Today's Guile 3 'core-updates' cannot pull yesterday's 2.2 master

Done

Details

4 participants

Ludovic Courtès
Christopher Baines
Marius Bakke
zimoun

Owner: unassigned

Submitted by: Christopher Baines

Severity: important

Christopher Baines wrote on 2 May 2020 17:47

Channel/inferior error with core-updates: Unbound variable: call-with-new-thread

Recipients:(address . bug-guix@gnu.org)

Message-ID:87h7wymj8a.fsf@cbaines.net

Noticed this when testing guix system build with core-updates. Here's a

small example which reproduces the issue:

(use-modules (guix channels)

(guix inferior))

(define channels

(list (channel

(name 'guix)

(url "https://git.savannah.gnu.org/git/guix.git")

(commit

"e02c2f85b36ce1c733bd908a210ce1182bdd2560"))))

(define inferior

(inferior-for-channels channels))

(first (lookup-inferior-packages inferior "linux-libre" "5.2.21"))

If you save that as a file then attempt to build it:

→ guix build -f test.scm

Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...

Backtrace:

4 (primitive-load "/gnu/store/8mv5bpjgxg9c369xnbb5rf1kv9r?")

In ice-9/eval.scm:

619:8 3 (_ #(#(#(#(#(#(#(#(#(#(#(?) ?) ?) ?) ?) ?) ?) ?) ?) ?) ?))

182:19 2 (proc #(#(#(#(#(#(#(#(#(#(# ?) ?) ?) ?) ?) ?) ?) ?) ?) ?))

142:16 1 (compile-top-call #<directory (guile-user) 7f1e0abc1f00> ?)

In unknown file:

0 (%resolve-variable (7 . call-with-new-thread) #<directo?>)

ERROR: In procedure %resolve-variable:

Unbound variable: call-with-new-thread

guix build: error: You found a bug: the program '/gnu/store/8mv5bpjgxg9c369xnbb5rf1kv9r6z5hw-compute-guix-derivation'

failed to compute the derivation for Guix (version: "e02c2f85b36ce1c733bd908a210ce1182bdd2560"; system: "x86_64-linux";

host version: "a8cb1e72ef351330d1521833c1b270dcc0da593f"; pull-version: 1).

Please report it by email to <bug-guix@gnu.org>.

Ludovic Courtès wrote on 5 May 2020 21:34

control message for bug #41028

Recipients:(address . control@debbugs.gnu.org)

Message-ID:87368ekwfj.fsf@gnu.org

severity 41028 important

quit

Ludovic Courtès wrote on 5 May 2020 23:24

Re: bug#41028: Channel/inferior error with core-updates: Unbound variable: call-with-new-thread

Recipients:(name . Christopher Baines)(address . mail@cbaines.net)(address . 41028@debbugs.gnu.org)

Message-ID:87r1vyjcs9.fsf@gnu.org

Hey!

Christopher Baines <mail@cbaines.net> skribis:

Toggle quote (17 lines)> → guix build -f test.scm 
> Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
> Backtrace:
>            4 (primitive-load "/gnu/store/8mv5bpjgxg9c369xnbb5rf1kv9r?")
> In ice-9/eval.scm:
>     619:8  3 (_ #(#(#(#(#(#(#(#(#(#(#(?) ?) ?) ?) ?) ?) ?) ?) ?) ?) ?))
>    182:19  2 (proc #(#(#(#(#(#(#(#(#(#(# ?) ?) ?) ?) ?) ?) ?) ?) ?) ?))
>    142:16  1 (compile-top-call #<directory (guile-user) 7f1e0abc1f00> ?)
> In unknown file:
>            0 (%resolve-variable (7 . call-with-new-thread) #<directo?>)
>
> ERROR: In procedure %resolve-variable:
> Unbound variable: call-with-new-thread
> guix build: error: You found a bug: the program '/gnu/store/8mv5bpjgxg9c369xnbb5rf1kv9r6z5hw-compute-guix-derivation'
> failed to compute the derivation for Guix (version: "e02c2f85b36ce1c733bd908a210ce1182bdd2560"; system: "x86_64-linux";
> host version: "a8cb1e72ef351330d1521833c1b270dcc0da593f"; pull-version: 1).

