Fix memory leaks

[mforthewin]

The program in its current state leaks memory from the formatStatContent function during its execution.

Instrumenting the binary with Valgrind's memcheck tool exposes the oversight:

$ valgrind -s --tool=memcheck --leak-check=full --show-leak-kinds=all $(which zps)
[...]
==30228== LEAK SUMMARY:
==30228==    definitely lost: 95,653 bytes in 382 blocks
==30228==    indirectly lost: 1,319,712 bytes in 8,369 blocks
==30228==      possibly lost: 0 bytes in 0 blocks
==30228==    still reachable: 11,136 bytes in 69 blocks
==30228==         suppressed: 0 bytes in 0 blocks
==30228== 
==30228== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 0 from 0)

Running the program compiled using gcc with -fsanitize=address -fsanitize=leak -fsanitize=undefined also would have shown the presence of leaked memory.

The origins of the leaks are calls to regcomp and strdup without being followed by their appropriate deallocating calls (regfree and free, respectively).

The commit c11d771 fixes this by:

• putting the free outside of the if statement's block, as it should be unconditional
• inserting the regfree call before returning

With these patches applied, the program runs like this:

$ valgrind -s --tool=memcheck --leak-check=full --show-leak-kinds=all ./zps
[...]
==31351== HEAP SUMMARY:
==31351==     in use at exit: 0 bytes in 0 blocks
==31351==   total heap usage: 16,183 allocs, 16,183 frees, 105,154,201 bytes allocated
==31351== 
==31351== All heap blocks were freed -- no leaks are possible
==31351== 
==31351== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Commit cb61943 simply adds #include guards to the header to avoid redefinitions.

[orhun]

Looks great. Thanks for your contribution! 🐻

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

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Files	Coverage Δ
src/zps.c	96.18% <100.00%> (+0.05%)	⬆️

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