- Add comprehensive documentation for shm::release(id), shm::remove(id), and shm::remove(name)
- release(id): Decrements ref count, cleans up memory and disk file when count reaches zero
- remove(id): Calls release(id) internally, then forces disk file cleanup (WARNING: do not use after release)
- remove(name): Only removes disk file, safe to use anytime
- Fix critical double-free bug in ShmTest test cases
- Problem: calling release(id) followed by remove(id) causes use-after-free crash
because release() already frees the id structure
- Solution: replace 'release(id); remove(id);' pattern with just 'remove(id)'
- Fixed tests: AcquireCreate, AcquireCreateOrOpen, GetMemory, GetMemoryNoSize,
RemoveById, SubtractReference
- Kept 'release(id); remove(name);' pattern unchanged (safe usage)
- Add explanatory comments in test code to prevent future misuse
Header changes (include/libipc/buffer.h):
- Rename: additional → mem_to_free (better semantic name)
- Add documentation comments explaining the parameter's purpose
- Clarifies that mem_to_free is passed to destructor instead of p
- Use case: when data pointer is offset into a larger allocation
Implementation changes (src/libipc/buffer.cpp):
- Update parameter name in constructor implementation
- No logic changes, just naming improvement
Test changes (test/test_buffer.cpp):
- Fix TEST_F(BufferTest, ConstructorWithMemToFree)
- Previous test caused crash: passed stack variable address to destructor
- New test correctly demonstrates the parameter's purpose:
* Allocate 100-byte block
* Use offset portion (bytes 25-75) as data
* Destructor receives original block pointer for proper cleanup
- Prevents double-free and invalid free errors
Semantic explanation:
buffer(data_ptr, size, destructor, mem_to_free)
On destruction:
destructor(mem_to_free ? mem_to_free : data_ptr, size)
This allows:
char* block = new char[100];
char* data = block + 25;
buffer buf(data, 50, my_free, block); // Frees 'block', not 'data'
- Change: byte_t const (& data)[N] → byte_t (& data)[N]
- Allows non-const byte arrays to be accepted by the constructor
- Fixes defect discovered by TEST_F(BufferTest, ConstructorFromByteArray)
- The const qualifier on array elements was too restrictive
- Keep char const & c unchanged as it's correct for single char reference
