57 lines
1.6 KiB
Go
57 lines
1.6 KiB
Go
// Package archiveutil helps dealing with common archive file formats.
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package archiveutil
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import (
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"archive/tar"
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"bufio"
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"bytes"
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"compress/bzip2"
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"compress/gzip"
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"fmt"
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"io"
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)
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// TODO: zstd support
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// TODO: xz support
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// OpenTar opens a `.tar`, `.tar.gz`, or `.tar.bz2` file.
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//
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// Peeks the first few bytes in the given reader and auto-detects the file format.
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// Returns a tar reader spliced together with a decompressor if necessary.
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func OpenTar(rawRd io.Reader) (*tar.Reader, error) {
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rd := bufio.NewReader(rawRd)
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magicBytes, err := rd.Peek(6)
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if err != nil {
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return nil, fmt.Errorf("failed to detect magic: %w", err)
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}
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uncompressedRd := io.Reader(rd)
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// Check first few bytes for known compression magics.
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if bytes.Equal(magicBytes[:2], []byte("BZ")) {
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uncompressedRd = bzip2.NewReader(rd)
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} else if bytes.Equal(magicBytes[:3], []byte{0x1f, 0x8b, 0x08}) {
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uncompressedRd, err = gzip.NewReader(rd)
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if err != nil {
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return nil, fmt.Errorf("invalid .tar.gz: %w", err)
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}
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} else if bytes.Equal(magicBytes[:6], []byte{0xfd, 0x37, 0x7a, 0x58, 0x5a, 0x00}) {
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return nil, fmt.Errorf(".tar.xz not supported yet")
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} else if bytes.Equal(magicBytes[1:4], []byte{0xb5, 0x2f, 0xfd}) {
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return nil, fmt.Errorf(".tar.zst not supported yet")
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} else {
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// Presumed uncompressed case.
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// Peek and see if we can find a valid tar header.
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peek, err := rd.Peek(1024)
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if err != nil {
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return nil, err
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}
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peekTar := tar.NewReader(bytes.NewReader(peek))
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if _, err = peekTar.Next(); err != nil {
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// Doesn't seem to be a valid tar header, bail.
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return nil, fmt.Errorf("unknown archive format")
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}
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}
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return tar.NewReader(uncompressedRd), nil
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}
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