widget/nsCUPSShim.cpp

   1 /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* ex: set tabstop=8 softtabstop=2 shiftwidth=2 expandtab: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsDebug.h"
   8 #include "nsString.h"
   9 #include "nsCUPSShim.h"
  10 #include "mozilla/ArrayUtils.h"
  11 #include "prlink.h"
  12
  13 #ifdef CUPS_SHIM_RUNTIME_LINK
  14
  15 // TODO: This is currently pointless as we always use the compile-time linked
  16 // version of CUPS, but in the future this may become a configure option.
  17 // We also cannot use NSPR's library suffix support, since that cannot handle
  18 // version number suffixes.
  19 #  ifdef XP_MACOSX
  20 static const char gCUPSLibraryName[] = "libcups.2.dylib";
  21 #  else
  22 static const char gCUPSLibraryName[] = "libcups.so.2";
  23 #  endif
  24
  25 template <typename FuncT>
  26 static bool LoadCupsFunc(PRLibrary*& lib, FuncT*& dest,
  27                          const char* const name) {
  28   dest = (FuncT*)PR_FindSymbol(lib, name);
  29   if (MOZ_UNLIKELY(!dest)) {
  30 #  ifdef DEBUG
  31     nsAutoCString msg(name);
  32     msg.AppendLiteral(" not found in CUPS library");
  33     NS_WARNING(msg.get());
  34 #  endif
  35 #  ifndef MOZ_TSAN
  36     // With TSan, we cannot unload libcups once we have loaded it because
  37     // TSan does not support unloading libraries that are matched from its
  38     // suppression list. Hence we just keep the library loaded in TSan builds.
  39     PR_UnloadLibrary(lib);
  40 #  endif
  41     lib = nullptr;
  42     return false;
  43   }
  44   return true;
  45 }
  46
  47 bool nsCUPSShim::Init() {
  48   mozilla::OffTheBooksMutexAutoLock lock(mInitMutex);
  49   if (mInited) {
  50     return true;
  51   }
  52
  53   mCupsLib = PR_LoadLibrary(gCUPSLibraryName);
  54   if (!mCupsLib) {
  55     return false;
  56   }
  57
  58 // This is a macro so that it could also load from libcups if we are configured
  59 // to use it as a compile-time dependency.
  60 #  define CUPS_SHIM_LOAD(NAME) \
  61     if (!LoadCupsFunc(mCupsLib, NAME, #NAME)) return false;
  62   CUPS_SHIM_ALL_FUNCS(CUPS_SHIM_LOAD)
  63 #  undef CUPS_SHIM_LOAD
  64   mInited = true;
  65   return true;
  66 }
  67
  68 #else  // CUPS_SHIM_RUNTIME_LINK
  69
  70 bool nsCUPSShim::Init() {
  71   mInited = true;
  72   return true;
  73 }
  74
  75 #endif