diff --git a/src/Makefile.am b/src/Makefile.am
index cb0ddd0..0114d4a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -11,6 +11,7 @@
 noinst_LTLIBRARIES = libharfbuzz-1.la
 
 HBSOURCES =  \
+	hb-blob.c \
 	hb-buffer.c \
 	hb-buffer-private.h \
 	hb-private.h \
@@ -22,11 +23,13 @@
 	hb-ot-layout-gsub-private.h \
 	hb-ot-layout-open-private.h \
 	hb-ot-layout-private.h \
+	hb-refcount-private.h \
 	$(NULL)
 
 HBHEADERS = \
-	hb-common.h \
+	hb-blob.h \
 	hb-buffer.h \
+	hb-common.h \
 	hb-ot-layout.h \
 	$(NULL)
 
diff --git a/src/hb-blob.c b/src/hb-blob.c
new file mode 100644
index 0000000..bcdf134
--- /dev/null
+++ b/src/hb-blob.c
@@ -0,0 +1,181 @@
+/*
+ * Copyright (C) 2009  Red Hat, Inc.
+ *
+ *  This is part of HarfBuzz, an OpenType Layout engine library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Red Hat Author(s): Behdad Esfahbod
+ */
+
+#include "hb-private.h"
+
+#include "hb-blob.h"
+#include "hb-refcount-private.h"
+
+struct _hb_blob_t {
+  const char *data;
+  unsigned int len;
+  hb_memory_mode_t mode;
+
+  hb_reference_count_t ref_count;
+  hb_destroy_func_t destroy;
+  void *user_data;
+};
+static hb_blob_t _hb_blob_nil = {
+  NULL,
+  0,
+  HB_MEMORY_MODE_READONLY,
+
+  HB_REFERENCE_COUNT_INVALID,
+  NULL,
+  NULL
+};
+
+static void
+_hb_blob_destroy_user_data (hb_blob_t *blob)
+{
+  if (blob->destroy) {
+    blob->destroy (blob->user_data);
+    blob->destroy = NULL;
+    blob->user_data = NULL;
+  }
+}
+
+hb_blob_t *
+hb_blob_create (const char        *data,
+		unsigned int       len,
+		hb_memory_mode_t   mode,
+		hb_destroy_func_t  destroy,
+		void              *user_data)
+{
+  hb_blob_t *blob;
+
+  blob = malloc (sizeof (hb_blob_t));
+  if (!blob) {
+    if (destroy)
+      destroy (user_data);
+    return &_hb_blob_nil;
+  }
+
+  blob->data = data;
+  blob->len = len;
+  blob->mode = mode;
+
+  HB_REFERENCE_COUNT_INIT (blob->ref_count, 1);
+  blob->destroy = destroy;
+  blob->user_data = user_data;
+
+  if (blob->mode == HB_MEMORY_MODE_DUPLICATE) {
+    blob->mode = HB_MEMORY_MODE_READONLY;
+    hb_blob_make_writeable (blob);
+  }
+
+  return blob;
+}
+
+hb_blob_t *
+hb_blob_reference (hb_blob_t *blob)
+{
+  if (blob == NULL || HB_REFERENCE_COUNT_IS_INVALID (blob->ref_count))
+    return blob;
+
+  assert (HB_REFERENCE_COUNT_HAS_REFERENCE (blob->ref_count));
+
+  _hb_reference_count_inc (blob->ref_count);
+
+  return blob;
+}
+
+void
+hb_blob_destroy (hb_blob_t *blob)
+{
+  if (blob == NULL || HB_REFERENCE_COUNT_IS_INVALID (blob->ref_count))
+    return;
+
+  assert (HB_REFERENCE_COUNT_HAS_REFERENCE (blob->ref_count));
+
+  if (!_hb_reference_count_dec_and_test (blob->ref_count))
+    return;
+
+  _hb_blob_destroy_user_data (blob);
+
+  free (blob);
+}
+
+const char *
+hb_blob_get_data (hb_blob_t    *blob,
+		  unsigned int *len)
+{
+  if (len)
+    *len = blob->len;
+
+  return blob->data;
+}
+
+hb_bool_t
+hb_blob_is_writeable (hb_blob_t *blob)
+{
+  return blob->mode == HB_MEMORY_MODE_WRITEABLE;
+}
+
+hb_bool_t
+hb_blob_try_writeable_inplace (hb_blob_t *blob)
+{
+  if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITEABLE) {
+    /* XXX
+     * mprotect
+    blob->mode == HB_MEMORY_MODE_WRITEABLE;
+    */
+  }
+
+  return blob->mode == HB_MEMORY_MODE_WRITEABLE;
+}
+
+/* DANGER: May rebase or nullify */
+void
+hb_blob_make_writeable (hb_blob_t *blob)
+{
+  if (blob->mode == HB_MEMORY_MODE_READONLY_NEVER_DUPLICATE)
+  {
+    _hb_blob_destroy_user_data (blob);
+    blob->data = NULL;
+    blob->len = 0;
+  }
+  else if (blob->mode == HB_MEMORY_MODE_READONLY)
+  {
+    char *new_data;
+
+    new_data = malloc (blob->len);
+    if (new_data)
+      memcpy (new_data, blob->data, blob->len);
+
+    _hb_blob_destroy_user_data (blob);
+
+    if (!new_data) {
+      blob->data = NULL;
+      blob->len = 0;
+    } else
+      blob->data = new_data;
+
+    blob->mode = HB_MEMORY_MODE_WRITEABLE;
+  }
+  else
+    hb_blob_try_writeable_inplace (blob);
+}
diff --git a/src/hb-blob.h b/src/hb-blob.h
new file mode 100644
index 0000000..6cb7c34
--- /dev/null
+++ b/src/hb-blob.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2009  Red Hat, Inc.
+ *
+ *  This is part of HarfBuzz, an OpenType Layout engine library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Red Hat Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_BLOB_H
+#define HB_BLOB_H
+
+#include "hb-common.h"
+
+HB_BEGIN_DECLS
+
+typedef struct _hb_blob_t hb_blob_t;
+typedef void (*hb_destroy_func_t) (void *user_data);
+
+typedef enum {
+  HB_MEMORY_MODE_DUPLICATE,
+  HB_MEMORY_MODE_READONLY,
+  HB_MEMORY_MODE_WRITEABLE,
+  HB_MEMORY_MODE_READONLY_NEVER_DUPLICATE,
+  HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITEABLE,
+} hb_memory_mode_t;
+
+hb_blob_t *
+hb_blob_create (const char        *data,
+		unsigned int       len,
+		hb_memory_mode_t   mode,
+		hb_destroy_func_t  destroy,
+		void              *user_data);
+
+hb_blob_t *
+hb_blob_reference (hb_blob_t *blob);
+
+void
+hb_blob_destroy (hb_blob_t *blob);
+
+const char *
+hb_blob_get_data (hb_blob_t    *blob,
+		  unsigned int *len);
+
+hb_bool_t
+hb_blob_is_writeable (hb_blob_t *blob);
+
+hb_bool_t
+hb_blob_try_writeable_inplace (hb_blob_t *blob);
+
+/* DANGER: May rebase or nullify */
+void
+hb_blob_make_writeable (hb_blob_t *blob);
+
+HB_END_DECLS
+
+#endif /* HB_BLOB_H */
diff --git a/src/hb-private.h b/src/hb-private.h
index 6698a7c..196bc3c 100644
--- a/src/hb-private.h
+++ b/src/hb-private.h
@@ -49,6 +49,8 @@
 
