cramfs: JavaScript parsing library

KS implementation details

License: MIT

References

This page hosts a formal specification of cramfs using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for JavaScript generated by Kaitai Struct depends on the JavaScript runtime library. You have to install it before you can parse data.

The JavaScript runtime library is available at npm:

npm install kaitai-struct

Code

See the usage examples in the JavaScript notes.

Parse structure from an ArrayBuffer:

var arrayBuffer = ...;
var data = new Cramfs(new KaitaiStream(arrayBuffer));

After that, one can get various attributes from the structure by accessing fields or properties like:

data.superBlock // => get super block

JavaScript source code to parse cramfs

Cramfs.js

// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    define(['kaitai-struct/KaitaiStream'], factory);
  } else if (typeof module === 'object' && module.exports) {
    module.exports = factory(require('kaitai-struct/KaitaiStream'));
  } else {
    root.Cramfs = factory(root.KaitaiStream);
  }
}(this, function (KaitaiStream) {
var Cramfs = (function() {
  function Cramfs(_io, _parent, _root) {
    this._io = _io;
    this._parent = _parent;
    this._root = _root || this;

    this._read();
  }
  Cramfs.prototype._read = function() {
    this.superBlock = new SuperBlockStruct(this._io, this, this._root);
  }

  var SuperBlockStruct = Cramfs.SuperBlockStruct = (function() {
    function SuperBlockStruct(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    SuperBlockStruct.prototype._read = function() {
      this.magic = this._io.readBytes(4);
      if (!((KaitaiStream.byteArrayCompare(this.magic, [69, 61, 205, 40]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([69, 61, 205, 40], this.magic, this._io, "/types/super_block_struct/seq/0");
      }
      this.size = this._io.readU4le();
      this.flags = this._io.readU4le();
      this.future = this._io.readU4le();
      this.signature = this._io.readBytes(16);
      if (!((KaitaiStream.byteArrayCompare(this.signature, [67, 111, 109, 112, 114, 101, 115, 115, 101, 100, 32, 82, 79, 77, 70, 83]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([67, 111, 109, 112, 114, 101, 115, 115, 101, 100, 32, 82, 79, 77, 70, 83], this.signature, this._io, "/types/super_block_struct/seq/4");
      }
      this.fsid = new Info(this._io, this, this._root);
      this.name = KaitaiStream.bytesToStr(this._io.readBytes(16), "ASCII");
      this.root = new Inode(this._io, this, this._root);
    }
    Object.defineProperty(SuperBlockStruct.prototype, 'flagFsidV2', {
      get: function() {
        if (this._m_flagFsidV2 !== undefined)
          return this._m_flagFsidV2;
        this._m_flagFsidV2 = ((this.flags >>> 0) & 1);
        return this._m_flagFsidV2;
      }
    });
    Object.defineProperty(SuperBlockStruct.prototype, 'flagHoles', {
      get: function() {
        if (this._m_flagHoles !== undefined)
          return this._m_flagHoles;
        this._m_flagHoles = ((this.flags >>> 8) & 1);
        return this._m_flagHoles;
      }
    });
    Object.defineProperty(SuperBlockStruct.prototype, 'flagWrongSignature', {
      get: function() {
        if (this._m_flagWrongSignature !== undefined)
          return this._m_flagWrongSignature;
        this._m_flagWrongSignature = ((this.flags >>> 9) & 1);
        return this._m_flagWrongSignature;
      }
    });
    Object.defineProperty(SuperBlockStruct.prototype, 'flagSortedDirs', {
      get: function() {
        if (this._m_flagSortedDirs !== undefined)
          return this._m_flagSortedDirs;
        this._m_flagSortedDirs = ((this.flags >>> 1) & 1);
        return this._m_flagSortedDirs;
      }
    });
    Object.defineProperty(SuperBlockStruct.prototype, 'flagShiftedRootOffset', {
      get: function() {
        if (this._m_flagShiftedRootOffset !== undefined)
          return this._m_flagShiftedRootOffset;
        this._m_flagShiftedRootOffset = ((this.flags >>> 10) & 1);
        return this._m_flagShiftedRootOffset;
      }
    });

    return SuperBlockStruct;
  })();

  var ChunkedDataInode = Cramfs.ChunkedDataInode = (function() {
    function ChunkedDataInode(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    ChunkedDataInode.prototype._read = function() {
      this.blockEndIndex = new Array(Math.floor(((this._parent.size + this._root.pageSize) - 1) / this._root.pageSize));
      for (var i = 0; i < Math.floor(((this._parent.size + this._root.pageSize) - 1) / this._root.pageSize); i++) {
        this.blockEndIndex[i] = this._io.readU4le();
      }
      this.rawBlocks = this._io.readBytesFull();
    }

    return ChunkedDataInode;
  })();

  var Inode = Cramfs.Inode = (function() {
    Inode.FileType = Object.freeze({
      FIFO: 1,
      CHRDEV: 2,
      DIR: 4,
      BLKDEV: 6,
      REG_FILE: 8,
      SYMLINK: 10,
      SOCKET: 12,

