c568191a93
* guix/profiles.scm (ca-certificate-bundle): Create $output/etc/ssl/certs if and only if CA-FILES is non-empty.
659 lines
24 KiB
Scheme
659 lines
24 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
|
||
;;; Copyright © 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
|
||
;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
|
||
;;; Copyright © 2014 Alex Kost <alezost@gmail.com>
|
||
;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
|
||
;;;
|
||
;;; This file is part of GNU Guix.
|
||
;;;
|
||
;;; GNU Guix is free software; you can redistribute it and/or modify it
|
||
;;; under the terms of the GNU General Public License as published by
|
||
;;; the Free Software Foundation; either version 3 of the License, or (at
|
||
;;; your option) any later version.
|
||
;;;
|
||
;;; GNU Guix is distributed in the hope that it will be useful, but
|
||
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
;;; GNU General Public License for more details.
|
||
;;;
|
||
;;; You should have received a copy of the GNU General Public License
|
||
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
|
||
|
||
(define-module (guix profiles)
|
||
#:use-module (guix utils)
|
||
#:use-module (guix records)
|
||
#:use-module (guix derivations)
|
||
#:use-module (guix packages)
|
||
#:use-module (guix gexp)
|
||
#:use-module (guix monads)
|
||
#:use-module (guix store)
|
||
#:use-module (ice-9 match)
|
||
#:use-module (ice-9 regex)
|
||
#:use-module (ice-9 ftw)
|
||
#:use-module (ice-9 format)
|
||
#:use-module (srfi srfi-1)
|
||
#:use-module (srfi srfi-9)
|
||
#:use-module (srfi srfi-11)
|
||
#:use-module (srfi srfi-19)
|
||
#:use-module (srfi srfi-26)
|
||
#:use-module (srfi srfi-34)
|
||
#:use-module (srfi srfi-35)
|
||
#:export (&profile-error
|
||
profile-error?
|
||
profile-error-profile
|
||
&profile-not-found-error
|
||
profile-not-found-error?
|
||
&missing-generation-error
|
||
missing-generation-error?
|
||
missing-generation-error-generation
|
||
|
||
manifest make-manifest
|
||
manifest?
|
||
manifest-entries
|
||
|
||
<manifest-entry> ; FIXME: eventually make it internal
|
||
manifest-entry
|
||
manifest-entry?
|
||
manifest-entry-name
|
||
manifest-entry-version
|
||
manifest-entry-output
|
||
manifest-entry-item
|
||
manifest-entry-dependencies
|
||
|
||
manifest-pattern
|
||
manifest-pattern?
|
||
|
||
manifest-remove
|
||
manifest-add
|
||
manifest-lookup
|
||
manifest-installed?
|
||
manifest-matching-entries
|
||
|
||
manifest-transaction
|
||
manifest-transaction?
|
||
manifest-transaction-install
|
||
manifest-transaction-remove
|
||
manifest-perform-transaction
|
||
manifest-transaction-effects
|
||
|
||
profile-manifest
|
||
package->manifest-entry
|
||
%default-profile-hooks
|
||
profile-derivation
|
||
generation-number
|
||
generation-numbers
|
||
profile-generations
|
||
relative-generation
|
||
previous-generation-number
|
||
generation-time
|
||
generation-file-name))
|
||
|
||
;;; Commentary:
|
||
;;;
|
||
;;; Tools to create and manipulate profiles---i.e., the representation of a
|
||
;;; set of installed packages.
|
||
;;;
|
||
;;; Code:
|
||
|
||
|
||
;;;
|
||
;;; Condition types.
|
||
;;;
|
||
|
||
(define-condition-type &profile-error &error
|
||
profile-error?
|
||
(profile profile-error-profile))
|
||
|
||
(define-condition-type &profile-not-found-error &profile-error
|
||
profile-not-found-error?)
|
||
|
||
(define-condition-type &missing-generation-error &profile-error
|
||
missing-generation-error?
|
||
(generation missing-generation-error-generation))
|
||
|
||
|
||
;;;
|
||
;;; Manifests.
|
||
;;;
|
||
|
||
(define-record-type <manifest>
|
||
(manifest entries)
|
||
manifest?
|
||
(entries manifest-entries)) ; list of <manifest-entry>
|
||
|
||
;; Convenient alias, to avoid name clashes.
|
||
(define make-manifest manifest)
|
||
|
||
(define-record-type* <manifest-entry> manifest-entry
|
||
make-manifest-entry
|
||
manifest-entry?
