* guix/hash.scm (open-sha256-input-port): New procedure. * tests/hash.scm (supports-unbuffered-cbip?): New procedure. ("open-sha256-input-port, empty", "open-sha256-input-port, hello", "open-sha256-input-port, hello, one two", "open-sha256-input-port, hello, read from wrapped port"): New tests.
* guix/hash.scm (GCRY_MD_SHA256): New macro. (sha256): Use it. (open-sha256-md, md-write, md-read, md-close, open-sha256-port, port-sha256): New procedures. * tests/hash.scm: New file. * Makefile.am (SCM_TESTS): Add it.