CODEWITHSUNDEEP
cvalgrind
VeVeVez
VeVeVez

Reputation: 90

Error: Conditional jump or move depends on uninitialised value - C valgrind

i'm new to C and i'm stucked with a common problem but really i'm not able to understand the reason in my case.

i have this method whose purpose is to initialize a Map with a specified name and check if it exists in a RED-BLACK Tree.

void reduceMap(char *mapName){

    Map *tempMap = (Map *) malloc(sizeof(Map));
    struct rbNode *tempNode = (struct rbNode *) malloc(sizeof(struct rbNode));

    copyName = stringCopy(mapName);

    tempMap->name = copyName;
    tempNode->data = tempMap;

    ...DO SEARCH HERE...

    freeMap(tempNode);

}

So i allocate memory for a Node which contains a Map, do the research and in the end free the memory of the temporary objects created. The structures of my objects are the following:

typedef struct{
    char *name;
    char *specification;
    Point *start, *end;
}Map;

struct rbNode{
    Color color;
    void *data;
    struct rbNode *parent, *leftChild, *rightChild;
};

The method stringCopy and freeMap are:

void freeMap(struct rbNode *node){
    if(node){

         free( ((Map *)node->data)->name );

         if(((Map *)node->data)->specification != NULL) 
             free( ((Map *)node->data)->specification );        

         free( (Map *)node->data );
         free(node);
     }
 }


 char *stringCopy(const char *source){
     char *copy = (char *)malloc(strlen(source) + 1);

     strcpy(copy,source);
     return copy;
 }

I'm testing the program using valgrind and this is the error i get:

Conditional jump or move depends on uninitialised value(s)
==5215==    at 0x8049DF3: freeMap (in /home/ve/Dropbox/progetto2016/Percorsi/percorsi)
==5215==    by 0x8048C40: reduceMap (in /home/ve/Dropbox/progetto2016/Percorsi/percorsi)
==5215==    by 0x80489DA: main (in /home/ve/Dropbox/progetto2016/Percorsi/percorsi)
==5215==  Uninitialised value was created by a heap allocation
==5215==    at 0x402C17C: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==5215==    by 0x8048B0A: reduceMap (in /home/ve/Dropbox/progetto2016/Percorsi/percorsi)
==5215==    by 0x80489DA: main (in /home/ve/Dropbox/progetto2016/Percorsi/percorsi)

I understand that the problem is caused by the allocation of tempMap and it seems that there is something not initialized int it but why? I only care about the name and the specification... I really do not understand.

Any help would be appreciate. Thank you

Upvotes: 3

Views: 2067

Answers (2)

4pie0
4pie0

Reputation: 29754

You do not initialize specification member in map

typedef struct{
    char *name;
    char *specification;
    Point *start, *end;
} Map;

but later you use this unintialized value to conditionally jump (if statement):

if(((Map *)node->data)->specification != NULL)

SOLUTION

Initialize all members of Map before you use them.

Upvotes: 1

StoryTeller - Unslander Monica
StoryTeller - Unslander Monica

Reputation: 170279

Simply put, it seems that in your reduceMap, this happens

Map *tempMap = (Map *) malloc(sizeof(Map));
tempMap->name = copyName;
tempMap->specification = /* what!?? */;

You don't initialize the entire allocated struct. Consider writing a map constructor (in the form of an initMap function), to match your destructor (freeMap).

Side note : Don't cast the result of malloc.

Upvotes: 2

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