[klee-dev] KLEE behaviour with function call to uclibc

[Shehbaz Jaffer]

Hello KLEE developers,

I am trying to understand how KLEE emulates environment variables. In particular, how do functions like getopt_long get executed with KLEE, when we give --sym-arg as an argument. getopt_long is found in unistd.h, and is available in uclibc. For a coreutils file like groups.c where the following line is encountered:

while ((optc = getopt_long (argc, argv, "", longopts, NULL)) != -1)

how would KLEE generate different inputs? for simplicity, consider the case where we use --sym-arg 1 10 as a command line argument which leads to argv[1] becoming a symbolic buffer of size 10, if my understanding is correct, when getopt_long is called, one of the two things can happen:

1) argv[1] is declared as a symbolic buffer, we explore all paths of getopt_long code in uclibc library, so all different if's / elses in getopt_long code will get forked and execute to give different optc values.
2) getopt_long is skipped, optc variable is made symbolic, and the main function in groups.c treats optc as symbolic value. on any successive if/else condition in groups.c containing optc, a new state is forked with new value of optc.

Is there a third (correct) way?

Please advise.

Thanks and Regards,
Shehbaz Jaffer