fix infinite recursion when PEX_PYTHON points at a symlink

Author: Matt Landis

pex/pex_bootstrapper.py

@@ -79,7 +79,7 @@ def maybe_reexec_pex():
   from .tracer import TRACER
 
   target_python = ENV.PEX_PYTHON
-  target = find_in_path(target_python)
+  target = os.path.realpath(find_in_path(target_python))
   if not target:
     die('Failed to find interpreter specified by PEX_PYTHON: %s' % target)
   current = os.path.realpath(sys.executable)

tests/test_integration.py

@@ -2,8 +2,9 @@
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
 import os
+import sys
 
-from twitter.common.contextutil import temporary_file
+from twitter.common.contextutil import environment_as, temporary_dir, temporary_file
 
 from pex.testing import run_simple_pex_test
 
@@ -30,3 +31,20 @@ def test_pex_interpreter():
     so, rc = run_simple_pex_test("", args=(fp.name,), coverage=True, env=env)
     assert so == b'Hello world\n'
     assert rc == 0
+
+
+def test_pex_python_symlink():
+  with temporary_dir() as td:
+    with environment_as(HOME=td):
+      symlink_path = os.path.join(td, 'python-symlink')
+      os.symlink(sys.executable, symlink_path)
+      pexrc_path = os.path.join(td, '.pexrc')
+      try:
+        with open(pexrc_path, 'w') as pexrc:
+          pexrc.write("PEX_PYTHON=%s" % symlink_path)
+
+        body = "print('Hello')"
+        _, rc = run_simple_pex_test(body, coverage=True)
+        assert rc == 0
+      finally:
+        os.unlink(pexrc_path)