The libsm library in the
sendmail source distribution offers a way to
provide memory leak detection and error checking that overlays the
usual malloc(3),
realloc(3), and free(3)
C-language library routines. To disable extra checking, define
SM_HEAP_CHECK as zero:
APPENDDEF(`confENVDEF', `-DSM_HEAP_CHECK=0')
If you choose to enable extra checking, it will not be turned on by
default. Instead you will need to turn it on and off with special
debugging command-line switches (we cover this soon). To enable extra
checking, define SM_HEAP_CHECK as 1:
APPENDDEF(`confENVDEF', `-DSM_HEAP_CHECK=1')
Once extra checking has been included in your
sendmail code, you can turn it on and off with
debugging command-line switches. The category is
sm_check_heap, and there are four meaningful
levels:
# /usr/sbin/sendmail -dsm_check_heap.level ...
The four meaningful values for level are shown
in Table 3-12.
Table 3-12. Debugging levels for memory validity checking
|
1
|
This level causes a table of all currently allocated blocks to be
maintained. The table is used by the sendmail
hooks sm_realloc( ) and
sm_free( ) to perform validity checks on their
first arguments.
|
|
2
|
With this level, a report will be printed just before
sendmail exits. That report contains a single
line listing the total storage allocation used in bytes.
|
|
3
|
With this level, a report will be printed just before
sendmail exits. That report, in addition to the
report given previously, will also list all leaked blocks of memory.
|
|
4
|
With this level, a report will be printed just before
sendmail exits. That report, in addition to the
reports given previously, will also list all allocated memory blocks.
|
The -dsm_check_heap command-line switch is most
useful when porting sendmail to a new machine.
It can also be valuable when adding new functions to
sendmail or to its companion programs.
To see if this compile-time macro is defined with your
sendmail binary, use the
-d0.12 debugging command-line switch.
