From 1f6efa3996dd1929fbc129203ce5009b620e6969 Mon Sep 17 00:00:00 2001
From: "Michael J. Spencer" <bigcheesegs@gmail.com>
Date: Mon, 29 Nov 2010 18:16:10 +0000
Subject: Merge System into Support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120298 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Support/DynamicLibrary.cpp | 177 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 177 insertions(+)
 create mode 100644 lib/Support/DynamicLibrary.cpp

(limited to 'lib/Support/DynamicLibrary.cpp')

diff --git a/lib/Support/DynamicLibrary.cpp b/lib/Support/DynamicLibrary.cpp
new file mode 100644
index 0000000000..cd9927a193
--- /dev/null
+++ b/lib/Support/DynamicLibrary.cpp
@@ -0,0 +1,177 @@
+//===-- DynamicLibrary.cpp - Runtime link/load libraries --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This header file implements the operating system DynamicLibrary concept.
+//
+// FIXME: This file leaks the ExplicitSymbols and OpenedHandles vector, and is
+// not thread safe!
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/DynamicLibrary.h"
+#include "llvm/Support/Mutex.h"
+#include "llvm/Config/config.h"
+#include <cstdio>
+#include <cstring>
+#include <map>
+#include <vector>
+
+// Collection of symbol name/value pairs to be searched prior to any libraries.
+static std::map<std::string, void*> *ExplicitSymbols = 0;
+
+namespace {
+
+struct ExplicitSymbolsDeleter {
+  ~ExplicitSymbolsDeleter() {
+    if (ExplicitSymbols)
+      delete ExplicitSymbols;
+  }
+};
+
+}
+
+static ExplicitSymbolsDeleter Dummy;
+
+void llvm::sys::DynamicLibrary::AddSymbol(const char* symbolName,
+                                          void *symbolValue) {
+  if (ExplicitSymbols == 0)
+    ExplicitSymbols = new std::map<std::string, void*>();
+  (*ExplicitSymbols)[symbolName] = symbolValue;
+}
+
+#ifdef LLVM_ON_WIN32
+
+#include "Windows/DynamicLibrary.inc"
+
+#else
+
+#if HAVE_DLFCN_H
+#include <dlfcn.h>
+using namespace llvm;
+using namespace llvm::sys;
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only TRULY operating system
+//===          independent code.
+//===----------------------------------------------------------------------===//
+
+static SmartMutex<true>* HandlesMutex;
+static std::vector<void *> *OpenedHandles = 0;
+
+static bool InitializeMutex() {
+  HandlesMutex = new SmartMutex<true>;
+  return HandlesMutex != 0;
+}
+
+static bool EnsureMutexInitialized() {
+  static bool result = InitializeMutex();
+  return result;
+}
+
+
+bool DynamicLibrary::LoadLibraryPermanently(const char *Filename,
+                                            std::string *ErrMsg) {
+  void *H = dlopen(Filename, RTLD_LAZY|RTLD_GLOBAL);
+  if (H == 0) {
+    if (ErrMsg) *ErrMsg = dlerror();
+    return true;
+  }
+#ifdef __CYGWIN__
+  // Cygwin searches symbols only in the main
+  // with the handle of dlopen(NULL, RTLD_GLOBAL).
+  if (Filename == NULL)
+    H = RTLD_DEFAULT;
+#endif
+  EnsureMutexInitialized();
+  SmartScopedLock<true> Lock(*HandlesMutex);
+  if (OpenedHandles == 0)
+    OpenedHandles = new std::vector<void *>();
+  OpenedHandles->push_back(H);
+  return false;
+}
+#else
+
+using namespace llvm;
+using namespace llvm::sys;
+
+bool DynamicLibrary::LoadLibraryPermanently(const char *Filename,
+                                            std::string *ErrMsg) {
+  if (ErrMsg) *ErrMsg = "dlopen() not supported on this platform";
+  return true;
+}
+#endif
+
+namespace llvm {
+void *SearchForAddressOfSpecialSymbol(const char* symbolName);
+}
+
+void* DynamicLibrary::SearchForAddressOfSymbol(const char* symbolName) {
+  // First check symbols added via AddSymbol().
+  if (ExplicitSymbols) {
+    std::map<std::string, void *>::iterator I =
+      ExplicitSymbols->find(symbolName);
+    std::map<std::string, void *>::iterator E = ExplicitSymbols->end();
+
+    if (I != E)
+      return I->second;
+  }
+
+#if HAVE_DLFCN_H
+  // Now search the libraries.
+  EnsureMutexInitialized();
+  SmartScopedLock<true> Lock(*HandlesMutex);
+  if (OpenedHandles) {
+    for (std::vector<void *>::iterator I = OpenedHandles->begin(),
+         E = OpenedHandles->end(); I != E; ++I) {
+      //lt_ptr ptr = lt_dlsym(*I, symbolName);
+      void *ptr = dlsym(*I, symbolName);
+      if (ptr) {
+        return ptr;
+      }
+    }
+  }
+#endif
+
+  if (void *Result = llvm::SearchForAddressOfSpecialSymbol(symbolName))
+    return Result;
+
+// This macro returns the address of a well-known, explicit symbol
+#define EXPLICIT_SYMBOL(SYM) \
+   if (!strcmp(symbolName, #SYM)) return &SYM
+
+// On linux we have a weird situation. The stderr/out/in symbols are both
+// macros and global variables because of standards requirements. So, we
+// boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
+#if defined(__linux__)
+  {
+    EXPLICIT_SYMBOL(stderr);
+    EXPLICIT_SYMBOL(stdout);
+    EXPLICIT_SYMBOL(stdin);
+  }
+#else
+  // For everything else, we want to check to make sure the symbol isn't defined
+  // as a macro before using EXPLICIT_SYMBOL.
+  {
+#ifndef stdin
+    EXPLICIT_SYMBOL(stdin);
+#endif
+#ifndef stdout
+    EXPLICIT_SYMBOL(stdout);
+#endif
+#ifndef stderr
+    EXPLICIT_SYMBOL(stderr);
+#endif
+  }
+#endif
+#undef EXPLICIT_SYMBOL
+
+  return 0;
+}
+
+#endif // LLVM_ON_WIN32
-- 
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