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authorLudovic Courtès <ludo@gnu.org>2014-04-21 23:23:34 +0200
committerLudovic Courtès <ludo@gnu.org>2014-04-21 23:24:23 +0200
commit50db7d82b3f3ab8ec382132b06a1400c0044b89e (patch)
tree8469b67270c8e189923a1c86a66f83f94d8e106a
parentace6924327142c8557349e7c52c594f71a6c079b (diff)
downloadguix-50db7d82b3f3ab8ec382132b06a1400c0044b89e.tar
guix-50db7d82b3f3ab8ec382132b06a1400c0044b89e.tar.gz
nar: Really really protect the temporary store directory from GC.
This is a follow-up to 6071b55e10b7b6e67d77ae058c8744834889e0b4. 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'.
-rw-r--r--guix/nar.scm39
1 files changed, 16 insertions, 23 deletions
diff --git a/guix/nar.scm b/guix/nar.scm
index 0bf8ac317d..6beda91c02 100644
--- a/guix/nar.scm
+++ b/guix/nar.scm
@@ -334,36 +334,29 @@ held."
(unlock-store-file target)))))
(define (temporary-store-file)
- "Return the file name of a temporary file created in the store that is
-protected from garbage collection."
+ "Return the file name of a temporary file created in the store."
(let* ((template (string-append (%store-prefix) "/guix-XXXXXX"))
(port (mkstemp! template)))
(close-port port)
-
- ;; Make sure TEMPLATE is not collected while we populate it.
- (add-permanent-root template)
-
- ;; There's a small window during which the GC could delete the file. Try
- ;; again if that happens.
- (if (file-exists? template)
- (begin
- ;; It's up to the caller to create that file or directory.
- (delete-file template)
- template)
- (begin
- (remove-permanent-root template)
- (temporary-store-file)))))
+ template))
(define-syntax-rule (with-temporary-store-file name body ...)
"Evaluate BODY with NAME bound to the file name of a temporary store item
protected from GC."
- (let ((name (temporary-store-file)))
- (dynamic-wind
- (const #t)
- (lambda ()
- body ...)
- (lambda ()
- (remove-permanent-root name)))))
+ (let loop ((name (temporary-store-file)))
+ (with-store store
+ ;; Add NAME to the current process' roots. (Opening this connection to
+ ;; the daemon allows us to reuse its code that deals with the
+ ;; per-process roots file.)
+ (add-temp-root store name)
+
+ ;; There's a window during which GC could delete NAME. Try again when
+ ;; that happens.
+ (if (file-exists? name)
+ (begin
+ (delete-file name)
+ body ...)
+ (loop (temporary-store-file))))))
(define* (restore-one-item port
#:key acl (verify-signature? #t) (lock? #t)