gecko-dev/mozglue/linker/Mappable.h

275 lines
7.7 KiB
C++

/* 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, with a few differences:
* - mapped memory is always MAP_PRIVATE, even though a given implementation
* may use something different internally.
* - memory after length and up to the end of the corresponding page is nulled
* out.
*/
class Mappable
{
public:
virtual ~Mappable() { }
virtual void *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 void *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);
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 void *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 void *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. */
size_t chunkAvailNum;
/* Mutex protecting decompression */
pthread_mutex_t mutex;
};
#endif /* Mappable_h */