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Dynamic memory tracker for C
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Dynamic Memory Tracker (DMT) Library


A small C library for detecting memory leaks, tracking memory usage and detecting invalid frees or reallocs. The library consists of two files (dmt.c and dmt.h) and provides wrappers for the 4 main dynamic memory functions in C (malloc, calloc, realloc and free). The library is currently thread unsafe.


The library should be dropped inside a C project and compiled along with it. The library provides the following macros and functions:

  • void* dmt_malloc(size_t size) A wrapper for malloc
  • void* dmt_calloc(size_t num, size_t size) A wrapper for calloc
  • void* dmt_realloc(void* ptr, size_t size) A wrapper for realloc
  • void dmt_free(void *ptr) A wrapper for free
  • size_t dmt_size(void* ptr) Returns the size in bytes of a pointer's allocation
  • void dmt_dump(FILE* fp) Dumps information about the currently unfreed allocations
  • size_t dmt_usage(void) Returns the total number of bytes currently allocated
  • int dmt_has(void* ptr) Returns non-zero if the pointer is allocated by dmt

The wrapper macros (dmt_malloc, dmt_calloc, dmt_realloc and dmt_free) should be used in place of the functions which they wrap (malloc, calloc, realloc and free). Their arguments and return values match those of the functions they wrap.

Additional options can be set by defining the following macros:

  • DMT_UNSAFE Avoids checking whether a pointer passed to dmt_free or dmt_realloc is valid -- this may offer a noticable speed increase in programs with many allocations
  • DMT_ABORT_NULL If malloc, calloc or realloc return with NULL, the program will abort with an error
  • DMT_STACK_TRACE (Linux only) When using dmt_dump each unfreed allocation is also accompanied with a stack trace from when the allocation was made. Additionally, if the program aborts with an error it will dump a stack trace to stderr


This library is free software; you can redistribute it and/or modify it under the terms of the MIT license. See LICENSE for details.

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