85 lines
1.6 KiB
Go
85 lines
1.6 KiB
Go
package storage
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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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)
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/*
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Valid for ProDos disks in 2MG format.
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See:
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https://apple2.org.za/gswv/a2zine/Docs/DiskImage_2MG_Info.txt
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*/
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const (
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file2mgPreamble = uint32(1196247346) // "2IMG"
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file2mgFormatProdos = 1
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file2mgVersion = 1
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)
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type file2mgHeader struct {
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Preamble uint32
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Creator uint32
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HeaderSize uint16
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Version uint16
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Format uint32
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Flags uint32
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Blocks uint32
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OffsetData uint32
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LengthData uint32
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OffsetComment uint32
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LengthComment uint32
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OffsetCreator uint32
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LengthCreator uint32
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}
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func parse2mg(bd *BlockDisk) error {
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fileInfo, err := bd.file.Stat()
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if err != nil {
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return err
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}
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var header file2mgHeader
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minHeaderSize := binary.Size(&header)
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if fileInfo.Size() < int64(minHeaderSize) {
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return errors.New("Invalid 2MG file")
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}
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err = readHeader(bd.file, &header)
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if err != nil {
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return err
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}
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bd.blocks = header.Blocks
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bd.dataOffset = header.OffsetData
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if fileInfo.Size() < int64(bd.dataOffset+bd.blocks*ProDosBlockSize) {
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return errors.New("The 2MG file is too small")
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}
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return nil
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}
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func readHeader(buf io.Reader, header *file2mgHeader) error {
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err := binary.Read(buf, binary.LittleEndian, header)
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if err != nil {
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return err
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}
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if header.Preamble != file2mgPreamble {
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return errors.New("The 2mg file must start with '2IMG'")
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}
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if header.Format != file2mgFormatProdos {
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return errors.New("Only prodos disks are supported")
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}
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if header.Version != file2mgVersion {
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return errors.New("Version of 2MG image not supported")
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}
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return nil
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}
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