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writer-buffer-mutation

Default severity: error

The io.Writer contract requires Write implementations not to modify the provided byte slice, even temporarily. Mutating an element or appending into the input can corrupt caller-owned data.

Bad

Section titled “Bad”
func (w *writer) Write(p []byte) (int, error) { p[0] = 0; return len(p), nil }

Good

Section titled “Good”
func (w *writer) Write(p []byte) (int, error) { return w.dst.Write(p) }