Segmentation fault: 11

[pilsang0512]

Hi, I'm trying to make a program that writes words to a text. The words are generated by a brute force program. I am getting a segmentation fault 11 but i don't know where i went wrong. Please help! Thanks!

#include <stdio.h>
#include <string.h>
#include <stdlib.h>


static const char alphabet[] =
        "abcdefghijklmnopqrstuvwxyz"
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "1234567890";


static const int alphabet_size = sizeof(alphabet) - 1;


void brute_impl(char * str, int index, int max_depth)
{
    int i;
    int sys;
    FILE *fp;
    fp=fopen("~/Desktop/passlist.txt", "w+");
    for (i = 0; i < alphabet_size; ++i)
    {
        str[index] = alphabet[i];


        if(index == max_depth-1)
        {
            fprintf(fp, "%s\n", str);
            fclose(fp);
        }


        else
        {
            brute_impl(str, index + 1, max_depth);
        }
    }
}

void brute_sequential(int max_len)
{
    char * buf = malloc(max_len + 1);
    int i;

    for (i = 1; i <= max_len; ++i)
    {
        memset(buf, 0, max_len + 1);
        brute_impl(buf, 0, i);
    }


    free(buf);
}


int main(void)
{
    brute_sequential(2);
    return 0;
}

[tabstop]

Once you close a file, it's a bit silly to keep trying to write to it. (That is: don't close your file until you've finished writing.)

[oogabooga]

It's incorrect to open a file for w+ when you are not planning to read from it (w+ means writing and reading, truncating (or creating) the file first). It's possible that you meant a (for "append"), although it would be more efficient to open the file for writing at the start of brute_sequential, closing it at the end, and pass the file pointer to brute_impl.

And you're not ending the recursion properly. You should test for your recursion base case before the alphabet loop, not inside it. I believe the test should be index == max_depth (not max_depth - 1). And it's probably best to explicitly zero-terminate the string before writing it instead of relying on the memset in brute_sequential.

Also, beware the combinatorial explosion! If you get your program working properly and run it with an argument of 8 instead of 2, it will (attempt to) generate a file of over 200,000 gigabytes.

[pilsang0512]

It's incorrect to open a file for w+ when you are not planning to read from it (w+ means writing and reading, truncating (or creating) the file first). It's possible that you meant a (for "append"), although it would be more efficient to open the file for writing at the start of brute_sequential, closing it at the end, and pass the file pointer to brute_impl.

How would this look like in the code?

[Salem]

How would this look like in the code?

That's a dead giveaway that you didn't write the original code to begin with.
c - Brute Force Password Cracking Algorithm - Stack Overflow

Two small crumbs to see if you're actually interested in learning, or just another freeloader looking for someone else to finish off what you found on the web to start with.

You pass fp in the same way you pass 2 (for example).

And ~ is a shell metacharacter for the home directory, fopen() won't understand it.