CODEWITHSUNDEEP
clinked-listsegmentation-fault
Vitor Villar
Vitor Villar

Reputation: 1925

Segfault in Linked List

i've this function, where i get data of database and i make an linked list. Each node of the list is a row.

This is the function

Row * fetch(Query* query)
{
    if (PQresultStatus(query->resultset) != PGRES_TUPLES_OK)
        return NULL;

    Row * row;
    row = (Row *) malloc(sizeof (Row));

    row->total_cols = PQnfields(query->resultset);
    int rows = PQntuples(query->resultset);

    int row_atual, col_atual;
    Row * aux;
    aux = row;

    for (row_atual = 0; row_atual < rows; row_atual++) {
        for (col_atual = 0; col_atual < aux->total_cols; col_atual++) {
            aux->cell[col_atual] = PQgetvalue(query->resultset, row_atual, col_atual);
        }
        aux->next_line = (Row *) malloc(sizeof(Row));
        aux = aux->next_line;
    }
    return row;
}

And this is struct row:

typedef struct row {
    int total_cols;
    char ** cell;
    struct row * next_line;
} Row;

The problem is when it reaches this point:

aux->next_line = (Row *) malloc(sizeof(Row));

I received a segmentation fault, and i don't know why! I can't see what's wrong. Someone knows?

Thanks!

Upvotes: 0

Views: 69

Answers (1)

AnatolyS
AnatolyS

Reputation: 4319

You did not allocate memory for the cell member but you use it to store data:

aux->cell[col_atual] = ...;

as the result you spoil memory at random addresses

Upvotes: 2

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