How to use dmalloc

 

How to use dmalloc

1. check whether dmalloc has been installed in your computer

Normally dmalloc has been installed in the system, you can check this using: gyliu@egodev05-35: whereis dmalloc

dmalloc: /usr/bin/dmalloc /usr/include/dmalloc.h

 

If it is not installed in your computer, you can get src from /scratch/dev/ego/gyliu/dmalloc-5.5.2, compile and install it on your computer, the process is same as building 3^rd party library.

 

2. setenv

Tcsh: setenv DMALLOC_OPTIONS "log=logname,debug=0x3"

Bash: export DMALLOC_OPTIONS=log=logname,debug=0x3

Note: logname is the file that will record your compile info.

 

3. You need to include dmalloc.h in your source code.

#include <dmalloc.h>

 

4. A simple example:

1 /* test.c for showing you how dmalloc works*/

      2 #include <stdio.h>

      3 #include <stdlib.h>

      4 #include <dmalloc.h>

      5

      6 void swap(int *a, int *b)

      7 {      

      8         *a = *a ^ *b;

      9         *b = *a ^ *b;

     10         *a = *a ^ *b;

     11 }

     12

     13 int main()

     14 {      

     15         char *str = malloc(100); /* malloc but not freed */

     16         int a = 9;

     17         int b = 8;

     18         swap(&a, &b);

     19         printf("%d    ", a);

     20         printf("%d/n ", b);

     21 }

 

setenv DMALLOC_OPTIONS "log=xjtuse,debug=0x3"

 

gcc -g t.c –ldmalloc

 

Then in your directory will generate your binary a.out and compiling record file xjtuse. Open xjutse, you can see it like this:

gyliu@egodev05-60: cat xjtuse

1193233343: 1: Dmalloc version '5.3.0' from 'http://dmalloc.com/'

1193233343: 1: flags = 0x3, logfile 'xjtuse'

1193233343: 1: interval = 0, addr = 0, seen # = 0, limit = 0

1193233343: 1: starting time = 1193233343

1193233343: 1: process pid = 24116

1193233343: 1: Dumping Chunk Statistics:

1193233343: 1: basic-block 4096 bytes, alignment 8 bytes, heap grows up

1193233343: 1: heap address range: 0x9a73000 to 0x9a79000, 24576 bytes

1193233343: 1:     user blocks: 1 blocks, 4068 bytes (16%)

1193233343: 1:    admin blocks: 5 blocks, 20480 bytes (83%)

1193233343: 1: external blocks: 0 blocks, 0 bytes (0%)

1193233343: 1:    total blocks: 6 blocks, 24576 bytes

1193233343: 1: heap checked 0

1193233343: 1: alloc calls: malloc 1, calloc 0, realloc 0, free 0

1193233343: 1: alloc calls: recalloc 0, memalign 0, valloc 0

1193233343: 1: alloc calls: new 0, delete 0

1193233343: 1:   current memory in use: 100 bytes (1 pnts)

1193233343: 1: total memory allocated: 100 bytes (1 pnts)

1193233343: 1: max in use at one time: 100 bytes (1 pnts)

1193233343: 1: max alloced with 1 call: 100 bytes

1193233343: 1: max unused memory space: 28 bytes (21%)

1193233343: 1: top 10 allocations:

1193233343: 1: total-size count in-use-size count source

1193233343: 1:         100      1         100      1 t.c:15

1193233343: 1:         100      1         100      1 Total of 1

1193233343: 1: Dumping Not-Freed Pointers Changed Since Start:

1193233343: 1: not freed: '0x9a73f80|s1' (100 bytes) from 't.c:15'

1193233343: 1: total-size count source

1193233343: 1:         100      1 t.c:15

1193233343: 1:         100      1 Total of 1

1193233343: 1: ending time = 1193233343, elapsed since start = 0:00:00

gyliu@egodev05-61: cat xjtuse | grep freed

1193233343: 1: not freed: '0x9a73f80|s1' (100 bytes) from 't.c:15'

 

This way, you can check which line you have malloc/calloc memory but did not free the memory.