Issue #7774: Set sys.executable to an empty string if argv[0] has been

set to an non existent program name and Python is unable to retrieve the real
program name.

Fix also sysconfig: if sys.executable is an empty string, use the current
working directory.

Lib/sysconfig.py

@@ -84,7 +84,12 @@ _PREFIX = os.path.normpath(sys.prefix)
 _EXEC_PREFIX = os.path.normpath(sys.exec_prefix)
 _CONFIG_VARS = None
 _USER_BASE = None
-_PROJECT_BASE = os.path.dirname(realpath(sys.executable))
+if sys.executable:
+    _PROJECT_BASE = os.path.dirname(realpath(sys.executable))
+else:
+    # sys.executable can be empty if argv[0] has been changed and Python is
+    # unable to retrieve the real program name
+    _PROJECT_BASE = realpath(os.getcwd())
 
 if os.name == "nt" and "pcbuild" in _PROJECT_BASE[-8:].lower():
     _PROJECT_BASE = realpath(os.path.join(_PROJECT_BASE, pardir))

Lib/test/test_sys.py

@@ -437,6 +437,17 @@ class SysModuleTest(unittest.TestCase):
         self.assertEqual(sys.call_tracing(str, (2,)), "2")
         self.assertRaises(TypeError, sys.call_tracing, str, 2)
 
+    def test_executable(self):
+        # Issue #7774: Ensure that sys.executable is an empty string if argv[0]
+        # has been set to an non existent program name and Python is unable to
+        # retrieve the real program name
+        import subprocess
+        p = subprocess.Popen(
+            ["nonexistent", "-c", 'import sys; print "executable=%r" % sys.executable'],
+            executable=sys.executable, stdout=subprocess.PIPE)
+        executable = p.communicate()[0].strip()
+        p.wait()
+        self.assertEqual(executable, "executable=''")
 
 class SizeofTest(unittest.TestCase):
 

Misc/NEWS

@@ -12,6 +12,10 @@ What's New in Python 2.7 beta 1?
 Core and Builtins
 -----------------
 
+- Issue #7774: Set sys.executable to an empty string if argv[0] has been
+  set to an non existent program name and Python is unable to retrieve the real
+  program name
+
 - Issue #3137: Don't ignore errors at startup, especially a keyboard interrupt
   (SIGINT). If an error occurs while importing the site module, the error is
   printed and Python exits. Initialize the GIL before importing the site

Modules/getpath.c

@@ -441,7 +441,7 @@ calculate_path(void)
 	}
 	else
 		progpath[0] = '\0';
-	if (progpath[0] != SEP)
+	if (progpath[0] != SEP && progpath[0] != '\0')
 		absolutize(progpath);
 	strncpy(argv0_path, progpath, MAXPATHLEN);
 	argv0_path[MAXPATHLEN] = '\0';