Fix potential race condition in initializing libpod

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

2 files changed, 13 insertions, 4 deletions

diff --git a/libpod/container.go b/libpod/container.go
index e1b002548..c53184ea3 100644
--- a/libpod/container.go
+++ b/libpod/container.go
@@ -413,7 +413,7 @@ func (c *Container) refresh() error {
 	defer c.lock.Unlock()
 
 	if !c.valid {
-		return errors.Wrapf(ErrCtrRemoved, "container %s has been removed from the state", c.ID())
+		return errors.Wrapf(ErrCtrRemoved, "container %s is not valid - may have been removed", c.ID())
 	}
 
 	// We need to get the container's temporary directory from c/storage
diff --git a/libpod/runtime.go b/libpod/runtime.go
index 7997679e2..103faf3f8 100644
--- a/libpod/runtime.go
+++ b/libpod/runtime.go
@@ -175,7 +175,19 @@ func NewRuntime(options ...RuntimeOption) (runtime *Runtime, err error) {
 
 	// We now need to see if the system has restarted
 	// We check for the presence of a file in our tmp directory to verify this
+	// This check must be locked to prevent races
+	runtimeAliveLock := filepath.Join(runtime.config.TmpDir, "alive.lck")
 	runtimeAliveFile := filepath.Join(runtime.config.TmpDir, "alive")
+	aliveLock, err := storage.GetLockfile(runtimeAliveLock)
+	if err != nil {
+		return nil, errors.Wrapf(err, "error acquiring runtime init lock")
+	}
+	// Acquire the lock and hold it until we return
+	// This ensures that no two processes will be in runtime.refresh at once
+	// TODO: we can't close the FD in this lock, so we should keep it around
+	// and use it to lock important operations
+	aliveLock.Lock()
+	defer aliveLock.Unlock()
 	_, err = os.Stat(runtimeAliveFile)
 	if err != nil {
 		// If the file doesn't exist, we need to refresh the state
@@ -260,9 +272,6 @@ func (r *Runtime) Shutdown(force bool) error {
 // Reconfigures the runtime after a reboot
 // Refreshes the state, recreating temporary files
 // Does not check validity as the runtime is not valid until after this has run
-// TODO: there's a potential race here, where multiple libpods could be in this
-// function before the runtime ready file is created
-// This probably doesn't matter as the actual container operations are locked
 func (r *Runtime) refresh(alivePath string) error {
 	// We need to refresh the state of all containers
 	ctrs, err := r.state.AllContainers()