README

PROJECT MY_GCOV

Hi there!

Language: C++ 14
Compilation: just type make

Usage:

For my_strace   : ./my_gcov --level1 <path_to_bin> [args]
eg              : ./my_gcov --level1 /bin/ls

For my_sscov    : ./my_gcov --level2 <output_file> <path_to_bin> [args]
eg              : ./my_gcov --level2 out /bin/ls

For my_addr2line    : ./my_gcov --level3 <path_to_bin> [args]
eg                  : ./my_gcov --level3 /bin/ls

For my_gcov         : ./my_gcov --level4 <path_to_bin> [args]
eg                  : ./my_gcov --level4 a.out

The level4 makes a cov_files directory where you can find
all result of coverage in .cov files.

I do the dwarf parsing in src/my_addr2line/dwarf.cc

Here is how I handle the level 4 :

I put breakpoints on every RET/CALL/JMP in the .text section as mentionned
in the subject.

I mprotect(PROT_READ | PROT_WRITE) all the dynamic library pages.
(I look for the page address in /proc/<pid>/maps)

When rip goes outside of .text in a dynamic library page, it segfault.
I catch the segfault and this time I mprotect(PROT_READ | PROT_WRITE) the
.text section and mprotect(PROT_READ | PROT_WRITE | PROT_EXEC) the dynamic
library pages.

etc etc.

With this trick I can find the begin and end of each basic block.

Of course I use the library capstone to display the assembly.

Project tested on Ubuntu x86_64 14.04 with g++ 4.8.2, 4.9.1, 4.9.2 and clang++ 3.5