[PATCH] valgrind tests: be super-super paranoid when creating symlinks

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jan 21, 2009, 22:31 UTC
Message-ID: <alpine.DEB.1.00.0901212331280.3586@pacific.mpi-cbg.de>
In-Reply-To: <alpine.DEB.1.00.0901212137130.3586@pacific.mpi-cbg.de>

Even if there is only a faint, almost neglible chance that two parallel tests create the symlinks needed for the valgrind test at the same time, Peff wrote more than just a couple mails about the issue.

To get rid of that threat^Wthread, use a locking mechanism to make sure a symlink is only created by one test invocation, and the other has to wait.

Peff, do you see how much I like you?

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 t/test-lib.sh |   15 +++++++++++++--
 1 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 6acc6e0..07e657e 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -490,8 +490,19 @@ else
 	make_symlink () {
 		test -h "$2" &&
 		test "$1" = "$(readlink "$2")" || {
-			rm -f "$2" &&
-			ln -s "$1" "$2"
+			# be super paranoid
+			if mkdir "$2".lock
+			then
+				rm -f "$2" &&
+				ln -s "$1" "$2" &&
+				rm -r "$2".lock
+			else
+				while test -d "$2".lock
+				do
+					say "Waiting for lock on $2."
+					sleep 1
+				done
+			fi
 		}
 	}

-- 
1.6.1.442.g112f5