Thread: sprintf being weird and giving me a segfult.

Hi, I'm trying to make a program to list files in a dir specified by a user, find all video files with magic and convert them so that the psp will play them. However I'm trying to pass the directory and file name to a function and in the function add them together with sprintf, but it's not working. No idea what's wrong with it, I'd be extremely grateful for any help. Here's the code:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <magic.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>

int mencoder_move()     {
        return 0;
}

int assesment(char *file_from_dir, const char *dir_to_conv)     {
        char *full_path;

        sprintf(full_path,"combined = %s%s\n", dir_to_conv, file_from_dir);
/*      strcat(full_path, file_from_dir);
        printf("%s\n %s\n %s\n", full_path, file_from_dir, dir_to_conv);
*/      
        return 0;
}

int magic_database(void)        {
        magic_t magic_cookie;
        magic_cookie = magic_open(MAGIC_MIME);
                if (magic_cookie == NULL) {
                printf("unable to initialize magic library\n");
                return 1;
                    }
        printf("Loading default magic database\n");
            if (magic_load(magic_cookie, NULL) != 0) {
                printf("cannot load magic database - %s\n", magic_error(magic_cookie));
                magic_close(magic_cookie);
                return 1;
            }
        return 0;
}

int main(int argc, char *argv[])
{
        /*find directory needed to convert*/
        if (argc != 3)  {
                printf("> Howto: %s <directory to convert> <directory to move converted files to>\n", argv[0]);
                return 1;
        }
        /*make directory to transfer files to*/
        if (mkdir(argv[2], S_IRWXU) != 0)       {
                printf("Could not create directory.\n");
                struct stat st;
                if (stat(argv[2], &st) == 0)
                        printf("%s already exists.\n", argv[2]);
                else
                        return 1;
        }
        
        magic_database();
        
        const char *user_dir;
        user_dir = argv[1];
        printf("Converting video files in: %s\n", user_dir);
                
        DIR *dir_convert;
        struct dirent *listing;
        dir_convert = opendir(user_dir);
        /*listing dir*/
        if (dir_convert != NULL)        {
                while ((listing = readdir(dir_convert)))        {
                        assesment(listing->d_name, user_dir);
                }
                (void) closedir (dir_convert);
        }
                else
                        perror("Could not open the directory"); 
        return 0;
}

Well it has a segmentation fault with sprinf, I've also tried printing out file_from_dir and dir_to_conv and they hold what they're supposed to.

Are you sure that would be the problem Salem? It's just that there's quite a bit of free memory.

Code:

                   total       used       free     shared    buffers     cached
Mem:          3958       1362       2596          0        114        684
-/+ buffers/cache:        562       3395
Swap:         3153          0       3153

Excuse my ignorance if I'm wrong.

I trespassed and it looks like I got shot! Allocated some memory for it and it's working now, thanks for the help. Yes the indentation is terrible, but it's fixed now.