lib/Support/DynamicLibrary.cpp

   1 //===-- DynamicLibrary.cpp - Runtime link/load libraries --------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 //  This header file implements the operating system DynamicLibrary concept.
  11 //
  12 // FIXME: This file leaks the ExplicitSymbols and OpenedHandles vector, and is
  13 // not thread safe!
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "llvm/Support/DynamicLibrary.h"
  18 #include "llvm/Support/Mutex.h"
  19 #include "llvm/Config/config.h"
  20 #include <cstdio>
  21 #include <cstring>
  22 #include <map>
  23 #include <vector>
  24
  25 // Collection of symbol name/value pairs to be searched prior to any libraries.
  26 static std::map<std::string, void*> *ExplicitSymbols = 0;
  27
  28 namespace {
  29
  30 struct ExplicitSymbolsDeleter {
  31   ~ExplicitSymbolsDeleter() {
  32     if (ExplicitSymbols)
  33       delete ExplicitSymbols;
  34   }
  35 };
  36
  37 }
  38
  39 static ExplicitSymbolsDeleter Dummy;
  40
  41 void llvm::sys::DynamicLibrary::AddSymbol(const char* symbolName,
  42                                           void *symbolValue) {
  43   if (ExplicitSymbols == 0)
  44     ExplicitSymbols = new std::map<std::string, void*>();
  45   (*ExplicitSymbols)[symbolName] = symbolValue;
  46 }
  47
  48 #ifdef LLVM_ON_WIN32
  49
  50 #include "Windows/DynamicLibrary.inc"
  51
  52 #else
  53
  54 #if HAVE_DLFCN_H
  55 #include <dlfcn.h>
  56 using namespace llvm;
  57 using namespace llvm::sys;
  58
  59 //===----------------------------------------------------------------------===//
  60 //=== WARNING: Implementation here must contain only TRULY operating system
  61 //===          independent code.
  62 //===----------------------------------------------------------------------===//
  63
  64 static std::vector<void *> *OpenedHandles = 0;
  65
  66
  67 static SmartMutex<true>& getMutex() {
  68   static SmartMutex<true> HandlesMutex;
  69   return HandlesMutex;
  70 }
  71
  72
  73 bool DynamicLibrary::LoadLibraryPermanently(const char *Filename,
  74                                             std::string *ErrMsg) {
  75   void *H = dlopen(Filename, RTLD_LAZY|RTLD_GLOBAL);
  76   if (H == 0) {
  77     if (ErrMsg) *ErrMsg = dlerror();
  78     return true;
  79   }
  80 #ifdef __CYGWIN__
  81   // Cygwin searches symbols only in the main
  82   // with the handle of dlopen(NULL, RTLD_GLOBAL).
  83   if (Filename == NULL)
  84     H = RTLD_DEFAULT;
  85 #endif
  86   SmartScopedLock<true> Lock(getMutex());
  87   if (OpenedHandles == 0)
  88     OpenedHandles = new std::vector<void *>();
  89   OpenedHandles->push_back(H);
  90   return false;
  91 }
  92 #else
  93
  94 using namespace llvm;
  95 using namespace llvm::sys;
  96
  97 bool DynamicLibrary::LoadLibraryPermanently(const char *Filename,
  98                                             std::string *ErrMsg) {
  99   if (ErrMsg) *ErrMsg = "dlopen() not supported on this platform";
 100   return true;
 101 }
 102 #endif
 103
 104 namespace llvm {
 105 void *SearchForAddressOfSpecialSymbol(const char* symbolName);
 106 }
 107
 108 void* DynamicLibrary::SearchForAddressOfSymbol(const char* symbolName) {
 109   // First check symbols added via AddSymbol().
 110   if (ExplicitSymbols) {
 111     std::map<std::string, void *>::iterator I =
 112       ExplicitSymbols->find(symbolName);
 113     std::map<std::string, void *>::iterator E = ExplicitSymbols->end();
 114
 115     if (I != E)
 116       return I->second;
 117   }
 118
 119 #if HAVE_DLFCN_H
 120   // Now search the libraries.
 121   SmartScopedLock<true> Lock(getMutex());
 122   if (OpenedHandles) {
 123     for (std::vector<void *>::iterator I = OpenedHandles->begin(),
 124          E = OpenedHandles->end(); I != E; ++I) {
 125       //lt_ptr ptr = lt_dlsym(*I, symbolName);
 126       void *ptr = dlsym(*I, symbolName);
 127       if (ptr) {
 128         return ptr;
 129       }
 130     }
 131   }
 132 #endif
 133
 134   if (void *Result = llvm::SearchForAddressOfSpecialSymbol(symbolName))
 135     return Result;
 136
 137 // This macro returns the address of a well-known, explicit symbol
 138 #define EXPLICIT_SYMBOL(SYM) \
 139    if (!strcmp(symbolName, #SYM)) return &SYM
 140
 141 // On linux we have a weird situation. The stderr/out/in symbols are both
 142 // macros and global variables because of standards requirements. So, we
 143 // boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
 144 #if defined(__linux__)
 145   {
 146     EXPLICIT_SYMBOL(stderr);
 147     EXPLICIT_SYMBOL(stdout);
 148     EXPLICIT_SYMBOL(stdin);
 149   }
 150 #else
 151   // For everything else, we want to check to make sure the symbol isn't defined
 152   // as a macro before using EXPLICIT_SYMBOL.
 153   {
 154 #ifndef stdin
 155     EXPLICIT_SYMBOL(stdin);
 156 #endif
 157 #ifndef stdout
 158     EXPLICIT_SYMBOL(stdout);
 159 #endif
 160 #ifndef stderr
 161     EXPLICIT_SYMBOL(stderr);
 162 #endif
 163   }
 164 #endif
 165 #undef EXPLICIT_SYMBOL
 166
 167   return 0;
 168 }
 169
 170 #endif // LLVM_ON_WIN32