substitute-binary: Support decompression from non-file ports.

* guix/scripts/substitute-binary.scm (filtered-port): Move to utils.scm.
  (decompressed-port): Upon "none", return '() as the second value.
  (guix-substitute-binary): Expect `decompressed-port' to return a list
  of PIDs as its second value.
* guix/utils.scm (filtered-port): New procedure.  Add case for when
  INPUT is not `file-port?'.
* tests/utils.scm ("filtered-port, file", "filtered-port, non-file"):
  New tests.

Merge branch 'master' into core-updates

Conflicts:
	Makefile.am
	gnu/packages/autotools.scm
	gnu/packages/guile.scm
	gnu/packages/python.scm
	gnu/packages/shishi.scm
	guix/gnu-maintenance.scm
	guix/scripts/build.scm
	guix/scripts/gc.scm
	guix/scripts/package.scm
	guix/scripts/substitute-binary.scm
	guix/ui.scm
	nix/nix-daemon/guix-daemon.cc
	test-env.in
	tests/nar.scm
	tests/store.scm

web: Factorize `http-get' hackery.

This should fix `substitute-binary --query' on Guile 2.0.5.

* guix/web.scm: New file.
* Makefile.am (MODULES): Add it.
* po/POTFILES.in: Add it.
* guix/gnu-maintenance.scm (http-fetch): Remove.
  (%package-list-url): Turn into a URI.
  (official-gnu-packages): Add #:text? #t to `http-fetch' call.
* guix/scripts/substitute-binary.scm (fetch): Remove `http' case, and
  use `http-fetch' instead.

substitute-binary: Remove expired cache entries once in a while.

* guix/scripts/substitute-binary.scm (%narinfo-expired-cache-entry-removal-delay):
  New variable.
  (obsolete?): New procedure, formerly in `lookup-narinfo'.
  (lookup-narinfo): Adjust accordingly.
  (remove-expired-cached-narinfos, maybe-remove-expired-cached-narinfo):
  New procedures.
  (guix-substitute-binary): Call `maybe-remove-expired-cached-narinfo'.

substitute-binary: Skip servers that use a different store prefix.

* guix/scripts/substitute-binary.scm (fetch-narinfo): Return #f when
  CACHE uses a store directory different from (%store-prefix).

substitute-binary: Call `open-cache' only when needed.

* guix/scripts/substitute-binary.scm (lookup-narinfo): Force CACHE when
  passing it to `fetch-narinfo'.
  (guix-substitute-binary): Delay calls to `open-cache'.

substitute-binary: Add a local cache.

* guix/scripts/substitute-binary.scm (%narinfo-cache-directory,
  %narinfo-ttl, %narinfo-negative-ttl): New variables.
  (with-atomic-file-output, object->fields, read-narinfo,
  write-narinfo, narinfo->string, string->narinfo, lookup-narinfo): New
  procedures.
  (fetch-narinfo): Adjust to use `read-narinfo'.
  (guix-substitute-binary): Ensure the existence of
  %NARINFO-CACHE-DIRECTORY.  Use `lookup-narinfo' instead of
  `fetch-narinfo'.

substitute-binary: Implement `--substitute'.

This allows build outputs to be transparently downloaded from
http://hydra.gnu.org, for example.

* config-daemon.ac: Check for `gzip', `bzip2', and `xz'.
* guix/config.scm.in (%gzip, %bzip2, %xz): New variable.
* guix/scripts/substitute-binary.scm (fetch): Return SIZE as a second value.
  (<narinfo>): Change `url' to `uri'.
  (make-narinfo): Rename to...
  (narinfo-maker): ... this.  Handle relative URLs.
  (fetch-narinfo): Adjust accordingly.
  (filtered-port, decompressed-port): New procedures.
  (guix-substitute-binary): Implement the `--substitute' case.
* tests/store.scm ("substitute query"): Use (%store-prefix) instead
  of (getenv "NIX_STORE_DIR").
  ("substitute"): New test.

substitute-binary: Correctly handle missing narinfos in `--query' mode.

* guix/scripts/substitute-binary.scm (guix-substitute-binary)["--query"]("have",
  "info"): Filter SUBSTITUTABLE through `narinfo?'.

substitute-binary: Fix communication of several store paths to the daemon.

* guix/scripts/substitute-binary.scm (guix-substitute-binary)["--query"]:
  Emit blank lines only after the complete list of store paths has been
  returned.

Add preliminary binary substituter.

* guix/scripts/substitute-binary.scm: New file.
* Makefile.am (MODULES): Add it.
* nix/scripts/substitute-binary.in: New file.
* config-daemon.ac: Produce nix/scripts/substitute-binary.
* daemon.am (nodist_pkglibexec_SCRIPTS): Add
  nix/scripts/substitute-binary.
* guix/store.scm (substitutable-path-info): Use the
  `query-substitutable-path-infos' RPC.
* nix/nix-daemon/guix-daemon.cc (main): Honor `NIX_SUBSTITUTERS'.
* pre-inst-env.in: Set `NIX_SUBSTITUTERS'.
* test-env.in: Leave `NIX_SUBSTITUTERS' unchanged.  Set
  `GUIX_BINARY_SUBSTITUTE_URL, and create
  $NIX_STATE_DIR/substituter-data.
  Run `guix-daemon' within `./pre-inst-env'.
* tests/store.scm ("substitute query"): New test.

substitute-binary: Implement `--substitute'.

This allows build outputs to be transparently downloaded from
http://hydra.gnu.org, for example.

* config-daemon.ac: Check for `gzip', `bzip2', and `xz'.
* guix/config.scm.in (%gzip, %bzip2, %xz): New variable.
* guix/scripts/substitute-binary.scm (fetch): Return SIZE as a second value.
  (<narinfo>): Change `url' to `uri'.
  (make-narinfo): Rename to...
  (narinfo-maker): ... this.  Handle relative URLs.
  (fetch-narinfo): Adjust accordingly.
  (filtered-port, decompressed-port): New procedures.
  (guix-substitute-binary): Implement the `--substitute' case.
* tests/store.scm ("substitute query"): Use (%store-prefix) instead
  of (getenv "NIX_STORE_DIR").
  ("substitute"): New test.

substitute-binary: Correctly handle missing narinfos in `--query' mode.

* guix/scripts/substitute-binary.scm (guix-substitute-binary)["--query"]("have",
  "info"): Filter SUBSTITUTABLE through `narinfo?'.

substitute-binary: Fix communication of several store paths to the daemon.

* guix/scripts/substitute-binary.scm (guix-substitute-binary)["--query"]:
  Emit blank lines only after the complete list of store paths has been
  returned.

Add preliminary binary substituter.

* guix/scripts/substitute-binary.scm: New file.
* Makefile.am (MODULES): Add it.
* nix/scripts/substitute-binary.in: New file.
* config-daemon.ac: Produce nix/scripts/substitute-binary.
* daemon.am (nodist_pkglibexec_SCRIPTS): Add
  nix/scripts/substitute-binary.
* guix/store.scm (substitutable-path-info): Use the
  `query-substitutable-path-infos' RPC.
* nix/nix-daemon/guix-daemon.cc (main): Honor `NIX_SUBSTITUTERS'.
* pre-inst-env.in: Set `NIX_SUBSTITUTERS'.
* test-env.in: Leave `NIX_SUBSTITUTERS' unchanged.  Set
  `GUIX_BINARY_SUBSTITUTE_URL, and create
  $NIX_STATE_DIR/substituter-data.
  Run `guix-daemon' within `./pre-inst-env'.
* tests/store.scm ("substitute query"): New test.