Add support for oci-archives#78
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Move read_blob, read_index, has_blob, and all derived read-only methods (fsck, find_referrers, open_image_this_platform, etc.) from impl OciDir into a new OciRead trait with default methods. OciDir implements the trait, so all existing call sites work once OciRead is in scope. A prelude module re-exports OciRead for convenient importing. This prepares for adding OciArchive (read-only tar-based backend) that will share the same read logic via the trait without any code duplication. It changes none of the behaviour, or the API (other than the requirement to import that prelude to use the trait). Signed-off-by: Alexander Larsson <alexl@redhat.com> Assisted-by: Claude Code (Claude Opus 4.6)
Add OciArchive, a read-only OCI image backend that reads directly from tar archives using pread for concurrent access. It implements OciRead so all manifest resolution, fsck, and referrer logic works without code duplication. Key changes: - ArchiveReader: a Read+Seek adapter over a region of a file using pread - OciArchive: scans tar entries on open, serves reads via ArchiveReader Assisted-by: Claude Code (Claude Opus 4.6) Signed-off-by: Alexander Larsson <alexl@redhat.com>
cgwalters
approved these changes
Jun 16, 2026
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| /// A reader for a region of a file, using pread for concurrent access. | ||
| #[derive(Debug)] | ||
| pub struct ArchiveReader { |
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Minor bike shed perhaps FileRangeReader
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| /// A reader for a region of a file, using pread for concurrent access. | ||
| #[derive(Debug)] | ||
| pub struct ArchiveReader { |
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I don't think this should be pub - let's audit this code for unnecessary pub
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This adds support for read-only access to oci-archives by abstracting out the read part of OciDir to a trait that then has a OciDir implementation and an OciArchive implementation.
The goal of this is to use it in composefs-rs to do an efficient local version of delta pulls without using the skopeo proxy (although it will also work for regular local oci-archive pulls).
This change is essentially API compat, except users need to add
use ocidir::prelude::*to pull in the new trait.