A summary of the IRC discussion and experiments:

1. The underlying problem is a missing (ice-9 threads) import in the

‘compute-guix-derivation’ script, fixed in

05e783871c2c69b402e088863d46f5be7915ac74.

2. The ‘%quirks’ mechanism in (guix channels) doesn’t work as is here

because what we would need to change is the #:guile parameter

passed to ‘gexp->script’ (the one defined in build-self.scm).

Attached a patch to add a quirk but that doesn’t solve the problem.

Possible solutions include:

a. Changing the value returned by ‘default-guile’ as used by

‘gexp->script’.

b. Supporting the definition of quirks that patch the code.

Thanks,

Ludo’.

Toggle diff (92 lines)diff --git a/guix/channels.scm b/guix/channels.scm
index 041fae2a9c..cbb0a97546 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -328,16 +328,34 @@ to '%package-module-path'."
           #f
           (apply throw args)))))
 
+(define (missing-ice-9-threads-import? source)
+  "Return true of %SELF-BUILD-FILE is missing an (ice-9 threads) import as
+described at <https://bugs.gnu.org/41028>."
+  (define content
+    (call-with-input-file (string-append source "/" %self-build-file)
+      read-string))
+
+  ;; The faulty code uses 'call-with-new-thread' without importing (ice-9
+  ;; threads).  However, the 'call-with-new-thread' binding is no longer
+  ;; available in the default name space on Guile 3.0.
+  (and (string-contains content "(call-with-new-thread")
+       (not (string-contains content "(ice-9 threads)"))))
+
 (define (guile-2.2.4)
   (module-ref (resolve-interface '(gnu packages guile))
               'guile-2.2.4))
 
+(define (guile-2.2)
+  (module-ref (resolve-interface '(gnu packages guile))
+              'guile-2.2))
+
 (define %quirks
   ;; List of predicate/package pairs.  This allows us provide information
   ;; about specific Guile versions that old Guix revisions might need to use
   ;; just to be able to build and run the trampoline in %SELF-BUILD-FILE.  See
   ;; <https://bugs.gnu.org/37506>
-  `((,syscalls-reexports-local-variables? . ,guile-2.2.4)))
+  `((,syscalls-reexports-local-variables? . ,guile-2.2.4)
+    (,missing-ice-9-threads-import? . ,guile-2.2)))
 
 (define* (guile-for-source source #:optional (quirks %quirks))
   "Return the Guile package to use when building SOURCE or #f if the default
@@ -372,32 +390,32 @@ package modules under SOURCE using CORE, an instance of Guix."
     (string-append source "/" %self-build-file))
 
   (if (file-exists? script)
-      (let ((build (save-module-excursion
-                    (lambda ()
-                      ;; Disable deprecation warnings; it's OK for SCRIPT to
-                      ;; use deprecated APIs and the user doesn't have to know
-                      ;; about it.
-                      (parameterize ((guix-warning-port
-                                      (%make-void-port "w")))
-                        (primitive-load script)))))
-            (guile (guile-for-source source)))
+      (mlet* %store-monad ((guile -> (guile-for-source source))
+                           (_        (mwhen guile
+                                       (set-guile-for-build (pk 'G guile))))
+                           (build -> (save-module-excursion
+                                      (lambda ()
+                                        ;; Disable deprecation warnings; it's
+                                        ;; OK for SCRIPT to use deprecated
+                                        ;; APIs and the user doesn't have to
+                                        ;; know about it.
+                                        (parameterize ((guix-warning-port
+                                                        (%make-void-port "w")))
+                                          (primitive-load script))))))
         ;; BUILD must be a monadic procedure of at least one argument: the
         ;; source tree.
         ;;
         ;; Note: BUILD can return #f if it does not support %PULL-VERSION.  In
         ;; the future we'll fall back to a previous version of the protocol
         ;; when that happens.
-        (mbegin %store-monad
-          (mwhen guile
-            (set-guile-for-build guile))
 
