Subject: bug#66519: b2sum, md5sum sha*sum etc broken on filenames including backslash

From: "Simon Richter M. Sc." <[email-masked]>
Date: Fri, 13 Oct 2023 14:31:18 +0200

I noticed some broken checksums with leading backslash and wrong 
filenames in my checksum files because the original filenames contained 
a backslash.

Way to reproduce:
% touch test\\test.file
% b2sum test\\test.file

expected output:
786a02f742015903c6c6fd852552d272912f4740e15847618a86e217f71f5419d25e1031afee585313896444934eb04b903a685b1448b755d56f701afe9be2ce 
  test\test.file

real broken output:
\786a02f742015903c6c6fd852552d272912f4740e15847618a86e217f71f5419d25e1031afee585313896444934eb04b903a685b1448b755d56f701afe9be2ce 
  test\\test.file

Tested with coreutils 9.3 and coreutils 9.4 and LC_ALL=C
Btw any chance we get b3sum included in coreutils?