Dogcows Code - chaz/yoink/blob - src/stlplus/portability/dynaload.cpp

   1 ////////////////////////////////////////////////////////////////////////////////
   2
   3 //   Author:    Andy Rushton
   4 //   Copyright: (c) Southampton University 1999-2004
   5 //              (c) Andy Rushton           2004 onwards
   6 //   License:   BSD License, see ../docs/license.html
   7
   8 ////////////////////////////////////////////////////////////////////////////////
   9 #include "dynaload.hpp"
  10
  11 #ifdef MSWINDOWS
  12 #include <windows.h>
  13 #else
  14 #include <dlfcn.h>
  15 #endif
  16
  17 ////////////////////////////////////////////////////////////////////////////////
  18
  19 #ifdef MSWINDOWS
  20
  21 static std::string last_error(void)
  22 {
  23   // get the last error code - if none, return the empty string
  24   DWORD err = GetLastError();
  25   if (err == 0) return std::string();
  26   // get the system message for this error code
  27   char* message;
  28   FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
  29                 0,
  30                 err,
  31                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
  32                 (LPTSTR)&message,
  33                 0,0);
  34   std::string result = message;
  35   LocalFree(message);
  36   // the error message is for some perverse reason newline terminated - remove this
  37   if (result[result.size()-1] == '\n')
  38     result.erase(result.end()-1);
  39   if (result[result.size()-1] == '\r')
  40     result.erase(result.end()-1);
  41   return result;
  42 }
  43
  44 #else
  45
  46 static std::string last_error(void)
  47 {
  48   return std::string(dlerror());
  49 }
  50
  51 #endif
  52
  53 ////////////////////////////////////////////////////////////////////////////////
  54
  55 namespace stlplus
  56 {
  57
  58   ////////////////////////////////////////////////////////////////////////////////
  59   // library management
  60
  61   // construct the object but do not load
  62   dynaload::dynaload(void) : m_handle(0)
  63   {
  64   }
  65
  66   // construct and load
  67   dynaload::dynaload(const std::string& library) : m_handle(0)
  68   {
  69     load(library);
  70   }
  71
  72   // destroy and unload if loaded
  73   dynaload::~dynaload(void)
  74   {
  75     unload();
  76   }
  77
  78   // load the library - return success or fail
  79   bool dynaload::load(const std::string& library)
  80   {
  81 #ifdef MSWINDOWS
  82     m_handle = (void*)LoadLibraryA(library.c_str());
  83 #elif defined(CYGWIN)
  84     m_handle = dlopen(library.c_str(),RTLD_NOW);
  85 #else
  86     std::string full_library = std::string("lib") + library + std::string(".so");
  87     m_handle = dlopen(full_library.c_str(),RTLD_NOW);
  88 #endif
  89     if (!m_handle)
  90     {
  91       m_error = load_error;
  92       m_text = last_error();
  93     }
  94     return loaded();
  95   }
  96
  97   // unload the library if loaded
  98   bool dynaload::unload(void)
  99   {
 100     if (!loaded()) return false;
 101 #ifdef MSWINDOWS
 102     int status = FreeLibrary((HINSTANCE)m_handle) ? 0 : 1;
 103 #else
 104     int status = dlclose(m_handle);
 105 #endif
 106     if (status != 0)
 107     {
 108       m_error = unload_error;
 109       m_text = last_error();
 110     }
 111     return status == 0;
 112   }
 113
 114   // test whether the library is loaded
 115   bool dynaload::loaded(void) const
 116   {
 117     return m_handle != 0;
 118   }
 119
 120   ////////////////////////////////////////////////////////////////////////////
 121   // symbol management
 122
 123   // test whether a function is exported by the library
 124   // does not set the error flag if fails
 125   bool dynaload::present(const std::string& name)
 126   {
 127     if (!loaded()) return false;
 128 #ifdef MSWINDOWS
 129     void* fn = (void*)GetProcAddress((HINSTANCE)m_handle,name.c_str());
 130 #else
 131     void* fn = dlsym(m_handle,name.c_str());
 132 #endif
 133     return fn != 0;
 134   }
 135
 136   // get the function as a generic pointer
 137   void* dynaload::symbol(const std::string& name)
 138   {
 139     if (!loaded()) return 0;
 140 #ifdef MSWINDOWS
 141     void* fn = (void*)GetProcAddress((HINSTANCE)m_handle,name.c_str());
 142 #else
 143     void* fn = dlsym(m_handle,name.c_str());
 144 #endif
 145     if (!fn)
 146     {
 147       m_error = symbol_error;
 148       m_text = last_error();
 149     }
 150     return fn;
 151   }
 152
 153   ////////////////////////////////////////////////////////////////////////////
 154   // error management
 155
 156   // test whether there has been an error
 157   bool dynaload::error(void) const
 158   {
 159     return m_error != no_error;
 160   }
 161
 162   // clear an error once it has been handled (or ignored)
 163   void dynaload::clear_error(void)
 164   {
 165     m_error = no_error;
 166     m_text = std::string();
 167   }
 168
 169   // get the type of the error as indicated by the enum error_t
 170   dynaload::error_t dynaload::error_type(void) const
 171   {
 172     return m_error;
 173   }
 174
 175   // get the text of the error as provided by the OS
 176   std::string dynaload::error_text(void) const
 177   {
 178     return m_text;
 179   }
 180
 181
 182 ////////////////////////////////////////////////////////////////////////////////
 183
 184 } // end namespace stlplus