-          ;; BUILD is usually quite costly.  Install a "trivial" build handler
-          ;; so we don't bounce an outer build-accumulator handler that could
-          ;; cause us to redo half of the BUILD computation several times just
-          ;; to realize it gives the same result.
-          (with-trivial-build-handler
-           (build source #:verbose? verbose? #:version commit
-                  #:pull-version %pull-version))))
+        ;; BUILD is usually quite costly.  Install a "trivial" build handler
+        ;; so we don't bounce an outer build-accumulator handler that could
+        ;; cause us to redo half of the BUILD computation several times just
+        ;; to realize it gives the same result.
+        (with-trivial-build-handler
+         (build source #:verbose? verbose? #:version commit
+                #:pull-version %pull-version)))
 
       ;; Build a set of modules that extend Guix using the standard method.
       (standard-module-derivation name source core dependencies)))

Ludovic Courtès wrote on 6 May 2020 23:42

Recipients:(address . 41028@debbugs.gnu.org)

Message-ID:87a72kg2qd.fsf@gnu.org

Comrades,

Christopher Baines <mail@cbaines.net> skribis:

Toggle quote (33 lines)> (use-modules (guix channels)
>              (guix inferior))
>
> (define channels
>   (list (channel
>          (name 'guix)
>          (url "https://git.savannah.gnu.org/git/guix.git")
>          (commit
>           "e02c2f85b36ce1c733bd908a210ce1182bdd2560"))))
>
> (define inferior
>   (inferior-for-channels channels))
>
> (first (lookup-inferior-packages inferior "linux-libre" "5.2.21"))
>
>
> If you save that as a file then attempt to build it:
>
>
> → guix build -f test.scm 
> Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
> Backtrace:
>            4 (primitive-load "/gnu/store/8mv5bpjgxg9c369xnbb5rf1kv9r?")
> In ice-9/eval.scm:
>     619:8  3 (_ #(#(#(#(#(#(#(#(#(#(#(?) ?) ?) ?) ?) ?) ?) ?) ?) ?) ?))
>    182:19  2 (proc #(#(#(#(#(#(#(#(#(#(# ?) ?) ?) ?) ?) ?) ?) ?) ?) ?))
>    142:16  1 (compile-top-call #<directory (guile-user) 7f1e0abc1f00> ?)
> In unknown file:
>            0 (%resolve-variable (7 . call-with-new-thread) #<directo?>)
>
> ERROR: In procedure %resolve-variable:
> Unbound variable: call-with-new-thread

The attached patches add a mechanism to patch the Guix source tree, and

then use that mechanism to add the missing (ice-9 threads) import. With

this I can do:

./pre-inst-env guix time-machine \

--commit=e02c2f85b36ce1c733bd908a210ce1182bdd2560 -- build linux-libre

… which is a simple way to do what the manifest above was about.

If we think a bit long-term, I think the %quirks and %patches mechanisms

are a necessary evil. The goal is for ‘build-self.scm’ to use as little

of the Guix API, as well as Guile APIs that are presumably here to stay.

But as we’re already seeing, there are unavoidably incompatibilities

that arise here and there. The good news is that we know today how to

modify yesterday’s code to work well, or which Guile version to use to

get it to run.

Thoughts?

Thanks,

Ludo’.

From 4ec2c3b5527b2189b3f767a980f80dee3c6717ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Wed, 6 May 2020 22:18:52 +0200
Subject: [PATCH 1/3] channels: Add 'latest-channel-instance'.

