Node Tar

Evented reading and writing of tar format archives.

Synopsis

The reader a tar archive and emits events.

var tar = require("./lib/tar"),
    fs  = require("fs");


function cat(tarfile, filename) {
  var body,
      bodyOffset  = 0,
      found       = false,
      reader      = new tar.Reader();
  reader.on("header", function (header) {
    if (header.filename == filename) {
      found = true;
      body = new Buffer(header.size);
    }
  });
  reader.on("data", function (header, chunk, offset, length) {
    if (header.filename == filename) {
      chunk.copy(body, bodyOffset, offset, offset + length);
    }
  });
  reader.on("footer", function (header) {
    if (header.filename == filename) {
      console.log(body.toString());
    }
  });
  reader.on("end", function () {
    if (!found) {
      console.log("Could not find " + filename + " in " + tarfile + ".");
    }
  });
  fs.readFile(tarfile, function (error, buffer) {
    reader.read(buffer, 0, buffer.length);
  });
}

cat("hello.tar", "hello/hello.txt");

tar

Node Tar exports the reader and writer classes in its exports.

var tar = require("tar");

tar.Reader()

Parses a tar file that is fed to it through its Buffer based read method, or alternatively through its file based readFile method.

// Import the tar library.
var tar = require("tar");

// Create a new tar reader.
var reader = new tar.Reader();

read(buffer[, offset][, length])

buffer

The buffer to read.

offset

The offset of the range of bytes to read in the buffer. This parameter is optional and the default value is 0.

length

The length of the range of bytes to read in the buffer. This parameter is optional and default value is buffer.length.

Use the read method to feed a tar file to the tar reader in chunks. This is useful for processing tar files as they are uploaded and decompressed.

on("header", function (header) {})

header

An object containing the tar header. Show the fields.

Called when a file header is encountered in the tar archive. The callback provides the header data as a JSON object.

on("data", function (header, buffer, offset, length) {})

header

An object containing the tar header. Show the fields.

buffer

The buffer containing the file data.

offset

The offset of the range of bytes of the file chunk in the buffer.

length

The length of the range of bytes of the file chunk in the buffer.

Called when data for a tar file entey is read from the tar file.

The buffer is the same buffer that is passed to read, and the offset and length indicate the region in the buffer that conatins the next chunk of file data. This is efficent because the tar reader is merely locating the file in the buffer you give it, instead of creating a copy.

on("footer", function (header) {})

header

An object containing the tar header. Show the fields.

Called after a file has been read from the tar archive. The callback provides the header data as a JSON object.

on("end", function () {})

Called when the end of the tar archive is reached.