diff --git a/src/du.c b/src/du.c
new file mode 100644
index 0000000..9cebecd
--- /dev/null
+++ b/src/du.c
@@ -0,0 +1,213 @@
+/* du.c */
+
+
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+
+/* Prefs */
+typedef int Prefs;
+#define PREFS_a 1
+#define PREFS_s 2 
+#define PREFS_x 4
+#define PREFS_k 8 
+#define PREFS_H 16
+#define PREFS_L 48
+
+
+/* du */
+static int _du_do(Prefs * prefs, char * filename);
+static void _du_print(Prefs * prefs, off_t size, char * filename);
+static int _du(Prefs * prefs, int argc, char * argv[])
+{
+	int res = 0;
+	int i;
+
+	if(argc == 0)
+		return _du_do(prefs, ".") == 0 ? 0 : 2;
+	for(i = 0; i < argc; i++)
+		res += _du_do(prefs, argv[i]);
+	return res == 0 ? 0 : 2;
+}
+
+static int _du_error(char * error)
+{
+	fprintf(stderr, "%s", "du: ");
+	perror(error);
+	return 1;
+}
+
+static off_t _du_blocks(Prefs * prefs, off_t size);
+static int _du_do_recursive(Prefs * prefs, char * filename);
+static int _du_do(Prefs * prefs, char * filename)
+{
+	int (* _stat)(const char * filename, struct stat * buf) = lstat;
+	struct stat st;
+
+	if(*prefs & PREFS_H)
+		_stat = stat;
+	if(_stat(filename, &st) != 0)
+		return _du_error(filename);
+	if(!S_ISDIR(st.st_mode))
+	{
+		_du_print(prefs, st.st_size, filename);
+		return 0;
+	}
+	return _du_do_recursive(prefs, filename);
+}
+
+static off_t _du_blocks(Prefs * prefs, off_t size)
+{
+	off_t unb;
+	off_t usize = 512;
+
+	if(*prefs & PREFS_k)
+		usize = 1024;
+	unb = size / usize;
+	if(unb * usize < size)
+		unb++;
+	return unb;
+}
+
+static int _recursive_do(Prefs * prefs, off_t * size, char ** filename);
+static int _du_do_recursive(Prefs * prefs, char * filename)
+{
+	off_t size = 0;
+	char * p;
+	int len;
+	int res;
+
+	len = strlen(filename);
+	if((p = malloc(len + 1)) == NULL)
+		return _du_error("malloc");
+	strcpy(p, filename);
+	res = _recursive_do(prefs, &size, &p);
+	printf("%ld %s\n", size, filename);
+	free(p);
+	return res;
+}
+
+static void _recursive_do_stat(Prefs * prefs, off_t * size, char ** filename);
+static int _recursive_do(Prefs * prefs, off_t * size, char ** filename)
+{
+	DIR * dir;
+	struct dirent * de;
+	int len;
+	char * p;
+
+	if((dir = opendir(*filename)) == NULL)
+		return _du_error(*filename);
+	readdir(dir);
+	readdir(dir);
+	len = strlen(*filename);
+	while((de = readdir(dir)) != NULL)
+	{
+		if((p = realloc(*filename, len + strlen(de->d_name) + 2))
+				== NULL)
+		{
+			_du_error("malloc");
+			continue;
+		}
+		*filename = p;
+		for(; len > 0 && p[len-1] == '/'; len--);
+		p[len] = '/';
+		strcpy(&p[len+1], de->d_name);
+		_recursive_do_stat(prefs, size, filename);
+	}
+	return closedir(dir) == 0 ? 0 : 1;
+}
+
+static void _recursive_do_stat(Prefs * prefs, off_t * size, char ** filename)
+{
+	int (* _stat)(const char * filename, struct stat * buf) = lstat;
+	struct stat st;
+	char * p;
+	off_t dirsize;
+
+	if(*prefs & PREFS_L)
+		_stat = stat;
+	if(_stat(*filename, &st) != 0)
+	{
+		_du_error(*filename);
+		return;
+	}
+	*size += _du_blocks(prefs, st.st_size);
+	if(S_ISDIR(st.st_mode))
+	{
+		dirsize = _du_blocks(prefs, st.st_size) - *size;
+		if((p = strdup(*filename)) == NULL)
+		{
+			_du_error("malloc");
+			return;
+		}
+		_recursive_do(prefs, size, filename);
+		printf("%ld %s\n", dirsize + *size, p);
+		free(p);
+	}
+	else if(*prefs & PREFS_a)
+		_du_print(prefs, st.st_size, *filename);
+}
+
+static void _du_print(Prefs * prefs, off_t size, char * filename)
+{
+	printf("%ld %s\n", _du_blocks(prefs, size), filename);
+}
+
+
+/* usage */
+static int _usage(void)
+{
+	fprintf(stderr, "%s", "Usage: du [-a | -s][-kx][-H | -L][file...]\n\
+  -a    report the size of every file encountered\n\
+  -s    report only the total sum for each of the specified files\n\
+  -k    write the file sizes in units of 1024 bytes rather than 512\n\
+  -x    evaluate file sizes only on the same device as the file specified\n\
+  -H    dereference specified files\n\
+  -L	dereference every file evaluated\n");
+	return 1;
+}
+
+
+/* main */
+int main(int argc, char * argv[])
+{
+	int o;
+	Prefs prefs;
+
+	memset(&prefs, 0, sizeof(Prefs));
+	while((o = getopt(argc, argv, "askxHL")) != -1)
+	{
+		switch(o)
+		{
+			case 'a':
+				prefs -= prefs & PREFS_s;
+				prefs |= PREFS_a;
+				break;
+			case 's':
+				prefs -= prefs & PREFS_a;
+				prefs |= PREFS_s;
+				break;
+			case 'k':
+				prefs |= PREFS_k;
+				break;
+			case 'x':
+				prefs |= PREFS_x;
+				break;
+			case 'H':
+				prefs |= PREFS_H;
+				break;
+			case 'L':
+				prefs |= PREFS_L;
+				break;
+			default:
+				return _usage();
+		}
+	}
+	return _du(&prefs, argc - optind, &argv[optind]);
+}