C - Opening differents files using same pointer - c

Question

I'm trying to retrieve informations by many plain-text files, which will be then stored in a proper struct. To do so, I'm using a function that takes member of the struct to populate and source of the plain-text file where the informations are stored.
Posting my "test" code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct _elem
{
const char *title;
int ok;
int almost;
int nope;
int hits;
float last_rank;
};
typedef struct _elem Chapter;
Chapter *generate_array(const char *source, int *elems);
int engine_start(Chapter *elem, char *source);
int main()
{
const char path_f[100];
int elements = 0;
int i = 0;
Chapter *dict;
printf("Insert the name of the source:\n");
scanf("%s", path_f);
printf("\nGenerating dictionary, please wait...\n");
dict = generate_array(path_f, &elements);
if (dict == NULL)
{
printf("Aborting.\n");
exit(1);
}
while (i < elements)
{
printf("Element %d:\n", (i + 1));
printf("\nTitle: %s\n", dict[i].title);
printf("Ok: %10d\n", dict[i].ok);
printf("Almost: %5d\n", dict[i].almost);
printf("Nope: %8d\n", dict[i].nope);
printf("Hits: %8d\n", dict[i].hits);
printf("Rank: %8.2f\n", dict[i].last_rank);
printf("\n");
i++;
}
return EXIT_SUCCESS;
}
Chapter *generate_array(const char *source, int *elems)
{
FILE *src;
int sources;
int i = 0;
char **srcs;
Chapter *generated;
src = fopen(source, "r");
if (src == NULL)
{
printf("[!!] Error while reading file!\n");
return NULL;
}
fscanf(src, "%d", &sources);
if (sources <= 0)
{
printf("[!!] Wrong number of sources, exiting.\n");
return NULL;
}
srcs = (char **) malloc(sizeof(char *) * sources);
while (i < sources && !feof(src))
{
srcs[i] = (char *) malloc(sizeof(char) * 100);
fscanf(src, "%s", srcs[i++]);
}
fclose(src);
generated = (Chapter *) malloc(sizeof(Chapter) * i);
*elems = i;
i = 0;
while (i < *elems)
{
if(engine_start( &generated[i], srcs[i] )) i++;
else
{
printf("[!!] Error in file %s, aborting.\n", srcs[i]);
return NULL;
}
}
return generated;
}
int engine_start(Chapter *elem, char *source)
{
FILE *parser;
int done = 0;
parser = fopen(source, "r");
if (parser == NULL) printf("[!!] Error while opening %s, aborting.\n", source);
else
{
fgets(elem->title, 100, parser);
fscanf(parser, "%d %d %d %d %f", &(elem->ok), &(elem->almost),
&(elem->nope), &(elem->hits),
&(elem->last_rank) );
fclose(parser);
done = 1;
}
return done;
}
Now this is the main file where are stored paths to the other plain-text files:
lol.dat
5
lold/lol1.dat
lold/lol2.dat
lold/lol3.dat
lold/lol4.dat
lold/lol5.dat
And one example of lolX.dat:
Qual'è la vittoria di cristo?
3 4 5 12 44.9
I'm getting SIGSEGV after the first iteration of "engine_start", probably due to FILE *parser (but I can be totally wrong, I don't know at this point).
Someone can guide me through this problem? Thank you.

Answer 1

Make the following changes and try-
struct _elem
{
char *title; // allocate the memory for this.
int ok;
int almost;
int nope;
int hits;
float last_rank;
};
You need to allocate memory for element title before assigning something to it.
int engine_start(Chapter *elem, char *source)
{
FILE *parser;
int done = 0;
parser = fopen(source, "r");
if (parser == NULL) printf("[!!] Error while opening %s, aborting.\n", source);
else
{
elem->title=(char *)malloc(100); // include this line.
fgets(elem->title, 100, parser);
fscanf(parser, "%d %d %d %d %f", &(elem->ok), &(elem->almost),
&(elem->nope), &(elem->hits),
&(elem->last_rank) );
fclose(parser);
done = 1;
}
return done;
}