md5: Fix input error check.

[des]

Summary

Fixes: 4849767cb16a
MFC after: 1 week
Sponsored by: Klara, Inc.

[tsoome]

sbin/md5/md5.c

685

There is actually potential problem. fread() can return value between 0 to sizeof(block) in case of error or eof, I guess it is ok to have short read in case of eof, but we probably want to be sure there was no error.

It may be better to use do {} while (!ferror() && !feof()) loop there.

689

len is already size_t, you can drop the type cast.

[des]

sbin/md5/md5.c

685

I don't see the problem. The next fread() would return zero which ends the loop, and ferror() after that will return non-zero and we will report the error.

[des]

Remove unnecessary cast.

[lwhsu]

I can confirm this fix the building issue with gcc12.