45 lines
1.4 KiB
Go
45 lines
1.4 KiB
Go
package wclayer
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import (
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"context"
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"strings"
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"sync"
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"github.com/Microsoft/hcsshim/internal/hcserror"
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"github.com/Microsoft/hcsshim/internal/oc"
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"go.opencensus.io/trace"
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)
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var prepareLayerLock sync.Mutex
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// PrepareLayer finds a mounted read-write layer matching path and enables the
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// the filesystem filter for use on that layer. This requires the paths to all
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// parent layers, and is necessary in order to view or interact with the layer
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// as an actual filesystem (reading and writing files, creating directories, etc).
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// Disabling the filter must be done via UnprepareLayer.
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func PrepareLayer(ctx context.Context, path string, parentLayerPaths []string) (err error) {
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title := "hcsshim::PrepareLayer"
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ctx, span := trace.StartSpan(ctx, title)
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defer span.End()
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defer func() { oc.SetSpanStatus(span, err) }()
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span.AddAttributes(
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trace.StringAttribute("path", path),
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trace.StringAttribute("parentLayerPaths", strings.Join(parentLayerPaths, ", ")))
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// Generate layer descriptors
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layers, err := layerPathsToDescriptors(ctx, parentLayerPaths)
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if err != nil {
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return err
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}
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// This lock is a temporary workaround for a Windows bug. Only allowing one
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// call to prepareLayer at a time vastly reduces the chance of a timeout.
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prepareLayerLock.Lock()
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defer prepareLayerLock.Unlock()
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err = prepareLayer(&stdDriverInfo, path, layers)
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if err != nil {
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return hcserror.New(err, title+" - failed", "")
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}
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return nil
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}
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