|
||
(name manifest-entry-name) ; string
|
||
(version manifest-entry-version) ; string
|
||
(output manifest-entry-output ; string
|
||
(default "out"))
|
||
(item manifest-entry-item) ; package | store path
|
||
(dependencies manifest-entry-dependencies ; (store path | package)*
|
||
(default '())))
|
||
|
||
(define-record-type* <manifest-pattern> manifest-pattern
|
||
make-manifest-pattern
|
||
manifest-pattern?
|
||
(name manifest-pattern-name) ; string
|
||
(version manifest-pattern-version ; string | #f
|
||
(default #f))
|
||
(output manifest-pattern-output ; string | #f
|
||
(default "out")))
|
||
|
||
(define (profile-manifest profile)
|
||
"Return the PROFILE's manifest."
|
||
(let ((file (string-append profile "/manifest")))
|
||
(if (file-exists? file)
|
||
(call-with-input-file file read-manifest)
|
||
(manifest '()))))
|
||
|
||
(define* (package->manifest-entry package #:optional output)
|
||
"Return a manifest entry for the OUTPUT of package PACKAGE. When OUTPUT is
|
||
omitted or #f, use the first output of PACKAGE."
|
||
(let ((deps (map (match-lambda
|
||
((label package)
|
||
(gexp-input package))
|
||
((label package output)
|
||
(gexp-input package output)))
|
||
(package-transitive-propagated-inputs package))))
|
||
(manifest-entry
|
||
(name (package-name package))
|
||
(version (package-version package))
|
||
(output (or output (car (package-outputs package))))
|
||
(item package)
|
||
(dependencies (delete-duplicates deps)))))
|
||
|
||
(define (manifest->gexp manifest)
|
||
"Return a representation of MANIFEST as a gexp."
|
||
(define (entry->gexp entry)
|
||
(match entry
|
||
(($ <manifest-entry> name version output (? string? path) (deps ...))
|
||
#~(#$name #$version #$output #$path #$deps))
|
||
(($ <manifest-entry> name version output (? package? package) (deps ...))
|
||
#~(#$name #$version #$output
|
||
(ungexp package (or output "out")) #$deps))))
|
||
|
||
(match manifest
|
||
(($ <manifest> (entries ...))
|
||
#~(manifest (version 1)
|
||
(packages #$(map entry->gexp entries))))))
|
||
|
||
(define (sexp->manifest sexp)
|
||
"Parse SEXP as a manifest."
|
||
(match sexp
|
||
(('manifest ('version 0)
|
||
('packages ((name version output path) ...)))
|
||
(manifest
|
||
(map (lambda (name version output path)
|
||
(manifest-entry
|
||
(name name)
|
||
(version version)
|
||
(output output)
|
||
(item path)))
|
||
name version output path)))
|
||
|
||
;; Version 1 adds a list of propagated inputs to the
|
||
;; name/version/output/path tuples.
|
||
(('manifest ('version 1)
|
||
('packages ((name version output path deps) ...)))
|
||
(manifest
|
||
(map (lambda (name version output path deps)
|
||
;; Up to Guix 0.7 included, dependencies were listed as ("gmp"
|
||
;; "/gnu/store/...-gmp") for instance. Discard the 'label' in
|
||
;; such lists.
|
||
(let ((deps (match deps
|
||
(((labels directories) ...)
|
||
directories)
|
||
((directories ...)
|
||
directories))))
|
||
(manifest-entry
|
||
(name name)
|
||
(version version)
|
||
(output output)
|
||
(item path)
|
||
(dependencies deps))))
|
||
name version output path deps)))
|
||
|
||
(_
|
||
(error "unsupported manifest format" manifest))))
|
||
|
||
(define (read-manifest port)
|
||
"Return the packages listed in MANIFEST."
|
||
(sexp->manifest (read port)))
|
||
|
||
(define (entry-predicate pattern)
|
||
"Return a procedure that returns #t when passed a manifest entry that
|
||
matches NAME/OUTPUT/VERSION. OUTPUT and VERSION may be #f, in which case they
|
||
are ignored."
