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982799f7a0
This works by defining a set of weak symbols in dynamic linker whose value would be provided by it. This has the same effect as preloading library that magically knows right addresses of functions shared between dynamic linker and LibC. We were previously passing the same information by rewriting values based on hardcoded library name, so the new approach seems a little nicer to me.
85 lines
2 KiB
C++
85 lines
2 KiB
C++
/*
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* Copyright (c) 2021, Gunnar Beutner <gunnar@beutner.name>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/ByteString.h>
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#include <AK/Types.h>
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#include <bits/dlfcn_integration.h>
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#include <dlfcn.h>
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#include <string.h>
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// These are filled in by the dynamic loader.
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[[gnu::weak]] DlCloseFunction __dlclose;
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[[gnu::weak]] DlOpenFunction __dlopen;
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[[gnu::weak]] DlSymFunction __dlsym;
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[[gnu::weak]] DlAddrFunction __dladdr;
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// FIXME: use thread_local and a String once TLS works
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#ifdef NO_TLS
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char* s_dlerror_text = NULL;
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bool s_dlerror_retrieved = false;
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#else
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__thread char* s_dlerror_text = NULL;
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__thread bool s_dlerror_retrieved = false;
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#endif
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static void store_error(ByteString const& error)
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{
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free(s_dlerror_text);
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s_dlerror_text = strdup(error.characters());
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s_dlerror_retrieved = false;
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}
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int dlclose(void* handle)
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{
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auto result = __dlclose(handle);
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if (result.is_error()) {
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store_error(result.error().text);
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return -1;
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}
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return 0;
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}
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char* dlerror()
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{
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if (s_dlerror_retrieved) {
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free(s_dlerror_text);
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s_dlerror_text = nullptr;
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}
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s_dlerror_retrieved = true;
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return const_cast<char*>(s_dlerror_text);
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}
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void* dlopen(char const* filename, int flags)
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{
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auto result = __dlopen(filename, flags);
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if (result.is_error()) {
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store_error(result.error().text);
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return nullptr;
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}
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return result.value();
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}
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void* dlsym(void* handle, char const* symbol_name)
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{
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auto result = __dlsym(handle, symbol_name);
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if (result.is_error()) {
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store_error(result.error().text);
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return nullptr;
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}
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return result.value();
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}
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int dladdr(void const* addr, Dl_info* info)
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{
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auto result = __dladdr(addr, info);
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if (result.is_error()) {
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// FIXME: According to the man page glibc does _not_ make the error
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// available via dlerror(), however we do. Does this break anything?
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store_error(result.error().text);
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return 0;
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}
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return 1;
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}
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