root@ubuntu:/home/ubuntu# valgrind ./a.out
==5561== Memcheck, a memory error detector
==5561== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==5561== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==5561== Command: ./a.out
==5561==
path --> '/root'
/root./
/root../
==5561== Invalid read of size 4
==5561==    at 0x52EC1BA: fread (iofread.c:37)
==5561==    by 0x401B82: encryptfile (test2.c:312)
==5561==    by 0x401976: ls_dir (test2.c:260)
==5561==    by 0x40165B: main (test2.c:194)
==5561==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==5561==
==5561==
==5561== Process terminating with default action of signal 11 (SIGSEGV)
==5561==  Access not within mapped region at address 0x0
==5561==    at 0x52EC1BA: fread (iofread.c:37)
==5561==    by 0x401B82: encryptfile (test2.c:312)
==5561==    by 0x401976: ls_dir (test2.c:260)
==5561==    by 0x40165B: main (test2.c:194)
==5561==  If you believe this happened as a result of a stack
==5561==  overflow in your program's main thread (unlikely but
==5561==  possible), you can try to increase the size of the
==5561==  main thread stack using the --main-stacksize= flag.
==5561==  The main thread stack size used in this run was 8388608.
==5561==
==5561== HEAP SUMMARY:
==5561==     in use at exit: 43,125 bytes in 90 blocks
==5561==   total heap usage: 96 allocs, 6 frees, 49,366 bytes allocated
==5561==
==5561== LEAK SUMMARY:
==5561==    definitely lost: 0 bytes in 0 blocks
==5561==    indirectly lost: 0 bytes in 0 blocks
==5561==      possibly lost: 0 bytes in 0 blocks
==5561==    still reachable: 43,125 bytes in 90 blocks
==5561==         suppressed: 0 bytes in 0 blocks
==5561== Rerun with --leak-check=full to see details of leaked memory
==5561==
==5561== For counts of detected and suppressed errors, rerun with: -v
==5561== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)