* guix/channels.scm (latest-channel-instance): New procedure.
(latest-channel-instances): Use it.
---
 guix/channels.scm | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

Toggle diff (52 lines)diff --git a/guix/channels.scm b/guix/channels.scm
index 041fae2a9c..4ffc366d6a 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -199,6 +199,14 @@ description file or its default value."
 channel INSTANCE."
   (channel-metadata-dependencies (channel-instance-metadata instance)))
 
+(define (latest-channel-instance store channel)
+  "Return the latest channel instance for CHANNEL."
+  (let-values (((checkout commit)
+                (latest-repository-commit store (channel-url channel)
+                                          #:ref (channel-reference
+                                                 channel))))
+    (channel-instance channel commit checkout)))
+
 (define* (latest-channel-instances store channels #:optional (previous-channels '()))
   "Return a list of channel instances corresponding to the latest checkouts of
 CHANNELS and the channels on which they depend.  PREVIOUS-CHANNELS is a list
@@ -224,20 +232,16 @@ of previously processed channels."
                            (G_ "Updating channel '~a' from Git repository at '~a'...~%")
                            (channel-name channel)
                            (channel-url channel))
-                   (let-values (((checkout commit)
-                                 (latest-repository-commit store (channel-url channel)
-                                                           #:ref (channel-reference
-                                                                  channel))))
-                     (let ((instance (channel-instance channel commit checkout)))
-                       (let-values (((new-instances new-channels)
-                                     (latest-channel-instances
-                                      store
-                                      (channel-instance-dependencies instance)
-                                      previous-channels)))
-                         (values (append (cons channel new-channels)
-                                         previous-channels)
-                                 (append (cons instance new-instances)
-                                         instances))))))))
+                   (let ((instance (latest-channel-instance store channel)))
+                     (let-values (((new-instances new-channels)
+                                   (latest-channel-instances
+                                    store
+                                    (channel-instance-dependencies instance)
+                                    previous-channels)))
+                       (values (append (cons channel new-channels)
+                                       previous-channels)
+                               (append (cons instance new-instances)
+                                       instances)))))))
            previous-channels
            '()                                    ;instances
            channels))
-- 
2.26.2

Attachment: 0002-channels-Add-mechanism-to-patch-checkouts-of-the-gui.patch

From 66e2ef6ae0958fa45e14c3528c767cd84e24a480 Mon Sep 17 00:00:00 2001

Subject: [PATCH 3/3] channels: Add patch for https://bugs.gnu.org/41028.

Without this patch, we couldn't jump from here to commits before

05e783871c2c69b402e088863d46f5be7915ac74 because the

'compute-guix-derivation' script would crash with an unbound-variable

error for 'call-with-new-thread'.

Fixes https://bugs.gnu.org/41028.

Reported by Christopher Baines <mail@cbaines.net>.

* guix/channels.scm (%bug-41028-patch): New variable.

(%patches): Add it.

---

guix/channels.scm | 27 ++++++++++++++++++++++++++-

1 file changed, 26 insertions(+), 1 deletion(-)

Toggle diff (51 lines)diff --git a/guix/channels.scm b/guix/channels.scm
index 75b53c3a8e..0fa036446c 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -38,6 +38,7 @@
                 #:select (source-properties->location
                           &error-location
                           &fix-hint))
+  #:use-module ((guix build utils) #:select (substitute*))
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-2)
   #:use-module (srfi srfi-9)
@@ -375,11 +376,35 @@ to '%package-module-path'."
   ;; <https://bugs.gnu.org/37506>
   `((,syscalls-reexports-local-variables? . ,guile-2.2.4)))
 
+
+(define %bug-41028-patch
+  ;; Patch for <https://bugs.gnu.org/41028>.  The faulty code is the
+  ;; 'compute-guix-derivation' body, which uses 'call-with-new-thread' without
+  ;; importing (ice-9 threads).  However, the 'call-with-new-thread' binding
+  ;; is no longer available in the default name space on Guile 3.0.
+  (let ()
+    (define (missing-ice-9-threads-import? source commit)
+      ;; Return true if %SELF-BUILD-FILE is missing an (ice-9 threads) import.
+      (define content
+        (call-with-input-file (string-append source "/" %self-build-file)
+          read-string))
+
+      (and (string-contains content "(call-with-new-thread")
+           (not (string-contains content "(ice-9 threads)"))))
+
+    (define (add-missing-ice-9-threads-import source)
+      ;; Add (ice-9 threads) import in the gexp of 'compute-guix-derivation'.
+      (substitute* (string-append source "/" %self-build-file)
+        (("^ +\\(use-modules \\(ice-9 match\\)\\)")
+         (object->string '(use-modules (ice-9 match) (ice-9 threads))))))
+
+   (patch missing-ice-9-threads-import? add-missing-ice-9-threads-import)))
+
 (define %patches
   ;; Bits of past Guix revisions can become incompatible with newer Guix and
   ;; Guile.  This variable lists <patch> records for the Guix source tree that
   ;; apply to the Guix source.
-  '())
+  (list %bug-41028-patch))
 
