lib/System/DynamicLibrary.cpp

   1 //===-- DynamicLibrary.cpp - Runtime link/load libraries --------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by Reid Spencer and is distributed under the
   6 // University of Illinois Open Source 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 <map>
  17
  18 // Collection of symbol name/value pairs to be searched prior to any libraries.
  19 static std::map<std::string, void *> g_symbols;
  20
  21 void llvm::sys::DynamicLibrary::AddSymbol(const char* symbolName,
  22                                           void *symbolValue) {
  23   g_symbols[symbolName] = symbolValue;
  24 }
  25
  26 // It is not possible to use ltdl.c on VC++ builds as the terms of its LGPL
  27 // license and special exception would cause all of LLVM to be placed under
  28 // the LGPL.  This is because the exception applies only when libtool is
  29 // used, and obviously libtool is not used with Visual Studio.  An entirely
  30 // separate implementation is provided in win32/DynamicLibrary.cpp.
  31
  32 #ifdef LLVM_ON_WIN32
  33
  34 #include "Win32/DynamicLibrary.inc"
  35
  36 #else
  37
  38 #include "ltdl.h"
  39 #include <cassert>
  40 using namespace llvm;
  41 using namespace llvm::sys;
  42
  43 //===----------------------------------------------------------------------===//
  44 //=== WARNING: Implementation here must contain only TRULY operating system
  45 //===          independent code.
  46 //===----------------------------------------------------------------------===//
  47
  48 static inline void check_ltdl_initialization() {
  49   static bool did_initialize_ltdl = false;
  50   if (!did_initialize_ltdl) {
  51     int Err = lt_dlinit();
  52     Err = Err; // Silence warning.
  53     assert(0 == Err && "Can't init the ltdl library");
  54     did_initialize_ltdl = true;
  55   }
  56 }
  57
  58 static std::vector<lt_dlhandle> OpenedHandles;
  59
  60 DynamicLibrary::DynamicLibrary() : handle(0) {
  61   check_ltdl_initialization();
  62
  63   lt_dlhandle a_handle = lt_dlopen(0);
  64
  65   assert(a_handle == 0 || "Can't open program as dynamic library");
  66
  67   handle = a_handle;
  68   OpenedHandles.push_back(a_handle);
  69 }
  70
  71 /*
  72 DynamicLibrary::DynamicLibrary(const char*filename) : handle(0) {
  73   check_ltdl_initialization();
  74
  75   lt_dlhandle a_handle = lt_dlopen(filename);
  76
  77   if (a_handle == 0)
  78     a_handle = lt_dlopenext(filename);
  79
  80   if (a_handle == 0)
  81     throw std::string("Can't open :") + filename + ": " + lt_dlerror();
  82
  83   handle = a_handle;
  84   OpenedHandles.push_back(a_handle);
  85 }
  86 */
  87
  88 DynamicLibrary::~DynamicLibrary() {
  89   lt_dlhandle a_handle = (lt_dlhandle) handle;
  90   if (a_handle) {
  91     lt_dlclose(a_handle);
  92
  93     for (std::vector<lt_dlhandle>::iterator I = OpenedHandles.begin(),
  94          E = OpenedHandles.end(); I != E; ++I) {
  95       if (*I == a_handle) {
  96         // Note: don't use the swap/pop_back trick here. Order is important.
  97         OpenedHandles.erase(I);
  98         return;
  99       }
 100     }
 101   }
 102 }
 103
 104 bool DynamicLibrary::LoadLibraryPermanently(const char *Filename,
 105                                             std::string *ErrMsg) {
 106   check_ltdl_initialization();
 107   lt_dlhandle a_handle = lt_dlopen(Filename);
 108
 109   if (a_handle == 0)
 110     a_handle = lt_dlopenext(Filename);
 111
 112   if (a_handle == 0) {
 113     if (ErrMsg)
 114       *ErrMsg = std::string("Can't open :") +
 115           (Filename ? Filename : "<current process>") + ": " + lt_dlerror();
 116     return true;
 117   }
 118
 119   lt_dlmakeresident(a_handle);
 120
 121   OpenedHandles.push_back(a_handle);
 122   return false;
 123 }
 124
 125 void* DynamicLibrary::SearchForAddressOfSymbol(const char* symbolName) {
 126   check_ltdl_initialization();
 127
 128   // First check symbols added via AddSymbol().
