[PATCH] system: Improve warning when using LUKS mapped devices without UUIDs.

DoneSubmitted by Maxim Cournoyer.
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2 participants
  • Ludovic Courtès
  • Maxim Cournoyer
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unassigned
Severity
normal
M
M
Maxim Cournoyer wrote on 14 May 08:05 +0200
(address . guix-patches@gnu.org)(name . Maxim Cournoyer)(address . maxim.cournoyer@gmail.com)
20220514060532.1011-1-maxim.cournoyer@gmail.com
This corrects two problems with the previous mapped devices warning:

1. It wasn't clear how to correct the situation.
2. The output would be repeated twice, as the procedure is called
twice during a system reconfigure.

* gnu/system.scm (operating-system-bootloader-crypto-devices): Memoize
procedure. Produce a single message for the combined problematic devices.
Add a hint to help users fix the warning.
---
gnu/system.scm | 42 +++++++++++++++++++++++-------------------
1 file changed, 23 insertions(+), 19 deletions(-)

Toggle diff (70 lines)
diff --git a/gnu/system.scm b/gnu/system.scm
index c3810cbeeb..b090eeae01 100644
--- a/gnu/system.scm
+++ b/gnu/system.scm
@@ -33,6 +33,7 @@
 (define-module (gnu system)
   #:use-module (guix inferior)
   #:use-module (guix store)
+  #:use-module (guix memoization)
   #:use-module (guix monads)
   #:use-module (guix gexp)
   #:use-module (guix records)
@@ -78,7 +79,9 @@ (define-module (gnu system)
   #:use-module (gnu system uuid)
   #:use-module (gnu system file-systems)
   #:use-module (gnu system mapped-devices)
+  #:use-module (ice-9 format)
   #:use-module (ice-9 match)
+  #:use-module (ice-9 receive)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-34)
@@ -600,25 +603,26 @@ (define (operating-system-boot-mapped-devices os)
                (any file-system-needed-for-boot? users)))
            devices)))
 
-(define (operating-system-bootloader-crypto-devices os)
-  "Return the subset of mapped devices that the bootloader must open.
-Only devices specified by uuid are supported."
-  (define (valid-crypto-device? dev)
-    (or (uuid? dev)
-        (begin
-          (warning (G_ "\
-mapped-device '~a' may not be mounted by the bootloader.~%")
-                   dev)
-          #f)))
-  (filter-map (match-lambda
-                ((and (= mapped-device-type type)
-                      (= mapped-device-source source))
-                 (and (eq? luks-device-mapping type)
-                      (valid-crypto-device? source)
-                      source))
-                (_ #f))
-              ;; XXX: Ordering is important, we trust the returned one.
-              (operating-system-boot-mapped-devices os)))
+(define operating-system-bootloader-crypto-devices
+  (mlambda (os)                         ;to avoid duplicated output
+    "Return the sources of the LUKS mapped devices specified by UUID."
+    ;; XXX: Device ordering is important, we trust the returned one.
+    (let ((luks-devices (filter (lambda (m)
+                                  (eq? luks-device-mapping
+                                       (mapped-device-type m)))
+                                (operating-system-boot-mapped-devices os))))
+      (receive (uuid-crypto-devices non-uuid-crypto-devices)
+          (partition (compose uuid? mapped-device-source) luks-devices)
+        (when (not (null? non-uuid-crypto-devices))
+          (warning (N_ "\
+the following mapped device may not be mounted by the bootloader: ~s
+hint: specify the mapped device source via its LUKS UUID.~%"
+                       "\
+the following mapped devices may not be mounted by the bootloader: ~s
+hint: specify the mapped device sources via their LUKS UUID.~%"
+                       (length non-uuid-crypto-devices))
+                   (map mapped-device-source non-uuid-crypto-devices)))
+        (map mapped-device-source uuid-crypto-devices)))))
 
 (define (device-mapping-services os)
   "Return the list of device-mapping services for OS as a list."
-- 
2.36.0
L
L
Ludovic Courtès wrote on 18 May 22:44 +0200
(name . Maxim Cournoyer)(address . maxim.cournoyer@gmail.com)(address . 55407@debbugs.gnu.org)
87ee0q1sfq.fsf@gnu.org
Hi!

Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:

Toggle quote (10 lines)
> This corrects two problems with the previous mapped devices warning:
>
> 1. It wasn't clear how to correct the situation.
> 2. The output would be repeated twice, as the procedure is called
> twice during a system reconfigure.
>
> * gnu/system.scm (operating-system-bootloader-crypto-devices): Memoize
> procedure. Produce a single message for the combined problematic devices.
> Add a hint to help users fix the warning.

[...]

Toggle quote (3 lines)
> +(define operating-system-bootloader-crypto-devices
> + (mlambda (os) ;to avoid duplicated output

Should be ‘mlambdaq’ so that OS is compared with ‘eq?’, which is cheaper
and better corresponds to what we want to achieve here.

Toggle quote (3 lines)
> + (receive (uuid-crypto-devices non-uuid-crypto-devices)
> + (partition (compose uuid? mapped-device-source) luks-devices)

I suggest using ‘let’ from (srfi srfi-71) for consistency.

Toggle quote (10 lines)
> + (when (not (null? non-uuid-crypto-devices))
> + (warning (N_ "\
> +the following mapped device may not be mounted by the bootloader: ~s
> +hint: specify the mapped device source via its LUKS UUID.~%"
> + "\
> +the following mapped devices may not be mounted by the bootloader: ~s
> +hint: specify the mapped device sources via their LUKS UUID.~%"
> + (length non-uuid-crypto-devices))
> + (map mapped-device-source non-uuid-crypto-devices)))

By convention, warnings should fit on a single line and not be full
sentences.

If we emit one warning per mapped device, we can report the source
location using:

(warning (mapped-device-location dev) (G_ "mapped device …"))

Given that we have location info, it might be better to report one
warning per device?

Last, hints should be reported either with ‘display-hint’ or with a
‘&fix-hint’ exception. The hint itself can be one or two paragraphs
using Texinfo markup.

All this should ensure consistent diagnostic reporting.

I hope this makes sense!

Thanks,
Ludo’.
M
M
Maxim Cournoyer wrote 7 days ago
(name . Ludovic Courtès)(address . ludo@gnu.org)(address . 55407-done@debbugs.gnu.org)
87o7zrbju2.fsf@gmail.com
Hi,

Ludovic Courtès <ludo@gnu.org> writes:

Toggle quote (22 lines)
> Hi!
>
> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
>
>> This corrects two problems with the previous mapped devices warning:
>>
>> 1. It wasn't clear how to correct the situation.
>> 2. The output would be repeated twice, as the procedure is called
>> twice during a system reconfigure.
>>
>> * gnu/system.scm (operating-system-bootloader-crypto-devices): Memoize
>> procedure. Produce a single message for the combined problematic devices.
>> Add a hint to help users fix the warning.
>
> [...]
>
>> +(define operating-system-bootloader-crypto-devices
>> + (mlambda (os) ;to avoid duplicated output
>
> Should be ‘mlambdaq’ so that OS is compared with ‘eq?’, which is cheaper
> and better corresponds to what we want to achieve here.

Done.

Toggle quote (5 lines)
>> + (receive (uuid-crypto-devices non-uuid-crypto-devices)
>> + (partition (compose uuid? mapped-device-source) luks-devices)
>
> I suggest using ‘let’ from (srfi srfi-71) for consistency.

Done.

Toggle quote (13 lines)
>> + (when (not (null? non-uuid-crypto-devices))
>> + (warning (N_ "\
>> +the following mapped device may not be mounted by the bootloader: ~s
>> +hint: specify the mapped device source via its LUKS UUID.~%"
>> + "\
>> +the following mapped devices may not be mounted by the bootloader: ~s
>> +hint: specify the mapped device sources via their LUKS UUID.~%"
>> + (length non-uuid-crypto-devices))
>> + (map mapped-device-source non-uuid-crypto-devices)))
>
> By convention, warnings should fit on a single line and not be full
> sentences.

