Re: [PATCH 1/5] Make xstrndup common

Josh Triplett [off-list ref] writes:

Daniel Barkalow wrote:
...

quoted

Good catch. Replacing the memcpy with strncpy solves this, right? 
(Potentially allocating a bit of extra memory if someone is actually using 
it on too short a string for some reason, of course).

That would work, but it seems bad to allocate excess memory.  How about just
using strlen and setting len to that if shorter, before doing the xmalloc and
memcpy?  Yes, that makes two passes over the string, but I don't see any way
around that.

Hand-rolling strnlen() would be needed anyway, because there is
no guarantee that the incoming string is NUL terminated.  In the
worst case the string may point at a region of memory filled
with non-NUL to the end, which coincides with a page boundary,
and the next page may be an unmapped one; your strlen() would
sigbus.