tests: Make sure the daemon reports substitute hash mismatches.

* tests/store.scm ("substitute, corrupt output hash"): New test.

Merge branch 'master' into core-updates

tests: Test recovery from 'valid-path?' RPCs with an invalid parameter.

* tests/store.scm ("valid-path? live", "valid-path? false", "valid-path?
  error", "valid-path? recovery"): New tests.

Merge branch 'master' into core-updates

store: Add 'hash-part->path'.

* guix/store.scm (hash-part->path): New procedure.
* tests/store.scm ("hash-part->path"): New test.

Merge branch 'master' into core-updates

tests: 'topologically-sorted' test handles different references orders.

* tests/store.scm ("topologically-sorted, more difficult"): Arrange to
  handle a different ordering of (references %store y).

store: 'export-paths' doesn't export references of the given files.

This fixes a regression introduced in
99fbddf9a623757e39d88bfb431f8f7d6f24b75b ("store: Change 'export-paths'
to always export in topological order.")

* guix/store.scm (export-paths): Define 'ordered' variable.  Iterate
  over it.
* tests/store.scm ("export/import paths, ensure topological order"): Add
  'file0'.  Adjust accordingly.

Merge branch 'master' into core-updates

Conflicts:
	gnu-system.am

store: Change 'export-paths' to always export in topological order.

* guix/store.scm (export-paths): Pass PATHS through
  'topologically-sorted' before iterating.
* tests/store.scm ("export/import paths, ensure topological order"): New
  test.

Merge branch 'master' into core-updates

store: Add 'topologically-sorted'.

* guix/store.scm (topologically-sorted): New procedure.
* tests/store.scm ("topologically-sorted, one item",
  "topologically-sorted, several items", "topologically-sorted, more
  difficult"): New tests.

store: Add 'register-path' procedure.

* guix/store.scm (register-path): New procedure.
* tests/store.scm ("register-path"): New test.
* guix/config.scm.in (%guix-register-program): New variable.
* configure.ac: Compute and substitute 'guix_sbindir'.  Compute
  'guix_prefix'.
* pre-inst-env.in: Define 'GUIX_REGISTER'.

Merge branch 'master' into core-updates

authenticate: Store the public key as part of the signature.

* guix/scripts/authenticate.scm (signature-sexp): New procedure.
  (guix-authenticate): Use it to produce the signature.  Adjust
  verification code accordingly.
* tests/store.scm ("import corrupt path"): Adjust test accordingly.

daemon: Implement signed archive import/export.

* guix/scripts/authenticate.scm, nix/scripts/guix-authenticate.in,
  tests/signing-key.pub, tests/signing-key.sec: New files.
* po/POTFILES.in: Add 'guix/scripts/authenticate.scm'.
* guix/store.scm (dump-port): New procedure.
  (process-stderr): Add 'user-port' optional parameter.  Handle
  the %STDERR-WRITE and %STDERR-READ cases as expected.
  (import-paths, export-path, export-paths): New procedures.
* tests/store.scm ("export/import several paths", "import corrupt
  path"): New tests.
* Makefile.am (MODULES): Add 'guix/scripts/authenticate.scm'.
  (EXTRA_DIST): Add 'tests/signing-key.{pub,sec}'.
* daemon.am (libstore_a_CPPFLAGS)[-DNIX_CONF_DIR]: Change 'NIX_CONF_DIR'
  to .../guix.  Change 'OPENSSL_PATH' to 'guix-authenticate'.
* config-daemon.ac: Instantiate 'nix/scripts/guix-authenticate'.
* nix/nix-daemon/guix-daemon.cc (main): Augment $PATH to include
  'settings.nixLibexecDir'.
* test-env.in: Export 'NIX_CONF_DIR' and 'NIX_LIBEXEC_DIR'.  Populate
  $NIX_CONF_DIR.

store: Add tests for 'store-path-package-name'.

* tests/store.scm ("store-path-package-name", "store-path-package-name
  #f"): New tests.

derivations: Use more keyword parameters for 'build-expression->derivation'.

* guix/derivations.scm (build-expression->derivation): Turn 'system' and
  'inputs' into keyword parameters.
  Adjust callers accordingly.
* gnu/system/linux.scm, gnu/system/vm.scm, guix/build-system/cmake.scm,
  guix/build-system/gnu.scm, guix/build-system/perl.scm,
  guix/build-system/python.scm, guix/build-system/trivial.scm,
  guix/download.scm, guix/packages.scm, guix/profiles.scm,
  guix/scripts/pull.scm, tests/derivations.scm, tests/guix-build.sh,
  tests/monads.scm, tests/store.scm, tests/union.scm: Adjust users of
  'build-expression->derivation' and 'derivation-expression'
  accordingly.
* doc/guix.texi (Derivations): Adjust 'build-expression->derivation'
  documentation accordingly.
  (The Store Monad): Likewise for 'derivation-expression'.

Merge branch 'master' into core-updates

Conflicts:
	guix/packages.scm

store: Make 'direct-store-path?' public.

* guix/store.scm (direct-store-path?): New procedure.
* guix/derivations.scm (derivation)[direct-store-path?]: Remove.
* tests/store.scm ("direct-store-path?"): New test.