Valgrind newbie can't seem to make it happy
I am working through a CS50 course online and the task is to load a dictionary into memory (I am using a data structure with a hash table chain) and check the contents of a text file for words into a dictionary. I wrote a load () function that loads a dictionary file and stores each word in memory. The function returns true when all words are loaded. Valgrind does not detect memory leaks. The problem is I have a ridiculous amount of read / write errors. This helped me figure out where they were coming from and I was combing through the gaps but couldn't seem to make the heads or tails.
Here's the relevant code:
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define HASH_SIZE 10
#define LENGTH 45
typedef struct node
{
char* word;
struct node* next;
} node;
// Globals
node* hashTable[HASH_SIZE];
unsigned int dictionary_size = 0;
/**
* Loads dictionary into memory. Returns true if successful else false.
**/
bool load(const char* dictionary)
{
// Initialize variables
char currentWord[LENGTH + 1];
int tableIndex;
// Open dictionary
FILE* dict = fopen(dictionary, "r");
if (dict == NULL)
return false;
while(fscanf(dict, "%s", currentWord) == 1)
{
// Get hash value of word
tableIndex = hash(currentWord);
// Initialize new node
node* newNode = malloc(sizeof(node));
newNode->word = malloc((strlen(currentWord) + 1) * sizeof(char));
if (newNode == NULL || newNode->word == NULL)
{
printf("Error: Out of memory\n");
return false;
}
// Copy word into new node
strcpy(newNode->word, currentWord);
newNode->next = NULL;
// If no collision, hash word into head of list
if (hashTable[tableIndex] == NULL)
hashTable[tableIndex] = newNode;
// Create a pointer and move down list
else
{
node* ptrNode = hashTable[tableIndex];
while (ptrNode->next != NULL)
ptrNode = ptrNode->next;
// Append node to end of linked list
ptrNode->next = newNode;
}
// Increase dictionary size
dictionary_size++;
// Free word member before actual node
free(newNode->word);
free(newNode);
}
// Close dictionary and return true
fclose(dict);
return true;
}
And my Valgrind:
==32487== Invalid read of size 4
==32487== at 0x8048989: load (my_new_test.c:120)
==32487== by 0x804873D: main (my_new_test.c:53)
==32487== Address 0x423b30c is 4 bytes inside a block of size 8 free'd
==32487== at 0x402B3D8: free (in /usr/lib/valgrind/vgpreload_memcheck-x86- linux.so)
==32487== by 0x80489D3: load (my_new_test.c:132)
==32487== by 0x804873D: main (my_new_test.c:53)
==32487==
==32487== Invalid write of size 4
==32487== at 0x80489AA: load (my_new_test.c:124)
==32487== by 0x804873D: main (my_new_test.c:53)
==32487== Address 0x423b30c is 4 bytes inside a block of size 8 free'd
==32487== at 0x402B3D8: free (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==32487== by 0x80489D3: load (my_new_test.c:132)
==32487== by 0x804873D: main (my_new_test.c:53)
==32487==
==32487== Invalid read of size 4
==32487== at 0x8048999: load (my_new_test.c:121)
==32487== by 0x804873D: main (my_new_test.c:53)
==32487== Address 0x423bb24 is 4 bytes inside a block of size 8 free'd
==32487== at 0x402B3D8: free (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==32487== by 0x80489D3: load (my_new_test.c:132)
==32487== by 0x804873D: main (my_new_test.c:53)
==32487== HEAP SUMMARY:
==32487== in use at exit: 0 bytes in 0 blocks
==32487== total heap usage: 286,183 allocs, 286,183 frees, 2,584,308 bytes allocated
==32487==
==32487== All heap blocks were freed -- no leaks are possible
==32487==
==32487== For counts of detected and suppressed errors, rerun with: -v
==32487== ERROR SUMMARY: 10000000 errors from 3 contexts (suppressed: 0 from 0)
I'm still very rude with Valgrind, but from what I'm collecting, my problem seems to be inside the else statement, mainly the generated pointer (node * ptrNode). Can anyone see what I can't see? Any help would be greatly appreciated!
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