b2sum: a new checksum utility with md5sum like interface

Note we don't support the --algorithm option of the
b2sum command in the external BLAKE2 project, as that
was deemed too confusing for users.
"BLAKE2b" was chosen as the default algorithm to use,
which is single threaded but performs well on 64 bit.

* src/blake2: CC0 source copied from external project.
* cfg.mk[VC_LIST_ALWAYS_EXCLUDE_REGEX]: Exclude blake2/
from syntax checks, make update-copyright, etc.
* src/local.mk: Reference the sources for b2sum,
and set the compilation flags.
* doc/coreutils.texi (b2sum invocation): Reference the
md5sum invocation node, and add descriptions of -l.
* tests/misc/b2sum.sh: Add new test.
* tests/local.mk: Reference new test.
* AUTHORS: Add new binary.
* README: Likewise.
* build-aux/gen-lists-of-programs.sh: Likewise.
* man/.gitignore: Likewise.
* scripts/git-hooks/commit-msg: Likewise.
* man/b2sum.x: New man page template.
* man/local.mk: Reference new template.
* src/.gitignore: Ignore new binaries.
* src/blake2/.gitignore: Ignore new build atrifacts.
* src/md5sum.c (usage): Describe the new -l option.
* NEWS: Mention the new program.

1 files changed, 31 insertions, 1 deletions

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 81101485c..d0694fdd0 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -37,6 +37,7 @@
 @dircategory Individual utilities
 @direntry
 * arch: (coreutils)arch invocation.             Print machine hardware name.
+* b2sum: (coreutils)b2sum invocation.           Print or check BLAKE2 digests.
 * base32: (coreutils)base32 invocation.         Base32 encode/decode data.
 * base64: (coreutils)base64 invocation.         Base64 encode/decode data.
 * basename: (coreutils)basename invocation.     Strip directory and suffix.
@@ -186,7 +187,7 @@ Free Documentation License''.
 * Output of entire files::       cat tac nl od base32 base64
 * Formatting file contents::     fmt pr fold
 * Output of parts of files::     head tail split csplit
-* Summarizing files::            wc sum cksum md5sum sha1sum sha2
+* Summarizing files::            wc sum cksum b2sum md5sum sha1sum sha2
 * Operating on sorted files::    sort shuf uniq comm ptx tsort
 * Operating on fields::          cut paste join
 * Operating on characters::      tr expand unexpand
@@ -259,6 +260,7 @@ Summarizing files
 * wc invocation::                Print newline, word, and byte counts
 * sum invocation::               Print checksum and block counts
 * cksum invocation::             Print CRC checksum and byte counts
+* b2sum invocation::             Print or check BLAKE2 digests
 * md5sum invocation::            Print or check MD5 digests
 * sha1sum invocation::           Print or check SHA-1 digests
 * sha2 utilities::               Print or check SHA-2 digests
@@ -3557,6 +3559,7 @@ contents of files.
 * wc invocation::               Print newline, word, and byte counts.
 * sum invocation::              Print checksum and block counts.
 * cksum invocation::            Print CRC checksum and byte counts.
+* b2sum invocation::            Print or check BLAKE2 digests.
 * md5sum invocation::           Print or check MD5 digests.
 * sha1sum invocation::          Print or check SHA-1 digests.
 * sha2 utilities::              Print or check SHA-2 digests.
@@ -3769,6 +3772,33 @@ options}.
 @exitstatus
 
 
+@node b2sum invocation
+@section @command{b2sum}: Print or check BLAKE2 digests
+
+@pindex b2sum
+@cindex BLAKE2
+@cindex 512-bit checksum
+@cindex checksum, 512-bit
+@cindex fingerprint, 512-bit
+@cindex message-digest, 512-bit
+
+@command{b2sum} computes a 512-bit checksum for each specified
+@var{file}.  The same usage and options as the @command{md5sum}
+command are supported.  @xref{md5sum invocation}.
+In addition @command{b2sum} supports the following options.
+
+@table @samp
+@item -l
+@itemx --length
+@opindex -l
+@opindex --length
+@cindex BLAKE2 hash length
+Change (shorten) the default digest length.
+This is specified in bits and thus must be a multiple of 8.
+This option is ignored when @option{--check} is specified,
+as the length is automatically determined when checking.
+@end table
+
 @node md5sum invocation
 @section @command{md5sum}: Print or check MD5 digests