|
||
(match pattern
|
||
(($ <manifest-pattern> name version output)
|
||
(match-lambda
|
||
(($ <manifest-entry> entry-name entry-version entry-output)
|
||
(and (string=? entry-name name)
|
||
(or (not entry-output) (not output)
|
||
(string=? entry-output output))
|
||
(or (not version)
|
||
(string=? entry-version version))))))))
|
||
|
||
(define (manifest-remove manifest patterns)
|
||
"Remove entries for each of PATTERNS from MANIFEST. Each item in PATTERNS
|
||
must be a manifest-pattern."
|
||
(define (remove-entry pattern lst)
|
||
(remove (entry-predicate pattern) lst))
|
||
|
||
(make-manifest (fold remove-entry
|
||
(manifest-entries manifest)
|
||
patterns)))
|
||
|
||
(define (manifest-add manifest entries)
|
||
"Add a list of manifest ENTRIES to MANIFEST and return new manifest.
|
||
Remove MANIFEST entries that have the same name and output as ENTRIES."
|
||
(define (same-entry? entry name output)
|
||
(match entry
|
||
(($ <manifest-entry> entry-name _ entry-output _ ...)
|
||
(and (equal? name entry-name)
|
||
(equal? output entry-output)))))
|
||
|
||
(make-manifest
|
||
(append entries
|
||
(fold (lambda (entry result)
|
||
(match entry
|
||
(($ <manifest-entry> name _ out _ ...)
|
||
(filter (negate (cut same-entry? <> name out))
|
||
result))))
|
||
(manifest-entries manifest)
|
||
entries))))
|
||
|
||
(define (manifest-lookup manifest pattern)
|
||
"Return the first item of MANIFEST that matches PATTERN, or #f if there is
|
||
no match.."
|
||
(find (entry-predicate pattern)
|
||
(manifest-entries manifest)))
|
||
|
||
(define (manifest-installed? manifest pattern)
|
||
"Return #t if MANIFEST has an entry matching PATTERN (a manifest-pattern),
|
||
#f otherwise."
|
||
(->bool (manifest-lookup manifest pattern)))
|
||
|
||
(define (manifest-matching-entries manifest patterns)
|
||
"Return all the entries of MANIFEST that match one of the PATTERNS."
|
||
(define predicates
|
||
(map entry-predicate patterns))
|
||
|
||
(define (matches? entry)
|
||
(any (lambda (pred)
|
||
(pred entry))
|
||
predicates))
|
||
|
||
(filter matches? (manifest-entries manifest)))
|
||
|
||
|
||
;;;
|
||
;;; Manifest transactions.
|
||
;;;
|
||
|
||
(define-record-type* <manifest-transaction> manifest-transaction
|
||
make-manifest-transaction
|
||
manifest-transaction?
|
||
(install manifest-transaction-install ; list of <manifest-entry>
|
||
(default '()))
|
||
(remove manifest-transaction-remove ; list of <manifest-pattern>
|
||
(default '())))
|
||
|
||
(define (manifest-transaction-effects manifest transaction)
|
||
"Compute the effect of applying TRANSACTION to MANIFEST. Return 4 values:
|
||
the list of packages that would be removed, installed, upgraded, or downgraded
|
||
when applying TRANSACTION to MANIFEST. Upgrades are represented as pairs
|
||
where the head is the entry being upgraded and the tail is the entry that will
|
||
replace it."
|
||
(define (manifest-entry->pattern entry)
|
||
(manifest-pattern
|
||
(name (manifest-entry-name entry))
|
||
(output (manifest-entry-output entry))))
|
||
|
||
(let loop ((input (manifest-transaction-install transaction))
|
||
(install '())
|
||
(upgrade '())
|
||
(downgrade '()))
|
||
(match input
|
||
(()
|
||
(let ((remove (manifest-transaction-remove transaction)))
|
||
(values (manifest-matching-entries manifest remove)
|
||
(reverse install) (reverse upgrade) (reverse downgrade))))
|
||
((entry rest ...)
|
||
;; Check whether installing ENTRY corresponds to the installation of a
|
||
;; new package or to an upgrade.
|
||
|
||
;; XXX: When the exact same output directory is installed, we're not
|
||
;; really upgrading anything. Add a check for that case.
|
||
(let* ((pattern (manifest-entry->pattern entry))
|
||
(previous (manifest-lookup manifest pattern))
|
||
(newer? (and previous
|
||
(version>=? (manifest-entry-version entry)
|
||
(manifest-entry-version previous)))))
|
||
(loop rest
|
||
(if previous install (cons entry install))
|
||
(if (and previous newer?)
|
||
(alist-cons previous entry upgrade)
|
||
upgrade)
|
||
(if (and previous (not newer?))
