Add support for BOM-signed env files (#501)

Author: hosni

src/Util/Str.php

@@ -41,11 +41,19 @@ public static function utf8(string $input, string $encoding = null)
                 \sprintf('Illegal character encoding [%s] specified.', $encoding)
             );
         }
-
+        $converted = $encoding === null ?
+            @\mb_convert_encoding($input, 'UTF-8') :
+            @\mb_convert_encoding($input, 'UTF-8', $encoding);
+        /**
+         * this is for support UTF-8 with BOM encoding
+         * @see https://en.wikipedia.org/wiki/Byte_order_mark
+         * @see https://github.com/vlucas/phpdotenv/issues/500
+         */
+        if (\substr($converted, 0, 3) == "\xEF\xBB\xBF") {
+            $converted = \substr($converted, 3);
+        }
         /** @var \GrahamCampbell\ResultType\Result<string,string> */
-        return Success::create(
-            $encoding === null ? @\mb_convert_encoding($input, 'UTF-8') : @\mb_convert_encoding($input, 'UTF-8', $encoding)
-        );
+        return Success::create($converted);
     }
 
     /**

tests/Dotenv/Store/StoreTest.php

@@ -127,4 +127,15 @@ public function testFileReadMultipleWithoutShortCircuitMode()
             $builder->make()->read()
         );
     }
+    public function testFileReadWithUtf8WithBomEncoding()
+    {
+        self::assertSame(
+            [
+                self::$folder.\DIRECTORY_SEPARATOR.'utf8-with-bom-encoding.env' => "FOO=bar\nBAR=baz\nSPACED=\"with spaces\"\n",
+            ],
+            Reader::read(
+                Paths::filePaths([self::$folder], ['utf8-with-bom-encoding.env'])
+            )
+        );
+    }
 }

tests/fixtures/env/utf8-with-bom-encoding.env

@@ -0,0 +1,3 @@
+FOO=bar
+BAR=baz
+SPACED="with spaces"