acd3fd03c5
This update allows the creation of docker-archive files when the destination does not exists or is empty. kpod save needs this functionality. Signed-off-by: Dan Walsh <dwalsh@redhat.com>
66 lines
2.4 KiB
Go
66 lines
2.4 KiB
Go
package archive
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import (
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"io"
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"os"
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"github.com/containers/image/docker/tarfile"
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"github.com/containers/image/types"
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"github.com/pkg/errors"
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)
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type archiveImageDestination struct {
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*tarfile.Destination // Implements most of types.ImageDestination
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ref archiveReference
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writer io.Closer
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}
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func newImageDestination(ctx *types.SystemContext, ref archiveReference) (types.ImageDestination, error) {
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if ref.destinationRef == nil {
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return nil, errors.Errorf("docker-archive: destination reference not supplied (must be of form <path>:<reference:tag>)")
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}
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// ref.path can be either a pipe or a regular file
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// in the case of a pipe, we require that we can open it for write
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// in the case of a regular file, we don't want to overwrite any pre-existing file
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// so we check for Size() == 0 below (This is racy, but using O_EXCL would also be racy,
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// only in a different way. Either way, it’s up to the user to not have two writers to the same path.)
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fh, err := os.OpenFile(ref.path, os.O_WRONLY|os.O_CREATE, 0644)
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if err != nil {
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return nil, errors.Wrapf(err, "error opening file %q", ref.path)
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}
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fhStat, err := fh.Stat()
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if err != nil {
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return nil, errors.Wrapf(err, "error statting file %q", ref.path)
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}
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if fhStat.Mode().IsRegular() && fhStat.Size() != 0 {
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return nil, errors.New("docker-archive doesn't support modifying existing images")
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}
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return &archiveImageDestination{
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Destination: tarfile.NewDestination(fh, ref.destinationRef),
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ref: ref,
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writer: fh,
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}, nil
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}
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// Reference returns the reference used to set up this destination. Note that this should directly correspond to user's intent,
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// e.g. it should use the public hostname instead of the result of resolving CNAMEs or following redirects.
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func (d *archiveImageDestination) Reference() types.ImageReference {
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return d.ref
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}
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// Close removes resources associated with an initialized ImageDestination, if any.
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func (d *archiveImageDestination) Close() error {
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return d.writer.Close()
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}
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// Commit marks the process of storing the image as successful and asks for the image to be persisted.
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// WARNING: This does not have any transactional semantics:
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// - Uploaded data MAY be visible to others before Commit() is called
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// - Uploaded data MAY be removed or MAY remain around if Close() is called without Commit() (i.e. rollback is allowed but not guaranteed)
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func (d *archiveImageDestination) Commit() error {
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return d.Destination.Commit()
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}
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