|
||
(alist-cons previous entry downgrade)
|
||
downgrade)))))))
|
||
|
||
(define (manifest-perform-transaction manifest transaction)
|
||
"Perform TRANSACTION on MANIFEST and return new manifest."
|
||
(let ((install (manifest-transaction-install transaction))
|
||
(remove (manifest-transaction-remove transaction)))
|
||
(manifest-add (manifest-remove manifest remove)
|
||
install)))
|
||
|
||
|
||
;;;
|
||
;;; Profiles.
|
||
;;;
|
||
|
||
(define (manifest-inputs manifest)
|
||
"Return a list of <gexp-input> objects for MANIFEST."
|
||
(append-map (match-lambda
|
||
(($ <manifest-entry> name version output thing deps)
|
||
;; THING may be a package or a file name. In the latter case,
|
||
;; assume it's already valid. Ditto for DEPS.
|
||
(cons (gexp-input thing output) deps)))
|
||
(manifest-entries manifest)))
|
||
|
||
(define (info-dir-file manifest)
|
||
"Return a derivation that builds the 'dir' file for all the entries of
|
||
MANIFEST."
|
||
(define texinfo ;lazy reference
|
||
(module-ref (resolve-interface '(gnu packages texinfo)) 'texinfo))
|
||
(define gzip ;lazy reference
|
||
(module-ref (resolve-interface '(gnu packages compression)) 'gzip))
|
||
|
||
(define build
|
||
#~(begin
|
||
(use-modules (guix build utils)
|
||
(srfi srfi-1) (srfi srfi-26)
|
||
(ice-9 ftw))
|
||
|
||
(define (info-file? file)
|
||
(or (string-suffix? ".info" file)
|
||
(string-suffix? ".info.gz" file)))
|
||
|
||
(define (info-files top)
|
||
(let ((infodir (string-append top "/share/info")))
|
||
(map (cut string-append infodir "/" <>)
|
||
(or (scandir infodir info-file?) '()))))
|
||
|
||
(define (install-info info)
|
||
(setenv "PATH" (string-append #+gzip "/bin")) ;for info.gz files
|
||
(zero?
|
||
(system* (string-append #+texinfo "/bin/install-info")
|
||
info (string-append #$output "/share/info/dir"))))
|
||
|
||
(mkdir-p (string-append #$output "/share/info"))
|
||
(every install-info
|
||
(append-map info-files
|
||
'#$(manifest-inputs manifest)))))
|
||
|
||
(gexp->derivation "info-dir" build
|
||
#:modules '((guix build utils))))
|
||
|
||
(define (ghc-package-cache-file manifest)
|
||
"Return a derivation that builds the GHC 'package.cache' file for all the
|
||
entries of MANIFEST, or #f if MANIFEST does not have any GHC packages."
|
||
(define ghc ;lazy reference
|
||
(module-ref (resolve-interface '(gnu packages haskell)) 'ghc))
|
||
|
||
(define build
|
||
#~(begin
|
||
(use-modules (guix build utils)
|
||
(srfi srfi-1) (srfi srfi-26)
|
||
(ice-9 ftw))
|
||
|
||
(define ghc-name-version
|
||
(let* ((base (basename #+ghc)))
|
||
(string-drop base
|
||
(+ 1 (string-index base #\-)))))
|
||
|
||
(define db-subdir
|
||
(string-append "lib/" ghc-name-version "/package.conf.d"))
|
||
|
||
(define db-dir
|
||
(string-append #$output "/" db-subdir))
|
||
|
||
(define (conf-files top)
|
||
(find-files (string-append top "/" db-subdir) "\\.conf$"))
|
||
|
||
(define (copy-conf-file conf)
|
||
(let ((base (basename conf)))
|
||
(copy-file conf (string-append db-dir "/" base))))
|
||
|
||
(system* (string-append #+ghc "/bin/ghc-pkg") "init" db-dir)
|
||
(for-each copy-conf-file
|
||
(append-map conf-files
|
||
'#$(manifest-inputs manifest)))
|
||
(let ((success
|
||
(zero?
|
||
(system* (string-append #+ghc "/bin/ghc-pkg") "recache"
|
||
(string-append "--package-db=" db-dir)))))
|
||
(for-each delete-file (find-files db-dir "\\.conf$"))
|
||
success)))
|
||
|
||
;; Don't depend on GHC when there's nothing to do.
