ANSI C - Program received signal SIGSEGV, Segmentation fault

Question

I am using ANSI C and getting "Program received signal SIGSEGV, Segmentation fault." for my below code when I run it. Compiling is fine. No error there.

#define MAX_LINE_SIZE 1024
#define DELIMITER ","
#define TICKET_NAME_LEN 40
#define TICKET_ZONE_LEN 10

struct stock_data 
{
    char ticket_name[TICKET_NAME_LEN+1];
    char ticket_type;
    char ticket_zone[TICKET_ZONE_LEN+1];
    unsigned int ticket_price;
    unsigned int stock_level;
};

typedef struct stock_node 
{
    struct stock_data * data;
    struct stock_node * next_node;
} stock_node;

char temp_line[MAX_LINE_SIZE];
char *token;
int i, count = 0;

stock_node * snode = NULL;
struct stock_data * sdata = NULL;

FILE *stock_file = fopen( stockfile, "r" );

while (fgets(temp_line, MAX_LINE_SIZE, stock_file) != NULL) {

  token = strtok (temp_line, DELIMITER);
  count++;

  snode = (stock_node *) realloc(snode, count * sizeof(stock_node));
  if (snode == NULL) { abort(); }  

  snode->data = (struct stock_data *) malloc(sizeof(struct stock_data));
  if (snode->data == NULL) { abort(); }  

  i = 1;

 while(token != NULL) {
     switch(i) {
        case 1:
           strcpy(snode[count - 1].data->ticket_name, token);
           break;
        case 2:
           snode[count - 1].data->ticket_type = token[0];
           break;
        case 3:
           strcpy(snode[count - 1].data->ticket_zone, token);
           break;
        case 4:
           snode[count - 1].data->ticket_price = atoi(token);
           break;
        case 5:
           snode[count - 1].data->stock_level = atoi(token);
           break;                                                            
     }

     token = strtok (NULL, DELIMITER);
     i++;
  }
}

I used the gdb tool to debug it and I found that I get the error for below lines: (For any of them. I tried with disabling them one by one and each of them caused the segfault error.)

strcpy(snode[count - 1].data->ticket_name, token);
snode[count - 1].data->ticket_type = token[0];
strcpy(snode[count - 1].data->ticket_zone, token);
snode[count - 1].data->ticket_price = atoi(token);
snode[count - 1].data->stock_level = atoi(token);

Answer 1

Well it looks like snode[count - 1].data is never initialized. Only the first index snode[0].data is allocated

I think you should replace

snode->data = (struct stock_data *) malloc(sizeof(struct stock_data));
if (snode->data == NULL) { abort(); }

By

snode[count - 1].data = (struct stock_data *) calloc(1, sizeof(struct stock_data));
if (snode[count - 1].data == NULL) { abort(); }