buf(9) woes: when does bcopy do nothing at all?

[Poul-Henning Kamp]

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In message <CAOtMX2gdw+eQQU_-DC+EgimbCyw6ynbX1haGLUmn1dApk4rMZw at mail.gmail.com>, Alan Somers writes:

>How is it possible that bcopy() doesn't affect its output array at all?

That conclusion does not follow from your example:

>bcopy(cp, iov->iov_base, cnt);
>r = memcmp(cp, iov->iov_base, cnt);
>if (r)
>    printf("uiomove: miscompare\n");

If [cp:cp+cnt] and [iov_base:iov_base+cnt] overlap the bcopy result
is undefined.

Try memmove instead ?

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