|
||
(and (any (cut string-prefix? "ghc" <>)
|
||
(map manifest-entry-name (manifest-entries manifest)))
|
||
(gexp->derivation "ghc-package-cache" build
|
||
#:modules '((guix build utils))
|
||
#:local-build? #t)))
|
||
|
||
(define (ca-certificate-bundle manifest)
|
||
"Return a derivation that builds a single-file bundle containing the CA
|
||
certificates in the /etc/ssl/certs sub-directories of the packages in
|
||
MANIFEST. Single-file bundles are required by programs such as Git and Lynx."
|
||
;; See <http://lists.gnu.org/archive/html/guix-devel/2015-02/msg00429.html>
|
||
;; for a discussion.
|
||
|
||
(define glibc-utf8-locales ;lazy reference
|
||
(module-ref (resolve-interface '(gnu packages base)) 'glibc-utf8-locales))
|
||
|
||
(define build
|
||
#~(begin
|
||
(use-modules (guix build utils)
|
||
(rnrs io ports)
|
||
(srfi srfi-1)
|
||
(srfi srfi-26)
|
||
(ice-9 ftw)
|
||
(ice-9 match))
|
||
|
||
(define (pem-file? file)
|
||
(string-suffix? ".pem" file))
|
||
|
||
(define (ca-files top)
|
||
(let ((cert-dir (string-append top "/etc/ssl/certs")))
|
||
(map (cut string-append cert-dir "/" <>)
|
||
(or (scandir cert-dir pem-file?) '()))))
|
||
|
||
(define (concatenate-files files result)
|
||
"Make RESULT the concatenation of all of FILES."
|
||
(define (dump file port)
|
||
(display (call-with-input-file file get-string-all)
|
||
port)
|
||
(newline port)) ;required, see <https://bugs.debian.org/635570>
|
||
|
||
(call-with-output-file result
|
||
(lambda (port)
|
||
(for-each (cut dump <> port) files))))
|
||
|
||
;; Some file names in the NSS certificates are UTF-8 encoded so
|
||
;; install a UTF-8 locale.
|
||
(setenv "LOCPATH" (string-append #+glibc-utf8-locales "/lib/locale"))
|
||
(setlocale LC_ALL "en_US.UTF-8")
|
||
|
||
(match (append-map ca-files '#$(manifest-inputs manifest))
|
||
(()
|
||
;; Since there are no CA files, just create an empty directory. Do
|
||
;; not create the etc/ssl/certs sub-directory, since that would
|
||
;; wrongfully lead to a message about 'SSL_CERT_DIR' needing to be
|
||
;; defined.
|
||
(mkdir #$output)
|
||
#t)
|
||
((ca-files ...)
|
||
(let ((result (string-append #$output "/etc/ssl/certs")))
|
||
(mkdir-p result)
|
||
(concatenate-files ca-files
|
||
(string-append result
|
||
"/ca-certificates.crt"))
|
||
#t)))))
|
||
|
||
(gexp->derivation "ca-certificate-bundle" build
|
||
#:modules '((guix build utils))
|
||
#:local-build? #t))
|
||
|
||
(define %default-profile-hooks
|
||
;; This is the list of derivation-returning procedures that are called by
|
||
;; default when making a non-empty profile.
|
||
(list info-dir-file
|
||
ghc-package-cache-file
|
||
ca-certificate-bundle))
|
||
|
||
(define* (profile-derivation manifest
|
||
#:key
|
||
(hooks %default-profile-hooks))
|
||
"Return a derivation that builds a profile (aka. 'user environment') with
|
||
the given MANIFEST. The profile includes additional derivations returned by
|
||
the monadic procedures listed in HOOKS--such as an Info 'dir' file, etc."
|
||
(mlet %store-monad ((extras (if (null? (manifest-entries manifest))
|
||
(return '())
|
||
(sequence %store-monad
|
||
(filter-map (lambda (hook)
|
||
(hook manifest))
|
||
hooks)))))
|
||
(define inputs
|
||
(append (map gexp-input extras)
|
||
(manifest-inputs manifest)))
|
||
|
||
(define builder
|
||
#~(begin
|
||
(use-modules (ice-9 pretty-print)
|
||
(guix build union))
|
||
|
||
(setvbuf (current-output-port) _IOLBF)
|
||
(setvbuf (current-error-port) _IOLBF)
|
||
|
||
(union-build #$output '#$inputs
|
||
#:log-port (%make-void-port "w"))
|
||
(call-with-output-file (string-append #$output "/manifest")
|
||
(lambda (p)
|
||
(pretty-print '#$(manifest->gexp manifest) p)))))
|
||
|
||
(gexp->derivation "profile" builder
|
||
#:modules '((guix build union))
|
||
#:local-build? #t)))
|
||
|
||
(define (profile-regexp profile)
|
||
"Return a regular expression that matches PROFILE's name and number."
