From 86cbd93ec1e439fba3e33016272db45d9597fba4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Thu, 14 Sep 2006 22:33:53 +0000
Subject: [PATCH] * nix-env --switch-generation / --list-generations /  
 --delete-generations: lock the profile to prevent (extremely   unlikely) race
 conditions.

---
 src/nix-env/main.cc | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/nix-env/main.cc b/src/nix-env/main.cc
index 7a6824b63..416f89bcc 100644
--- a/src/nix-env/main.cc
+++ b/src/nix-env/main.cc
@@ -943,6 +943,9 @@ static const int prevGen = -2;
 
 static void switchGeneration(Globals & globals, int dstGen)
 {
+    PathLocks lock;
+    lockProfile(lock, globals.profile);
+    
     int curGen;
     Generations gens = findGenerations(globals.profile, curGen);
 
@@ -1004,6 +1007,9 @@ static void opListGenerations(Globals & globals,
     if (opArgs.size() != 0)
         throw UsageError(format("no arguments expected"));
 
+    PathLocks lock;
+    lockProfile(lock, globals.profile);
+    
     int curGen;
     Generations gens = findGenerations(globals.profile, curGen);
 
@@ -1032,6 +1038,9 @@ static void opDeleteGenerations(Globals & globals,
     if (opFlags.size() > 0)
         throw UsageError(format("unknown flag `%1%'") % opFlags.front());
 
+    PathLocks lock;
+    lockProfile(lock, globals.profile);
+    
     int curGen;
     Generations gens = findGenerations(globals.profile, curGen);