 (define* (guile-for-source source #:optional (quirks %quirks))
   "Return the Guile package to use when building SOURCE or #f if the default
-- 
2.26.2

Ludovic Courtès wrote on 6 May 2020 23:42

control message for bug #41028

Recipients:(address . control@debbugs.gnu.org)

Message-ID:878si4g2ov.fsf@gnu.org

retitle 41028 Today's Guile 3 'core-updates' cannot pull yesterday's 2.2 master

quit

Ludovic Courtès wrote on 7 May 2020 10:12

Re: bug#41028: Channel/inferior error with core-updates: Unbound variable: call-with-new-thread

Recipients:(name . Christopher Baines)(address . mail@cbaines.net)

Message-ID:87k11oduzx.fsf@gnu.org

Hey!

Ludovic Courtès <ludo@gnu.org> skribis:

Toggle quote (9 lines)

> The attached patches add a mechanism to patch the Guix source tree, and

> then use that mechanism to add the missing (ice-9 threads) import. With

> this I can do:

> ./pre-inst-env guix time-machine \

> --commit=e02c2f85b36ce1c733bd908a210ce1182bdd2560 -- build linux-libre

> … which is a simple way to do what the manifest above was about.

Given the enthusiasm expressed on IRC, I went ahead and pushed. :-)

ff3ca7979e channels: Add patch for https://bugs.gnu.org/41028.

053b10c3ef channels: Add mechanism to patch checkouts of the 'guix channel.

4ba425060a channels: Add 'latest-channel-instance'.

So… it might be that today is merge day?

Ludo’.

Closed

zimoun wrote on 7 May 2020 12:05

Recipients:(address . 41028-done@debbugs.gnu.org)

Message-ID:CAJ3okZ3ATDRh=unpPVzVgWPbVBiZKeOnyJAR6=vvJXN1psfT7w@mail.gmail.com

Hi Ludo,

On Thu, 7 May 2020 at 10:13, Ludovic Courtès <ludo@gnu.org> wrote:

Toggle quote (6 lines)

> Given the enthusiasm expressed on IRC, I went ahead and pushed. :-)

> ff3ca7979e channels: Add patch for <https://bugs.gnu.org/41028>.

> 053b10c3ef channels: Add mechanism to patch checkouts of the 'guix channel.

> 4ba425060a channels: Add 'latest-channel-instance'.

Just to be sure to well-understand: the versions before 05e783 were

broken (guix build failed) and the proposed in-place mechanism is a

way to fix them, right?

If yes, that's awesome!

Cheers,

simon

Christopher Baines wrote on 8 May 2020 11:37

Recipients:(name . Ludovic Courtès)(address . ludo@gnu.org)

Message-ID:87sggag42e.fsf@cbaines.net

Ludovic Courtès <ludo@gnu.org> writes:

Toggle quote (19 lines)> Ludovic Courtès <ludo@gnu.org> skribis:
>
>> The attached patches add a mechanism to patch the Guix source tree, and
>> then use that mechanism to add the missing (ice-9 threads) import.  With
>> this I can do:
>>
>>   ./pre-inst-env guix time-machine \
>>      --commit=e02c2f85b36ce1c733bd908a210ce1182bdd2560 -- build linux-libre
>>
>> … which is a simple way to do what the manifest above was about.
>
> Given the enthusiasm expressed on IRC, I went ahead and pushed.  :-)
>
>   ff3ca7979e channels: Add patch for <https://bugs.gnu.org/41028>.
>   053b10c3ef channels: Add mechanism to patch checkouts of the 'guix channel.
>   4ba425060a channels: Add 'latest-channel-instance'.
>
> So… it might be that today is merge day?