|
||
(make-regexp (string-append "^" (regexp-quote (basename profile))
|
||
"-([0-9]+)")))
|
||
|
||
(define (generation-number profile)
|
||
"Return PROFILE's number or 0. An absolute file name must be used."
|
||
(or (and=> (false-if-exception (regexp-exec (profile-regexp profile)
|
||
(basename (readlink profile))))
|
||
(compose string->number (cut match:substring <> 1)))
|
||
0))
|
||
|
||
(define (generation-numbers profile)
|
||
"Return the sorted list of generation numbers of PROFILE, or '(0) if no
|
||
former profiles were found."
|
||
(define* (scandir name #:optional (select? (const #t))
|
||
(entry<? (@ (ice-9 i18n) string-locale<?)))
|
||
;; XXX: Bug-fix version introduced in Guile v2.0.6-62-g139ce19.
|
||
(define (enter? dir stat result)
|
||
(and stat (string=? dir name)))
|
||
|
||
(define (visit basename result)
|
||
(if (select? basename)
|
||
(cons basename result)
|
||
result))
|
||
|
||
(define (leaf name stat result)
|
||
(and result
|
||
(visit (basename name) result)))
|
||
|
||
(define (down name stat result)
|
||
(visit "." '()))
|
||
|
||
(define (up name stat result)
|
||
(visit ".." result))
|
||
|
||
(define (skip name stat result)
|
||
;; All the sub-directories are skipped.
|
||
(visit (basename name) result))
|
||
|
||
(define (error name* stat errno result)
|
||
(if (string=? name name*) ; top-level NAME is unreadable
|
||
result
|
||
(visit (basename name*) result)))
|
||
|
||
(and=> (file-system-fold enter? leaf down up skip error #f name lstat)
|
||
(lambda (files)
|
||
(sort files entry<?))))
|
||
|
||
(match (scandir (dirname profile)
|
||
(cute regexp-exec (profile-regexp profile) <>))
|
||
(#f ; no profile directory
|
||
'(0))
|
||
(() ; no profiles
|
||
'(0))
|
||
((profiles ...) ; former profiles around
|
||
(sort (map (compose string->number
|
||
(cut match:substring <> 1)
|
||
(cute regexp-exec (profile-regexp profile) <>))
|
||
profiles)
|
||
<))))
|
||
|
||
(define (profile-generations profile)
|
||
"Return a list of PROFILE's generations."
|
||
(let ((generations (generation-numbers profile)))
|
||
(if (equal? generations '(0))
|
||
'()
|
||
generations)))
|
||
|
||
(define* (relative-generation profile shift #:optional
|
||
(current (generation-number profile)))
|
||
"Return PROFILE's generation shifted from the CURRENT generation by SHIFT.
|
||
SHIFT is a positive or negative number.
|
||
Return #f if there is no such generation."
|
||
(let* ((abs-shift (abs shift))
|
||
(numbers (profile-generations profile))
|
||
(from-current (memq current
|
||
(if (negative? shift)
|
||
(reverse numbers)
|
||
numbers))))
|
||
(and from-current
|
||
(< abs-shift (length from-current))
|
||
(list-ref from-current abs-shift))))
|
||
|
||
(define* (previous-generation-number profile #:optional
|
||
(number (generation-number profile)))
|
||
"Return the number of the generation before generation NUMBER of
|
||
PROFILE, or 0 if none exists. It could be NUMBER - 1, but it's not the
|
||
case when generations have been deleted (there are \"holes\")."
|
||
(or (relative-generation profile -1 number)
|
||
0))
|
||
|
||
(define (generation-file-name profile generation)
|
||
"Return the file name for PROFILE's GENERATION."
|
||
(format #f "~a-~a-link" profile generation))
|
||
|
||
(define (generation-time profile number)
|
||
"Return the creation time of a generation in the UTC format."
|
||
(make-time time-utc 0
|
||
(stat:ctime (stat (generation-file-name profile number)))))
|
||
|
||
;;; profiles.scm ends here
|