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