* guix/zlib.scm (make-gzip-input-port)[gzfile]: Error out if (drain-input port) returns a non-empty string. * guix/zlib.scm (make-gzip-output-port)[gzfile]: Call 'force-output'.
* guix/zlib.scm (gzread!): Augment docstring to clarify when zero is returned (based on reading zlib code). (make-gzip-input-port)[read!]: Remove scary comment.
* guix/zlib.scm, tests/zlib.scm: New files. * Makefile.am (MODULES): Add guix/zlib.scm. (SCM_TESTS): Add tests/zlib.scm. * m4/guix.m4 (GUIX_LIBGCRYPT_LIBDIR): New macro. * configure.ac (LIBGCRYPT_LIBDIR): Use it. Define and substitute 'LIBZ'. * guix/config.scm.in (%libz): New variable.