Compare cJSON objects in the same code every time program is executed - c

Question

I have a code which is always running in the background. compareContents() reads contents from a file periodically (based on an event) and stores it in a cSJON object. I have to compare current contents of the file (cJSON object) with the previous contents (again a cJSON object) everytime, but I am getting a memory leak. Please help.
cJSON * prev = NULL, *current = NULL;
bool compare = false;
bool compareJSON(cJSON *i,cJSON *j) /* referred from https://cjson.docsforge.com/master/api/cJSON_Compare/ */
{
if (i->type != j->type) {
return false;
}
if (i->type == cJSON_Number && (i->valueint != j->valueint)) {
return false;
}
if (i->type == cJSON_String && strcmp(i->valuestring,j->valuestring)){
return false;
}
if (i->type==cJSON_Array)
{
cJSON *ic = i->child, *jc = j->child;
while (ic && jc)
{
if (!compareJSON(ic, jc)) {
return false;
}
ic = ic->next, jc = jc->next;
}
if (ic || jc)
return false;
}
if (i->type == cJSON_Object)
{
cJSON *ic = i->child;
while (ic)
{
cJSON *jc = cJSON_GetObjectItem(j,ic->string);
if (!jc || !compareJSON(ic,jc)){
return false;
}
ic = ic->next;
}
// And again, for j == i.
cJSON *jc = j->child;
while (jc)
{
cJSON *ic=cJSON_GetObjectItem(i,jc->string);
if (!ic || !compareJSON(ic,jc)){
return false;
}
jc = jc->next;
}
}
return true;
}
bool compareContents(){
int fd = open("/tmp/abc.txt", O_RDONLY);
char* data = (char *)malloc(st.st_size + 1); //st.st_size obtained from fstat
int n = read(fd, data, st.st_size);
data[n] = '\0';
cJSON* root = cJSON_Parse(data);
if(prev == NULL){ //first time execution of program
prev = root;
}
else {
if(current){
prev = current;
}
}
current = cJSON_Duplicate(root,1);
if (prev && current)
{
compare = compareJSON(prev,current);
}
if (fd >= 0)
close(fd);
if (access("/tmp/abc.txt", F_OK) == 0 && remove("/tmp/abc.txt") != 0){
printf("Error deleting the file\n");
}
if (data)
free(data);
if (root)
cJSON_Delete(root);
return compare;
}

Answer 1

I am not sure, but this seems like dynamic copy?
current = cJSON_Duplicate(root,1);
That is you never free current and prev if it was not null. Maybe start from this point? Seems like memory leak.