liblttng-ust-libc is used for instrumenting some calls to libc in a program, without need for recompiling it. This library defines a malloc() function that is instrumented with a tracepoint. It also calls the libc malloc afterwards. When loaded with LD_PRELOAD, it replaces the libc malloc() function, in effect instrumenting all calls to malloc(). The same is performed for free(). See the "run" script for a usage example.