     '-c' ], decompress_cmd => [ 'xz',     '-d', '-c' ], level_min => 0, level_max => 9, threads => '-T' },
   lzo    => { name => 'lzo',    format => 'lzo', compress_cmd => [ 'lzop',   '-c' ], decompress_cmd => [ 'lzop',   '-d', '-c' ], level_min => 1, level_max => 9 },
   lz4    => { name => 'lz4',    format => 'lz4', compress_cmd => [ 'lz4',    '-c' ], decompress_cmd => [ 'lz4',    '-d', '-c' ], level_min => 1, level_max => 9 },
-  zstd   => { name => 'zstd',   format => 'zst', compress_cmd => [ 'zstd',   '-c' ], decompress_cmd => [ 'zstd',   '-d', '-c' ], level_min => 1, level_max => 19, threads => '-T' },
+  zstd   => { name => 'zstd',   format => 'zst', compress_cmd => [ 'zstd',   '-c' ], decompress_cmd => [ 'zstd',   '-d', '-c' ], level_min => 1, level_max => 19, threads => '-T', long => '--long=' },
  );
 
 my $compress_format_alt = join '|', map { $_->{format} } values %compression; # note: this contains duplicate alternations
@@ -108,10 +108,12 @@ my %config_options = (
   stream_buffer_remote        => { default => undef,     accept => [ "no" ], accept_regexp => qr/^[0-9]+[kmgKMG%]?$/  },  # NOTE: requires 'mbuffer' command on remote hosts
   stream_compress             => { default => undef,     accept => [ "no", (keys %compression) ] },
   stream_compress_level       => { default => "default", accept => [ "default" ], accept_numeric => 1 },
+  stream_compress_long        => { default => "default", accept => [ "default" ], accept_numeric => 1 },
   stream_compress_threads     => { default => "default", accept => [ "default" ], accept_numeric => 1 },
 
   raw_target_compress         => { default => undef,     accept => [ "no", (keys %compression) ] },
   raw_target_compress_level   => { default => "default", accept => [ "default" ], accept_numeric => 1 },
+  raw_target_compress_long    => { default => "default", accept => [ "default" ], accept_numeric => 1 },
   raw_target_compress_threads => { default => "default", accept => [ "default" ], accept_numeric => 1 },
   raw_target_encrypt          => { default => undef,     accept => [ "no", "gpg", "openssl_enc" ] },
   raw_target_block_size       => { default => "128K",    accept_regexp => qr/^[0-9]+[kmgKMG]?$/ },
@@ -681,6 +683,15 @@ sub compress_cmd_text($;$)
       WARN_ONCE "Threading is not supported for '$cc->{name}', ignoring";
     }
   }
+  if(defined($def->{long}) && ($def->{long} ne "default")) {
+    my $long_opt = $cc->{long};
+    if($long_opt) {
+      push @cmd, $long_opt . $def->{long};
+    }
+    else {
+      WARN_ONCE "Long distance matching is not supported for '$cc->{name}', ignoring";
+    }
+  }
   return { cmd_text => join(' ', @cmd) };
 }
 
@@ -3943,6 +3954,7 @@ sub config_compress_hash($$)
   return {
     key     => $compress_key,
     level   => config_key($config, $config_key . "_level"),
+    long    => config_key($config, $config_key . "_long"),
     threads => config_key($config, $config_key . "_threads"),
   };
 }
diff --git a/doc/btrbk.conf.5.asciidoc b/doc/btrbk.conf.5.asciidoc
index 553cb32..aed8d24 100644
--- a/doc/btrbk.conf.5.asciidoc
+++ b/doc/btrbk.conf.5.asciidoc
@@ -298,6 +298,11 @@ option in ssh_config(5).
     fastest compression). Defaults to ``default'' (the default
     compression level of '<compress_command>').
 
+*stream_compress_long* default|<number>::
+    Enable long distance matching for the specified
+    '<compress_command>'. Refer to the related man-page for details.
+    Only supported for "zstd".
+
 *stream_compress_threads* default|<number>::
     Number of threads to use for <compress_command>. Only supported
     for "pigz", "pbzip2", "zstd" and recent versions of "xz".
@@ -569,6 +574,9 @@ Additional options for raw targets:
     zstd.
 *raw_target_compress_level* default|<number>::
     Compression level for the specified <compress_command>.
+*raw_target_compress_long* default|<number>::
+    Enable long distance matching for the specified
+    '<compress_command>'.
 *raw_target_compress_threads* default|<number>::
     Number of threads to use for <compress_command>.
 *raw_target_split* <size>|no::