adding file.c file.h and fix ccc.c %s is null

Makefile

@@ -3,7 +3,7 @@
 
 TARGET = ccc
 MANPAGE = ccc.1
-SRC = ccc.c util.c
+SRC = ccc.c util.c file.c
 
 # Flags
 LDFLAGS = $(shell pkg-config --libs ncurses)

ccc.c

@@ -135,7 +135,7 @@ void list_cwd_files()
             {
                 // memory allocation failed
                 perror("ccc");
-                fprintf(stderr, "ccc: Cannot read filename %s.", filename);
+                fprintf(stderr, "ccc: Cannot read filename %s.", ep->d_name);
                 exit(EXIT_FAILURE); 
             }
             // can't be strncmp as that filter out dotfiles

file.c

@@ -0,0 +1,84 @@
+#include <string.h>
+
+#include "util.h"
+
+// files in a link list data structure
+typedef struct file {
+    char *filename;
+    // put some more useful stat here
+    struct file *next;
+} file;
+
+file *files = NULL;
+
+/*
+ * get length of files linked list
+ */
+long files_len()
+{
+    file *current = files;
+    int count = 0;
+    while (current != NULL)
+    {
+        count++;
+        current = current->next;
+    }
+    return count;
+}
+
+long add_file(char *filename)
+{
+    file *current = files;
+    file *new_file = memalloc(sizeof(file));
+    char *buf = strdup(filename);
+    if (!buf)
+    {
+        perror("ccc");
+    }
+    new_file->filename = buf;
+    new_file->next = NULL;
+    if (current == NULL)
+    {
+        files = new_file;
+        return 0;
+    }
+    long index = 1;
+    while (current->next != NULL)
+    {
+        current = current->next;
+        index++;
+    }
+    current->next = new_file;
+    return index;
+}
+
+file *get_file(long index)
+{
+    file *current = files;
+    if (index == 0)
+    {
+        return current;
+    }
+    if (index > files_len())
+    {
+        return NULL;
+    }
+    for (long i = 0; i < index; i++)
+    {
+        current = current->next;
+    }
+    return current;
+}
+
+char *get_filename(long index)
+{
+    file *file = get_file(index);
+    if (!file)
+    {
+        return file->filename;
+    }
+    else
+    {
+        return NULL;
+    }
+}

file.h

@@ -0,0 +1,15 @@
+#ifndef FILE_H_
+#define FILE_H_
+
+typedef struct file {
+    char *filename;
+    // put some more useful stat here
+    struct file *next;
+} file;
+
+long files_len();
+long add_file(char *filename);
+file *get_file(long index);
+char *get_filename(long index);
+
+#endif