HP aC++/HP C A.06.25 Programmer's Guide

+check=malloc
The +check=malloc option enables memory leak and heap corruption checks at
runtime. It will cause the user program to abort for writes beyond boundaries of heap
objects, free or realloc calls for a pointer that is not a valid heap object, and
out-of-memory conditions. Memory leak information is captured and written out to a
log file when the program exits. The name of the logfile is printed out before program
termination.
The +check=malloc option works by intercepting all heap allocation and deallocation
calls. This is done by the use of a debug malloc library, librtc.so. The option works
for programs that use the system malloc or for user provided malloc routines in a
shared library. The librtc.so library is also used by the HP WDB debugger to provide
heap memory checking features in the debugger. Please refer to the HP WDB debugger
documentation for more information about heap memory checking. The librtc.so
library is shipped as part of the wdb product. Please install the HP WDB bundled with
the compiler or a more recent version of wdb to get full functionality.
The default behavior of the +check=malloc option can be changed by users providing
their own rtcconfig file. The user specified rtcconfig file can be in the current
directory or in a directory specified by the GDBRTC_CONFIG environment variable.
The default configuration used by the +check=malloc option is:
check_bounds=1;check_free=1;scramble_block=1;
abort_on_bounds=1;abort_on_bad_free=1;abort_on_nomem=1;
check_leaks=1;min_leak_size=0;check_heap=0;
frame_count=4;output_dir=.;
When +check=bounds:pointer is also turned on, it can check freed memory
read/write. But the check needs to retain freed memory which is not turned on by
default. To turn on the feature, set the following environment variable at runtime:
RTC_MALLOC_CONFIG="retain_freed_blocks=1"
Or add "retain_freed_blocks=1" to the rtcconfig file. When malloc failes to allocate
specified memory, the runtime system will free the retained freed memory and try to
allocate memory.
For a description for the above configuration parameters and the full list of other
parameters, please refer to the HP WDB debugger documentation.
+check=stack[:frame|:variables|:none]
The +check=stack[:frame|:variables|:none] option enables runtime checks
to detect writes outside stack boundaries. Markers are placed before and after the whole
stack frame and around some stack variables. On procedure exit, a check is done to see
if any marker has been overwritten. If any stack check fails, an error message and stack
trace is written to stderr and the program is aborted. The stack checks are not
performed for an abnormal exit from the procedure (for example, using longjmp,
exit, abort, or exception handling).
Runtime Checking Options 107