StatefulMem* functions should be library functions.

We want the BIOS to implement the stub functions, but that shouldn't include
our StatefulMem* functions.

Also, we ensure that we don't accidently use native linux functions instead
of the stub functions.

Review URL: http://codereview.chromium.org/2255006

vboot_firmware/lib/stateful_util.c

@@ -0,0 +1,55 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Stub implementations of utility functions which call their linux-specific
+ * equivalents.
+ */
+
+#include "stateful_util.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void* StatefulMemcpy(MemcpyState* state, void* dst,
+                     uint64_t len) {
+  if (state->overrun)
+    return NULL;
+  if (len > state->remaining_len) {
+    state->overrun = 1;
+    return NULL;
+  }
+  Memcpy(dst, state->remaining_buf, len);
+  state->remaining_buf += len;
+  state->remaining_len -= len;
+  return dst;
+}
+
+const void* StatefulMemcpy_r(MemcpyState* state, const void* src,
+                             uint64_t len) {
+  if (state->overrun)
+    return NULL;
+  if (len > state->remaining_len) {
+    state->overrun = 1;
+    return NULL;
+  }
+  Memcpy(state->remaining_buf, src, len);
+  state->remaining_buf += len;
+  state->remaining_len -= len;
+  return src;
+}
+
+const void* StatefulMemset_r(MemcpyState* state, const uint8_t val,
+                             uint64_t len) {
+  if (state->overrun)
+    return NULL;
+  if (len > state->remaining_len) {
+    state->overrun = 1;
+    return NULL;
+  }
+  Memset(state->remaining_buf, val, len);
+  state->remaining_buf += len;
+  state->remaining_len -= len;
+  return state;                         // have to return something non-NULL
+}