How to fix this memory leaks about strdup - valgrind

Question

Thanks for your help, the problem has been solved！
I am a new to C, I I wondered why strdup can case memory leaks, because I free it after strup
valgrind code:
==29885==
==29885== HEAP SUMMARY:
==29885== in use at exit: 37 bytes in 2 blocks
==29885== total heap usage: 28 allocs, 26 frees, 17,131 bytes allocated
==29885==
==29885== Searching for pointers to 2 not-freed blocks
==29885== Checked 124,824 bytes
==29885==
==29885== 5 bytes in 1 blocks are indirectly lost in loss record 1 of 2
==29885== at 0x40057A1: malloc (vg_replace_malloc.c:270)
==29885== by 0x2D6B4F: strdup (in /lib/tls/i686/nosegneg/libc-2.3.4.so)
==29885== by 0x804CD3C: new_node (parser.c:355)
==29885== by 0x804C263: identifier (parser.c:75)
==29885== by 0x804940D: yyparse (vtl4.y:111)
==29885== by 0x8049FD4: main (vtl4.y:225)
==29885==
==29885== 37 (32 direct, 5 indirect) bytes in 1 blocks are definitely lost in loss record 2 of 2
==29885== at 0x40057A1: malloc (vg_replace_malloc.c:270)
==29885== by 0x804CCEA: new_node (parser.c:347)
==29885== by 0x804C263: identifier (parser.c:75)
==29885== by 0x804940D: yyparse (vtl4.y:111)
==29885== by 0x8049FD4: main (vtl4.y:225)
==29885==
==29885== LEAK SUMMARY:
==29885== definitely lost: 32 bytes in 1 blocks
==29885== indirectly lost: 5 bytes in 1 blocks
==29885== possibly lost: 0 bytes in 0 blocks
==29885== still reachable: 0 bytes in 0 blocks
==29885== suppressed: 0 bytes in 0 blocks
==29885==
==29885== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 12 from 8)
--29885--
--29885-- used_suppression: 12 Ubuntu-stripped-ld.so
==29885==
==29885== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 12 from 8)
new_node (parser.c:355):
struct simpleNode *new_node(JJT jjt,char *node_image){
struct simpleNode *a = malloc(sizeof(struct simpleNode));
if (a==NULL) {
yyerror("FUNC[%s]error:Init a new simple error,out of space!",__func__);
exit(0);
}
a->info.astn = jjt;
a->info.node_name = jjtNodeName[jjt];
**355>>**a->info.image = strdup(node_image);
a->info.already_rendered = cJSON_False;
a->parent = NULL;
a->firstChild = NULL;
a->nextSibling = NULL;
return a;
}
identifier (parser.c:75):
struct simpleNode* identifier(char *identifier){
printf("%s node!key:%s\n",__func__,identifier);
**75>>**struct simpleNode *a = new_node(JJTIDENTIFIER,identifier);
free(identifier);//I free it after use strdup in new_node
return a;
}
the struct simpleteNode :
struct nodeInfo {
char *image;
int already_rendered;//是否已经被渲染过了,防止子节点被重复渲染,默认为cJSON_False
JJT astn;//node编号
const char * node_name;
char *current_tpl_name;
};
struct simpleNode {
struct nodeInfo info;
struct simpleNode* firstChild;//第一个孩子
struct simpleNode* nextSibling;//右兄弟
struct simpleNode* parent;//父亲
};
at last I will free all the pointers
void free_tree(struct simpleNode* n){
//遍历
struct simpleNode *x = n;
if (x) {
//printf("==========Begin to free %s, image=%s=============\n",x->info.node_name,cJSON_Print(x->info.image));
//free_tree(x->firstChild);
//__free(x);
free_tree(x->firstChild);
free_tree(x->nextSibling);
__free(x);
//__free(x);
}
}
void free_nodeInfo(struct simpleNode* n){
if (n!=NULL) {
printf("==============begin delete %s node!\n",n->info.node_name);
struct nodeInfo ni = n->info;
free(ni.image);
// if (ni.current_tpl_name!=NULL) {
// free(ni.current_tpl_name);
// }
free(n);
printf("==============delete node done!\n");
}
}
void __free(struct simpleNode *n){
//printf("==========__free %s, image=%s=============\n",n->info.node_name,cJSON_Print(n->info.image));
//dump_tree(n);
if (n) {
//printf("==============begin delete %s node!\n",n->info.node_name);
free_nodeInfo(n);
}
}
I checked more related issues, but does not solve，please help me！

Answer 1

struct simpleNode* reference_index(struct simpleNode* identifier_n,
struct simpleNode* index_n) {
- struct simpleNode *a = new_node(JJTIDENTIFIER, identifier_n->info.image);//the wrong code
+ struct simpleNode *a = identifier_n;//the right code
struct simpleNode *index = new_node(JJTINDEX, "index");
addChild(index, index_n);
addChild(a, index);
}
I should not be repeated to create a new node a ,because the parameter is already a node identifier_n,when I free identifier_n ,the info.image of node a is already freed,so At this time when I free a->info.image this will cause problems.
I am sorry for my poor English.