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package wclayer
import (
"sync"
"github.com/Microsoft/hcsshim/internal/hcserror"
"github.com/sirupsen/logrus"
)
var prepareLayerLock sync.Mutex
// PrepareLayer finds a mounted read-write layer matching path 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(path string, parentLayerPaths []string) (err error) {
title := "hcsshim::PrepareLayer"
fields := logrus.Fields{
"path": path,
}
logrus.WithFields(fields).Debug(title)
defer func() {
if err != nil {
fields[logrus.ErrorKey] = err
logrus.WithFields(fields).Error(err)
} else {
logrus.WithFields(fields).Debug(title + " - succeeded")
}
}()
// Generate layer descriptors
layers, err := layerPathsToDescriptors(parentLayerPaths)
if err != nil {
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(&stdDriverInfo, path, layers)
if err != nil {
return hcserror.New(err, title+" - failed", "")
}
return nil
}
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