91 lines
2.5 KiB
Go
91 lines
2.5 KiB
Go
package virtual
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import (
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"archive/tar"
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"bytes"
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"compress/gzip"
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"errors"
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"fmt"
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"io"
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"strings"
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"time"
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)
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// AlpineMember is one member's decompressed APKINDEX for a directory; Index is
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// nil when the member does not serve that directory.
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type AlpineMember struct {
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RemoteName string
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Index []byte
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}
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// AlpineRepo is a merged directory: its APKINDEX.tar.gz plus, per
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// "<name>-<version>.apk" apk will request, the member that owns it.
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type AlpineRepo struct {
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Index []byte
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Owners map[string][]byte
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}
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func (r *AlpineRepo) index() []byte { return r.Index }
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func (r *AlpineRepo) files() map[string][]byte { return r.Owners }
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// MergeAlpine merges members' APKINDEX records. Members are in priority order:
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// the first to carry a (P, V, A) wins. The index is unsigned, like the local
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// and github_alpine indexes it merges.
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func MergeAlpine(members []AlpineMember) *AlpineRepo {
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repo := &AlpineRepo{Owners: map[string][]byte{}}
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seen := map[string]bool{}
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var b bytes.Buffer
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for _, m := range members {
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for _, rec := range splitStanzas(m.Index) {
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p, v, a := stanzaField(rec, "P"), stanzaField(rec, "V"), stanzaField(rec, "A")
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key := p + "\x00" + v + "\x00" + a
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if p == "" || v == "" || seen[key] {
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continue
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}
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seen[key] = true
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if _, ok := repo.Owners[p+"-"+v+".apk"]; !ok {
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repo.Owners[p+"-"+v+".apk"] = []byte(m.RemoteName)
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}
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b.WriteString(rec)
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b.WriteString("\n\n")
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}
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}
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var t bytes.Buffer
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tw := tar.NewWriter(&t)
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_ = tw.WriteHeader(&tar.Header{Name: "APKINDEX", Mode: 0o644, Size: int64(b.Len()), Typeflag: tar.TypeReg, ModTime: time.Unix(0, 0)})
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_, _ = tw.Write(b.Bytes())
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_ = tw.Close()
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repo.Index = gzipDeterministic(t.Bytes())
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return repo
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}
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// apkIndexText extracts the APKINDEX entry from an APKINDEX.tar.gz, skipping a
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// leading signature stream if present.
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func apkIndexText(body []byte) ([]byte, error) {
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zr, err := gzip.NewReader(bytes.NewReader(body))
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if err != nil {
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return nil, err
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}
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tr := tar.NewReader(zr)
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for {
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hdr, err := tr.Next()
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if errors.Is(err, io.EOF) {
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return nil, fmt.Errorf("no APKINDEX entry")
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}
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if err != nil {
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return nil, err
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}
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if hdr.Name == "APKINDEX" {
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return io.ReadAll(tr)
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}
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}
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}
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// alpinePath splits a request into its directory and file, or ok is false for
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// anything but an APKINDEX.tar.gz or .apk.
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func alpinePath(p string) (dir, file string, ok bool) {
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i := strings.LastIndex(p, "/")
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dir, file = p[:i+1], p[i+1:]
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return dir, file, dir != "" && (file == "APKINDEX.tar.gz" || strings.HasSuffix(file, ".apk"))
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}
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