mirror of
https://github.com/vbatts/tar-split.git
synced 2024-12-23 05:46:30 +00:00
67 lines
1.7 KiB
Go
67 lines
1.7 KiB
Go
package asm
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import (
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"bytes"
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"fmt"
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"hash/crc64"
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"io"
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"github.com/vbatts/tar-split/tar/storage"
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)
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// NewOutputTarStream returns an io.ReadCloser that is an assembled tar archive
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// stream.
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//
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// It takes a storage.FileGetter, for mapping the file payloads that are to be read in,
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// and a storage.Unpacker, which has access to the rawbytes and file order
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// metadata. With the combination of these two items, a precise assembled Tar
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// archive is possible.
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func NewOutputTarStream(fg storage.FileGetter, up storage.Unpacker) io.ReadCloser {
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// ... Since these are interfaces, this is possible, so let's not have a nil pointer
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if fg == nil || up == nil {
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return nil
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}
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pr, pw := io.Pipe()
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go func() {
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for {
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entry, err := up.Next()
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if err != nil {
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pw.CloseWithError(err)
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return
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}
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switch entry.Type {
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case storage.SegmentType:
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if _, err := pw.Write(entry.Payload); err != nil {
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pw.CloseWithError(err)
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return
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}
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case storage.FileType:
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if entry.Size == 0 {
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continue
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}
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fh, err := fg.Get(entry.Name)
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if err != nil {
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pw.CloseWithError(err)
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return
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}
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c := crc64.New(storage.CRCTable)
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tRdr := io.TeeReader(fh, c)
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if _, err := io.Copy(pw, tRdr); err != nil {
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fh.Close()
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pw.CloseWithError(err)
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return
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}
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if !bytes.Equal(c.Sum(nil), entry.Payload) {
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// I would rather this be a comparable ErrInvalidChecksum or such,
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// but since it's coming through the PipeReader, the context of
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// _which_ file would be lost...
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fh.Close()
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pw.CloseWithError(fmt.Errorf("file integrity checksum failed for %q", entry.Name))
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return
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}
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fh.Close()
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}
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}
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}()
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return pr
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}
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