offload: Have 'build-machines' honor its argument.

* guix/scripts/offload.scm (build-machines): Honor FILE.

offload: Do not try to retrieve anything upon build failure.

* guix/scripts/offload.scm (offload): Add 'log-port' keyword parameter.
  Handle log display here.  Return the result of (close-pipe pipe).
  (process-request): Adjust 'offload' call site accordingly.  Call
  'retrieve-files' only when 'offload' returns zero; exit when 'offload'
  returns non-zero.

Add 'guix offload' as a daemon build hook.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_NO_BUILD_HOOK): New macro.
  (options): Add '--no-build-hook'.
  (parse_opt): Handle it.
  (main)[HAVE_DAEMON_OFFLOAD_HOOK]: Set 'useBuildHook' by default.
  Set $NIX_BUILD_HOOK to our offload hook unless otherwise specified.
  [!HAVE_DAEMON_OFFLOAD_HOOK]: Clear 'useBuildHook'.
* pre-inst-env.in: Set and export NIX_BUILD_HOOK.
* nix/scripts/offload.in, guix/scripts/offload.scm: New files.
* guix/ui.scm (show-guix-help)[internal?]: Add "offload".
* config-daemon.ac: Call 'GUIX_CHECK_UNBUFFERED_CBIP'.
  Instantiate 'nix/scripts/offload'.  Set 'BUILD_DAEMON_OFFLOAD'
  conditional, and optionally define 'HAVE_DEAMON_OFFLOAD_HOOK' cpp
  macro.
* daemon.am (nodist_pkglibexec_SCRIPTS)[BUILD_DAEMON_OFFLOAD]: Add it.
* Makefile.am (MODULES)[BUILD_DAEMON_OFFLOAD]: Add
  'guix/scripts/offload.scm'.
  (EXTRA_DIST)[!BUILD_DAEMON_OFFLOAD]: Likewise.
* m4/guix.m4 (GUIX_CHECK_UNBUFFERED_CBIP): New macro.
* doc/guix.texi (Setting Up the Daemon): Move most of the body to...
  (Build Environment Setup): ... this.  New subsection.
  (Daemon Offload Setup): New subsection.

pki: Factorize signature manipulation procedures.

* guix/pki.scm (signature-subject, signature-signed-data,
  valid-signature?): New procedures.
* guix/scripts/authenticate.scm (guix-authenticate): Adjust to use
  them.

Update 'nix-upstream' sub-module; adjust build system, doc, and substituter.

* nix-upstream: Update sub-module.
* daemon.am (libutil_a_SOURCES): Add affinity.cc.
  (libutil_headers): Add affinity.hh.
  (libexec_PROGRAMS, nix_setuid_helper_SOURCES,
  nix_setuid_helper_CPPFLAGS, nix_setuid_helper_LDADD): Remove.
* doc/guix.texi (Setting Up the Daemon): Remove paragraph about
  'nix-setuid-helper'.
* guix/scripts/substitute-binary.scm (guix-substitute-binary): Exit 0 when
  %CACHE-URL has an HTTP scheme and looking up its host fails.
  Always print a newline to stdout when starting.

guix package: Gracefully handle EPIPE on '--search'.

* guix/scripts/package.scm (guix-package): Wrap body of 'search' in
  'leave-on-EPIPE'.

config: '%state-directory' always honors $NIX_STATE_DIR.

* guix/config.scm.in (%state-directory): Honor $NIX_STATE_DIR.
* guix/scripts/package.scm (%profile-directory): Use %state-directory
  directly.
* guix/store.scm (%default-socket-path, log-file): Likewise.

archive: Add '--missing'.

* guix/scripts/archive.scm (show-help, %options): Add '--missing'.
  (guix-archive)[lines]: New procedure.
  Use it to honor '--missing'.
* tests/guix-archive.sh: Add tests.
* doc/guix.texi (Invoking guix archive): Document '--missing'.

archive: Make sure $sysconfdir/guix exists.

* guix/pki.scm (ensure-acl): Make sure the directory of %ACL-FILE
  exists.
* guix/scripts/archive.scm (generate-key-pair): Likewise for
  %PUBLIC-KEY-FILE.

guix build: Add '--no-build-hook'.

* guix/scripts/build.scm (%default-options): Add 'build-hook?' pair.
  (show-help, %options): Add --no-build-hook.
  (guix-build): Pass the 'build-hook?' value to 'set-build-options'.
* doc/guix.texi (Invoking guix build): Document '--no-build-hook'.

guix package: Gracefully deal with EPIPE on stdout for --list-*.

* guix/scripts/package.scm (leave-on-EPIPE): New macro.
  (guix-package): Use it for 'list-installed', 'list-available', and
  '--list-generations'.
* tests/guix-package.sh: Add test.

archive: Add '--authorize'.

* guix/scripts/archive.scm (authorize-key): New procedure.
  (guix-archive): Call it when OPTS contains 'authorize-key'.
* tests/guix-archive.sh: Add test with invalid public key.
* guix/pki.scm: Export '%acl-file'.
* doc/guix.texi (Invoking guix archive): Make it clear that '--import'
  works only with authorized keys.  Document '--authorize'.

archive: Add '--generate-key'.

* guix/pk-crypto.scm (error-source, error-string): New procedures.
* guix/pki.scm (%private-key-file): New variable.
* guix/scripts/archive.scm (show-help): Document '--generate-key'.
  (%options): Add "generate-key".
  (generate-key-pair): New procedure.
  (guix-archive): Call 'generate-key' when OPTS contains a
  'generate-key' pair.
* doc/guix.texi (Setting Up the Daemon): Suggest generating a key pair.
  (Invoking guix archive): Document '--generate-key'.

authenticate: Consistently use 'leave' for fatal error reporting.

* guix/scripts/authenticate.scm (guix-authenticate): Replace all uses of
  'format' + 'exit' with 'leave'.

authenticate: Disallow imports signed with unauthorized keys.

* guix/scripts/authenticate.scm (signature-sexp): Remove.
  (guix-authenticate): Upon '-verify', check whether the signature's
  public key passes 'authorized-key?'.

Move 'with-atomic-file-output' to (guix utils).

* guix/scripts/substitute-binary.scm (with-atomic-file-output): Move to...
* guix/utils.scm (with-atomic-file-output): ... here.

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.

pk-crypto: Rename 'gcry-sexp' to 'canonical-sexp'.

* guix/pk-crypto.scm: Rename procedures, variables, etc. from
  'gcry-sexp' to 'canonical-sexp'.  Add comment with references.
* guix/scripts/authenticate.scm, tests/pk-crypto.scm: Adjust
  accordingly.

Add 'guix archive'.

* guix/scripts/archive.scm, tests/guix-archive.sh: New files.
* Makefile.am (MODULES): Add 'archive.scm'.
  (SH_TESTS): Add 'guix-archive.sh'.
* doc/guix.texi (Invoking guix archive): New section.
* guix/scripts/build.scm: Export 'derivation-from-expression'.
* guix/scripts/package.scm: Export 'specification->package+output'.

guix build: Improve procedural decomposition.

* guix/scripts/build.scm (%store): Remove.
  (derivation-from-expression): Add 'store' parameter.  Adjust caller
  accordingly.
  (register-root): New procedure, formerly within 'guix-build'.
  (options->derivations): New procedure, formerly inline within
  'guix-build'.
  (guix-build): Adjust accordingly.