24 lines
587 B
Go
24 lines
587 B
Go
package iout
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import (
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"errors"
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"fmt"
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"io"
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)
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func CopyRange(w io.Writer, r io.Reader, start, length int64) error {
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if _, err := io.CopyN(io.Discard, r, start); err != nil && !errors.Is(err, io.EOF) {
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return fmt.Errorf("discard %d: %w", start, err)
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}
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if length == 0 {
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if _, err := io.Copy(w, r); err != nil && !errors.Is(err, io.EOF) {
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return fmt.Errorf("direct copy: %w", err)
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}
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return nil
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}
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if _, err := io.CopyN(w, io.MultiReader(r, NewNullReader()), length); err != nil && !errors.Is(err, io.EOF) {
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return fmt.Errorf("copy %d: %w", length, err)
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}
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return nil
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}
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