This is a Guix-specific convention, right? I couldn't find a reference
to it in the GNU Standards (info standards) document. I'd be more of
the thinking that warnings directed at *users* should be as human
readable as possible; the motivation for my fix was because that for
more than a year, I read that warning without having clue about what it
really meant and had to review the source to get the answer.

Toggle quote (8 lines)
> If we emit one warning per mapped device, we can report the source
> location using:
>
> (warning (mapped-device-location dev) (G_ "mapped device …"))
>
> Given that we have location info, it might be better to report one
> warning per device?

Done!

Toggle quote (8 lines)
> Last, hints should be reported either with ‘display-hint’ or with a
> ‘&fix-hint’ exception. The hint itself can be one or two paragraphs
> using Texinfo markup.
>
> All this should ensure consistent diagnostic reporting.
>
> I hope this makes sense!

It does. I didn't know about warning accepting the location like that,
and I thought hints were only usable via conditions, so I've learned a
couple new things here.

With the following changes:

Toggle snippet (67 lines)
modified gnu/system.scm
@@ -43,6 +43,7 @@ (define-module (gnu system)
#:use-module ((guix utils) #:select (substitute-keyword-arguments))
#:use-module (guix i18n)
#:use-module (guix diagnostics)
+ #:use-module (guix ui)
#:use-module (gnu packages admin)
#:use-module (gnu packages base)
#:use-module (gnu packages bash)
@@ -81,11 +82,11 @@ (define-module (gnu system)
#:use-module (gnu system mapped-devices)
#:use-module (ice-9 format)
#:use-module (ice-9 match)
- #:use-module (ice-9 receive)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
+ #:use-module (srfi srfi-71)
#:use-module (rnrs bytevectors)
#:export (operating-system
operating-system?
@@ -604,25 +605,25 @@ (define (operating-system-boot-mapped-devices os)
devices)))

(define operating-system-bootloader-crypto-devices
- (mlambda (os) ;to avoid duplicated output
+ (mlambdaq (os) ;to avoid duplicated output
"Return the sources of the LUKS mapped devices specified by UUID."
;; XXX: Device ordering is important, we trust the returned one.
- (let ((luks-devices (filter (lambda (m)
- (eq? luks-device-mapping
- (mapped-device-type m)))
- (operating-system-boot-mapped-devices os))))
- (receive (uuid-crypto-devices non-uuid-crypto-devices)
- (partition (compose uuid? mapped-device-source) luks-devices)
- (when (not (null? non-uuid-crypto-devices))
- (warning (N_ "\
-the following mapped device may not be mounted by the bootloader: ~s
-hint: specify the mapped device source via its LUKS UUID.~%"
- "\
-the following mapped devices may not be mounted by the bootloader: ~s
-hint: specify the mapped device sources via their LUKS UUID.~%"
- (length non-uuid-crypto-devices))
- (map mapped-device-source non-uuid-crypto-devices)))
- (map mapped-device-source uuid-crypto-devices)))))
+ (let* ((luks-devices (filter (lambda (m)
+ (eq? luks-device-mapping
+ (mapped-device-type m)))
+ (operating-system-boot-mapped-devices os)))
+ (uuid-crypto-devices non-uuid-crypto-devices
+ (partition (compose uuid? mapped-device-source)
+ luks-devices)))
+ (when (not (null? non-uuid-crypto-devices))
+ (for-each (lambda (dev)
+ (warning
+ (source-properties->location (mapped-device-location dev))
+ (G_ "mapped device '~a' may be ignored by bootloader~%")
+ (mapped-device-source dev)))
+ non-uuid-crypto-devices)
+ (display-hint "Specify mapped device sources via their LUKS UUID."))
+ (map mapped-device-source uuid-crypto-devices))))

(define (device-mapping-services os)
"Return the list of device-mapping services for OS as a list."

