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From: Maxim Cournoyer <maxim.cournoyer@gmail.com>
To: 64746@debbugs.gnu.org
Cc: "Ludovic Courtès" <ludo@gnu.org>,
	"Maxim Cournoyer" <maxim.cournoyer@gmail.com>,
	"Simon Tournier" <zimon.toutoune@gmail.com>,
	"Christopher Baines" <guix@cbaines.net>,
	"Josselin Poiret" <dev@jpoiret.xyz>,
	"Ludovic Courtès" <ludo@gnu.org>,
	"Mathieu Othacehe" <othacehe@gnu.org>,
	"Ricardo Wurmus" <rekado@elephly.net>,
	"Simon Tournier" <zimon.toutoune@gmail.com>,
	"Tobias Geerinckx-Rice" <me@tobias.gr>
Subject: [bug#64746] [PATCH v2 3/3] scripts: time-machine: Error when attempting to visit too old commits.
Date: Tue, 15 Aug 2023 15:44:09 -0400	[thread overview]
Message-ID: <7ce3ce800ab5dde1cdaaf272a54738be6256c1b3.1692128648.git.maxim.cournoyer@gmail.com> (raw)
In-Reply-To: <340786ccd3d40c0c8906028dc20af5ae9b0aa6b9.1692128648.git.maxim.cournoyer@gmail.com>

* doc/guix.texi (Invoking guix time-machine): Document limitation.
* guix/inferior.scm (cached-channel-instance): New VALIDATE-CHANNELS
argument.  Use it to validate channels when there are no cache hit.
* guix/scripts/time-machine.scm
(%options): Tag the given reference with 'tag-or-commit instead of 'commit.
(%oldest-possible-commit): New variable.
(guix-time-machine) <validate-guix-channel>: New nested procedure.  Pass it to
the 'cached-channel-instance' call.
* tests/guix-time-machine.sh: New test.
* Makefile.am (SH_TESTS): Register it.

Suggested-by: Simon Tournier <zimon.toutoune@gmail.com>
Reviewed-by: Ludovic Courtès <ludo@gnu.org>

---

Changes in v2:
- Test it
- Delay validation work to inside cached-channel-instance, when there's no
cache hit
- Expound doc to mention possible problems and possible workarounds

 Makefile.am                   |  1 +
 doc/guix.texi                 | 14 +++++++++
 guix/inferior.scm             | 57 ++++++++++++++++++++---------------
 guix/scripts/time-machine.scm | 38 +++++++++++++++++++++--
 tests/guix-time-machine.sh    | 28 +++++++++++++++++
 5 files changed, 110 insertions(+), 28 deletions(-)
 create mode 100644 tests/guix-time-machine.sh

diff --git a/Makefile.am b/Makefile.am
index 5ffcb6a12d..4228c07803 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -615,6 +615,7 @@ SH_TESTS =					\
   tests/guix-refresh.sh				\
   tests/guix-shell.sh				\
   tests/guix-shell-export-manifest.sh		\
+  tests/guix-time-machine.sh			\
   tests/guix-graph.sh				\
   tests/guix-describe.sh			\
   tests/guix-repl.sh     			\
diff --git a/doc/guix.texi b/doc/guix.texi
index b50feed4c4..a3754b7019 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -5060,6 +5060,20 @@ Invoking guix time-machine
 large number of packages; the result is cached though and subsequent
 commands targeting the same commit are almost instantaneous.
 
