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package hcsshim
import (
"sync"
"github.com/sirupsen/logrus"
)
var prepareLayerLock sync.Mutex
// PrepareLayer finds a mounted read-write layer matching layerId and enables the
// the filesystem filter for use on that layer. This requires the paths to all
// parent layers, and is necessary in order to view or interact with the layer
// as an actual filesystem (reading and writing files, creating directories, etc).
// Disabling the filter must be done via UnprepareLayer.
func PrepareLayer(info DriverInfo, layerId string, parentLayerPaths []string) error {
title := "hcsshim::PrepareLayer "
logrus.Debugf(title+"flavour %d layerId %s", info.Flavour, layerId)
// Generate layer descriptors
layers, err := layerPathsToDescriptors(parentLayerPaths)
if err != nil {
return err
}
// Convert info to API calling convention
infop, err := convertDriverInfo(info)
if err != nil {
logrus.Error(err)
return err
}
// This lock is a temporary workaround for a Windows bug. Only allowing one
// call to prepareLayer at a time vastly reduces the chance of a timeout.
prepareLayerLock.Lock()
defer prepareLayerLock.Unlock()
err = prepareLayer(&infop, layerId, layers)
if err != nil {
err = makeErrorf(err, title, "layerId=%s flavour=%d", layerId, info.Flavour)
logrus.Error(err)
return err
}
logrus.Debugf(title+"succeeded flavour=%d layerId=%s", info.Flavour, layerId)
return nil
}
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