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