+Due to @command{guix time-machine} relying on the ``inferiors''
+mechanism (@pxref{Inferiors}), the oldest commit it can travel to is
+commit @samp{6298c3ff} (``v1.0.0''), dated May 1@sup{st}, 2019, which is
+the first release that included the inferiors mechanism.  An error is
+returned when attempting to navigate to older commits.  Note that
+although it should technically be possible to travel to such an old
+commit, the ease to do so will largely depend on the availability of
+binary substitutes.  When traveling to a distant past, some packages may
+not easily build from source anymore.  One such example are old versions
+of Python 2 which had time bombs in its test suite, in the form of
+expiring SSL certificates.  This particular problem can be worked around
+by setting the hardware clock to a value in the past before attempting
+the build.
+
 @quotation Note
 The history of Guix is immutable and @command{guix time-machine}
 provides the exact same software as they are in a specific Guix
diff --git a/guix/inferior.scm b/guix/inferior.scm
index 5dfd30a6c8..fca6fb4b22 100644
--- a/guix/inferior.scm
+++ b/guix/inferior.scm
@@ -871,11 +871,15 @@ (define* (cached-channel-instance store
                                   #:key
                                   (authenticate? #t)
                                   (cache-directory (%inferior-cache-directory))
-                                  (ttl (* 3600 24 30)))
+                                  (ttl (* 3600 24 30))
+                                  validate-channels)
   "Return a directory containing a guix filetree defined by CHANNELS, a list of channels.
-The directory is a subdirectory of CACHE-DIRECTORY, where entries can be reclaimed after TTL seconds.
-This procedure opens a new connection to the build daemon.  AUTHENTICATE?
-determines whether CHANNELS are authenticated."
+The directory is a subdirectory of CACHE-DIRECTORY, where entries can be
+reclaimed after TTL seconds.  This procedure opens a new connection to the
+build daemon.  AUTHENTICATE? determines whether CHANNELS are authenticated.
+VALIDATE-CHANNELS, if specified, must be a one argument procedure accepting a
+list of channels that can be used to validate the channels; it should raise an
+exception in case of problems."
   (define commits
     ;; Since computing the instances of CHANNELS is I/O-intensive, use a
     ;; cheaper way to get the commit list of CHANNELS.  This limits overhead
@@ -923,27 +927,30 @@ (define* (cached-channel-instance store
 
   (if (file-exists? cached)
       cached
-      (run-with-store store
-        (mlet* %store-monad ((instances
-                              -> (latest-channel-instances store channels
-                                                           #:authenticate?
-                                                           authenticate?))
-                             (profile
-                              (channel-instances->derivation instances)))
-          (mbegin %store-monad
-            ;; It's up to the caller to install a build handler to report
-            ;; what's going to be built.
-            (built-derivations (list profile))
-
-            ;; Cache if and only if AUTHENTICATE? is true.
-            (if authenticate?
-                (mbegin %store-monad
-                  (symlink* (derivation->output-path profile) cached)
-                  (add-indirect-root* cached)
-                  (return cached))
-                (mbegin %store-monad
-                  (add-temp-root* (derivation->output-path profile))
-                  (return (derivation->output-path profile)))))))))
+      (begin
+        (when (procedure? validate-channels)
+          (validate-channels channels))
+        (run-with-store store
+          (mlet* %store-monad ((instances
+                                -> (latest-channel-instances store channels
+                                                             #:authenticate?
+                                                             authenticate?))
+                               (profile
+                                (channel-instances->derivation instances)))
+            (mbegin %store-monad
+              ;; It's up to the caller to install a build handler to report
+              ;; what's going to be built.
+              (built-derivations (list profile))
+
+              ;; Cache if and only if AUTHENTICATE? is true.
+              (if authenticate?
+                  (mbegin %store-monad
+                    (symlink* (derivation->output-path profile) cached)
+                    (add-indirect-root* cached)
+                    (return cached))
+                  (mbegin %store-monad
+                    (add-temp-root* (derivation->output-path profile))
+                    (return (derivation->output-path profile))))))))))
 
 (define* (inferior-for-channels channels
                                 #:key
diff --git a/guix/scripts/time-machine.scm b/guix/scripts/time-machine.scm
index d7c71ef705..e4fe511382 100644
--- a/guix/scripts/time-machine.scm
+++ b/guix/scripts/time-machine.scm
@@ -2,6 +2,7 @@
 ;;; Copyright © 2019 Konrad Hinsen <konrad.hinsen@fastmail.net>
 ;;; Copyright © 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
+;;; Copyright © 2023 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -19,13 +20,15 @@
 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (guix scripts time-machine)
+  #:use-module (guix channels)
+  #:use-module (guix diagnostics)
   #:use-module (guix ui)
   #:use-module (guix scripts)
   #:use-module (guix inferior)
   #:use-module (guix store)
   #:use-module (guix status)
   #:use-module ((guix git)
-                #:select (with-git-error-handling))
+                #:select (update-cached-checkout with-git-error-handling))
   #:use-module ((guix utils)
                 #:select (%current-system))
   #:use-module ((guix scripts pull)
@@ -38,9 +41,17 @@ (define-module (guix scripts time-machine)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-37)
+  #:use-module (srfi srfi-71)
   #:export (guix-time-machine))
 
