bbbe67bf7c
* Vendors packages * Adds a Makefile that uses docker to build a static binary against musl using alpine linux. Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>
59 lines
2.3 KiB
Go
59 lines
2.3 KiB
Go
package shared
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import (
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"bytes"
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"fmt"
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"io"
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"os"
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)
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// DetectCompression detects compression from a file name.
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func DetectCompression(fname string) ([]string, string, []string, error) {
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f, err := os.Open(fname)
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if err != nil {
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return nil, "", nil, err
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}
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defer f.Close()
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return DetectCompressionFile(f)
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}
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// DetectCompressionFile detects the compression type of a file and returns the tar arguments needed
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// to unpack the file, compression type (in the form of a file extension), and the command needed
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// to decompress the file to an uncompressed tarball.
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func DetectCompressionFile(f io.Reader) ([]string, string, []string, error) {
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// read header parts to detect compression method
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// bz2 - 2 bytes, 'BZ' signature/magic number
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// gz - 2 bytes, 0x1f 0x8b
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// lzma - 6 bytes, { [0x000, 0xE0], '7', 'z', 'X', 'Z', 0x00 } -
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// xy - 6 bytes, header format { 0xFD, '7', 'z', 'X', 'Z', 0x00 }
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// tar - 263 bytes, trying to get ustar from 257 - 262
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header := make([]byte, 263)
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_, err := f.Read(header)
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if err != nil {
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return nil, "", nil, err
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}
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switch {
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case bytes.Equal(header[0:2], []byte{'B', 'Z'}):
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return []string{"-jxf"}, ".tar.bz2", []string{"bzip2", "-d"}, nil
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case bytes.Equal(header[0:2], []byte{0x1f, 0x8b}):
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return []string{"-zxf"}, ".tar.gz", []string{"gzip", "-d"}, nil
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case (bytes.Equal(header[1:5], []byte{'7', 'z', 'X', 'Z'}) && header[0] == 0xFD):
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return []string{"-Jxf"}, ".tar.xz", []string{"xz", "-d"}, nil
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case (bytes.Equal(header[1:5], []byte{'7', 'z', 'X', 'Z'}) && header[0] != 0xFD):
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return []string{"--lzma", "-xf"}, ".tar.lzma", []string{"lzma", "-d"}, nil
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case bytes.Equal(header[0:3], []byte{0x5d, 0x00, 0x00}):
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return []string{"--lzma", "-xf"}, ".tar.lzma", []string{"lzma", "-d"}, nil
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case bytes.Equal(header[257:262], []byte{'u', 's', 't', 'a', 'r'}):
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return []string{"-xf"}, ".tar", []string{}, nil
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case bytes.Equal(header[0:4], []byte{'h', 's', 'q', 's'}):
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return []string{"-xf"}, ".squashfs", []string{"sqfs2tar", "--no-skip"}, nil
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case bytes.Equal(header[0:3], []byte{'Q', 'F', 'I'}):
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return []string{""}, ".qcow2", []string{"qemu-img", "convert", "-O", "raw"}, nil
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case bytes.Equal(header[0:4], []byte{0x28, 0xb5, 0x2f, 0xfd}):
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return []string{"--zstd", "-xf"}, ".tar.zst", []string{"zstd", "-d"}, nil
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default:
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return nil, "", nil, fmt.Errorf("Unsupported compression")
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}
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}
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