mozglue/linker/Zip.h
author Jim Blandy <jimb@mozilla.com>
Tue, 24 Jun 2014 22:12:07 -0700
changeset 199513 69d61e42d5dfbf4588b72449249ff3e7f2125304
parent 188626 4cb70de5fd6aea678aa5985a1eb92d4af1eab153
child 213895 3554e60ef779185b7a5725bbed120e8b47c755c2
permissions -rw-r--r--
Bug 914753: Make Emacs file variable header lines correct, or at least consistent. DONTBUILD r=ehsan The -*- file variable lines -*- establish per-file settings that Emacs will pick up. This patch makes the following changes to those lines (and touches nothing else): - Never set the buffer's mode. Years ago, Emacs did not have a good JavaScript mode, so it made sense to use Java or C++ mode in .js files. However, Emacs has had js-mode for years now; it's perfectly serviceable, and is available and enabled by default in all major Emacs packagings. Selecting a mode in the -*- file variable line -*- is almost always the wrong thing to do anyway. It overrides Emacs's default choice, which is (now) reasonable; and even worse, it overrides settings the user might have made in their '.emacs' file for that file extension. It's only useful when there's something specific about that particular file that makes a particular mode appropriate. - Correctly propagate settings that establish the correct indentation level for this file: c-basic-offset and js2-basic-offset should be js-indent-level. Whatever value they're given should be preserved; different parts of our tree use different indentation styles. - We don't use tabs in Mozilla JS code. Always set indent-tabs-mode: nil. Remove tab-width: settings, at least in files that don't contain tab characters. - Remove js2-mode settings that belong in the user's .emacs file, like js2-skip-preprocessor-directives.

/* 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 Zip_h
#define Zip_h

#include <cstring>
#include <stdint.h>
#include <vector>
#include <zlib.h>
#include "Utils.h"
#include "mozilla/RefPtr.h"

/**
 * Forward declaration
 */
class ZipCollection;

/**
 * Class to handle access to Zip archive streams. The Zip archive is mapped
 * in memory, and streams are direct references to that mapped memory.
 * Zip files are assumed to be correctly formed. No boundary checks are
 * performed, which means hand-crafted malicious Zip archives can make the
 * code fail in bad ways. However, since the only intended use is to load
 * libraries from Zip archives, there is no interest in making this code
 * safe, since the libraries could contain malicious code anyways.
 */
class Zip: public mozilla::external::AtomicRefCounted<Zip>
{
public:
  MOZ_DECLARE_REFCOUNTED_TYPENAME(Zip)
  /**
   * Create a Zip instance for the given file name. Returns nullptr in case
   * of failure.
   */
  static mozilla::TemporaryRef<Zip> Create(const char *filename);

  /**
   * Create a Zip instance using the given buffer.
   */
  static mozilla::TemporaryRef<Zip> Create(void *buffer, size_t size) {
    return Create(nullptr, buffer, size);
  }

private:
  static mozilla::TemporaryRef<Zip> Create(const char *filename,
                                           void *buffer, size_t size);

  /**
   * Private constructor
   */
  Zip(const char *filename, void *buffer, size_t size);

public:
  /**
   * Destructor
   */
  ~Zip();

  /**
   * Class used to access Zip archive item streams
   */
  class Stream
  {
  public:
    /**
     * Stream types
     */
    enum Type {
      STORE = 0,
      DEFLATE = 8
    };

    /**
     * Constructor
     */
    Stream(): compressedBuf(nullptr), compressedSize(0), uncompressedSize(0)
            , type(STORE) { }

    /**
     * Getters
     */
    const void *GetBuffer() { return compressedBuf; }
    size_t GetSize() { return compressedSize; }
    size_t GetUncompressedSize() { return uncompressedSize; }
    Type GetType() { return type; }

    /**
     * Returns a z_stream for use with inflate functions using the given
     * buffer as inflate output. The caller is expected to allocate enough
     * memory for the Stream uncompressed size.
     */
    z_stream GetZStream(void *buf)
    {
      z_stream zStream;
      memset(&zStream, 0, sizeof(zStream));
      zStream.avail_in = compressedSize;
      zStream.next_in = reinterpret_cast<Bytef *>(
                        const_cast<void *>(compressedBuf));
      zStream.avail_out = uncompressedSize;
      zStream.next_out = static_cast<Bytef *>(buf);
      return zStream;
    }

  protected:
    friend class Zip;
    const void *compressedBuf;
    size_t compressedSize;
    size_t uncompressedSize;
    Type type;
  };

  /**
   * Returns a stream from the Zip archive.
   */
  bool GetStream(const char *path, Stream *out) const;

  /**
   * Returns the file name of the archive
   */
  const char *GetName() const
  {
    return name;
  }

private:
  /* File name of the archive */
  char *name;
  /* Address where the Zip archive is mapped */
  void *mapped;
  /* Size of the archive */
  size_t size;

  /**
   * Strings (file names, comments, etc.) in the Zip headers are NOT zero
   * terminated. This class is a helper around them.
   */
  class StringBuf
  {
  public:
    /**
     * Constructor
     */
    StringBuf(const char *buf, size_t length): buf(buf), length(length) { }

    /**
     * Returns whether the string has the same content as the given zero
     * terminated string.
     */
    bool Equals(const char *str) const
    {
      return strncmp(str, buf, length) == 0;
    }

  private:
    const char *buf;
    size_t length;
  };

