lib/System/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 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/System/DynamicLibrary.h"
  15 #include "llvm/Config/config.h"
  16 #include <cstdio>
  17 #include <cstring>
  18 #include <map>
  19
  20 // Collection of symbol name/value pairs to be searched prior to any libraries.
  21 std::map<std::string, void *> &g_symbols() {
  22   static std::map<std::string, void *> symbols;
  23   return symbols;
  24 }
  25
  26 void llvm::sys::DynamicLibrary::AddSymbol(const char* symbolName,
  27                                           void *symbolValue) {
  28   g_symbols()[symbolName] = symbolValue;
  29 }
  30
  31 // It is not possible to use ltdl.c on VC++ builds as the terms of its LGPL
  32 // license and special exception would cause all of LLVM to be placed under
  33 // the LGPL.  This is because the exception applies only when libtool is
  34 // used, and obviously libtool is not used with Visual Studio.  An entirely
  35 // separate implementation is provided in win32/DynamicLibrary.cpp.
  36
  37 #ifdef LLVM_ON_WIN32
  38
  39 #include "Win32/DynamicLibrary.inc"
  40
  41 #else
  42
  43 //#include "ltdl.h"
  44 #include <dlfcn.h>
  45 #include <cassert>
  46 using namespace llvm;
  47 using namespace llvm::sys;
  48
  49 //===----------------------------------------------------------------------===//
  50 //=== WARNING: Implementation here must contain only TRULY operating system
  51 //===          independent code.
  52 //===----------------------------------------------------------------------===//
  53
  54 //static std::vector<lt_dlhandle> OpenedHandles;
  55 static std::vector<void *> OpenedHandles;
  56
  57 DynamicLibrary::DynamicLibrary() {}
  58
  59 DynamicLibrary::~DynamicLibrary() {
  60   while(!OpenedHandles.empty()) {
  61     void *H = OpenedHandles.back();   OpenedHandles.pop_back();
  62     dlclose(H);
  63   }
  64 }
  65
  66 bool DynamicLibrary::LoadLibraryPermanently(const char *Filename,
  67                                             std::string *ErrMsg) {
  68   void *H = dlopen(Filename, RTLD_LAZY|RTLD_GLOBAL);
  69   if (H == 0) {
  70     if (ErrMsg)
  71       *ErrMsg = dlerror();
  72     return true;
  73   }
  74   OpenedHandles.push_back(H);
  75   return false;
  76 }
  77
  78 void* DynamicLibrary::SearchForAddressOfSymbol(const char* symbolName) {
  79   //  check_ltdl_initialization();
  80
  81   // First check symbols added via AddSymbol().
  82   std::map<std::string, void *>::iterator I = g_symbols().find(symbolName);
  83   if (I != g_symbols().end())
  84     return I->second;
  85
  86   // Now search the libraries.
  87   for (std::vector<void *>::iterator I = OpenedHandles.begin(),
  88        E = OpenedHandles.end(); I != E; ++I) {
  89     //lt_ptr ptr = lt_dlsym(*I, symbolName);
  90     void *ptr = dlsym(*I, symbolName);
  91     if (ptr)
  92       return ptr;
  93   }
  94
  95 #define EXPLICIT_SYMBOL(SYM) \
  96    extern void *SYM; if (!strcmp(symbolName, #SYM)) return &SYM
  97
  98   // If this is darwin, it has some funky issues, try to solve them here.  Some
  99   // important symbols are marked 'private external' which doesn't allow
 100   // SearchForAddressOfSymbol to find them.  As such, we special case them here,
 101   // there is only a small handful of them.
 102
 103 #ifdef __APPLE__
 104   {
 105     EXPLICIT_SYMBOL(__ashldi3);
 106     EXPLICIT_SYMBOL(__ashrdi3);
 107     EXPLICIT_SYMBOL(__cmpdi2);
 108     EXPLICIT_SYMBOL(__divdi3);
 109     EXPLICIT_SYMBOL(__eprintf);
 110     EXPLICIT_SYMBOL(__fixdfdi);
 111     EXPLICIT_SYMBOL(__fixsfdi);
 112     EXPLICIT_SYMBOL(__fixunsdfdi);
 113     EXPLICIT_SYMBOL(__fixunssfdi);
 114     EXPLICIT_SYMBOL(__floatdidf);
 115     EXPLICIT_SYMBOL(__floatdisf);
 116     EXPLICIT_SYMBOL(__lshrdi3);
 117     EXPLICIT_SYMBOL(__moddi3);
 118     EXPLICIT_SYMBOL(__udivdi3);
 119     EXPLICIT_SYMBOL(__umoddi3);
 120   }
 121 #endif
 122
 123 #ifdef __CYGWIN__
 124   {
 125     EXPLICIT_SYMBOL(_alloca);
 126     EXPLICIT_SYMBOL(__main);
 127   }
 128 #endif
 129
 130 #undef EXPLICIT_SYMBOL
 131
 132 // This macro returns the address of a well-known, explicit symbol
 133 #define EXPLICIT_SYMBOL(SYM) \
 134    if (!strcmp(symbolName, #SYM)) return &SYM
 135
 136 // On linux we have a weird situation. The stderr/out/in symbols are both
 137 // macros and global variables because of standards requirements. So, we
 138 // boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
 139 #if defined(__linux__)
 140   {
 141     EXPLICIT_SYMBOL(stderr);
 142     EXPLICIT_SYMBOL(stdout);
 143     EXPLICIT_SYMBOL(stdin);
 144   }
 145 #else
 146   // For everything else, we want to check to make sure the symbol isn't defined
 147   // as a macro before using EXPLICIT_SYMBOL.
 148   {
 149 #ifndef stdin
 150     EXPLICIT_SYMBOL(stdin);
 151 #endif
 152 #ifndef stdout
 153     EXPLICIT_SYMBOL(stdout);
 154 #endif
 155 #ifndef stderr
 156     EXPLICIT_SYMBOL(stderr);
 157 #endif
 158   }
 159 #endif
 160 #undef EXPLICIT_SYMBOL
 161
 162   return 0;
 163 }
 164
 165 #endif // LLVM_ON_WIN32