minor, provide sha1 sum comparator tool shack(1)

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
fix, obey the congruent 448 mod 512 rule for the last chunk

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, provide the actual comparator, print nothing if all's good, otherwise ...

print the actual sha sum.

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, allow prefix matches for the reference shas on the command line

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
fix, PEBKAC, use suffix comparisons when checking prefix

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
test, provide regression tests for shack utility

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, refactor path fiddling into prepend_path()

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, also prepend argv[0] path and current directory to PATH

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, use static space for path caching and prepending

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'core/path'

* core/path:
  minor, use static space for path caching and prepending
  minor, also prepend argv[0] path and current directory to PATH
  minor, refactor path fiddling into prepend_path()
Merge branch 'feat/shack'

* feat/shack:
  test, provide regression tests for shack utility
  fix, PEBKAC, use suffix comparisons when checking prefix
  minor, allow prefix matches for the reference shas on the command line
  minor, provide the actual comparator, print nothing if all's good, otherwise ...
  fix, obey the congruent 448 mod 512 rule for the last chunk
  minor, provide sha1 sum comparator tool shack(1)