* Admit only valid OCI layout files when loading image.
- Adds `AdmissionMapper` protocol for validating archive
member paths and normalizing them to relative paths
under the extraction root directory.
- Renames `Reader.swift` to `ArchiveReader.swift` to
match type name.
- Rework `TempDir` to address `NSString.utf8String`
deprecation warning in Swift 6.2.3.
- Rework `ArchiveReader.extractContent()` to use an
`AdmissionMapper` to validate and remap archive
members before extracting.
- Adds `IdentityAdmissionWrapper` for naive extraction.
- Adds `NoSymlinkAdmissionWrapper` that only extracts
regular files and directories under the extraction root.
- Adds `OCIImageAdmissionWrapper` that only extracts
valid OCI image layout paths.
- Use `OCIImageAdmissionWrapper` for `cctl image load`
and print rejected paths.
* PR feedback.
* Adds public init() for TrustedAdmissionMapper.
* Replace AdmissionMapper with more secure extraction.
- Adds FileDescriptor.mkdirSecure() to prevent
root escapes on member pathnames, and to prevent
symlink traversal.
- Adds FileDescriptor.unlinkRecursive() to
facilitate overwrites when there are multiple
archive entries with the same member path.
- Adds FileDescriptor.validateSymlinkTargetInRoot()
to validate that extracted symlink targets do
not escape the root.
- Rewrite ArchiveReader.extractContents() to use
secure path functions.
* Remove unneeded symlink check, rename files.
* Simplify the lexical normalizer workaround.
* Reject member paths containing parent traversal components.
* Remove unused lexical normalization workaround.
* Fix leaking fds, extract absolute members as relative.
