Prevent launching node.js script file in working directory.

The PATHEXT environment variable on Windows often includes .JS, which means running "node" can try to execute a file named "node.js" in the current working directory. As npm-installed executable scripts are often executed in directories containing .js files, this is not unlikely.

This change works around it by locally stripping the .JS extension from the PATHEXT environment variable.

index.js

@@ -99,13 +99,17 @@ function writeShim_ (from, to, prog, args, cb) {
   // @IF EXIST "%~dp0\node.exe" (
   //   "%~dp0\node.exe" "%~dp0\.\node_modules\npm\bin\npm-cli.js" %*
   // ) ELSE (
+  //   SETLOCAL
+  //   SET PATHEXT=%PATHEXT:;.JS;=;%
   //   node "%~dp0\.\node_modules\npm\bin\npm-cli.js" %*
   // )
   var cmd
   if (longProg) {
     cmd = "@IF EXIST " + longProg + " (\r\n"
         + "  " + longProg + " " + args + " " + target + " %*\r\n"
         + ") ELSE (\r\n"
+        + "  @SETLOCAL\r\n"
+        + "  @SET PATHEXT=%PATHEXT:;.JS;=;%\r\n"
         + "  " + prog + " " + args + " " + target + " %*\r\n"
         + ")"
   } else {

test/basic.js

@@ -50,6 +50,8 @@ test('env shebang', function (t) {
             "@IF EXIST \"%~dp0\\node.exe\" (\r"+
             "\n  \"%~dp0\\node.exe\"  \"%~dp0\\from.env\" %*\r"+
             "\n) ELSE (\r"+
+            "\n  @SETLOCAL\r"+
+            "\n  @SET PATHEXT=%PATHEXT:;.JS;=;%\r"+
             "\n  node  \"%~dp0\\from.env\" %*\r"+
             "\n)")
     t.end()
@@ -86,6 +88,8 @@ test('env shebang with args', function (t) {
             "@IF EXIST \"%~dp0\\node.exe\" (\r"+
             "\n  \"%~dp0\\node.exe\"  --expose_gc \"%~dp0\\from.env.args\" %*\r"+
             "\n) ELSE (\r"+
+            "\n  @SETLOCAL\r"+
+            "\n  @SET PATHEXT=%PATHEXT:;.JS;=;%\r"+
             "\n  node  --expose_gc \"%~dp0\\from.env.args\" %*\r"+
             "\n)")
     t.end()
@@ -123,6 +127,8 @@ test('explicit shebang', function (t) {
             "@IF EXIST \"%~dp0\\/usr/bin/sh.exe\" (\r" +
             "\n  \"%~dp0\\/usr/bin/sh.exe\"  \"%~dp0\\from.sh\" %*\r" +
             "\n) ELSE (\r" +
+            "\n  @SETLOCAL\r"+
+            "\n  @SET PATHEXT=%PATHEXT:;.JS;=;%\r"+
             "\n  /usr/bin/sh  \"%~dp0\\from.sh\" %*\r" +
             "\n)")
     t.end()
@@ -160,6 +166,8 @@ test('explicit shebang with args', function (t) {
             "@IF EXIST \"%~dp0\\/usr/bin/sh.exe\" (\r" +
             "\n  \"%~dp0\\/usr/bin/sh.exe\"  -x \"%~dp0\\from.sh.args\" %*\r" +
             "\n) ELSE (\r" +
+            "\n  @SETLOCAL\r"+
+            "\n  @SET PATHEXT=%PATHEXT:;.JS;=;%\r"+
             "\n  /usr/bin/sh  -x \"%~dp0\\from.sh.args\" %*\r" +
             "\n)")
     t.end()