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From: ludo@gnu.org (Ludovic Courtès)
To: Nikita Karetnikov <nikita@karetnikov.org>
Cc: bug-guix@gnu.org
Subject: Re: [PATCH] Add 'guix hash'.
Date: Wed, 10 Apr 2013 13:54:30 +0200	[thread overview]
Message-ID: <87k3oa1tzd.fsf@gnu.org> (raw)
In-Reply-To: <8738uy7gim.fsf@karetnikov.org> (Nikita Karetnikov's message of "Wed, 10 Apr 2013 15:48:49 +0400")

Nikita Karetnikov <nikita@karetnikov.org> skribis:

>> Ah, TOCTTOU, right.
>
>> You could do:
>
>>   (let ((hash (catch 'system-error
>>                 (lambda ()
>>                   (call-with-input-file ...))
>>                 (lambda args
>>                   (leave (_ "error ..." (strerror (system-error-errno args))))))))
>>     ...)
>
> Here is what I did (I'll remove "guix hash" when we have "warning"):
>
>       (match args
>         ((file)
>          (catch 'system-error
>            (lambda ()
>              (format #t "~a~%"
>                      (call-with-input-file file
>                        (compose fmt sha256 get-bytevector-all))))
>            (lambda args
>              (leave (_ "~a: ~a~%")
>                     "guix hash" (strerror (system-error-errno args))))))
>         (_
>          (leave (_ "~a: wrong number of arguments~%")
>                 "guix hash")))))

Looks good.

> I guess that "wrong number of arguments" can be handled by
> (lambda args ...).  Still, the above feels much safer.

Not sure what you mean, but the above snippet is OK.

Ludo’.

  reply	other threads:[~2013-04-10 11:54 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-01  5:06 [PATCH] Add 'guix hash' Nikita Karetnikov
2013-04-03  8:34 ` Ludovic Courtès
2013-04-05 14:04   ` Nikita Karetnikov
2013-04-05 14:14     ` Nikita Karetnikov
2013-04-05 16:15       ` Ludovic Courtès
2013-04-10 11:48         ` Nikita Karetnikov
2013-04-10 11:54           ` Ludovic Courtès [this message]
2013-04-10 12:21             ` Nikita Karetnikov
2013-04-10 17:30               ` Ludovic Courtès
2013-04-05 16:13     ` Ludovic Courtès
2013-04-09 16:28       ` Nikita Karetnikov
2013-04-11 20:35         ` Ludovic Courtès
2013-04-12  5:24           ` master: FAIL: tests/guix-package.sh (was: [PATCH] Add 'guix hash'.) Nikita Karetnikov
2013-04-12  6:48             ` master: FAIL: tests/guix-package.sh Nikita Karetnikov
2013-04-12 16:24             ` Ludovic Courtès
2013-04-18  5:01       ` Enhanced 'warning' (was: [PATCH] Add 'guix hash'.) Nikita Karetnikov
2013-04-18  5:06         ` Enhanced 'warning' Nikita Karetnikov
2013-04-18 11:55         ` Ludovic Courtès
2013-04-18 19:27           ` Nikita Karetnikov
2013-04-18 20:59             ` Ludovic Courtès
2013-04-19 20:16               ` [PATCH] ui: Add a 'define-diagnostic' macro. (was: Enhanced 'warning') Nikita Karetnikov
2013-04-20  5:48                 ` [PATCH] ui: Add a 'define-diagnostic' macro Nikita Karetnikov
2013-04-20  9:10                   ` Ludovic Courtès
2013-04-20 17:33                     ` Nikita Karetnikov
2013-04-20 19:55                       ` Ludovic Courtès
2013-04-20  9:09                 ` Ludovic Courtès
2013-04-21 18:14       ` [PATCH] Add 'guix hash' Nikita Karetnikov
2013-04-21 19:02         ` Ludovic Courtès

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