Memory Access Violation readdir

Question

Hello i have to write in c (linux) function to remove all file from directory i cannot use remove function or execl only unlink and rmdir.

i used readdir :

    int removefile( char *file)
{
struct dirent * entry;
DIR *dir;
char *p;
char *d;
char *tmp;
dir = opendir(file);
errno =0;
strcpy( d, file );//kopiowanie file do p
strcat( d, "/" );//dodawanie /
strcpy(tmp,d);//kopiowanie d do tmp
strcpy(p,d); //kopiowanie d do p


while((entry=readdir(dir)) !=NULL)
{
    if(entry->d_type==DT_REG)
    {
    strcat(d,entry->d_name);
    int a=unlink(d);
    strcpy(d,tmp);
    }
    else if(entry->d_type==DT_DIR)
    {
    strcat(p,entry->d_name);
        int b=removefile(p);
        int c=rmdir(p);
        strcpy(p,tmp);
    }   
}

closedir(dir);
return 0;
}

but i get Memory Access Violation thx

You have to check that `opendir()` returned non-*NULL* pointer. — Iharob Al Asimi, Apr 19 '18 at 10:56
You have *multiple* errors, most (if not all) of them related to pointers. For example, where do `d` or `p` point? And does `opendir` succeed? — Some programmer dude, Apr 19 '18 at 10:56

Iharob Al Asimi · Accepted Answer · 2018-04-19T11:04:53.563

You did not allocate memory for your strings.

To "create" a string in c you need to request some storage to put it in, you can do it by defining an array like the following

char string[SIZE];

where SIZE is a reasonably large number.

This is perhaps what you wanted, but you still need to check errors everywhere

int removefile(const char *const dirpath)
{
    struct dirent *entry;
    DIR *dir;
    dir = opendir(dirpath);
    if (dir == NULL)
        return -1;
    while ((entry = readdir(dir)) != NULL) {
        char path[256];
        // Build the path string
        snprintf(path, sizeof(path), "%s/%s", dirpath, entry->d_name);
        if (entry->d_type == DT_REG) {            
            unlink(path);
        } else if (entry->d_type == DT_DIR) {
            // Recurse into the directory
            removefile(path);
            // Remove the directory
            rmdir(path);
        }
    }
    closedir(dir);
    return 0
}

Note: Read the documentation of snprintf() and also read a simple and complete tutorial about c-strings.

yeah thats help but do u know why recursion (removefile) never ends ? — M.B, Apr 19 '18 at 23:57
because you are not skipping the `'.'` directory and it's entering it over and over. — Iharob Al Asimi, Apr 20 '18 at 01:25

Memory Access Violation readdir

1 Answers1