From 79637de5aa208d66fd2c8cef46c849c7c9f3bcba Mon Sep 17 00:00:00 2001
From: Axel Burri <axel@tty0.ch>
Date: Thu, 29 Dec 2016 13:05:08 +0100
Subject: [PATCH] btrbk: raw_target_encrypt: always set "gpg
 --no-random-seed-file": prevents creation of "~/.gnupg/random_seed" with
 slight perfomance penalty.

We set "--no-random-seed-file" because one of the btrbk
design principles is to not create any files unasked. Enabling
"--no-random-seed-file" creates ~/.gnupg/random_seed, and as
such depends on $HOME to be set correctly (think on running in
cron). From gpg2(1) man page:
  --no-random-seed-file GnuPG uses a file to store its
  internal random pool over invocations This makes random
  generation faster; however sometimes write operations are not
  desired. This option can be used to achieve that with the cost
  of slower random generation.
---
 ChangeLog |  3 +++
 btrbk     | 12 +++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 23fd8e5..9c85073 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,9 @@
 btrbk-current
 
   * Show aggregate "size" and "used" for "usage" action (close #119).
+  * raw_target_encrypt: Always set "gpg --no-random-seed-file":
+    prevents creation of "~/.gnupg/random_seed" with slight perfomance
+    penalty.
 
 btrbk-0.24.0
 
diff --git a/btrbk b/btrbk
index c156b27..5b49e93 100755
--- a/btrbk
+++ b/btrbk
@@ -1296,9 +1296,19 @@ sub btrfs_send_to_file($$$$;@)
     push @cmd_pipe, { compress => $opts{compress} }; # does nothing if already compressed by rsh_compress_out
   }
   if($opts{encrypt}) {
+    # NOTE: We set "--no-random-seed-file" since one of the btrbk
+    # design principles is to never create any files unasked. Enabling
+    # "--no-random-seed-file" creates ~/.gnupg/random_seed, and as
+    # such depends on $HOME to be set correctly (which e.g. is set to
+    # "/" by some cron daemons). From gpg2(1) man page:
+    #   --no-random-seed-file GnuPG uses a file to store its
+    #   internal random pool over invocations This makes random
+    #   generation faster; however sometimes write operations are not
+    #   desired. This option can be used to achieve that with the cost
+    #   of slower random generation.
     die unless($opts{encrypt}->{type} eq "gpg");
     $target_filename .= '.gpg';
-    my @gpg_options = ( '--batch', '--no-tty', '--trust-model', 'always' );
+    my @gpg_options = ( '--batch', '--no-tty', '--no-random-seed-file', '--trust-model', 'always' );
     push @gpg_options, ( '--compress-algo', 'none' ) if($opts{compress});  # NOTE: if --compress-algo is not set, gpg might still compress according to OpenPGP standard.
     push(@gpg_options, ( '--no-default-keyring', '--keyring', $opts{encrypt}->{keyring} )) if($opts{encrypt}->{keyring});
     push(@gpg_options, ( '--default-recipient', $opts{encrypt}->{recipient} )) if($opts{encrypt}->{recipient});