* Just do the buf check early and fail out
* If the offset being searched is:
00110000 00 b5 7e 45 61 e2 76 d3 c1 78 dd 15 95 cd 1f f1 |..~Ea.v..x......|
.. and the match string is '.!/bin/sh'
.. then it'll set the match string[0] to '\0', do a strncmp() against
the read buffer, find it's matching two zero-length strings, and think
that's where to start.
MFC after: 2 weeks
28d507fcec