The Tor Browser: mozglue/linker/Mappable.h@b8a032363ba2 (annotated)

mozglue/linker/Mappable.h@b8a032363ba2 (annotated)

mozglue/linker/Mappable.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef Mappable_h
 #define Mappable_h
 #include <sys/types.h>
 #include <pthread.h>
 #include "Zip.h"
 #include "SeekableZStream.h"
 #include "mozilla/RefPtr.h"
 #include "mozilla/Scoped.h"
 #include "zlib.h"
 /**
  * Abstract class to handle mmap()ing from various kind of entities, such as
  * plain files or Zip entries. The virtual members are meant to act as the
  * equivalent system functions, except mapped memory is always MAP_PRIVATE,
  * even though a given implementation may use something different internally.
  */
 class Mappable: public mozilla::RefCounted<Mappable>
 {
 public:
   MOZ_DECLARE_REFCOUNTED_TYPENAME(Mappable)
   virtual ~Mappable() { }
   virtual MemoryRange mmap(const void *addr, size_t length, int prot, int flags,
                            off_t offset) = 0;
   enum Kind {
     MAPPABLE_FILE,
     MAPPABLE_EXTRACT_FILE,
     MAPPABLE_DEFLATE,
     MAPPABLE_SEEKABLE_ZSTREAM
   };
   virtual Kind GetKind() const = 0;
 private:
   virtual void munmap(void *addr, size_t length) {
     ::munmap(addr, length);
   }
   /* Limit use of Mappable::munmap to classes that keep track of the address
    * and size of the mapping. This allows to ignore ::munmap return value. */
   friend class Mappable1stPagePtr;
   friend class LibHandle;
 public:
   /**
    * Ensures the availability of the memory pages for the page(s) containing
    * the given address. Returns whether the pages were successfully made
    * available.
    */
   virtual bool ensure(const void *addr) { return true; }
   /**
    * Indicate to a Mappable instance that no further mmap is going to happen.
    */
   virtual void finalize() = 0;
   /**
    * Shows some stats about the Mappable instance.
    * Meant for MappableSeekableZStream only.
    * As Mappables don't keep track of what they are instanciated for, the name
    * argument is used to make the stats logging useful to the reader. The when
    * argument is to be used by the caller to give an identifier of the when
    * the stats call is made.
    */
   virtual void stats(const char *when, const char *name) const { }
   /**
    * Returns the maximum length that can be mapped from this Mappable for
    * offset = 0.
    */
   virtual size_t GetLength() const = 0;
 };
 /**
  * Mappable implementation for plain files
  */
 class MappableFile: public Mappable
 {
 public:
   ~MappableFile() { }
   /**
    * Create a MappableFile instance for the given file path.
    */
   static Mappable *Create(const char *path);
   /* Inherited from Mappable */
   virtual MemoryRange mmap(const void *addr, size_t length, int prot, int flags, off_t offset);
   virtual void finalize();
   virtual size_t GetLength() const;
   virtual Kind GetKind() const { return MAPPABLE_FILE; };
 protected:
   MappableFile(int fd): fd(fd) { }
 private:
   /* File descriptor */
   AutoCloseFD fd;
 };
 /**
  * Mappable implementation for deflated stream in a Zip archive
  * Inflates the complete stream into a cache file.
  */
 class MappableExtractFile: public MappableFile
 {
 public:
   ~MappableExtractFile();
   /**
    * Create a MappableExtractFile instance for the given Zip stream. The name
    * argument is used to create the cache file in the cache directory.
    */
   static Mappable *Create(const char *name, Zip *zip, Zip::Stream *stream);
   /* Override finalize from MappableFile */
   virtual void finalize() {}
   virtual Kind GetKind() const { return MAPPABLE_EXTRACT_FILE; };
 private:
   MappableExtractFile(int fd, char *path)
   : MappableFile(fd), path(path), pid(getpid()) { }
   /**
    * AutoUnlinkFile keeps track or a file name and removes (unlinks) the file
    * when the instance is destroyed.
    */
   struct AutoUnlinkFileTraits: public mozilla::ScopedDeleteArrayTraits<char>
   {
     static void release(char *value)
     {
       if (!value)
         return;
       unlink(value);
       mozilla::ScopedDeleteArrayTraits<char>::release(value);
     }
   };
