58 lines
991 B
Go
58 lines
991 B
Go
package layer
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import (
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"io"
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"net/http"
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)
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type (
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detector struct {
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io.Reader
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err error
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data []byte
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}
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errReader struct {
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data []byte
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err error
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offset int
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}
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)
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const contentTypeDetectSize = 512
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func newReader(data []byte, err error) *errReader {
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return &errReader{data: data, err: err}
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}
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func (r *errReader) Read(b []byte) (int, error) {
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if r.offset >= len(r.data) {
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return 0, io.EOF
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}
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n := copy(b, r.data[r.offset:])
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r.offset += n
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if r.offset >= len(r.data) {
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return n, r.err
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}
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return n, nil
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}
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func newDetector(reader io.Reader) *detector {
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return &detector{
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data: make([]byte, contentTypeDetectSize),
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Reader: reader,
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}
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}
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func (d *detector) Detect() (string, error) {
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n, err := d.Reader.Read(d.data)
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if err != nil && err != io.EOF {
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d.err = err
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return "", err
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}
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d.data = d.data[:n]
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return http.DetectContentType(d.data), nil
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}
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func (d *detector) MultiReader() io.Reader {
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return io.MultiReader(newReader(d.data, d.err), d.Reader)
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}
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