jochen
10f76cafc4
Betterbird's pinned .tar.xz failed on the build seat with "this build seat has no xz to read it": the seat's image is the catalogue's build-agent recipe, which installs git and docker-cli alone, and xz had been added only to cmd/mesh-builder/Dockerfile, which the seat does not build from. The stream is now read with github.com/ulikunitz/xz (vendored), its dictionary capped at xz's own largest preset, and what it unpacks to bounded as before; the xz line in the unused Dockerfile is taken back out.
Package xz
This Go language package supports the reading and writing of xz compressed streams. It includes also a gxz command for compressing and decompressing data. The package is completely written in Go and doesn't have any dependency on any C code.
The package is currently under development. There might be bugs and APIs are not considered stable. At this time the package cannot compete with the xz tool regarding compression speed and size. The algorithms there have been developed over a long time and are highly optimized. However there are a number of improvements planned and I'm very optimistic about parallel compression and decompression. Stay tuned!
Using the API
The following example program shows how to use the API.
package main
import (
"bytes"
"io"
"log"
"os"
"github.com/ulikunitz/xz"
)
func main() {
const text = "The quick brown fox jumps over the lazy dog.\n"
var buf bytes.Buffer
// compress text
w, err := xz.NewWriter(&buf)
if err != nil {
log.Fatalf("xz.NewWriter error %s", err)
}
if _, err := io.WriteString(w, text); err != nil {
log.Fatalf("WriteString error %s", err)
}
if err := w.Close(); err != nil {
log.Fatalf("w.Close error %s", err)
}
// decompress buffer and write output to stdout
r, err := xz.NewReader(&buf)
if err != nil {
log.Fatalf("NewReader error %s", err)
}
if _, err = io.Copy(os.Stdout, r); err != nil {
log.Fatalf("io.Copy error %s", err)
}
}
Documentation
You can find the full documentation at pkg.go.dev.
Using the gxz compression tool
The package includes a gxz command line utility for compression and decompression.
Use following command for installation:
$ go get github.com/ulikunitz/xz/cmd/gxz
To test it call the following command.
$ gxz bigfile
After some time a much smaller file bigfile.xz will replace bigfile. To decompress it use the following command.
$ gxz -d bigfile.xz
Security & Vulnerabilities
The security policy is documented in SECURITY.md.
The software is not affected by the supply chain attack on the original xz implementation, CVE-2024-3094. This implementation doesn't share any files with the original xz implementation and no patches or pull requests are accepted without a review.
All security advisories for this project are published under github.com/ulikunitz/xz/security/advisories.