Duc-Tam Nguyen
fafa3dfa51
BuildZIM walks a cloned host directory, turns every file into a content entry with a MIME inferred from its extension, picks a main page, and adds the standard metadata plus a mainPage redirect. state.json is skipped. BuildBinary appends the archive to a copy of kage behind a KAGEPCK1 trailer, and Embedded detects that trailer at startup so the binary serves itself. Handler maps / to the main page and /path to a content entry, the same handler the embedded viewer uses.
51 lines
1.3 KiB
Go
51 lines
1.3 KiB
Go
package pack
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import (
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"encoding/binary"
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"io"
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"os"
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)
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// Embedded inspects the running executable for an appended ZIM archive. If the
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// KAGEPCK1 trailer is present, it returns a ReaderAt bounded to the archive, its
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// size, and ok=true; the file handle stays open for the life of the process so
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// the viewer can serve from it. A normal kage build has no trailer, so the cost
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// to every ordinary invocation is one Open plus a 24-byte ReadAt.
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func Embedded() (ra io.ReaderAt, size int64, ok bool) {
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exe, err := os.Executable()
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if err != nil {
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return nil, 0, false
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}
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f, err := os.Open(exe)
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if err != nil {
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return nil, 0, false
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}
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info, err := f.Stat()
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if err != nil {
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_ = f.Close()
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return nil, 0, false
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}
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total := info.Size()
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if total < int64(trailerLen) {
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_ = f.Close()
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return nil, 0, false
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}
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tr := make([]byte, trailerLen)
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if _, err := f.ReadAt(tr, total-int64(trailerLen)); err != nil {
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_ = f.Close()
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return nil, 0, false
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}
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if string(tr[:8]) != trailerMagic || string(tr[trailerLen-8:]) != trailerMagic {
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_ = f.Close()
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return nil, 0, false
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}
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zlen := int64(binary.LittleEndian.Uint64(tr[8:16]))
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start := total - int64(trailerLen) - zlen
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if zlen <= 0 || start < 0 {
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_ = f.Close()
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return nil, 0, false
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}
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return io.NewSectionReader(f, start, zlen), zlen, true
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}
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