Skip to content

Document the semantics of the metadata created by pkg/compression #2605

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
vrothberg merged 1 commit into from
Oct 24, 2024
Merged

Document the semantics of the metadata created by pkg/compression #2605

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 12 additions & 2 deletions pkg/compression/compression.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -99,8 +99,18 @@ func CompressStream(dest io.Writer, algo Algorithm, level *int) (io.WriteCloser,
return internal.AlgorithmCompressor(algo)(dest, m, level)
}

// CompressStreamWithMetadata returns the compressor by its name. If the compression
// generates any metadata, it is written to the provided metadata map.
// CompressStreamWithMetadata returns the compressor by its name.
//
// Compressing a stream may create integrity data that allows consuming the compressed byte stream
// while only using subsets of the compressed data (if the compressed data is seekable and most
// of the uncompressed data is already present via other means), while still protecting integrity
// of the compressed stream against unwanted modification. (In OCI container images, this metadata
// is usually carried in manifest annotations.)
//
// Such a partial decompression is not implemented by this package; it is consumed e.g. by
// github.com/containers/storage/pkg/chunked .
//
// If the compression generates such metadata, it is written to the provided metadata map.
func CompressStreamWithMetadata(dest io.Writer, metadata map[string]string, algo Algorithm, level *int) (io.WriteCloser, error) {
return internal.AlgorithmCompressor(algo)(dest, metadata, level)
}
Expand Down
9 changes: 9 additions & 0 deletions pkg/compression/internal/types.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,15 @@ package internal
import "io"

// CompressorFunc writes the compressed stream to the given writer using the specified compression level.
//
// Compressing a stream may create integrity data that allows consuming the compressed byte stream
// while only using subsets of the compressed data (if the compressed data is seekable and most
// of the uncompressed data is already present via other means), while still protecting integrity
// of the compressed stream against unwanted modification. (In OCI container images, this metadata
// is usually carried in manifest annotations.)
//
// If the compression generates such metadata, it is written to the provided metadata map.
//
// The caller must call Close() on the stream (even if the input stream does not need closing!).
type CompressorFunc func(io.Writer, map[string]string, *int) (io.WriteCloser, error)

Expand Down