 #include <stdlib.h>
 #include <stdio.h> /* XXX */
+#include <string.h>
+#include <assert.h>
 
 /* Basics */
 
diff --git a/src/hb-refcount-private.h b/src/hb-refcount-private.h
new file mode 100644
index 0000000..e8acb25
--- /dev/null
+++ b/src/hb-refcount-private.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright © 2007 Chris Wilson
+ *
+ *  This is part of HarfBuzz, an OpenType Layout engine library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Contributor(s):
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#ifndef HB_REFCOUNT_PRIVATE_H
+#define HB_REFCOUNT_PRIVATE_H
+
+typedef int hb_atomic_int_t;
+
+/* Encapsulate operations on the object's reference count */
+typedef struct {
+  hb_atomic_int_t ref_count;
+} hb_reference_count_t;
+
+/* XXX add real atomic ops */
+#define _hb_reference_count_inc(RC) ((RC).ref_count++)
+#define _hb_reference_count_dec_and_test(RC) ((RC).ref_count-- == 1)
+
+#define HB_REFERENCE_COUNT_INIT(RC, VALUE) ((RC).ref_count = (VALUE))
+
+#define HB_REFERENCE_COUNT_GET_VALUE(RC) ((RC).ref_count+0)
+#define HB_REFERENCE_COUNT_SET_VALUE(RC, VALUE) ((RC).ref_count = (VALUE), 0)
+
+#define HB_REFERENCE_COUNT_INVALID_VALUE ((hb_atomic_int_t) -1)
+#define HB_REFERENCE_COUNT_INVALID {HB_REFERENCE_COUNT_INVALID_VALUE}
+
+#define HB_REFERENCE_COUNT_IS_INVALID(RC) (HB_REFERENCE_COUNT_GET_VALUE (RC) == HB_REFERENCE_COUNT_INVALID_VALUE)
+
+#define HB_REFERENCE_COUNT_HAS_REFERENCE(RC) (HB_REFERENCE_COUNT_GET_VALUE (RC) > 0)
+
+#endif /* HB_REFCOUNT_PRIVATE_H */