|MTRACE(3)||Linux Programmer's Manual||MTRACE(3)|
NAMEmtrace, muntrace - malloc tracing
DESCRIPTIONThe mtrace() function installs hook functions for the memory-allocation functions ( malloc(3), realloc(3) memalign(3), free(3)). These hook functions record tracing information about memory allocation and deallocation. The tracing information can be used to discover memory leaks and attempts to free nonallocated memory in a program.
CONFORMING TOThese functions are GNU extensions.
NOTESIn normal usage, mtrace() is called once at the start of execution of a program, and muntrace() is never called.
BUGSThe line-number information produced by mtrace(1) is not always precise: the line number references may refer to the previous or following (non-blank) line of the source code.
EXAMPLEThe shell session below demonstrates the use of the mtrace() function and the mtrace(1) command in a program that has memory leaks at two different locations. The demonstration uses the following program:
$ cat t_mtrace.c
main(int argc, char *argv)
for (j = 0; j < 2; j++)
malloc(100); /* Never freed--a memory leak */
calloc(16, 16); /* Never freed--a memory leak */
When we run the program as follows, we see that mtrace() diagnosed memory leaks at two different locations in the program:
$ cc -g t_mtrace.c -o t_mtrace
$ export MALLOC_TRACE=/tmp/t
$ mtrace ./t_mtrace $MALLOC_TRACE
Memory not freed:
Address Size Caller
0x084c9378 0x64 at /home/cecilia/t_mtrace.c:12
0x084c93e0 0x64 at /home/cecilia/t_mtrace.c:12
0x084c9448 0x100 at /home/cecilia/t_mtrace.c:16
The first two messages about unfreed memory correspond to the two malloc(3) calls inside the for loop. The final message corresponds to the call to calloc(3) (which in turn calls malloc(3)).
SEE ALSOmtrace(1), malloc(3), malloc_hook(3), mcheck(3)
COLOPHONThis page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.