      1: "FIFO",
      2: "CHRDEV",
      4: "DIR",
      6: "BLKDEV",
      8: "REG_FILE",
      10: "SYMLINK",
      12: "SOCKET",
    });

    function Inode(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    Inode.prototype._read = function() {
      this.mode = this._io.readU2le();
      this.uid = this._io.readU2le();
      this.sizeGid = this._io.readU4le();
      this.namelenOffset = this._io.readU4le();
      this.name = KaitaiStream.bytesToStr(this._io.readBytes(this.namelen), "utf-8");
    }
    Object.defineProperty(Inode.prototype, 'attr', {
      get: function() {
        if (this._m_attr !== undefined)
          return this._m_attr;
        this._m_attr = ((this.mode >>> 9) & 7);
        return this._m_attr;
      }
    });
    Object.defineProperty(Inode.prototype, 'asRegFile', {
      get: function() {
        if (this._m_asRegFile !== undefined)
          return this._m_asRegFile;
        var io = this._root._io;
        var _pos = io.pos;
        io.seek(this.offset);
        this._m_asRegFile = new ChunkedDataInode(io, this, this._root);
        io.seek(_pos);
        return this._m_asRegFile;
      }
    });
    Object.defineProperty(Inode.prototype, 'permU', {
      get: function() {
        if (this._m_permU !== undefined)
          return this._m_permU;
        this._m_permU = ((this.mode >>> 6) & 7);
        return this._m_permU;
      }
    });
    Object.defineProperty(Inode.prototype, 'asSymlink', {
      get: function() {
        if (this._m_asSymlink !== undefined)
          return this._m_asSymlink;
        var io = this._root._io;
        var _pos = io.pos;
        io.seek(this.offset);
        this._m_asSymlink = new ChunkedDataInode(io, this, this._root);
        io.seek(_pos);
        return this._m_asSymlink;
      }
    });
    Object.defineProperty(Inode.prototype, 'permO', {
      get: function() {
        if (this._m_permO !== undefined)
          return this._m_permO;
        this._m_permO = (this.mode & 7);
        return this._m_permO;
      }
    });
    Object.defineProperty(Inode.prototype, 'size', {
      get: function() {
        if (this._m_size !== undefined)
          return this._m_size;
        this._m_size = (this.sizeGid & 16777215);
        return this._m_size;
      }
    });
    Object.defineProperty(Inode.prototype, 'gid', {
      get: function() {
        if (this._m_gid !== undefined)
          return this._m_gid;
        this._m_gid = (this.sizeGid >>> 24);
        return this._m_gid;
      }
    });
    Object.defineProperty(Inode.prototype, 'permG', {
      get: function() {
        if (this._m_permG !== undefined)
          return this._m_permG;
        this._m_permG = ((this.mode >>> 3) & 7);
        return this._m_permG;
      }
    });
    Object.defineProperty(Inode.prototype, 'namelen', {
      get: function() {
        if (this._m_namelen !== undefined)
          return this._m_namelen;
        this._m_namelen = ((this.namelenOffset & 63) << 2);
        return this._m_namelen;
      }
    });
    Object.defineProperty(Inode.prototype, 'asDir', {
      get: function() {
        if (this._m_asDir !== undefined)
          return this._m_asDir;
        var io = this._root._io;
        var _pos = io.pos;
        io.seek(this.offset);
        this._raw__m_asDir = io.readBytes(this.size);
        var _io__raw__m_asDir = new KaitaiStream(this._raw__m_asDir);
        this._m_asDir = new DirInode(_io__raw__m_asDir, this, this._root);
        io.seek(_pos);
        return this._m_asDir;
      }
    });
    Object.defineProperty(Inode.prototype, 'type', {
      get: function() {
        if (this._m_type !== undefined)
          return this._m_type;
        this._m_type = ((this.mode >>> 12) & 15);
        return this._m_type;
      }
    });
    Object.defineProperty(Inode.prototype, 'offset', {
      get: function() {
        if (this._m_offset !== undefined)
          return this._m_offset;
        this._m_offset = (((this.namelenOffset >>> 6) & 67108863) << 2);
        return this._m_offset;
      }
    });

    return Inode;
  })();

  var DirInode = Cramfs.DirInode = (function() {
    function DirInode(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    DirInode.prototype._read = function() {
      if (this._io.size > 0) {
        this.children = [];
        var i = 0;
        while (!this._io.isEof()) {
          this.children.push(new Inode(this._io, this, this._root));
          i++;
        }
      }
    }

    return DirInode;
  })();

  var Info = Cramfs.Info = (function() {
    function Info(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    Info.prototype._read = function() {
      this.crc = this._io.readU4le();
      this.edition = this._io.readU4le();
      this.blocks = this._io.readU4le();
      this.files = this._io.readU4le();
    }

    return Info;
  })();
  Object.defineProperty(Cramfs.prototype, 'pageSize', {
    get: function() {
      if (this._m_pageSize !== undefined)
        return this._m_pageSize;
      this._m_pageSize = 4096;
      return this._m_pageSize;
    }
  });

  return Cramfs;
})();
return Cramfs;
}));