Caleb Gardner
86 lines
2.0 KiB
Go
86 lines
2.0 KiB
Go
package squashfs
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import (
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"encoding/binary"
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"errors"
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"io"
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"github.com/CalebQ42/GoSquashfs/internal/inode"
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)
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type FragmentEntryRaw struct {
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Start uint64
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Size uint32
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_unused uint32
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}
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type FragmentEntry struct {
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start uint64
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size uint32
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compressed bool
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}
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//NewFragmentEntry reads a fragment entry from the given io.Reader.
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func (r *Reader) NewFragmentEntry(rdr io.Reader) (*FragmentEntry, error) {
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var entry FragmentEntry
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var raw FragmentEntryRaw
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err := binary.Read(rdr, binary.LittleEndian, &raw)
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if err != nil {
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return nil, err
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}
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entry.start = raw.Start
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entry.compressed = raw.Size&0x1000000 == 0x1000000
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entry.size = raw.Size &^ 0x1000000
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return &entry, nil
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}
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//GetFragmentDataFromInode returns the fragment data for a given inode.
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//If the inode does not have a fragment, harmlessly returns an empty slice without an error.
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func (r *Reader) GetFragmentDataFromInode(in *inode.Inode) ([]byte, error) {
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var size uint32
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var fragIndex uint32
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var fragOffset uint32
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if in.Type == inode.BasicFileType {
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bf := in.Info.(inode.BasicFile)
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if !bf.Fragmented {
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return make([]byte, 0), nil
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}
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if bf.Init.BlockStart == 0 {
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size = bf.Init.Size
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} else {
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size = bf.BlockSizes[len(bf.BlockSizes)-1]
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}
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fragIndex = bf.Init.FragmentIndex
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fragOffset = bf.Init.FragmentOffset
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} else if in.Type == inode.ExtFileType {
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bf := in.Info.(inode.ExtendedFile)
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if !bf.Fragmented {
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return make([]byte, 0), nil
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}
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if bf.Init.BlockStart == 0 {
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size = bf.Init.Size
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} else {
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size = bf.BlockSizes[len(bf.BlockSizes)-1]
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}
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fragIndex = bf.Init.FragmentIndex
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fragOffset = bf.Init.FragmentOffset
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} else {
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return nil, errors.New("Inode type not supported")
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}
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frag := r.fragEntries[fragIndex]
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datRdr, err := r.NewDataReader(int64(frag.start), []uint32{frag.size})
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if err != nil {
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return nil, err
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}
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_, err = datRdr.Seek(int64(fragOffset), io.SeekStart)
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if err != nil {
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return nil, err
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}
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tmp := make([]byte, size)
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_, err = datRdr.Read(tmp)
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if err != nil {
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return nil, err
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}
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return tmp, nil
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}
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