Wonderful :) I've had a chance to try this out now, and it works. I was

able to reconfigure my system.

One even more niche issue is that because I'm using this channel in my

system configuration, the patching happens as root, but it's the cached

channel in my users home directory that's patched. This means that

build-self.scm becomes owned by root.

I noticed this when I went to pull:

→ guix pull --branch=core-updates

Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...

guix pull: error: Git error: could not open '/home/chris/.cache/guix/checkouts/pjmkglp4t7znuugeurpurzikxq3tnlaywmisyr27shj7apsnalwq/build-aux/build-self.scm' for writing: Permission denied

I'm not sure what the neat way of addressing this is, but maybe the file

ownership can be recorded prior to patching, and reset afterwards if

it's changed.

Thanks again for looking at the original issue Ludo,

Chris

Closed

Marius Bakke wrote on 8 May 2020 16:35

Recipients:(address . 41028-done@debbugs.gnu.org)

Message-ID:875zd6336j.fsf@devup.no

Christopher Baines <mail@cbaines.net> writes:

Toggle quote (40 lines)> Ludovic Courtès <ludo@gnu.org> writes:
>
>> Ludovic Courtès <ludo@gnu.org> skribis:
>>
>>> The attached patches add a mechanism to patch the Guix source tree, and
>>> then use that mechanism to add the missing (ice-9 threads) import.  With
>>> this I can do:
>>>
>>>   ./pre-inst-env guix time-machine \
>>>      --commit=e02c2f85b36ce1c733bd908a210ce1182bdd2560 -- build linux-libre
>>>
>>> … which is a simple way to do what the manifest above was about.
>>
>> Given the enthusiasm expressed on IRC, I went ahead and pushed.  :-)
>>
>>   ff3ca7979e channels: Add patch for <https://bugs.gnu.org/41028>.
>>   053b10c3ef channels: Add mechanism to patch checkouts of the 'guix channel.
>>   4ba425060a channels: Add 'latest-channel-instance'.
>>
>> So… it might be that today is merge day?
>
> Wonderful :) I've had a chance to try this out now, and it works. I was
> able to reconfigure my system.
>
> One even more niche issue is that because I'm using this channel in my
> system configuration, the patching happens as root, but it's the cached
> channel in my users home directory that's patched. This means that
> build-self.scm becomes owned by root.
>
> I noticed this when I went to pull:
>
>   → guix pull --branch=core-updates
>   Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
>   guix pull: error: Git error: could not open '/home/chris/.cache/guix/checkouts/pjmkglp4t7znuugeurpurzikxq3tnlaywmisyr27shj7apsnalwq/build-aux/build-self.scm' for writing: Permission denied
>
>
> I'm not sure what the neat way of addressing this is, but maybe the file
> ownership can be recorded prior to patching, and reset afterwards if
> it's changed.

I took a stab at exactly this:

From 993dd0d36ba8e67af5c60d73cb1f9d60741f5418 Mon Sep 17 00:00:00 2001
From: Marius Bakke <mbakke@fastmail.com>
Date: Fri, 8 May 2020 16:23:55 +0200
Subject: [PATCH] channels: Preserve permissions when patching
 https://bugs.gnu.org/41028.