 129   std::map<std::string, void *>::iterator I = g_symbols.find(symbolName);
 130   if (I != g_symbols.end())
 131     return I->second;
 132
 133   // Now search the libraries.
 134   for (std::vector<lt_dlhandle>::iterator I = OpenedHandles.begin(),
 135        E = OpenedHandles.end(); I != E; ++I) {
 136     lt_ptr ptr = lt_dlsym(*I, symbolName);
 137     if (ptr)
 138       return ptr;
 139   }
 140
 141   // If this is darwin, it has some funky issues, try to solve them here.  Some
 142   // important symbols are marked 'private external' which doesn't allow
 143   // SearchForAddressOfSymbol to find them.  As such, we special case them here,
 144   // there is only a small handful of them.
 145
 146 #ifdef __APPLE__
 147 #define EXPLICIT_SYMBOL(SYM) \
 148    extern void *SYM; if (!strcmp(symbolName, #SYM)) return &SYM
 149   {
 150     EXPLICIT_SYMBOL(__ashldi3);
 151     EXPLICIT_SYMBOL(__ashrdi3);
 152     EXPLICIT_SYMBOL(__cmpdi2);
 153     EXPLICIT_SYMBOL(__divdi3);
 154     EXPLICIT_SYMBOL(__eprintf);
 155     EXPLICIT_SYMBOL(__fixdfdi);
 156     EXPLICIT_SYMBOL(__fixsfdi);
 157     EXPLICIT_SYMBOL(__fixunsdfdi);
 158     EXPLICIT_SYMBOL(__fixunssfdi);
 159     EXPLICIT_SYMBOL(__floatdidf);
 160     EXPLICIT_SYMBOL(__floatdisf);
 161     EXPLICIT_SYMBOL(__lshrdi3);
 162     EXPLICIT_SYMBOL(__moddi3);
 163     EXPLICIT_SYMBOL(__udivdi3);
 164     EXPLICIT_SYMBOL(__umoddi3);
 165   }
 166 #undef EXPLICIT_SYMBOL
 167 #endif
 168
 169 // This macro returns the address of a well-known, explicit symbol
 170 #define EXPLICIT_SYMBOL(SYM) \
 171    if (!strcmp(symbolName, #SYM)) return &SYM
 172
 173 // On linux we have a weird situation. The stderr/out/in symbols are both
 174 // macros and global variables because of standards requirements. So, we
 175 // boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
 176 #if defined(__linux__)
 177   {
 178     EXPLICIT_SYMBOL(stderr);
 179     EXPLICIT_SYMBOL(stdout);
 180     EXPLICIT_SYMBOL(stdin);
 181   }
 182 #else
 183   // For everything else, we want to check to make sure the symbol isn't defined
 184   // as a macro before using EXPLICIT_SYMBOL.
 185   {
 186 #ifndef stdin
 187     EXPLICIT_SYMBOL(stdin);
 188 #endif
 189 #ifndef stdout
 190     EXPLICIT_SYMBOL(stdout);
 191 #endif
 192 #ifndef stderr
 193     EXPLICIT_SYMBOL(stderr);
 194 #endif
 195   }
 196 #endif
 197 #undef EXPLICIT_SYMBOL
 198
 199   return 0;
 200 }
 201
 202 void *DynamicLibrary::GetAddressOfSymbol(const char *symbolName) {
 203   assert(handle != 0 && "Invalid DynamicLibrary handle");
 204   return lt_dlsym((lt_dlhandle) handle, symbolName);
 205 }
 206
 207 #endif // LLVM_ON_WIN32
 208
 209 DEFINING_FILE_FOR(SystemDynamicLibrary)