diff --git a/tools/atree/fs.cpp b/tools/atree/fs.cpp
new file mode 100644
index 0000000..15d6092
--- /dev/null
+++ b/tools/atree/fs.cpp
@@ -0,0 +1,142 @@
+#include "fs.h"
+#include "files.h"
+#include <unistd.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <string>
+#include <vector>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <host/CopyFile.h>
+
+using namespace std;
+
+static bool
+is_dir(const string& path)
+{
+    int err;
+    struct stat st;
+    err = stat(path.c_str(), &st);
+    return err != 0 || S_ISDIR(st.st_mode);
+}
+
+static int
+remove_file(const string& path)
+{
+    int err = unlink(path.c_str());
+    if (err != 0) {
+        fprintf(stderr, "error deleting file %s (%s)\n", path.c_str(),
+                strerror(errno));
+        return errno;
+    }
+    return 0;
+}
+
+int
+remove_recursively(const string& path)
+{
+    int err;
+
+    if (is_dir(path)) {
+        DIR *d = opendir(path.c_str());
+        if (d == NULL) {
+            fprintf(stderr, "error getting directory contents %s (%s)\n",
+                    path.c_str(), strerror(errno));
+            return errno;
+        }
+
+        vector<string> files;
+        vector<string> dirs;
+
+        struct dirent *ent;
+        while (NULL != (ent = readdir(d))) {
+            if (0 == strcmp(".", ent->d_name)
+                    || 0 == strcmp("..", ent->d_name)) {
+                continue;
+            }
+            string full = path;
+            full += '/';
+            full += ent->d_name;
+#ifdef HAVE_DIRENT_D_TYPE
+            bool is_directory = (ent->d_type == DT_DIR);
+#else
+	    	// If dirent.d_type is missing, then use stat instead
+			struct stat stat_buf;
+			stat(full.c_str(), &stat_buf);
+			bool is_directory = S_ISDIR(stat_buf.st_mode);
+#endif
+            if (is_directory) {
+                dirs.push_back(full);
+            } else {
+                files.push_back(full);
+            }
+        }
+        closedir(d);
+
+        for (vector<string>::iterator it=files.begin(); it!=files.end(); it++) {
+            err = remove_file(*it);
+            if (err != 0) {
+                return err;
+            }
+        }
+
+        for (vector<string>::iterator it=dirs.begin(); it!=dirs.end(); it++) {
+            err = remove_recursively(*it);
+            if (err != 0) {
+                return err;
+            }
+        }
+
+        err = rmdir(path.c_str());
+        if (err != 0) {
+            fprintf(stderr, "error deleting directory %s (%s)\n", path.c_str(),
+                    strerror(errno));
+            return errno;
+        }
+        return 0;
+    } else {
+        return remove_file(path);
+    }
+}
+
+int
+mkdir_recursively(const string& path)
+{
+    int err;
+    size_t pos = 0;
+    while (true) {
+        pos = path.find('/', pos);
+        string p = path.substr(0, pos);
+        struct stat st;
+        err = stat(p.c_str(), &st);
+        if (err != 0) {
+            err = mkdir(p.c_str(), 0770);
+            if (err != 0) {
+                fprintf(stderr, "can't create directory %s (%s)\n",
+                        path.c_str(), strerror(errno));
+                return errno;
+            }
+        }
+        else if (!S_ISDIR(st.st_mode)) {
+            fprintf(stderr, "can't create directory %s because %s is a file.\n",
+                        path.c_str(), p.c_str());
+            return 1;
+        }
+        pos++;
+        if (p == path) {
+            return 0;
+        }
+    }
+}
+
+int
+copy_file(const string& src, const string& dst)
+{
+    int err;
+
+    err = copyFile(src.c_str(), dst.c_str(),
+                    COPY_NO_DEREFERENCE | COPY_FORCE | COPY_PERMISSIONS);
+    return err;
+}