src/LoadableModule.cc

   1 /*
   2  * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #include "squid.h"
  10 #include "base/TextException.h"
  11 #include "libltdl/ltdl.h" /* generated file */
  12 #include "LoadableModule.h"
  13
  14 // Note: We must use preprocessor instead of C ifs because if dlopen()
  15 // is seen by the static linker, the linker will complain.
  16
  17 LoadableModule::LoadableModule(const SBuf &aName):
  18     theName(aName)
  19 {
  20     // Initialise preloaded symbol lookup table.
  21     LTDL_SET_PRELOADED_SYMBOLS();
  22     if (lt_dlinit() != 0)
  23         throw TexcHere("internal error: cannot initialize libtool module loader");
  24 }
  25
  26 LoadableModule::~LoadableModule()
  27 {
  28     if (loaded())
  29         unload();
  30     assert(lt_dlexit() == 0); // XXX: replace with a warning
  31 }
  32
  33 bool
  34 LoadableModule::loaded() const
  35 {
  36     return theHandle != nullptr;
  37 }
  38
  39 void
  40 LoadableModule::load()
  41 {
  42     if (loaded())
  43         throw TexcHere("internal error: reusing LoadableModule object");
  44
  45     theHandle = openModule();
  46
  47     if (!loaded())
  48         throw TexcHere(errorMsg());
  49 }
  50
  51 void
  52 LoadableModule::unload()
  53 {
  54     if (!loaded())
  55         throw TexcHere("internal error: unloading not loaded module");
  56
  57     if (!closeModule())
  58         throw TexcHere(errorMsg());
  59
  60     theHandle = nullptr;
  61 }
  62
  63 void *
  64 LoadableModule::openModule()
  65 {
  66     return lt_dlopen(theName.c_str());
  67 }
  68
  69 bool
  70 LoadableModule::closeModule()
  71 {
  72     // we cast to avoid including ltdl.h in LoadableModule.h
  73     return lt_dlclose(static_cast<lt_dlhandle>(theHandle)) == 0;
  74 }
  75
  76 const char *
  77 LoadableModule::errorMsg()
  78 {
  79     return lt_dlerror();
  80 }
  81