1/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
2 * Use of this source code is governed by a BSD-style license that can be
3 * found in the LICENSE file.
4 */
5
6/*
7 * Helper functions/wrappers for memory allocations, manipulation and
8 * comparison.
9 */
10
11#ifndef VBOOT_FIRMWARE_LIB_STATEFUL_UTIL_H_
12#define VBOOT_FIRMWARE_LIB_STATEFUL_UTIL_H_
13
14#include "sysincludes.h"
15
16/* Track remaining data to be read in a buffer. */
17typedef struct MemcpyState {
18	uint8_t *remaining_buf;
19	uint64_t remaining_len;  /* Remaining length of the buffer. */
20	uint8_t overrun;  /* Flag set to 1 when an overrun occurs. */
21} MemcpyState;
22
23/**
24 * Initialize a stateful buffer struct to point to the buffer, with the
25 * specified remaining length in bytes.
26 */
27void StatefulInit(MemcpyState *state, void *buf, uint64_t len);
28
29/**
30 * Skip [len] bytes only if there's enough data to skip according to [state].
31 *
32 * On success, return a meaningless but non-NULL pointer and updates [state].
33 * On failure, return NULL, set state->overrun to 1.
34 *
35 * Useful for iterating through a binary blob to populate a struct. After the
36 * first failure (buffer overrun), successive calls will always fail.
37 */
38void *StatefulSkip(MemcpyState *state, uint64_t len);
39
40/**
41 * Copy [len] bytes into [dst] only if there's enough data to read according
42 * to [state].
43 *
44 * On success, return [dst] and update [state].
45 * On failure, return NULL, set state->overrun to 1.
46 *
47 * Useful for iterating through a binary blob to populate a struct. After the
48 * first failure (buffer overrun), successive calls will always fail.
49 */
50void *StatefulMemcpy(MemcpyState *state, void *dst, uint64_t len);
51
52/**
53 * Like StatefulMemcpy() but copies in the opposite direction, populating
54 * data from [src] into the buffer encapsulated in state [state].
55 *
56 * On success, return [src] and update [state].
57 * On failure, return NULL, set state->overrun to 1.
58 *
59 * Useful for iterating through a structure to populate a binary blob. After the
60 * first failure (buffer overrun), successive calls will always fail.
61 */
62const void *StatefulMemcpy_r(MemcpyState *state, const void *src, uint64_t len);
63
64/**
65 * Like StatefulMemcpy_r() but fills a portion of the encapsulated buffer with
66 * a constant value.
67 *
68 * On success, return a meaningless but non-NULL pointer and updates [state].
69 * On failure, return NULL, set state->overrun to 1.
70 *
71 * After the first failure (buffer overrun), successive calls will always fail.
72 */
73const void *StatefulMemset_r(MemcpyState *state, const uint8_t val,
74                             uint64_t len);
75
76#endif
77