publish: Publish build logs.

* guix/scripts/publish.scm (render-log-file): New procedure.
(make-request-handler): Add "log" case.
* tests/publish.scm ("/log/NAME")
("/log/NAME not found"): New tests.
* doc/guix.texi (Invoking guix publish): Document /log URLs.

publish: Use 'x-raw-file' internal response header.

This adjusts the workaround for <http://bugs.gnu.org/21093> so that it's
not limited to a single content-type.

* guix/scripts/publish.scm (render-nar/cached): Add the 'x-raw-file'
header on the response.
(render-content-addressed-file): Likewise.
(with-content-length): Remove the 'x-raw-file' header.
(http-write): Instead of dispatching on 'application/octet-stream',
check whether 'x-raw-file' is set to determine whether to spawn a
thread.

publish: Save bandwidth on narinfo 404s.

This saves 18 bytes on each 404 narinfo response.

* guix/scripts/publish.scm (render-narinfo): Pass #:phrase to
'not-found'.
(render-narinfo/cached): Likewise.

guix build: Support '--with-source=PACKAGE@VERSION=URI'.

* guix/scripts/build.scm (numeric-extension?, tarball-base-name): New
procedures, formerly in 'package-with-source'.
(transform-package-source)[new-sources]: Look for '=' in URI.  Each
element of the list of now a (PKG VERSION SOURCE) tuple.
Pass VERSION to 'package-with-source'.
(package-with-source): Add 'version' parameter and honor it.
* tests/scripts-build.scm ("options->transformation, with-source, PKG=URI")
("options->transformation, with-source, PKG@VER=URI"): New tests.
* doc/guix.texi (Package Transformation Options): Document the new
forms.

guix system: Check mapped devices upon 'init' and 'reconfigure'.

* guix/scripts/system.scm (check-mapped-devices): New procedure.
(perform-action): Add call to 'check-mapped-devices'.

guix gc: '--verify=foo' is reported as an error.

Fixes <https://bugs.gnu.org/29761>.
Reported by Martin Castillo <castilma@uni-bremen.de>.

* guix/scripts/gc.scm (argument->verify-options): New procedure.
(%options) ["verify"]: Adjust to use it.
* tests/guix-gc.sh: Add test.

guix: offload: Add "status" sub-command.

* guix/scripts/offload.scm (check-machine-status): New procedure.
(guix-offload): Call it when the argument is "status".
* doc/guix.texi (Daemon Offload Setup): Document it.

scripts: system: Add --expression option.

* guix/scripts/system.scm (show-help): Add expression option.
(%options): Ditto.
(guix-system): Allow commands taking a file as an argument to use an
expression instead.
(process-action): Read operating-system from expression or file.
* doc/guix.texi (Invoking guix system): Introduce the expression option.

bootloader: Factorize write-file-on-device.

* gnu/bootloader/extlinux.scm (install-extlinux): Factorize bootloader
writing in a new procedure write-file-on-device defined in (gnu build
bootloader).
* gnu/build/bootloader.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add new file.
* gnu/system/vm.scm (qemu-img): Adapt to import and use (gnu build bootloader)
module during derivation building.
* gnu/scripts/system.scm (bootloader-installer-derivation): Ditto.

lint: 'check-vulnerabilities' also checks package properties.

* guix/scripts/lint.scm (check-vulnerabilities): Also check for CVEs
listed as mitigated in the package properties.
* tests/lint.scm ("cve: known safe from vulnerability"): New test.

scripts: All commands enable build hooks by default.

* guix/scripts/archive.scm (%default-options): Add 'build-hook?'.
* guix/scripts/copy.scm (%default-options): Likewise.
* guix/scripts/environment.scm (%default-options): Likewise.
* guix/scripts/pack.scm (%default-options): Likewise.
* guix/scripts/package.scm (%default-options): Likewise.
* guix/scripts/pull.scm (%default-options): Likewise.

bootloader: extlinux: Stop using dd binary.

* gnu/bootloader/extlinux.scm (dd): Remove it,
(install-extlinux): replace dd call by Guile I/O procedures.
* gnu/system/vm.scm (qemu-image): Add (ice-9 binary-ports) to used-modules
list to provide "get-bytevector-n" and "put-bytevector".
* guix/scripts/system.scm (bootloader-installer-derivation): Ditto.

scripts: Default to Guile 2.2 as the guile-for-build.

* guix/scripts/environment.scm (guix-environment): '%guile-for-build'
now defaults to GUILE-2.2 instead of GUILE-2.0.
* guix/scripts/package.scm (guix-package): Likewise.
* guix/scripts/pull.scm (guix-pull): Likewise.

Do not set '%fresh-auto-compile'.

* guix/scripts/offload.scm (build-machines): Comment out
'(set! %fresh-auto-compile #t)' since with Guile 2.2.3 it could lead to
an actual rebuild of everything that gets loaded from there on.  See
<https://bugs.gnu.org/29226>.
* guix/ui.scm (load*): Likewise.

guix system: 'init' displays a progress bar while copying.

Until now it would print the name of each store item being copied, which
was verbose and unhelpful.

* guix/scripts/system.scm (copy-closure): Use 'progress-reporter/bar'
and 'call-with-progress-reporter'.
(guix-system): Parameterize 'current-terminal-columns'.

guix system: Simplify closure copy.

* guix/scripts/system.scm (copy-item): Add 'references' argument and
remove 'references*' call.  Turn into a non-monadic procedure.
(copy-closure): Remove initial call to 'references*'.  Only pass ITEM to
'topologically-sorted*' since that's equivalent.  Compute the list of
references corresponding to TO-COPY and pass it to 'copy-item'.

weather: Use (guix progress) for progress report.

* guix/progress.scm (start-progress-reporter!, stop-progress-reporter!)
(progress-reporter-report!): New procedures.
* guix/scripts/weather.scm (call-with-progress-reporter): New procedure.
(package-outputs)[update-progress!]: Remove.
Use 'call-with-progress-reporter' instead.
(guix-weather): Parameterize 'current-terminal-columns'.

lint: Adjust file-name length test for out-of-tree file names.

* guix/scripts/lint.scm (check-patch-file-names): Adjust
file-name-length calculation.

lint: 'patch-file-names' checks for file name length.

Reported at <https://bugs.gnu.org/27943>
by Danny Milosavljevic <dannym@scratchpost.org>.

* guix/scripts/lint.scm (%distro-directory): New variable.
(check-patch-file-names): Add check for the file name length.
* tests/lint.scm ("patches: file name too long"): New test.

Revert "Add (guix self) and use it when pulling."

This reverts commit 5f93d97005897c2d859f0be1bdff34c88467ec61.

'guix pull' would fail because (guix self) needs 'scheme-files'
from (guix discovery), which was not exported until now.