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. */
17 typedef 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  */
27 void 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  */
38 void *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  */
50 void *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  */
62 const 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  */
73 const void *StatefulMemset_r(MemcpyState *state, const uint8_t val,
74                              uint64_t len);
75 
76 #endif
77