1 files changed, 215 insertions, 0 deletions
diff --git a/llvm/lib/Support/DynamicLibrary.cpp b/llvm/lib/Support/DynamicLibrary.cpp
new file mode 100644
index 000000000000..d23716016fb2
--- /dev/null
+++ b/llvm/lib/Support/DynamicLibrary.cpp
@@ -0,0 +1,215 @@
+//===-- 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);
+}