dlSharedLibrary.cpp

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#include "blocxx/BLOCXX_config.h"
#if defined(BLOCXX_USE_DL)
#include "blocxx/dlSharedLibrary.hpp"
#include "blocxx/Format.hpp"
#include "blocxx/Mutex.hpp"
#include "blocxx/MutexLock.hpp"
#include "blocxx/GlobalMutex.hpp"
#include <dlfcn.h>
#ifdef BLOCXX_HAVE_FCNTL_H
// For O_RDONLY
#include <fcntl.h>
#endif

#include "blocxx/Types.hpp"

#if defined(BLOCXX_USE_FAKE_LIBS)
#include "blocxx/FileSystem.hpp"
#include "blocxx/File.hpp"
#include "blocxx/Array.hpp"

#define BLOCXX_FAKELIB_HEADING "FAKE"
#define BLOCXX_FAKELIB_HEADING_LENGTH 4

#endif

#include <iostream>

namespace BLOCXX_NAMESPACE
{

// static
bool dlSharedLibrary::s_call_dlclose = true;

GlobalMutex dlSharedLibrary_guard = BLOCXX_GLOBAL_MUTEX_INIT();

dlSharedLibrary::dlSharedLibrary(void * libhandle, const String& libName)
   : SharedLibrary(), m_libhandle( libhandle ), m_libName(libName)
{
#if defined(BLOCXX_USE_FAKE_LIBS)
   // Find out if it is a fake library.
   m_fakeLibrary = dlSharedLibrary::isFakeLibrary(libName);

   if ( m_fakeLibrary )
   {
      initializeSymbolMap();
   }
#endif /* defined(BLOCXX_USE_FAKE_LIBS) */
}
  
dlSharedLibrary::~dlSharedLibrary()
{
#if !defined(BLOCXX_VALGRIND_SUPPORT) // dlclose()ing shared libs make it impossible to see where memory leaks occurred with valgrind.
   if (s_call_dlclose)
   {
      dlclose( m_libhandle );
   }
#endif
}
bool dlSharedLibrary::doGetFunctionPointer(const String& functionName,
      void** fp) const
{
   MutexLock l(dlSharedLibrary_guard);
#if defined(BLOCXX_USE_FAKE_LIBS)
   String realFunctionName = functionName;
   // If this is a fake library, extract convert the requested function
   // name into the proper function name for the main executable.
   if ( m_fakeLibrary )
   {
      Map<String,String>::const_iterator symIter = m_symbolMap.find(functionName);
      if ( symIter == m_symbolMap.end() )
      {
         return false;
      }
      realFunctionName = symIter->second;
   }
   *fp = dlsym( m_libhandle, realFunctionName.c_str() );
#else
   *fp = dlsym( m_libhandle, functionName.c_str() );
#endif /* defined(BLOCXX_USE_FAKE_LIBS) */
     
   if (!*fp)
   {
      return false;
   }
   return true;
}

bool dlSharedLibrary::isFakeLibrary(const String& library_path)
{
   bool fake = false;
#if defined(BLOCXX_USE_FAKE_LIBS)
   if ( FileSystem::canRead(library_path) )
   {
      // Read the beginning of the file and see if it
      // contains the fake library heading.
      int libfd = open(library_path.c_str(), O_RDONLY);

      if ( libfd )
      {
         char buffer[(BLOCXX_FAKELIB_HEADING_LENGTH) + 1];
         size_t num_read = read(libfd, buffer,(BLOCXX_FAKELIB_HEADING_LENGTH));
         if ( num_read == (BLOCXX_FAKELIB_HEADING_LENGTH) )
         {
            // Null terminate it.
            buffer[BLOCXX_FAKELIB_HEADING_LENGTH] = '\0';
            if ( String(BLOCXX_FAKELIB_HEADING) == buffer )
            {
               // Yes, it's a fake library.
               fake = true;
            }
         }
         close(libfd);
      }
   }
#endif
   return fake;
}

#if defined(BLOCXX_USE_FAKE_LIBS)
void dlSharedLibrary::initializeSymbolMap()
{
   if ( ! m_fakeLibrary )
   {
      return;
   }
   // Read the contents of the file to find out what the function names
   // (normally available from dlsym) are mapped to functions in the main
   // program. 
   StringArray lines = FileSystem::getFileLines(m_libName);

   for ( StringArray::const_iterator iter = lines.begin();
      iter != lines.end();
      ++iter )
   {
      // Skip commented lines.  
      if ( iter->startsWith('#') )
      {
         continue;
      }
      StringArray current_line = iter->tokenize("=");
      // Skip invalid lines.
      if ( current_line.size() != 2 )
      {
         continue;
      }
      // Add the data into the map.
      String option = String(current_line[0]).trim();
      String value = String(current_line[1]).trim();
      m_symbolMap[option] = value;
   }      
}
#endif /* defined(BLOCXX_USE_FAKE_LIBS) */

} // end namespace BLOCXX_NAMESPACE

#endif