+;;; The required inferiors mechanism relied on by 'guix time-machine' was
+;;; firmed up in v1.0.0; it is the oldest, safest commit that can be travelled
+;;; to.
+(define %oldest-possible-commit
+  "6298c3ffd9654d3231a6f25390b056483e8f407c") ;v1.0.0
+
 \f
 ;;;
 ;;; Command-line options.
@@ -81,7 +92,7 @@ (define %options
                                (alist-delete 'repository-url result))))
          (option '("commit") #t #f
                  (lambda (opt name arg result)
-                   (alist-cons 'ref `(commit . ,arg) result)))
+                   (alist-cons 'ref `(tag-or-commit . ,arg) result)))
          (option '("branch") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'ref `(branch . ,arg) result)))
@@ -140,8 +151,27 @@ (define-command (guix-time-machine . args)
      (let* ((opts         (parse-args args))
             (channels     (channel-list opts))
             (command-line (assoc-ref opts 'exec))
+            (ref          (assoc-ref opts 'ref))
             (substitutes?  (assoc-ref opts 'substitutes?))
             (authenticate? (assoc-ref opts 'authenticate-channels?)))
+
+       (define (validate-guix-channel channels)
+         "Finds the Guix channel among CHANNELS, and validates that REF as
+captured from the closure, a git reference specification such as a commit hash
+or tag associated to CHANNEL, is valid and new enough to satisfy the 'guix
+time-machine' requirements.  A `formatted-message' condition is raised
+otherwise."
+         (let* ((guix-channel (find guix-channel? channels))
+                (checkout commit relation (update-cached-checkout
+                                           (channel-url guix-channel)
+                                           #:ref (or ref '())
+                                           #:starting-commit
+                                           %oldest-possible-commit)))
+           (unless (memq relation '(ancestor self))
+             (raise (formatted-message
+                     (G_ "cannot travel past commit `~a' from May 1st, 2019")
+                     (string-take %oldest-possible-commit 12))))))
+
        (when command-line
          (let* ((directory
                  (with-store store
@@ -153,6 +183,8 @@ (define-command (guix-time-machine . args)
                                                          #:dry-run? #f)
                        (set-build-options-from-command-line store opts)
                        (cached-channel-instance store channels
-                                                #:authenticate? authenticate?)))))
+                                                #:authenticate? authenticate?
+                                                #:validate-channels
+                                                validate-guix-channel)))))
                 (executable (string-append directory "/bin/guix")))
            (apply execl (cons* executable executable command-line))))))))
diff --git a/tests/guix-time-machine.sh b/tests/guix-time-machine.sh
new file mode 100644
index 0000000000..8b62ef75ea
--- /dev/null
+++ b/tests/guix-time-machine.sh
@@ -0,0 +1,28 @@
+# GNU Guix --- Functional package management for GNU
+# Copyright © 2023 Maxim Cournoyer <maxim.cournoyer@gmail.com>
+#
+# 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/>.
+
+#
+# Test the 'guix time-machine' command-line utility.
+#
+
+guix time-machine --version
+
+# Visiting a commit older than v1.0.0 fails.
+! guix time-machine --commit=v0.15.0
+
+exit 0
-- 
2.41.0





