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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: Fri, 05 Apr 2013 18:15:42 +0200	[thread overview]
Message-ID: <87zjxdvtqp.fsf@gnu.org> (raw)
In-Reply-To: <871uap5ak8.fsf@karetnikov.org> (Nikita Karetnikov's message of "Fri, 05 Apr 2013 18:14:31 +0400")

Nikita Karetnikov <nikita@karetnikov.org> skribis:

>> +         (if (file-exists? file)
>> +             (format #t "~a~%"
>> +                     (call-with-input-file file
>> +                       (compose fmt sha256 get-bytevector-all)))
>
> Oh, Mark warned me about 'file-exists?' some time ago.
>
> How can I do the same but avoid a race condition?

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))))))))
    ...)

Ludo’.

  reply	other threads:[~2013-04-05 16:16 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 [this message]
2013-04-10 11:48         ` Nikita Karetnikov
2013-04-10 11:54           ` Ludovic Courtès
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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