/* All the following types need to be packed */
#pragma pack(1)
public:
  /**
   * A Zip archive is an aggregate of entities which all start with a
   * signature giving their type. This template is to be used as a base
   * class for these entities.
   */
  template <typename T>
  class SignedEntity
  {
  public:
    /**
     * Equivalent to reinterpret_cast<const T *>(buf), with an additional
     * check of the signature.
     */
    static const T *validate(const void *buf)
    {
      const T *ret = static_cast<const T *>(buf);
      if (ret->signature == T::magic)
        return ret;
      return nullptr;
    }

    SignedEntity(uint32_t magic): signature(magic) { }
  private:
    le_uint32 signature;
  };

private:
  /**
   * Header used to describe a Local File entry. The header is followed by
   * the file name and an extra field, then by the data stream.
   */
  struct LocalFile: public SignedEntity<LocalFile>
  {
    /* Signature for a Local File header */
    static const uint32_t magic = 0x04034b50;

    /**
     * Returns the file name
     */
    StringBuf GetName() const
    {
      return StringBuf(reinterpret_cast<const char *>(this) + sizeof(*this),
                       filenameSize);
    }

    /**
     * Returns a pointer to the data associated with this header
     */
    const void *GetData() const
    {
      return reinterpret_cast<const char *>(this) + sizeof(*this)
             + filenameSize + extraFieldSize;
    }
    
    le_uint16 minVersion;
    le_uint16 generalFlag;
    le_uint16 compression;
    le_uint16 lastModifiedTime;
    le_uint16 lastModifiedDate;
    le_uint32 CRC32;
    le_uint32 compressedSize;
    le_uint32 uncompressedSize;
    le_uint16 filenameSize;
    le_uint16 extraFieldSize;
  };

  /**
   * In some cases, when a zip archive is created, compressed size and CRC
   * are not known when writing the Local File header. In these cases, the
   * 3rd bit of the general flag in the Local File header is set, and there
   * is an additional header following the compressed data.
   */
  struct DataDescriptor: public SignedEntity<DataDescriptor>
  {
    /* Signature for a Data Descriptor header */
    static const uint32_t magic = 0x08074b50;

    le_uint32 CRC32;
    le_uint32 compressedSize;
    le_uint32 uncompressedSize;
  };

  /**
   * Header used to describe a Central Directory Entry. The header is
   * followed by the file name, an extra field, and a comment.
   */
  struct DirectoryEntry: public SignedEntity<DirectoryEntry>
  {
    /* Signature for a Central Directory Entry header */
    static const uint32_t magic = 0x02014b50;

    /**
     * Returns the file name
     */
    StringBuf GetName() const
    {
      return StringBuf(reinterpret_cast<const char *>(this) + sizeof(*this),
                       filenameSize);
    }

    /**
     * Returns  the Central Directory Entry following this one.
     */
    const DirectoryEntry *GetNext() const
    {
      return validate(reinterpret_cast<const char *>(this) + sizeof(*this)
                      + filenameSize + extraFieldSize + fileCommentSize);
    }

    le_uint16 creatorVersion;
    le_uint16 minVersion;
    le_uint16 generalFlag;
    le_uint16 compression;
    le_uint16 lastModifiedTime;
    le_uint16 lastModifiedDate;
    le_uint32 CRC32;
    le_uint32 compressedSize;
    le_uint32 uncompressedSize;
    le_uint16 filenameSize;
    le_uint16 extraFieldSize;
    le_uint16 fileCommentSize;
    le_uint16 diskNum;
    le_uint16 internalAttributes;
    le_uint32 externalAttributes;
    le_uint32 offset;
  };

  /**
   * Header used to describe the End of Central Directory Record.
   */
  struct CentralDirectoryEnd: public SignedEntity<CentralDirectoryEnd>
  {
    /* Signature for the End of Central Directory Record */
    static const uint32_t magic = 0x06054b50;

    le_uint16 diskNum;
    le_uint16 startDisk;
    le_uint16 recordsOnDisk;
    le_uint16 records;
    le_uint32 size;
    le_uint32 offset;
    le_uint16 commentSize;
  };
#pragma pack()

  /**
   * Returns the first Directory entry
   */
  const DirectoryEntry *GetFirstEntry() const;

  /* Pointer to the Local File Entry following the last one GetStream() used.
   * This is used by GetStream to avoid scanning the Directory Entries when the
   * requested entry is that one. */
  mutable const LocalFile *nextFile;

  /* Likewise for the next Directory entry */
  mutable const DirectoryEntry *nextDir;

  /* Pointer to the Directory entries */
  mutable const DirectoryEntry *entries;
};

/**
 * Class for bookkeeping Zip instances
 */
class ZipCollection
{
public:
  static ZipCollection Singleton;

  /**
   * Get a Zip instance for the given path. If there is an existing one
   * already, return that one, otherwise create a new one.
   */
  static mozilla::TemporaryRef<Zip> GetZip(const char *path);

protected:
  friend class Zip;
  /**
   * Register the given Zip instance. This method is meant to be called
   * by Zip::Create.
   */
  static void Register(Zip *zip);

  /**
   * Forget about the given Zip instance. This method is meant to be called
   * by the Zip destructor.
   */
  static void Forget(Zip *zip);

private:
  /* Zip instances bookkept in this collection */
  std::vector<Zip *> zips;
};

#endif /* Zip_h */