mozglue/baseprofiler/lul/AutoObjectMapper.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   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 #ifndef AutoObjectMapper_h
   8 #define AutoObjectMapper_h
   9
  10 #include <string>
  11
  12 #include "mozilla/Attributes.h"
  13 #include "PlatformMacros.h"
  14
  15 // A (nearly-) RAII class that maps an object in and then unmaps it on
  16 // destruction.  This base class version uses the "normal" POSIX
  17 // functions: open, fstat, close, mmap, munmap.
  18
  19 class MOZ_STACK_CLASS AutoObjectMapperPOSIX {
  20  public:
  21   // The constructor does not attempt to map the file, because that
  22   // might fail.  Instead, once the object has been constructed,
  23   // call Map() to attempt the mapping.  There is no corresponding
  24   // Unmap() since the unmapping is done in the destructor.  Failure
  25   // messages are sent to |aLog|.
  26   explicit AutoObjectMapperPOSIX(void (*aLog)(const char*));
  27
  28   // Unmap the file on destruction of this object.
  29   ~AutoObjectMapperPOSIX();
  30
  31   // Map |fileName| into the address space and return the mapping
  32   // extents.  If the file is zero sized this will fail.  The file is
  33   // mapped read-only and private.  Returns true iff the mapping
  34   // succeeded, in which case *start and *length hold its extent.
  35   // Once a call to Map succeeds, all subsequent calls to it will
  36   // fail.
  37   bool Map(/*OUT*/ void** start, /*OUT*/ size_t* length, std::string fileName);
  38
  39  protected:
  40   // If we are currently holding a mapped object, these record the
  41   // mapped address range.
  42   void* mImage;
  43   size_t mSize;
  44
  45   // A logging sink, for complaining about mapping failures.
  46   void (*mLog)(const char*);
  47
  48  private:
  49   // Are we currently holding a mapped object?  This is private to
  50   // the base class.  Derived classes need to have their own way to
  51   // track whether they are holding a mapped object.
  52   bool mIsMapped;
  53
  54   // Disable copying and assignment.
  55   AutoObjectMapperPOSIX(const AutoObjectMapperPOSIX&);
  56   AutoObjectMapperPOSIX& operator=(const AutoObjectMapperPOSIX&);
  57   // Disable heap allocation of this class.
  58   void* operator new(size_t);
  59   void* operator new[](size_t);
  60   void operator delete(void*);
  61   void operator delete[](void*);
  62 };
  63
  64 #endif  // AutoObjectMapper_h