diff --git a/tools/applypatch/applypatch.h b/tools/applypatch/applypatch.h
new file mode 100644
index 0000000..3059e22
--- /dev/null
+++ b/tools/applypatch/applypatch.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef _APPLYPATCH_H
+#define _APPLYPATCH_H
+
+#include "mincrypt/sha.h"
+
+typedef struct _Patch {
+  uint8_t sha1[SHA_DIGEST_SIZE];
+  const char* patch_filename;
+} Patch;
+
+typedef struct _FileContents {
+  uint8_t sha1[SHA_DIGEST_SIZE];
+  unsigned char* data;
+  size_t size;
+  struct stat st;
+} FileContents;
+
+// When there isn't enough room on the target filesystem to hold the
+// patched version of the file, we copy the original here and delete
+// it to free up space.  If the expected source file doesn't exist, or
+// is corrupted, we look to see if this file contains the bits we want
+// and use it as the source instead.
+#define CACHE_TEMP_SOURCE "/cache/saved.file"
+
+// applypatch.c
+size_t FreeSpaceForFile(const char* filename);
+
+// xdelta3.c
+int ApplyXDelta3Patch(const unsigned char* old_data, ssize_t old_size,
+                      const char* patch_filename,
+                      FILE* output, SHA_CTX* ctx);
+
+// bsdiff.c
+void ShowBSDiffLicense();
+int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
+                     const char* patch_filename,
+                     FILE* output, SHA_CTX* ctx);
+
+// freecache.c
+int MakeFreeSpaceOnCache(size_t bytes_needed);
+
+#endif