* guix/channels.scm (%bug-41028-patch): Record permissions before invoking
SUBSTITUTE* and reset afterwards if file permissions differ from the current user.
---
 guix/channels.scm | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

Toggle diff (32 lines)diff --git a/guix/channels.scm b/guix/channels.scm
index 0fa036446c..a102d5bc35 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -393,10 +393,21 @@ to '%package-module-path'."
            (not (string-contains content "(ice-9 threads)"))))
 
     (define (add-missing-ice-9-threads-import source)
-      ;; Add (ice-9 threads) import in the gexp of 'compute-guix-derivation'.
-      (substitute* (string-append source "/" %self-build-file)
-        (("^ +\\(use-modules \\(ice-9 match\\)\\)")
-         (object->string '(use-modules (ice-9 match) (ice-9 threads))))))
+      (let* ((self-build-file (string-append source "/" %self-build-file))
+             ;; Record permissions so that we can reset it afterwards in case
+             ;; we run this as the root user (see <https://bugs.gnu.org/41028#29>).
+             ;; TODO: Ideally SUBSTITUTE* would preserve permissions itself.
+             (stat  (stat self-build-file))
+             (owner (stat:uid stat))
+             (group (stat:gid stat)))
+
+        ;; Add (ice-9 threads) import in the gexp of 'compute-guix-derivation'.
+        (substitute* self-build-file
+          (("^ +\\(use-modules \\(ice-9 match\\)\\)")
+           (object->string '(use-modules (ice-9 match) (ice-9 threads)))))
+
+        (unless (and (eq? (getuid) owner) (eq? (getgid) group))
+          (chown self-build-file owner group))))
 
    (patch missing-ice-9-threads-import? add-missing-ice-9-threads-import)))
 
-- 
2.26.2

WDYT?

Currently in the process of testing it locally, feedback appreciated.

Closed

Christopher Baines wrote on 8 May 2020 16:47

Recipients:(name . Marius Bakke)(address . mbakke@fastmail.com)

Message-ID:87r1vufpqp.fsf@cbaines.net

Marius Bakke <mbakke@fastmail.com> writes:

Toggle quote (44 lines)> Christopher Baines <mail@cbaines.net> writes:
>
>> Ludovic Courtès <ludo@gnu.org> writes:
>>
>>> Ludovic Courtès <ludo@gnu.org> skribis:
>>>
>>>> The attached patches add a mechanism to patch the Guix source tree, and
>>>> then use that mechanism to add the missing (ice-9 threads) import.  With
>>>> this I can do:
>>>>
>>>>   ./pre-inst-env guix time-machine \
>>>>      --commit=e02c2f85b36ce1c733bd908a210ce1182bdd2560 -- build linux-libre
>>>>
>>>> … which is a simple way to do what the manifest above was about.
>>>
>>> Given the enthusiasm expressed on IRC, I went ahead and pushed.  :-)
>>>
>>>   ff3ca7979e channels: Add patch for <https://bugs.gnu.org/41028>.
>>>   053b10c3ef channels: Add mechanism to patch checkouts of the 'guix channel.
>>>   4ba425060a channels: Add 'latest-channel-instance'.
>>>
>>> So… it might be that today is merge day?
>>
>> Wonderful :) I've had a chance to try this out now, and it works. I was
>> able to reconfigure my system.
>>
>> One even more niche issue is that because I'm using this channel in my
>> system configuration, the patching happens as root, but it's the cached
>> channel in my users home directory that's patched. This means that
>> build-self.scm becomes owned by root.
>>
>> I noticed this when I went to pull:
>>
>>   → guix pull --branch=core-updates
>>   Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
>>   guix pull: error: Git error: could not open '/home/chris/.cache/guix/checkouts/pjmkglp4t7znuugeurpurzikxq3tnlaywmisyr27shj7apsnalwq/build-aux/build-self.scm' for writing: Permission denied
>>
>>
>> I'm not sure what the neat way of addressing this is, but maybe the file
>> ownership can be recorded prior to patching, and reset afterwards if
>> it's changed.
>
> I took a stab at exactly this:

Awesome, thanks. I haven't tried it, but it looks good :)

Closed

Marius Bakke wrote on 8 May 2020 20:19

Recipients:(address . 41028-done@debbugs.gnu.org)

Message-ID:87368a2stk.fsf@devup.no

Marius Bakke <mbakke@fastmail.com> writes:

