[gentoo-catalyst] [PATCH] catalyst: generate .sha256 file if any digest is enabled

[Georgy Yakovlev <gyakovlev@gentoo.org>]

checksum format is simple one, identical to one
sha256sum from coreutils produces, lines starting with # are ignored.

example:[1]

# SHA256 HASH
xxxx.....  stage3-....tar.xz

systemd upstream calls it suse-style .sha256 files.[0]
infra already supports inline signing of files.

Bug: https://bugs.gentoo.org/821568
[0] https://github.com/systemd/systemd/blob/aedec452b9e5dd197881f2164fb205dfe8bfdcec/src/import/pull-common.c#L236
[1] https://mirrors.edge.kernel.org/opensuse/distribution/leap/15.0/iso/openSUSE-Leap-15.0-DVD-x86_64.iso.sha256
Signed-off-by: Georgy Yakovlev <gyakovlev@gentoo.org>
---
 catalyst/base/genbase.py  | 3 +++
 doc/catalyst-config.5.txt | 7 ++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/catalyst/base/genbase.py b/catalyst/base/genbase.py
index 6d039a8f..1643b1dc 100644
--- a/catalyst/base/genbase.py
+++ b/catalyst/base/genbase.py
@@ -43,3 +43,6 @@ class GenBase():
             for f in [path, path + '.CONTENTS.gz']:
                 for i in self.settings['digests']:
                     file.write(self.generate_hash(f, name=i))
+
+        with io.open(path + '.sha256', 'w', encoding='utf-8') as sha256file:
+            sha256file.write(self.generate_hash(path, name='sha256'))
diff --git a/doc/catalyst-config.5.txt b/doc/catalyst-config.5.txt
index 003d40b6..ca9335d6 100644
--- a/doc/catalyst-config.5.txt
+++ b/doc/catalyst-config.5.txt
@@ -38,9 +38,10 @@ Basic configuration
 *digests*::
 Create a `.DIGESTS` file containing the hash output from any of the
 supported options below.  Adding them all may take a long time.
-(example: `md5 sha1 sha512 whirlpool`).  The set of supported hashes
-is dependent on the version of Python. To see the set of hashes
-supported by the version of Python in use, run
+(example: `md5 sha1 sha512 whirlpool`).  Enabling ANY digest will
+generate `.sha256` file in addition `.DIGESTS` file.  The set of
+supported hashes is dependent on the version of Python. To see the
+set of hashes supported by the version of Python in use, run
 +
 ---------------------------------
 $ python3 -c 'import hashlib; print(hashlib.algorithms_available)'
-- 
2.33.1