mtrace is an interactive dynamic memory tracer/debugger for C and C++ using GLIBC, which intercepts and reports all kinds of dynamic memory allocations using a preloaded library.

It supports the developer to get statistics about the memory usage and finding memory leaks in an arbitrate application. There is no need of modification of the source code nor any recompilation.

Unlike other dynamic memory tracer, mtrace is able to find no longer referenced memory allocation by scanning all writable memory mappings of the program against the addresses of the allocation. If the memory address will be not found during a scan there is a high change for a missing reference and therefore for a memory leak.

The mtrace utility was designed to run in a very constrained environment, like small embedded systems. This is one of the reasons for a client/server architecture. The server runs on the target side and the interactive client runs on the host side, the communication is done via TCP. If server and client are on the same machine then the communication can be done via UNIX Domain Socket. Both sides can run on different architectures, address sizes and endianness, but for tracing 64 bit programs the client must be compiled as a 64 bit program. On the host side all binaries (including debug information) must be accessible, there is no need for debug information on the target side.

The preloaded library libmemtrace.so intercepts the following GLIBC calls:

• malloc()
• memalign()
• realloc()
• free()
• posix_memalign()
• aligned_alloc()
• valloc()
• pvalloc()
• mmap()
• munmap()
• clone()
• system()
• execve()
• exit()

The operator new() method is using malloc(), so memory allocations of a C++ application can also be traced.

Tracing child process it currently not full implemented, but will be one of the next steps.

Future version will use breakpoints instead of a preloaded library, which makes it possible to attach the memory leak debugger to an application at any time, similarly to strace or ltrace. This features allows also to trace internal libc allocations, statical linked programs and other C libraries (uClibc, bionic).

Currently mtrace supports only Linux, but there are plans to support different operating systems like Windows (sigh).

Stay tuned...