It produced this output:

Toggle snippet (9 lines)
/home/maxim/stow/guix/hurd.scm:109:8: warning: mapped device '/dev/sda2' may be ignored by bootloader
/home/maxim/stow/guix/hurd.scm:113:8: warning: mapped device '/dev/sdb2' may be ignored by bootloader
/home/maxim/stow/guix/hurd.scm:117:8: warning: mapped device '/dev/sdc2' may be ignored by bootloader
hint: Specify mapped device sources via their LUKS UUID.

updating checkout of 'file:///home/maxim/src/mcron'...
retrieved commit a233aab1b6770bece7538cda8381df824b7560b6

which compares favorably to before the change:

Toggle snippet (28 lines)
$ ./pre-inst-env guix system reconfigure ~/stow/guix/hurd.scm
guix system: warning: mapped-device '/dev/sda2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdb2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdc2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sda2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdb2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdc2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sda2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdb2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdc2' may not be mounted by the bootloader.
updating checkout of 'file:///home/maxim/src/mcron'...
retrieved commit a233aab1b6770bece7538cda8381df824b7560b6
guix system: warning: mapped-device '/dev/sda2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdb2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdc2' may not be mounted by the bootloader.
updating checkout of 'file:///home/maxim/src/mcron'...
retrieved commit a233aab1b6770bece7538cda8381df824b7560b6
substitute: updating substitutes from 'http://127.0.0.1:8181'... 100.0%

[...]

activating system...
guix system: warning: mapped-device '/dev/sda2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdb2' may not be mounted by the bootloader.
guix system: warning: mapped-device '/dev/sdc2' may not be mounted by the bootloader.
[...]

Pushed as 39a9404c99.

Thanks for the useful comments!

Maxim
Closed
L
L
Ludovic Courtès wrote 6 days ago
(name . Maxim Cournoyer)(address . maxim.cournoyer@gmail.com)(address . 55407-done@debbugs.gnu.org)
87h75iu94k.fsf@gnu.org
Hi!

Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:

Toggle quote (15 lines)
>>> + (warning (N_ "\
>>> +the following mapped device may not be mounted by the bootloader: ~s
>>> +hint: specify the mapped device source via its LUKS UUID.~%"
>>> + "\
>>> +the following mapped devices may not be mounted by the bootloader: ~s
>>> +hint: specify the mapped device sources via their LUKS UUID.~%"
>>> + (length non-uuid-crypto-devices))
>>> + (map mapped-device-source non-uuid-crypto-devices)))
>>
>> By convention, warnings should fit on a single line and not be full
>> sentences.
>
> This is a Guix-specific convention, right? I couldn't find a reference
> to it in the GNU Standards (info standards) document.

It’s more or less the GNU convention (info "(standards) Errors").

The bit about hints is Guix-specific, but it’s the same idea: having a
consistent way to report diagnostics.

Toggle quote (6 lines)
> I'd be more of the thinking that warnings directed at *users* should
> be as human readable as possible; the motivation for my fix was
> because that for more than a year, I read that warning without having
> clue about what it really meant and had to review the source to get
> the answer.

Yes, and I agree that’s a problem. Hopefully hints help address that.

(The Elm compiler for instance is famous for having verbose diagnostics
*and* hints. Perhaps something to look at and take inspiration from in
the future.)

Toggle quote (7 lines)
> It produced this output:
>
> /home/maxim/stow/guix/hurd.scm:109:8: warning: mapped device '/dev/sda2' may be ignored by bootloader
> /home/maxim/stow/guix/hurd.scm:113:8: warning: mapped device '/dev/sdb2' may be ignored by bootloader
> /home/maxim/stow/guix/hurd.scm:117:8: warning: mapped device '/dev/sdc2' may be ignored by bootloader
> hint: Specify mapped device sources via their LUKS UUID.

Nice. You could even add an @example block in the hint to illustrate
what that means.

Toggle quote (2 lines)
> Pushed as 39a9404c99.

Thank you!

Ludo’.
Closed
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