Trigger an error if there is an incomplete entry at the end of stream (#83)

* Check if there is an incomplete entry at the end of the input

An error will be raised if the last entry wans't complete.

This will only work in node >= v8, since that's where _final()
was introduced. Older node versions will ignore that function and
will be unaffected.

* Add padding at the end of gnu-long-path.tar

This test case file was actually to short. The new code checking for
unexpected end of file rejected it. Gnu tar agrees, it also failed to
extract it with "Unexpected EOF in archive".

* Added test case to check handling of incomplete data

This tests that an error event is created when the input file
is incomplete.

* Check callback directly instead of passing extra parameter

extract.js

@@ -48,6 +48,7 @@ var Extract = function (opts) {
   this._offset = 0
   this._buffer = bl()
   this._missing = 0
+  this._partial = false
   this._onparse = noop
   this._header = null
   this._stream = null
@@ -181,6 +182,7 @@ var Extract = function (opts) {
     self._parse(header.size, onstreamend)
     oncontinue()
   }
+  this._onheader = onheader
 
   this._parse(512, onheader)
 }
@@ -200,6 +202,7 @@ Extract.prototype._parse = function (size, onparse) {
   if (this._destroyed) return
   this._offset += size
   this._missing = size
+  if (onparse === this._onheader) this._partial = false
   this._onparse = onparse
 }
 
@@ -217,6 +220,7 @@ Extract.prototype._write = function (data, enc, cb) {
   var s = this._stream
   var b = this._buffer
   var missing = this._missing
+  if (data.length) this._partial = true
 
   // we do not reach end-of-chunk now. just forward it
 
@@ -246,4 +250,9 @@ Extract.prototype._write = function (data, enc, cb) {
   this._onparse()
 }
 
+Extract.prototype._final = function (cb) {
+  if (this._partial) cb(new Error('unexpected end of data'))
+  cb()
+}
+
 module.exports = Extract

test/extract.js

@@ -570,3 +570,23 @@ test('latin-1', function (t) { // can unpack filenames encoded in latin-1
 
   extract.end(fs.readFileSync(fixtures.LATIN1_TAR))
 })
+
+test('incomplete', function (t) {
+  t.plan(2)
+
+  var extract = tar.extract()
+
+  extract.on('entry', function (header, stream, callback) {
+    callback()
+  })
+
+  extract.on('error', function (err) {
+    t.same(err.message, 'unexpected end of data')
+  })
+
+  extract.on('finish', function () {
+    t.ok(true)
+  })
+
+  extract.end(fs.readFileSync(fixtures.INCOMPLETE_TAR))
+})

test/fixtures/index.js

@@ -16,3 +16,4 @@ exports.LARGE_UID_GID = path.join(__dirname, 'large-uid-gid.tar')
 exports.BASE_256_SIZE = path.join(__dirname, 'base-256-size.tar')
 exports.HUGE = path.join(__dirname, 'huge.tar.gz')
 exports.LATIN1_TAR = path.join(__dirname, 'latin1.tar')
+exports.INCOMPLETE_TAR = path.join(__dirname, 'incomplete.tar')