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 "mozilla/Logging.h"
  12 #include "prlink.h"
  13
  14 #ifdef CUPS_SHIM_RUNTIME_LINK
  15
  16 mozilla::LazyLogModule gCupsLinkLog("CupsLink");
  17
  18 #  define DEBUG_LOG(...) \
  19     MOZ_LOG(gCupsLinkLog, mozilla::LogLevel::Debug, (__VA_ARGS__))
  20
  21 // TODO: This is currently pointless as we always use the compile-time linked
  22 // version of CUPS, but in the future this may become a configure option.
  23 // We also cannot use NSPR's library suffix support, since that cannot handle
  24 // version number suffixes.
  25 #  ifdef XP_MACOSX
  26 static const char gCUPSLibraryName[] = "libcups.2.dylib";
  27 #  else
  28 static const char gCUPSLibraryName[] = "libcups.so.2";
  29 #  endif
  30
  31 static bool LoadCupsFunc(PRLibrary* aLib, void** aDest, const char* const aName,
  32                          nsCUPSShim::Optional aOptional) {
  33   *aDest = PR_FindSymbol(aLib, aName);
  34   if (!*aDest) {
  35     DEBUG_LOG("%s not found in CUPS library", aName);
  36     return bool(aOptional);
  37   }
  38   return true;
  39 }
  40
  41 nsCUPSShim::nsCUPSShim() {
  42   mCupsLib = PR_LoadLibrary(gCUPSLibraryName);
  43   if (!mCupsLib) {
  44     DEBUG_LOG("CUPS library not found");
  45     return;
  46   }
  47
  48   bool success = true;
  49
  50   // This is a macro so that it could also load from libcups if we are
  51   // configured to use it as a compile-time dependency.
  52   //
  53   // We try to load all functions even if some fail so that we get the debug log
  54   // unconditionally.
  55 #  define CUPS_SHIM_LOAD(opt_, fn_) \
  56     success |=                      \
  57         LoadCupsFunc(mCupsLib, reinterpret_cast<void**>(&fn_), #fn_, opt_);
  58   CUPS_SHIM_ALL_FUNCS(CUPS_SHIM_LOAD)
  59 #  undef CUPS_SHIM_LOAD
  60
  61   if (!success) {
  62 #  ifndef MOZ_TSAN
  63     // With TSan, we cannot unload libcups once we have loaded it because
  64     // TSan does not support unloading libraries that are matched from its
  65     // suppression list. Hence we just keep the library loaded in TSan builds.
  66     PR_UnloadLibrary(mCupsLib);
  67 #  endif
  68     mCupsLib = nullptr;
  69     return;
  70   }
  71
  72   // Set mInitOkay only if all cups functions are loaded successfully.
  73   mInitOkay = true;
  74 }
  75
  76 #endif