85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
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#pragma once
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#include <flipper_application/elf/elf_api_interface.h>
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Symbol table entry
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*/
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struct sym_entry {
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uint32_t hash;
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uint32_t address;
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};
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/**
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* @brief Resolver for API entries using a pre-sorted table with hashes
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* @param interface pointer to HashtableApiInterface
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* @param name function name
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* @param address output for function address
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* @return true if the table contains a function
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*/
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bool elf_resolve_from_hashtable(
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const ElfApiInterface* interface,
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const char* name,
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Elf32_Addr* address);
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#ifdef __cplusplus
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}
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#include <array>
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#include <algorithm>
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/**
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* @brief HashtableApiInterface is an implementation of ElfApiInterface
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* that uses a hash table to resolve function addresses.
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* table_cbegin and table_cend must point to a sorted array of sym_entry
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*/
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struct HashtableApiInterface : public ElfApiInterface {
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const sym_entry *table_cbegin, *table_cend;
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};
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#define API_METHOD(x, ret_type, args_type) \
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sym_entry { \
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.hash = elf_gnu_hash(#x), .address = (uint32_t)(static_cast<ret_type(*) args_type>(x)) \
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}
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#define API_VARIABLE(x, var_type) \
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sym_entry { .hash = elf_gnu_hash(#x), .address = (uint32_t)(&(x)), }
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constexpr bool operator<(const sym_entry& k1, const sym_entry& k2) {
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return k1.hash < k2.hash;
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}
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/**
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* @brief Calculate hash for a string using the ELF GNU hash algorithm
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* @param s string to calculate hash for
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* @return hash value
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*/
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constexpr uint32_t elf_gnu_hash(const char* s) {
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uint32_t h = 0x1505;
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for(unsigned char c = *s; c != '\0'; c = *++s) {
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h = (h << 5) + h + c;
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}
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return h;
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}
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/* Compile-time check for hash collisions in API table.
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* Usage: static_assert(!has_hash_collisions(api_methods), "Hash collision detected");
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*/
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template <std::size_t N>
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constexpr bool has_hash_collisions(const std::array<sym_entry, N>& api_methods) {
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for(std::size_t i = 0; i < (N - 1); ++i) {
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if(api_methods[i].hash == api_methods[i + 1].hash) {
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return true;
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}
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}
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return false;
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}
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#endif
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