This fuzzer shows how to implement grammar-aware fuzzing. Gramatron uses grammar automatons in conjunction with aggressive mutation operators to synthesize complex bug triggers. auto.json records grammar automaton of php,which is corresponding to libafl::generators::Automatonand serialized into auto.postcard. libafl::generators::gramatron will generate valid grammar sequences using Automaton and then pass them into harness. The function of harness is to print the original input.

When you use cargo run, You may see output as follows:

b=mlhs_node.isz(c,c, )
d=false.keyword__FILE__(c,b,a,b)
a=select.Jan(d)
a=first.literal( )
b=[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,nil].DomainError(c)
next a
b=Oo.gsub(a,d,b)
d=0.hex( )