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diff --git a/mozglue/linker/Zip.h b/mozglue/linker/Zip.h
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+/* 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 <pthread.h>
+#include "Utils.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/RefCounted.h"
+#include "mozilla/RefPtr.h"
+
+/**
+ * Helper class wrapping z_stream to avoid malloc() calls during
+ * inflate. Do not use for deflate.
+ * inflateInit allocates two buffers:
+ * - one for its internal state, which is "approximately 10K bytes" according
+ *   to inflate.h from zlib.
+ * - one for the compression window, which depends on the window size passed
+ *   to inflateInit2, but is never greater than 32K (1 << MAX_WBITS).
+ * Those buffers are created at instantiation time instead of when calling
+ * inflateInit2. When inflateInit2 is called, it will call zxx_stream::Alloc
+ * to get both these buffers. zxx_stream::Alloc will choose one of the
+ * pre-allocated buffers depending on the requested size.
+ */
+class zxx_stream: public z_stream
+{
+public:
+  /* Forward declaration */
+  class StaticAllocator;
+
+  explicit zxx_stream(StaticAllocator *allocator_=nullptr)
+  : allocator(allocator_)
+  {
+    memset(this, 0, sizeof(z_stream));
+    zalloc = Alloc;
+    zfree = Free;
+    opaque = this;
+  }
+
+private:
+  static void *Alloc(void *data, uInt items, uInt size)
+  {
+    zxx_stream *zStream = reinterpret_cast<zxx_stream *>(data);
+    if (zStream->allocator) {
+      return zStream->allocator->Alloc(items, size);
+    }
+    size_t buf_size = items * size;
+    return ::operator new(buf_size);
+  }
+
+  static void Free(void *data, void *ptr)
+  {
+    zxx_stream *zStream = reinterpret_cast<zxx_stream *>(data);
+    if (zStream->allocator) {
+      zStream->allocator->Free(ptr);
+    } else {
+      ::operator delete(ptr);
+    }
+  }
+
+  /**
+   * Helper class for each buffer in StaticAllocator.
+   */
+  template <size_t Size>
+  class ZStreamBuf
+  {
+  public:
+    ZStreamBuf() : inUse(false) { }
+
+    bool get(char*& out)
+    {
+      if (!inUse) {
+        inUse = true;
+        out = buf;
+        return true;
+      } else {
+        return false;
+      }
+    }
+
+    void Release()
+    {
+      memset(buf, 0, Size);
+      inUse = false;
+    }
+
+    bool Equals(const void *other) { return other == buf; }
+
+    static const size_t size = Size;
+
+  private:
+    char buf[Size];
+    bool inUse;
+  };
+
+public:
+  /**
+   * Special allocator that uses static buffers to allocate from.
+   */
+  class StaticAllocator
+  {
+  public:
+    void *Alloc(uInt items, uInt size)
+    {
+      if (items == 1 && size <= stateBuf1.size) {
+        char* res = nullptr;
+        if (stateBuf1.get(res) || stateBuf2.get(res)) {
+          return res;
+        }
+        MOZ_CRASH("ZStreamBuf already in use");
+      } else if (items * size == windowBuf1.size) {
+        char* res = nullptr;
+        if (windowBuf1.get(res) || windowBuf2.get(res)) {
+          return res;
+        }
+        MOZ_CRASH("ZStreamBuf already in use");
+      } else {
+        MOZ_CRASH("No ZStreamBuf for allocation");
+      }
+    }
+
+    void Free(void *ptr)
+    {
+      if (stateBuf1.Equals(ptr)) {
+        stateBuf1.Release();
+      } else if (stateBuf2.Equals(ptr)) {
+        stateBuf2.Release();
+      }else if (windowBuf1.Equals(ptr)) {
+        windowBuf1.Release();
+      } else if (windowBuf2.Equals(ptr)) {
+        windowBuf2.Release();
+      } else {
+        MOZ_CRASH("Pointer doesn't match a ZStreamBuf");
+      }
+    }
+
+    // 0x3000 is an arbitrary size above 10K.
+    ZStreamBuf<0x3000> stateBuf1, stateBuf2;
+    ZStreamBuf<1 << MAX_WBITS> windowBuf1, windowBuf2;
+  };
+
+private:
+  StaticAllocator *allocator;
+};
+
+/**
+ * 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 already_AddRefed<Zip> Create(const char *filename);
+
+  /**
+   * Create a Zip instance using the given buffer.
+   */
+  static already_AddRefed<Zip> Create(void *buffer, size_t size) {
+    return Create(nullptr, buffer, size);
+  }
+
+private:
+  static already_AddRefed<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)
+            , CRC32(0)
+            , type(STORE) { }
+
+    /**
+     * Getters
+     */
+    const void *GetBuffer() { return compressedBuf; }
+    size_t GetSize() { return compressedSize; }
+    size_t GetUncompressedSize() { return uncompressedSize; }
+    size_t GetCRC32() { return CRC32; }
+    Type GetType() { return type; }
+
+    /**
+     * Returns a zxx_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.
+     */
+    zxx_stream GetZStream(void *buf)
+    {
+      zxx_stream 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;
+    size_t CRC32;
+    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 && str[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;
+
+  mutable pthread_mutex_t mutex;
+};
+
+/**
+ * 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 already_AddRefed<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 */