Run KLEE, the involuntary base64 decoder

# Compile emitting LLVM bytecode to attract KLEE to its prey :-)
user@machine:~/folder$ clang -I../klee/include -emit-llvm -c -g base64encode.c
base64encode.c:37:3: warning: implicit declaration of function '__assert_fail' is invalid in C99 [-Wimplicit-function-declaration]
  klee_assert(!(!error &&
  ^
../klee/include/klee/klee.h:96:6: note: expanded from macro 'klee_assert'
   : __assert_fail (#expr, __FILE__, __LINE__, __PRETTY_FUNCTION__))    \
     ^
1 warning generated.

# Release the KLEEken!
user@machine:~/folder$ time klee --libc=uclibc --posix-runtime base64encode.bc
KLEE: NOTE: Using klee-uclibc : /home/user/klee/Release+Asserts/lib/klee-uclibc.bca
KLEE: NOTE: Using model: /home/user/klee/Release+Asserts/lib/libkleeRuntimePOSIX.bca
KLEE: output directory is "/home/user/folder/klee-out-0"
KLEE: WARNING: undefined reference to function: klee_posix_prefer_cex
KLEE: WARNING ONCE: calling external: syscall(16, 0, 21505, 35235760)
KLEE: WARNING ONCE: calling __user_main with extra arguments.
KLEE: ERROR: /home/user/folder/base64encode.c:37: ASSERTION FAIL: !(!error && new_dest_size == dest_size && same(new_dest, dest, new_dest_size))
KLEE: NOTE: now ignoring this error at this location

KLEE: done: total instructions = 7742
KLEE: done: completed paths = 20
KLEE: done: generated tests = 20

real    0m1.706s
user    0m1.555s
sys 0m0.150s

# That was fast... could it be?
user@machine:~/folder$ ls klee-last/*.err
klee-last/test000020.assert.err

# No escape from KLEEality! :-)
user@machine:~/folder$ ktest-tool klee-last/test000020.ktest
ktest file : 'klee-last/test000020.ktest'
args       : ['base64encode.bc']
num objects: 2
object    0: name: 'model_version'
object    0: size: 4
object    0: data: '\x01\x00\x00\x00'
object    1: name: 'new_src'
object    1: size: 14
object    1: data: 'Hello, world!\x00'