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nar: Really really protect the temporary store directory from GC.
This is a follow-up to 6071b55e10
.
See <https://lists.gnu.org/archive/html/guix-devel/2014-04/msg00167.html>
for the original report, and
<https://lists.gnu.org/archive/html/guix-devel/2014-04/msg00198.html>
for an alternate solution that has been discussed.
* guix/nar.scm (temporary-store-file): Remove call to
'add-permanent-root'; don't loop.
(with-temporary-store-file): Rewrite using 'with-store' and
'add-temp-root'.
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parent
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1 changed files with 16 additions and 23 deletions
39
guix/nar.scm
39
guix/nar.scm
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@ -334,36 +334,29 @@ (define* (finalize-store-file source target
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(unlock-store-file target)))))
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(define (temporary-store-file)
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"Return the file name of a temporary file created in the store that is
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protected from garbage collection."
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"Return the file name of a temporary file created in the store."
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(let* ((template (string-append (%store-prefix) "/guix-XXXXXX"))
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(port (mkstemp! template)))
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(close-port port)
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;; Make sure TEMPLATE is not collected while we populate it.
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(add-permanent-root template)
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;; There's a small window during which the GC could delete the file. Try
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;; again if that happens.
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(if (file-exists? template)
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(begin
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;; It's up to the caller to create that file or directory.
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(delete-file template)
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template)
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(begin
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(remove-permanent-root template)
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(temporary-store-file)))))
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template))
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(define-syntax-rule (with-temporary-store-file name body ...)
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"Evaluate BODY with NAME bound to the file name of a temporary store item
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protected from GC."
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(let ((name (temporary-store-file)))
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(dynamic-wind
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(const #t)
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(lambda ()
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body ...)
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(lambda ()
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(remove-permanent-root name)))))
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(let loop ((name (temporary-store-file)))
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(with-store store
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;; Add NAME to the current process' roots. (Opening this connection to
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;; the daemon allows us to reuse its code that deals with the
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;; per-process roots file.)
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(add-temp-root store name)
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;; There's a window during which GC could delete NAME. Try again when
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;; that happens.
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(if (file-exists? name)
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(begin
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(delete-file name)
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body ...)
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(loop (temporary-store-file))))))
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(define* (restore-one-item port
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#:key acl (verify-signature? #t) (lock? #t)
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