strange error building print/texinfo

[Eugene Grosbein]

On 17.10.2015 16:57, Eugene Grosbein wrote:
> On 17.10.2015 05:00, Sean Bruno wrote:
> 
>> I just built print/texinfo with the lastes qemu-user-static without an
>> issue:
>> http://tasty.ysv.freebsd.org/build.html?mastername=11mips-default&build=
>> 2015-10-16_18h26m15s
> 
> I've digged it: install(1) calls mmap() inside its copy() function:
> 
>         /*
>          * Mmap and write if less than 8M (the limit is so we don't totally
>          * trash memory on big files.  This is really a minor hack, but it
>          * wins some CPU back.
>          */
>         done_copy = 0;
>         if (size <= 8 * 1048576 && trymmap(from_fd) &&
>             (p = mmap(NULL, (size_t)size, PROT_READ, MAP_SHARED,
>                     from_fd, (off_t)0)) != MAP_FAILED) {
>                 nw = write(to_fd, p, size);
> 
> 
> mmap() returns NULL in my case, not MAP_FAILD.
> There is no check for NULL and write() returns EFAULT for attempt to write to NULL.

Source file is zero bytes length. It seems, mmap returns NULL in such case only.