7deeb68d47
Naive migration, without any tries to start application closes #25 Signed-off-by: Evgeniy Kulikov <kim@nspcc.ru>
49 lines
716 B
Go
49 lines
716 B
Go
package layer
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import "io"
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type offsetWriter struct {
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io.Writer
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written int64
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skipped int64
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offset int64
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length int64
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}
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func newWriter(w io.Writer, offset, length int64) io.Writer {
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return &offsetWriter{
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Writer: w,
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offset: offset,
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length: length,
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}
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}
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func (w *offsetWriter) Write(p []byte) (int, error) {
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ln := len(p)
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length := int64(ln)
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offset := w.offset - w.skipped
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if length-offset < 0 {
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w.skipped += length
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return ln, nil
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}
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length -= offset
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left := w.length - w.written
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if left-length < 0 || length-left < length {
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length = left
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} else {
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return 0, nil
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}
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n, err := w.Writer.Write(p[offset : offset+length])
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w.written += int64(n)
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w.skipped += offset
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return n, err
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}
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