From 108e14bb189fd0fb291d3494f9f3915070a7052e Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Sun, 5 Aug 2012 18:17:55 -0400 Subject: [PATCH] Fix race condition when two processes create the same link in /nix/store/.links --- src/libstore/optimise-store.cc | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc index c05447f4a2..b9b878d2a4 100644 --- a/src/libstore/optimise-store.cc +++ b/src/libstore/optimise-store.cc @@ -102,11 +102,11 @@ void LocalStore::optimisePath_(OptimiseStats & stats, const Path & path) /* Nope, create a hard link in the links directory. */ makeMutable(path); MakeImmutable mk1(path); - - if (link(path.c_str(), linkPath.c_str()) == -1) + if (link(path.c_str(), linkPath.c_str()) == 0) return; + if (errno != EEXIST) throw SysError(format("cannot link `%1%' to `%2%'") % linkPath % path); - - return; + /* Fall through if another process created ‘linkPath’ before + we did. */ } /* Yes! We've seen a file with the same contents. Replace the