mtrace
function is called it looks for an environment
variable named MALLOC_TRACE
. This variable is supposed to
contain a valid file name. The user must have write access. If the
file already exists it is truncated. If the environment variable is not
set or it does not name a valid file which can be opened for writing
nothing is done. The behaviour of malloc
etc. is not changed.
For obvious reasons this also happens if the application is installed
with the SUID or SGID bit set.
If the named file is successfully opened, mtrace
installs special
handlers for the functions malloc
, realloc
, and
free
(see section Memory Allocation Hooks). From then on, all uses of these
functions are traced and protocolled into the file. There is now of
course a speed penalty for all calls to the traced functions so tracing
should not be enabled during normal use.
This function is a GNU extension and generally not available on other systems. The prototype can be found in `mcheck.h'.
muntrace
function can be called after mtrace
was used
to enable tracing the malloc
calls. If no (succesful) call of
mtrace
was made muntrace
does nothing.
Otherwise it deinstalls the handlers for malloc
, realloc
,
and free
and then closes the protocol file. No calls are
protocolled anymore and the program runs again at full speed.
This function is a GNU extension and generally not available on other systems. The prototype can be found in `mcheck.h'.
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