  parent reply	other threads:[~2023-08-15 20:13 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1689823648.git.maxim.cournoyer@gmail.com>
2023-07-20 16:34 ` [bug#64746] [PATCH 2/2] scripts: time-machine: Error when attempting to visit too old commits Maxim Cournoyer
2023-07-22  2:00   ` Maxim Cournoyer
2023-08-08 15:58     ` Ludovic Courtès
2023-08-10 14:47       ` Maxim Cournoyer
2023-08-10 16:56         ` Ludovic Courtès
2023-08-11  7:19           ` Josselin Poiret via Guix-patches via
2023-08-12 20:32             ` Ludovic Courtès
2023-08-15 18:57       ` Maxim Cournoyer
2023-08-15 16:14   ` Ludovic Courtès
2023-08-16 14:46     ` Simon Tournier
2023-08-16 18:41       ` Maxim Cournoyer
2023-08-17 14:06         ` [bug#65352] Fix time-machine and network Simon Tournier
2023-08-17 14:09           ` [bug#65352] [PATCH 1/2] guix: git: Fix the procedure reference-available? Simon Tournier
2023-08-17 14:09             ` [bug#65352] [PATCH 2/2] scripts: pull: Remove unused reference pair Simon Tournier
2023-08-17 15:41               ` [bug#65352] Fix time-machine and network Maxim Cournoyer
2023-08-17 16:08                 ` Simon Tournier
2023-08-23  2:56                   ` Maxim Cournoyer
2023-08-23  8:32                     ` Simon Tournier
2023-08-23 20:25                       ` Maxim Cournoyer
2023-08-21 14:00                 ` Ludovic Courtès
2023-08-21 15:58                   ` Maxim Cournoyer
2023-08-22 16:27                     ` Ludovic Courtès
2023-08-23  2:14                       ` Maxim Cournoyer
2023-08-21 13:57             ` Ludovic Courtès
2023-09-04  8:49             ` Ludovic Courtès
2023-09-04 11:34               ` Simon Tournier
2023-09-05 20:33                 ` Maxim Cournoyer
2023-09-05 20:48                   ` Simon Tournier
2023-09-04  9:32             ` Ludovic Courtès
2023-09-04 17:37               ` Simon Tournier
2023-09-06  0:22                 ` Maxim Cournoyer
2023-09-05 20:39               ` Maxim Cournoyer
2023-09-05 20:56                 ` Simon Tournier
2023-09-06  2:39                   ` Maxim Cournoyer
2023-09-05 13:24             ` bug#65352: " Maxim Cournoyer
2023-09-05 13:43               ` [bug#65352] " Simon Tournier
2023-09-06  0:04                 ` bug#65352: " Maxim Cournoyer
2023-09-06  0:58                   ` [bug#65352] " Simon Tournier
2023-09-06  2:00                     ` Maxim Cournoyer
2023-09-07 11:15                       ` Simon Tournier
2023-09-06 10:32           ` [bug#65352] time-machine, unavailable network or Savannah down Simon Tournier
2023-09-06 14:17             ` [bug#65352] [PATCH v2] DRAFT git: Avoid touching the network unless needed in 'reference-available?' Simon Tournier
2023-09-13 20:16               ` [bug#65352] Fix time-machine and network Ludovic Courtès
2023-09-13  0:32                 ` Simon Tournier
2023-09-14  8:50                   ` Ludovic Courtès
2023-09-14  9:04                   ` Ludovic Courtès
2023-09-14  9:42                     ` Simon Tournier
2023-09-22 13:54                       ` bug#65352: " Simon Tournier
2023-09-25  9:32                     ` [bug#65352] " Ludovic Courtès
2023-09-25  9:57                       ` Simon Tournier
2023-09-25 11:21                         ` Simon Tournier
2023-09-25 15:01                         ` Ludovic Courtès
2023-09-25 15:58                           ` Simon Tournier
2023-09-06 17:41             ` [bug#65352] time-machine, unavailable network or Savannah down Maxim Cournoyer
2023-09-06 23:21               ` Simon Tournier
2023-08-15 19:44   ` [bug#64746] [PATCH v2 1/3] git: Clarify commit relation reference in doc Maxim Cournoyer
2023-08-15 19:44     ` [bug#64746] [PATCH v2 2/3] pull: Tag commit argument with 'tag-or-commit Maxim Cournoyer
2023-08-16 15:02       ` Simon Tournier
2023-08-16 18:47         ` Maxim Cournoyer
2023-08-17 14:45           ` Simon Tournier
2023-08-17 18:16             ` Maxim Cournoyer
2023-08-17 18:47               ` Simon Tournier
2023-08-23  2:54                 ` [bug#64746] [PATCH 2/2] scripts: time-machine: Error when attempting to visit too old commits Maxim Cournoyer
2023-08-23  8:27                   ` Simon Tournier
2023-08-15 19:44     ` Maxim Cournoyer [this message]
2023-08-16 15:39       ` [bug#64746] [PATCH v2 3/3] " Simon Tournier
2023-08-17  1:41         ` bug#64746: " Maxim Cournoyer

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