Fixes EioDriver and UvDriver readlink implementation

lib/EioDriver.php

@@ -296,10 +296,19 @@ public function readlink(string $path): Promise {
         $this->poll->listen($deferred->promise());
 
         $priority = \EIO_PRI_DEFAULT;
-        \eio_readlink($path, $priority, [$this, "onGenericResult"], $deferred);
+        \eio_readlink($path, $priority, [$this, "onReadlink"], $deferred);
 
         return $deferred->promise();
     }
+
+    private function onReadlink($deferred, $result, $req) {
+        if ($result === -1) {
+            $deferred->fail(new FilesystemException(\eio_get_last_error($req)));
+        } else {
+            $deferred->resolve($result);
+        }
+    }
+
     private function onGenericResult($deferred, $result, $req) {
         if ($result === -1) {
             $deferred->fail(new FilesystemException(\eio_get_last_error($req)));

lib/UvDriver.php

@@ -312,8 +312,14 @@ public function readlink(string $path): Promise {
         $deferred = new Deferred;
         $this->poll->listen($deferred->promise());
 
-        \uv_fs_readlink($this->loop, $path, function ($fh) use ($deferred) {
-            $deferred->resolve((bool) $fh);
+        \uv_fs_readlink($this->loop, $path, function ($fh, $target) use ($deferred) {
+            if (!(bool) $fh) {
+                $deferred->fail(new FilesystemException("Could not read symbolic link"));
+
+                return;
+            }
+
+            $deferred->resolve($target);
         });
 
         return $deferred->promise();

test/DriverTest.php

@@ -57,6 +57,43 @@ public function testSymlink() {
         });
     }
 
+    public function testReadlink() {
+        $this->execute(function () {
+            $fixtureDir = Fixture::path();
+
+            $original = "{$fixtureDir}/small.txt";
+            $link = "{$fixtureDir}/symlink.txt";
+            \symlink($original, $link);
+
+            $this->assertSame($original, yield File\readlink($link));
+        });
+    }
+
+    public function readlinkPathProvider() {
+        return [
+            'nonExistingPath' => [function () {
+                return Fixture::path() . '/' . uniqid();
+            }],
+            'notLink' => [function () {
+                return Fixture::path();
+            }],
+        ];
+    }
+
+    /**
+     * @dataProvider readlinkPathProvider
+     * @expectedException \Amp\File\FilesystemException
+     *
+     * @param \Closure $linkResolver
+     */
+    public function testReadlinkError(\Closure $linkResolver) {
+        $this->execute(function () use ($linkResolver) {
+            $link = $linkResolver();
+
+            yield File\readlink($link);
+        });
+    }
+
     public function testLstat() {
         $this->execute(function () {
             $fixtureDir = Fixture::path();

test/UvDriverTest.php

@@ -22,4 +22,13 @@ protected function execute(callable $cb) {
             asyncCall($cb);
         });
     }
+
+    /**
+     * @dataProvider readlinkPathProvider
+     *
+     * @param \Closure $linkResolver
+     */
+    public function testReadlinkError(\Closure $linkResolver) {
+        $this->markTestSkipped('UvDriver Test Skipped: Causes Crash');
+    }
 }