avb_property_descriptor.h
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/* SPDX-License-Identifier: MIT */
/*
* Copyright (C) 2016 The Android Open Source Project
*/
#if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION)
#error "Never include this file directly, include libavb.h instead."
#endif
#ifndef AVB_PROPERTY_DESCRIPTOR_H_
#define AVB_PROPERTY_DESCRIPTOR_H_
#include "avb_descriptor.h"
#ifdef __cplusplus
extern "C" {
#endif
/* A descriptor for properties (free-form key/value pairs).
*
* Following this struct are |key_num_bytes| bytes of key data,
* followed by a NUL byte, then |value_num_bytes| bytes of value data,
* followed by a NUL byte and then enough padding to make the combined
* size a multiple of 8.
*/
typedef struct AvbPropertyDescriptor {
AvbDescriptor parent_descriptor;
uint64_t key_num_bytes;
uint64_t value_num_bytes;
} AVB_ATTR_PACKED AvbPropertyDescriptor;
/* Copies |src| to |dest| and validates, byte-swapping fields in the
* process if needed. Returns true if valid, false if invalid.
*
* Data following the struct is not validated nor copied.
*/
bool avb_property_descriptor_validate_and_byteswap(
const AvbPropertyDescriptor* src,
AvbPropertyDescriptor* dest) AVB_ATTR_WARN_UNUSED_RESULT;
/* Convenience function for looking up the value for a property with
* name |key| in a vbmeta image. If |key_size| is 0, |key| must be
* NUL-terminated.
*
* The |image_data| parameter must be a pointer to a vbmeta image of
* size |image_size|.
*
* This function returns a pointer to the value inside the passed-in
* image or NULL if not found. Note that the value is always
* guaranteed to be followed by a NUL byte.
*
* If the value was found and |out_value_size| is not NULL, the size
* of the value is returned there.
*
* This function is O(n) in number of descriptors so if you need to
* look up a lot of values, you may want to build a more efficient
* lookup-table by manually walking all descriptors using
* avb_descriptor_foreach().
*
* Before using this function, you MUST verify |image_data| with
* avb_vbmeta_image_verify() and reject it unless it's signed by a
* known good public key.
*/
const char* avb_property_lookup(const uint8_t* image_data,
size_t image_size,
const char* key,
size_t key_size,
size_t* out_value_size)
AVB_ATTR_WARN_UNUSED_RESULT;
/* Like avb_property_lookup() but parses the intial portions of the
* value as an unsigned 64-bit integer. Both decimal and hexadecimal
* representations (e.g. "0x2a") are supported. Returns false on
* failure and true on success. On success, the parsed value is
* returned in |out_value|.
*/
bool avb_property_lookup_uint64(const uint8_t* image_data,
size_t image_size,
const char* key,
size_t key_size,
uint64_t* out_value)
AVB_ATTR_WARN_UNUSED_RESULT;
#ifdef __cplusplus
}
#endif
#endif /* AVB_PROPERTY_DESCRIPTOR_H_ */