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/*
* Copyright (c) 2019 Samsung Electronics Co., Ltd. All Rights Reserved
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "symbol_searcher.h"
#include <dlfcn.h>
#include <link.h>
struct SymbolDescription
{
const char *name;
void *address = nullptr; // address in memory where this symbol can be found
SymbolDescription(const char *name) : name(name) {}
};
using InfoAboutLoadedLib = struct dl_phdr_info *;
static void tryToFindSymbolInLinkedLibraries(SymbolDescription &symbol);
static void tryToFindSymbolInAllLoadedLibraries(SymbolDescription &symbol);
static int checkIfLibraryContainsSymbol(InfoAboutLoadedLib library_description, size_t /* size */,
void *data);
static bool isSymbolAddressNotInTheSameTranslationUnit(SymbolDescription *symbol);
void *findSymbol(const char *name)
{
SymbolDescription symbol(name);
tryToFindSymbolInLinkedLibraries(symbol);
if (!symbol.address)
{
tryToFindSymbolInAllLoadedLibraries(symbol);
}
return symbol.address;
}
static void tryToFindSymbolInLinkedLibraries(SymbolDescription &symbol)
{
symbol.address = dlsym(RTLD_NEXT, symbol.name);
}
static void tryToFindSymbolInAllLoadedLibraries(SymbolDescription &symbol)
{
dl_iterate_phdr(checkIfLibraryContainsSymbol, &symbol);
}
static int checkIfLibraryContainsSymbol(InfoAboutLoadedLib library_description, size_t /* size */,
void *data)
{
SymbolDescription *symbol = (SymbolDescription *)data;
void *handle = dlopen(library_description->dlpi_name, RTLD_NOW);
symbol->address = dlsym(handle, symbol->name);
dlclose(handle);
if (symbol->address && isSymbolAddressNotInTheSameTranslationUnit(symbol))
{
return 1;
}
return 0;
}
static bool isSymbolAddressNotInTheSameTranslationUnit(SymbolDescription *symbol)
{
void *handle = dlopen("", RTLD_NOW);
void *addressInTheSameTranslationUnit = dlsym(handle, symbol->name);
dlclose(handle);
return addressInTheSameTranslationUnit == nullptr ||
addressInTheSameTranslationUnit != symbol->address;
}
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