   typedef mozilla::Scoped<AutoUnlinkFileTraits> AutoUnlinkFile;
   /* Extracted file */
   AutoUnlinkFile path;
   /* Id of the process that initialized the instance */
   pid_t pid;
 };
 class _MappableBuffer;
 /**
  * Mappable implementation for deflated stream in a Zip archive.
  * Inflates the mapped bits in a temporary buffer.
  */
 class MappableDeflate: public Mappable
 {
 public:
   ~MappableDeflate();
   /**
    * Create a MappableDeflate instance for the given Zip stream. The name
    * argument is used for an appropriately named temporary file, and the Zip
    * instance is given for the MappableDeflate to keep a reference of it.
    */
   static Mappable *Create(const char *name, Zip *zip, Zip::Stream *stream);
   /* Inherited from Mappable */
   virtual MemoryRange mmap(const void *addr, size_t length, int prot, int flags, off_t offset);
   virtual void finalize();
   virtual size_t GetLength() const;
   virtual Kind GetKind() const { return MAPPABLE_DEFLATE; };
 private:
   MappableDeflate(_MappableBuffer *buf, Zip *zip, Zip::Stream *stream);
   /* Zip reference */
   mozilla::RefPtr<Zip> zip;
   /* Decompression buffer */
   mozilla::ScopedDeletePtr<_MappableBuffer> buffer;
   /* Zlib data */
   z_stream zStream;
 };
 /**
  * Mappable implementation for seekable zStreams.
  * Inflates the mapped bits in a temporary buffer, on demand.
  */
 class MappableSeekableZStream: public Mappable
 {
 public:
   ~MappableSeekableZStream();
   /**
    * Create a MappableSeekableZStream instance for the given Zip stream. The
    * name argument is used for an appropriately named temporary file, and the
    * Zip instance is given for the MappableSeekableZStream to keep a reference
    * of it.
    */
   static Mappable *Create(const char *name, Zip *zip,
                                          Zip::Stream *stream);
   /* Inherited from Mappable */
   virtual MemoryRange mmap(const void *addr, size_t length, int prot, int flags, off_t offset);
   virtual void munmap(void *addr, size_t length);
   virtual void finalize();
   virtual bool ensure(const void *addr);
   virtual void stats(const char *when, const char *name) const;
   virtual size_t GetLength() const;
   virtual Kind GetKind() const { return MAPPABLE_SEEKABLE_ZSTREAM; };
 private:
   MappableSeekableZStream(Zip *zip);
   /* Zip reference */
   mozilla::RefPtr<Zip> zip;
   /* Decompression buffer */
   mozilla::ScopedDeletePtr<_MappableBuffer> buffer;
   /* Seekable ZStream */
   SeekableZStream zStream;
   /* Keep track of mappings performed with MappableSeekableZStream::mmap so
    * that they can be realized by MappableSeekableZStream::ensure.
    * Values stored in the struct are those passed to mmap */
   struct LazyMap
   {
     const void *addr;
     size_t length;
     int prot;
     off_t offset;
     /* Returns addr + length, as a pointer */
     const void *end() const {
       return reinterpret_cast<const void *>
              (reinterpret_cast<const unsigned char *>(addr) + length);
     }
     /* Returns offset + length */
     const off_t endOffset() const {
       return offset + length;
     }
     /* Returns the offset corresponding to the given address */
     const off_t offsetOf(const void *ptr) const {
       return reinterpret_cast<uintptr_t>(ptr)
              - reinterpret_cast<uintptr_t>(addr) + offset;
     }
     /* Returns whether the given address is in the LazyMap range */
     const bool Contains(const void *ptr) const {
       return (ptr >= addr) && (ptr < end());
     }
   };
   /* List of all mappings */
   std::vector<LazyMap> lazyMaps;
   /* Array keeping track of which chunks have already been decompressed.
    * Each value is the number of pages decompressed for the given chunk. */
   mozilla::ScopedDeleteArray<unsigned char> chunkAvail;
   /* Number of chunks that have already been decompressed. */
   mozilla::Atomic<size_t> chunkAvailNum;
   /* Mutex protecting decompression */
   pthread_mutex_t mutex;
 };
 #endif /* Mappable_h */

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mozglue/linker/Mappable.h@b8a032363ba2 (annotated)

mozglue/linker/Mappable.h