Current git cve-bin-tool is very slow

[rossburton]

Using the 0.2 release I can scan an entire rootfs in 107 seconds.

With current git master, I got bored and gave up after five minutes. A quick look at strace shows that it has been spending the last few minutes slowly working through libc.so (17M) and is still going.

I'm sure there's a good reason why the use of file/strings was removed and scanning in Python has been done but this is far too slow. Python is slower than C but this is clearly an algorithmic problem.

[rossburton]

Update: after 45 minutes it is still scanning. strace reveals that it is now scanning 4KB/second, so there's presumably an algorithmic problem somewhere.

I suggest reverting the strings/file patches until they can be added back without catastrophic performance regressions.

[terriko]

ouch. I think rather than reverting I'll switch it to use strings/file if they're available, but we should see what we can do about the performance for those platforms where we need the python implementation.