40 lines
820 B
Go
40 lines
820 B
Go
package meta
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import (
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"errors"
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"io"
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"io/ioutil"
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)
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// verifyPadding verifies the body of a Padding metadata block. It should only
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// contain zero-padding.
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//
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// ref: https://www.xiph.org/flac/format.html#metadata_block_padding
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func (block *Block) verifyPadding() error {
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zr := zeros{r: block.lr}
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_, err := io.Copy(ioutil.Discard, zr)
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return err
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}
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// Errors returned by zeros.Read.
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var (
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ErrInvalidPadding = errors.New("invalid padding")
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)
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// zeros implements an io.Reader, with a Read method which returns an error if
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// any byte read isn't zero.
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type zeros struct {
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r io.Reader
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}
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// Read returns an error if any byte read isn't zero.
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func (zr zeros) Read(p []byte) (n int, err error) {
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n, err = zr.r.Read(p)
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for i := 0; i < n; i++ {
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if p[i] != 0 {
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return n, ErrInvalidPadding
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}
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}
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return n, err
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}
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