GtkTextBuffer and non UTF8 chars

[Magnus-swe <magnus-swe telia com>]

The application crashes when i run this code more then 2 times 
and wont set the text at all if there are swedish chars in it.
Im using GTK+ 2.0.5.


/* Read a textfile and put the contents in a textview. */
  
void
on_files_textview_map               (GtkWidget       *widget,
                                     gpointer         user_data)
{
    FILE *fp;
    long size_buffer;
    char *file_buffer;
    char *get_file_buffer;
    GtkTextBuffer *file_text_buffer;
 files_textview = lookup_widget (GTK_WIDGET (widget), "files_textview");


    if( (fp = fopen("/var/log/xferlog", "r")) == NULL)
    {
       strcpy(info_buffer, "Cant find /var/log/xferlog.\n\n");
       strcat(info_buffer, "If youre running GProFTPD as root\n");
       strcat(info_buffer, "the xferlog has been added for you.\n");
       error_window = create_error_window ();
       gtk_widget_show (error_window);
       system("touch /var/log/xferlog");
       return;
    }
    fseek(fp, 0, SEEK_END);
    size_buffer = ftell(fp);
    rewind(fp);
    file_buffer=(char *)malloc(size_buffer);
    get_file_buffer=(char *)malloc(size_buffer);
    while (fgets(file_buffer, size_buffer, fp)!=NULL)
    {
       strcat(get_file_buffer, file_buffer);
    }
file_text_buffer =          
gtk_text_view_get_buffer(GTK_TEXT_VIEW(files_textview));
    gtk_text_buffer_set_text(file_text_buffer, get_file_buffer, -1);
    fclose(fp);
    free(file_buffer);
    free(get_file_buffer);
}

I hope that someone can find the time to help me with this problem.

// Magnus-swe