Allow to create a file when filesystem don't support hard links (#44)

* Allow to create a file when filesystem don't support hard links

* Changed option name from `allowCreateFilesForHardLinks` to `hardlinkAsFilesFallback`

Author: piranna

index.js

@@ -247,7 +247,16 @@ exports.extract = function (cwd, opts) {
     var onlink = function () {
       if (win32) return next() // skip links on win for now before it can be tested
       xfs.unlink(name, function () {
-        xfs.link(path.resolve(cwd, header.linkname), name, stat)
+        var srcpath = path.resolve(cwd, header.linkname)
+
+        xfs.link(srcpath, name, function (err) {
+          if (err && err.code === 'EPERM' && opts.hardlinkAsFilesFallback) {
+            stream = xfs.createReadStream(srcpath)
+            return onfile()
+          }
+
+          stat(err)
+        })
       })
     }