From b9a31d90e907db0a593ec80aacc35a0523a009f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Fri, 29 Aug 2014 14:53:15 +0200
Subject: [PATCH] offload: Ignore EEXIST when registering a .drv as a GC root.
Fixes <http://bugs.gnu.org/18115>.
Reported by Mark H Weaver <mhw@netris.org>.
* guix/scripts/offload.scm (register-gc-root)[script]: Wrap 'symlink'
call in "catch 'system-error", and ignore EEXIST errors.
---
guix/scripts/offload.scm | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/guix/scripts/offload.scm b/guix/scripts/offload.scm
index c17de34acca..b3b502425cc 100644
--- a/guix/scripts/offload.scm
+++ b/guix/scripts/offload.scm
@@ -316,8 +316,17 @@ (define script
(let ((root-directory (string-append %state-directory
"/gcroots/tmp")))
(false-if-exception (mkdir root-directory))
- (symlink ,file
- (string-append root-directory "/" ,%gc-root-file)))))
+ (catch 'system-error
+ (lambda ()
+ (symlink ,file
+ (string-append root-directory "/" ,%gc-root-file)))
+ (lambda args
+ ;; If FILE already exists, we can assume that either it's a stale
+ ;; reference (which is fine), or another process is already
+ ;; building the derivation represented by FILE (which is fine
+ ;; too.) Thus, do nothing in that case.
+ (unless (= EEXIST (system-error-errno args))
+ (apply throw args)))))))
(let ((pipe (remote-pipe machine OPEN_READ
`("guile" "-c" ,(object->string script)))))
--
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