os: File.Write cannot return io.ErrShortWrite

[dominikh]

What version of Go are you using (go version)?

go version devel +13cdd814ea Tue May 16 21:01:42 2017 +0000 linux/amd64

(*os.File).Write is supposed to return an error on short writes. The assignment in

go/src/os/file.go

Line 145 in 13cdd81

err = io.ErrShortWrite

however has no effect, because e is the error being returned, not err.

Making the obvious fix will break a bunch of tests in pipe_test.go, which suggests it might also change the behaviour of real programs. Is it just a matter of calling epipecheck before checking for a short write?

[ianlancetaylor]

I think it's just a bug I introduced in the internal/poll work. Will fix.

[gopherbot]

CL https://golang.org/cl/43558 mentions this issue.