Toggle quote (62 lines)> Christopher Baines <mail@cbaines.net> writes:
>
>> One even more niche issue is that because I'm using this channel in my
>> system configuration, the patching happens as root, but it's the cached
>> channel in my users home directory that's patched. This means that
>> build-self.scm becomes owned by root.
>>
>> I noticed this when I went to pull:
>>
>>   → guix pull --branch=core-updates
>>   Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
>>   guix pull: error: Git error: could not open '/home/chris/.cache/guix/checkouts/pjmkglp4t7znuugeurpurzikxq3tnlaywmisyr27shj7apsnalwq/build-aux/build-self.scm' for writing: Permission denied
>>
>>
>> I'm not sure what the neat way of addressing this is, but maybe the file
>> ownership can be recorded prior to patching, and reset afterwards if
>> it's changed.
>
> I took a stab at exactly this:
>
> From 993dd0d36ba8e67af5c60d73cb1f9d60741f5418 Mon Sep 17 00:00:00 2001
> From: Marius Bakke <mbakke@fastmail.com>
> Date: Fri, 8 May 2020 16:23:55 +0200
> Subject: [PATCH] channels: Preserve permissions when patching
>  <https://bugs.gnu.org/41028>.
>
> * guix/channels.scm (%bug-41028-patch): Record permissions before invoking
> SUBSTITUTE* and reset afterwards if file permissions differ from the current user.
> ---
>  guix/channels.scm | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/guix/channels.scm b/guix/channels.scm
> index 0fa036446c..a102d5bc35 100644
> --- a/guix/channels.scm
> +++ b/guix/channels.scm
> @@ -393,10 +393,21 @@ to '%package-module-path'."
>             (not (string-contains content "(ice-9 threads)"))))
>  
>      (define (add-missing-ice-9-threads-import source)
> -      ;; Add (ice-9 threads) import in the gexp of 'compute-guix-derivation'.
> -      (substitute* (string-append source "/" %self-build-file)
> -        (("^ +\\(use-modules \\(ice-9 match\\)\\)")
> -         (object->string '(use-modules (ice-9 match) (ice-9 threads))))))
> +      (let* ((self-build-file (string-append source "/" %self-build-file))
> +             ;; Record permissions so that we can reset it afterwards in case
> +             ;; we run this as the root user (see <https://bugs.gnu.org/41028#29>).
> +             ;; TODO: Ideally SUBSTITUTE* would preserve permissions itself.
> +             (stat  (stat self-build-file))
> +             (owner (stat:uid stat))
> +             (group (stat:gid stat)))
> +
> +        ;; Add (ice-9 threads) import in the gexp of 'compute-guix-derivation'.
> +        (substitute* self-build-file
> +          (("^ +\\(use-modules \\(ice-9 match\\)\\)")
> +           (object->string '(use-modules (ice-9 match) (ice-9 threads)))))
> +
> +        (unless (and (eq? (getuid) owner) (eq? (getgid) group))
> +          (chown self-build-file owner group))))
>  
>     (patch missing-ice-9-threads-import? add-missing-ice-9-threads-import)))

Ludovic pointed out on IRC that 'sudo guix system build foo.scm' with an

inferior will update the cached checkout (typically

~/.cache/guix/checkouts/pjmkglp4t7znuugeurpurzikxq3tnlaywmisyr27shj7apsnalwq)

as root, and break subsequent unprivileged 'guix pull' operations anyway.

Which is partially correct: .git/index and .git/refs/heads/master will

be owned by root in that case, but you are still allowed to unlink() and

rename() such files as long as you own the directory, so libgit2 will

successfully reset permissions on the checkout even after pulling as

root!

It fails to do that for build-self.scm because it does not know it has

changed, and tries opening it directly with O_WRONLY (which fails). I

can confirm that this patch solves that problem, and unprivileged 'guix

pull' works again even after previously using sudo.

Now, users are likely to run into other issues when using inferiors with

sudo (e.g. if new directories are added), so I'm not sure if this patch

is worth the effort.

Perhaps the Guix git cache should be per-uid, but that requires more

intrusive changes.

Thoughts?

Closed

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