Caleb Gardner
85 lines
1.9 KiB
Go
85 lines
1.9 KiB
Go
package squashfs
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import (
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"bytes"
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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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//FileReader provides a io.Reader interface for files within a squashfs archive
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type FileReader struct {
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r *Reader
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data *dataReader
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fragmentData []byte
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fragged bool
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fragOnly bool
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read int
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FileSize int //FileSize is the total size of the given file
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}
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var (
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//ErrPathIsNotFile returns when trying to read from a file, but the given path is NOT a file.
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ErrPathIsNotFile = errors.New("The given path is not a file")
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)
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//ReadFile provides a squashfs.FileReader for the file at the given location.
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func (r *Reader) ReadFile(location string) (*FileReader, error) {
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var rdr FileReader
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rdr.r = r
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in, err := r.GetInodeFromPath(location)
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if err != nil {
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return nil, err
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}
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if in.Type != inode.BasicFileType && in.Type != inode.ExtFileType {
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return nil, ErrPathIsNotFile
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}
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switch in.Type {
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case inode.BasicFileType:
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fil := in.Info.(inode.BasicFile)
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rdr.fragged = fil.Fragmented
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rdr.fragOnly = fil.Init.BlockStart == 0
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rdr.FileSize = int(fil.Init.Size)
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case inode.ExtFileType:
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fil := in.Info.(inode.ExtendedFile)
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rdr.fragged = fil.Fragmented
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rdr.fragOnly = fil.Init.BlockStart == 0
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rdr.FileSize = int(fil.Init.Size)
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}
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if rdr.fragged {
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rdr.fragmentData, err = r.getFragmentDataFromInode(in)
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if err != nil {
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return nil, err
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}
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}
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if !rdr.fragOnly {
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rdr.data, err = r.newDataReaderFromInode(in)
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}
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return &rdr, nil
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}
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func (f *FileReader) Read(p []byte) (int, error) {
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if f.fragOnly {
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n, err := bytes.NewBuffer(f.fragmentData[f.read:]).Read(p)
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f.read += n
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if err != nil {
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return n, err
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}
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return n, nil
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}
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var read int
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n, err := f.data.Read(p)
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read += n
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if f.fragged && err == io.EOF {
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n, err = bytes.NewBuffer(f.fragmentData).Read(p[read:])
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read += n
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if err != nil {
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return read, err
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}
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} else if err != nil {
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return read, err
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}
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return read, nil
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}
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