Segfault in my csv_loader() function - c

Question

I'm trying to write a csv parser in C, but every time I get a segfault in this function. I don't know how to fix it.
char*** csv_loader(char *filename){
FILE* file_xx;
file_xx = fopen(filename, "r");
if(file_xx==NULL){
printf("Failed to open File, no such file or directory!\n");
return 0;
}
int c_=0;
int **linenumbers;
int l=lines(filename);
linenumbers=malloc(sizeof(int)*l);
char*** loaded_csv;
int counter_line=0;
int counter_row=0;
loaded_csv=malloc(sizeof(char **) *l);
loaded_csv[0][0]=malloc(getfirstcolumn(filename)*sizeof(char)+2);
if(NULL==loaded_csv){
printf("Failed to initialize 'char** loaded_csv'!\n");
return 0;
}
int c_c=0;
int *cm=get_column_map(filename);
for(c_c=0;c_c<l;c_c++){
loaded_csv[c_c]=malloc(sizeof(char *)*cm[c_c]);
}
while(c_!=EOF){
c_=getc(file_xx);
if(c_=='\n'){
linenumbers[counter_line][cm[counter_line]]=counter_row+2;
loaded_csv[counter_line][cm[counter_line]]=malloc(counter_row*sizeof(char));
if(NULL == loaded_csv[counter_line][cm[counter_line]]){
return 0;
}
loaded_csv[counter_line][counter_row]='\0';
counter_row=0;
counter_line++;
}else{
if(c_==','){
counter_row=0;
}else{
counter_row++;
}
}
}
fclose(file_xx);
FILE*fgetsread;
fgetsread=fopen(filename, "r");
int ident, ident_c;
for(ident=0;ident<l;ident++){
for(ident_c=0;ident_c<cm[ident];ident_c++){
fgets(loaded_csv[ident][ident_c], linenumbers[ident][ident_c], fgetsread);
loaded_csv[ident][ident_c][linenumbers[ident][ident_c]-2]='\0';
}
}
fclose(fgetsread);
free(linenumbers);
return loaded_csv;
}
The Debugger says it's this line:
loaded_csv[0][0]=malloc(getfirstcolumn(filename)*sizeof(char)+2);
Does anyone know what's the bug? I'm yet new to C and anyway try to understand the malloc thing...
PS: the other functions are here: http://pastebin.com/VQZ4d5UU

Answer 1

So, you've allocated space on the line right before:
loaded_csv=malloc(sizeof(char **) *l);
That is fine and dandy, but loaded_csv[0] isn't yet initialized to somewhere you own. So, when you do the following line
loaded_csv[0][0]=malloc(getfirstcolumn(filename)*sizeof(char)+2);
you are trying to set a variable located in some random location (wherever loaded_csv[0] happens to be right then).
If you want to touch loaded_csv[0][0], you'll have to make sure that loaded_csv[0] is pointing to valid memory first (probably by allocating memory for it via malloc before you allocate something for loaded_csv[0][0].)

Answer 2

You've got a problem with this line:
loaded_csv[0][0]=malloc(getfirstcolumn(filename)*sizeof(char)+2);
Which suggest you are not allocating and initializing loaded_csv[0][0] right.
Here is an example of how to initialize and use a char ***var:
#include <windows.h>
#include <ansi_c.h>
char *** Create3D(int p, int c, int r);
int main(void)
{
char ***pppVar;
pppVar = Create3D(10,10,10);
//test pppVar;
strcpy(pppVar[0][0], "asdfasf");
strcpy(pppVar[0][1], "the ball");
return 0;
}
char *** Create3D(int p, int c, int r)
{
char *space;
char ***arr;
int x,y;
space = calloc (p*c*r*sizeof(char),sizeof(char));
arr = calloc(p * sizeof(char **), sizeof(char));
for(x = 0; x < p; x++)
{
arr[x] = calloc(c * sizeof(char *),sizeof(char));
for(y = 0; y < c; y++)
{
arr[x][y] = ((char *)space + (x*(c*r) + y*r));
}
}
return arr;
}
Be sure to keep track of and free(x) appropriately.