Re: [suse-programming-e] False memleak detected?

19 Jun 2006


      On Monday 19 June 2006 7:55 am, Verdi March wrote:
...
Hi,
Valgrind detected memleak on one of my test case, which is
a standard, textbook insertion sort. However, I don't see
any problem with the testcase. I'm wondering if this is
a false alarm, and should submit a bug report.
I'm using SuSE 10.1, and valgrind-3.2.0-11.1 from opensuse build
service.
The followings are the test case and the output of valgrind.
I've marked the offending line (line 36) in the testcase.
/************************** Test Case ************************/
#include <stdio.h>
#include <stdlib.h>
typedef struct _int_struct {
    int                 i;
    struct _int_struct  *next;
} IntStruct;
typedef struct _int_list {
    IntStruct *head;
} IntList;
int insert(IntList *ilist, int i);
int insertion_sort(IntList *ilist, IntStruct *is);
int main() {
    IntStruct *is;
    IntList ilist;
ilist.head = NULL;
insert(&ilist, 500);
    insert(&ilist, 100);
printf("ilist: ");
    for (is = ilist.head; is; is = is->next)
        printf("%d ", is->i);
    printf("\n");
return 0;
}
int insert(IntList *ilist, int i) {
    IntStruct *is = (IntStruct *) calloc(1, sizeof(IntStruct)); /* line
36 */ is->i = i;
    return insertion_sort(ilist, is);
}
int insertion_sort(IntList *ilist, IntStruct *is) {
    IntStruct **isp;
    for (isp = &ilist->head; *isp; isp = &((*isp)->next)) {
        if (is->i < (*isp)->i) {
            is->next = *isp;
            break;
        } else if (is->i == (*isp)->i) {
            /* return FALSE; */
            return 0;
        }
    }
*isp = is;
/* return TRUE; */
    return 1;
}
You very definitely have a memory leak.
You create your list using calloc(3), but you fail to free that list.
-- 
Jerry Feldman <gaf@blu.org>
Boston Linux and Unix user group
http://www.blu.org PGP key id:C5061EA9
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