Subject: Re: [bug#50960] [PATCH 09/10] cache: Gracefully handle non-existent cache.

From: Maxime Devos <[email-masked]>
Date: Sat, 02 Oct 2021 15:28:51 +0200

Ludovic Courtès schreef op za 02-10-2021 om 12:22 [+0200]:
> * guix/cache.scm (maybe-remove-expired-cache-entries): Ignore ENOENT
> when writing EXPIRY-FILE.
> ---
>  guix/cache.scm | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/guix/cache.scm b/guix/cache.scm
> index 0401a9d428..51009809bd 100644
> --- a/guix/cache.scm
> +++ b/guix/cache.scm
> @@ -101,7 +101,13 @@ CLEANUP-PERIOD denotes the minimum time between two cache cleanups."
>                                    #:now now
>                                    #:entry-expiration entry-expiration
>                                    #:delete-entry delete-entry)
> -    (call-with-output-file expiry-file
> -      (cute write (time-second now) <>))))
> +    (catch 'system-error
> +      (lambda ()
> +        (call-with-output-file expiry-file
> +          (cute write (time-second now) <>)))
> +      (lambda args
> +        ;; ENOENT means CACHE does not exist.
> +        (unless (= ENOENT (system-error-errno args))

And EROFS perhaps, such that "guix shell" works even if the root file system was
remounted read-only for some reason and all the necessary derivations have already
been built.

Greetings,
Maxime.