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| //===-- DynamicLibrary.cpp - Runtime link/load libraries --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the operating system DynamicLibrary concept.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/DynamicLibrary.h"
#include "llvm-c/Support.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Config/config.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Mutex.h"
#include <cstdio>
#include <cstring>
#include <vector>
using namespace llvm;
using namespace llvm::sys;
// All methods for HandleSet should be used holding SymbolsMutex.
class DynamicLibrary::HandleSet {
typedef std::vector<void *> HandleList;
HandleList Handles;
void *Process;
public:
static void *DLOpen(const char *Filename, std::string *Err);
static void DLClose(void *Handle);
static void *DLSym(void *Handle, const char *Symbol);
HandleSet() : Process(nullptr) {}
~HandleSet();
HandleList::iterator Find(void *Handle) {
return std::find(Handles.begin(), Handles.end(), Handle);
}
bool Contains(void *Handle) {
return Handle == Process || Find(Handle) != Handles.end();
}
bool AddLibrary(void *Handle, bool IsProcess = false, bool CanClose = true) {
#ifdef _WIN32
assert((Handle == this ? IsProcess : !IsProcess) && "Bad Handle.");
#endif
if (LLVM_LIKELY(!IsProcess)) {
if (Find(Handle) != Handles.end()) {
if (CanClose)
DLClose(Handle);
return false;
}
Handles.push_back(Handle);
} else {
#ifndef _WIN32
if (Process) {
if (CanClose)
DLClose(Process);
if (Process == Handle)
return false;
}
#endif
Process = Handle;
}
return true;
}
void *LibLookup(const char *Symbol, DynamicLibrary::SearchOrdering Order) {
if (Order & SO_LoadOrder) {
for (void *Handle : Handles) {
if (void *Ptr = DLSym(Handle, Symbol))
return Ptr;
}
} else {
for (void *Handle : llvm::reverse(Handles)) {
if (void *Ptr = DLSym(Handle, Symbol))
return Ptr;
}
}
return nullptr;
}
void *Lookup(const char *Symbol, DynamicLibrary::SearchOrdering Order) {
assert(!((Order & SO_LoadedFirst) && (Order & SO_LoadedLast)) &&
"Invalid Ordering");
if (!Process || (Order & SO_LoadedFirst)) {
if (void *Ptr = LibLookup(Symbol, Order))
return Ptr;
}
if (Process) {
// Use OS facilities to search the current binary and all loaded libs.
if (void *Ptr = DLSym(Process, Symbol))
return Ptr;
// Search any libs that might have been skipped because of RTLD_LOCAL.
if (Order & SO_LoadedLast) {
if (void *Ptr = LibLookup(Symbol, Order))
return Ptr;
}
}
return nullptr;
}
};
namespace {
// Collection of symbol name/value pairs to be searched prior to any libraries.
static llvm::ManagedStatic<llvm::StringMap<void *>> ExplicitSymbols;
// Collection of known library handles.
static llvm::ManagedStatic<DynamicLibrary::HandleSet> OpenedHandles;
// Lock for ExplicitSymbols and OpenedHandles.
static llvm::ManagedStatic<llvm::sys::SmartMutex<true>> SymbolsMutex;
}
#ifdef _WIN32
#include "Windows/DynamicLibrary.inc"
#else
#include "Unix/DynamicLibrary.inc"
#endif
char DynamicLibrary::Invalid;
DynamicLibrary::SearchOrdering DynamicLibrary::SearchOrder =
DynamicLibrary::SO_Linker;
namespace llvm {
void *SearchForAddressOfSpecialSymbol(const char *SymbolName) {
return DoSearch(SymbolName); // DynamicLibrary.inc
}
}
void DynamicLibrary::AddSymbol(StringRef SymbolName, void *SymbolValue) {
SmartScopedLock<true> Lock(*SymbolsMutex);
(*ExplicitSymbols)[SymbolName] = SymbolValue;
}
DynamicLibrary DynamicLibrary::getPermanentLibrary(const char *FileName,
std::string *Err) {
// Force OpenedHandles to be added into the ManagedStatic list before any
// ManagedStatic can be added from static constructors in HandleSet::DLOpen.
HandleSet& HS = *OpenedHandles;
void *Handle = HandleSet::DLOpen(FileName, Err);
if (Handle != &Invalid) {
SmartScopedLock<true> Lock(*SymbolsMutex);
HS.AddLibrary(Handle, /*IsProcess*/ FileName == nullptr);
}
return DynamicLibrary(Handle);
}
DynamicLibrary DynamicLibrary::addPermanentLibrary(void *Handle,
std::string *Err) {
SmartScopedLock<true> Lock(*SymbolsMutex);
// If we've already loaded this library, tell the caller.
if (!OpenedHandles->AddLibrary(Handle, /*IsProcess*/false, /*CanClose*/false))
*Err = "Library already loaded";
return DynamicLibrary(Handle);
}
void *DynamicLibrary::getAddressOfSymbol(const char *SymbolName) {
if (!isValid())
return nullptr;
return HandleSet::DLSym(Data, SymbolName);
}
void *DynamicLibrary::SearchForAddressOfSymbol(const char *SymbolName) {
{
SmartScopedLock<true> Lock(*SymbolsMutex);
// First check symbols added via AddSymbol().
if (ExplicitSymbols.isConstructed()) {
StringMap<void *>::iterator i = ExplicitSymbols->find(SymbolName);
if (i != ExplicitSymbols->end())
return i->second;
}
// Now search the libraries.
if (OpenedHandles.isConstructed()) {
if (void *Ptr = OpenedHandles->Lookup(SymbolName, SearchOrder))
return Ptr;
}
}
return llvm::SearchForAddressOfSpecialSymbol(SymbolName);
}
//===----------------------------------------------------------------------===//
// C API.
//===----------------------------------------------------------------------===//
LLVMBool LLVMLoadLibraryPermanently(const char *Filename) {
return llvm::sys::DynamicLibrary::LoadLibraryPermanently(Filename);
}
void *LLVMSearchForAddressOfSymbol(const char *symbolName) {
return llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(symbolName);
}
void LLVMAddSymbol(const char *symbolName, void *symbolValue) {
return llvm::sys::DynamicLibrary::AddSymbol(symbolName, symbolValue);
}
|