Bp 2.5 ansible interpreter py3 (#36561)

* Fix types when evaluating interpreter (#36541)

* Fix types when evaluating interpreter. Fixes #36536
* Rename variables that contain bytes to b_*
* Get rid of to_text() and to_bytes() calls that do nothing (because the
  data is already the proper type)

(cherry picked from commit a4df4d33ac72e048694f662a358d96b7f487bf83)

* Changelog entry for the ansible_*_interpreter fix

2 files changed, 24 insertions, 15 deletions

diff --git a/changelogs/fragments/py3-ansible_interpreter.yaml b/changelogs/fragments/py3-ansible_interpreter.yaml
new file mode 100644
index 0000000000..7f92f62379
--- /dev/null
+++ b/changelogs/fragments/py3-ansible_interpreter.yaml
@@ -0,0 +1,4 @@
+bugfixes:
+- Fix for ansible_*_interpreter on Python3 when using non-newstyle modules.
+  Those include old-style ansible modules and Ansible modules written in
+  non-python scripting languages (https://github.com/ansible/ansible/pull/36541)
diff --git a/lib/ansible/executor/module_common.py b/lib/ansible/executor/module_common.py
index fe0704aca1..893feabd5b 100644
--- a/lib/ansible/executor/module_common.py
+++ b/lib/ansible/executor/module_common.py
@@ -35,7 +35,7 @@ from io import BytesIO
 from ansible.release import __version__, __author__
 from ansible import constants as C
 from ansible.errors import AnsibleError
-from ansible.module_utils._text import to_bytes, to_text
+from ansible.module_utils._text import to_bytes, to_text, to_native
 from ansible.plugins.loader import module_utils_loader, ps_module_utils_loader
 from ansible.plugins.shell.powershell import async_watchdog, async_wrapper, become_wrapper, leaf_exec, exec_wrapper
 # Must import strategy and use write_locks from there
@@ -60,6 +60,7 @@ REPLACER_SELINUX = b"<<SELINUX_SPECIAL_FILESYSTEMS>>"
 # We could end up writing out parameters with unicode characters so we need to
 # specify an encoding for the python source file
 ENCODING_STRING = u'# -*- coding: utf-8 -*-'
+b_ENCODING_STRING = b'# -*- coding: utf-8 -*-'
 
 # module_common is relative to module_utils, so fix the path
 _MODULE_UTILS_PATH = os.path.join(os.path.dirname(__file__), '..', 'module_utils')
@@ -911,25 +912,29 @@ def modify_module(module_name, module_path, module_args, task_vars=None, templar
     if module_style == 'binary':
         return (b_module_data, module_style, to_text(shebang, nonstring='passthru'))
     elif shebang is None:
-        lines = b_module_data.split(b"\n", 1)
-        if lines[0].startswith(b"#!"):
-            shebang = lines[0].strip()
-            args = shlex.split(str(shebang[2:]))
+        b_lines = b_module_data.split(b"\n", 1)
+        if b_lines[0].startswith(b"#!"):
+            b_shebang = b_lines[0].strip()
+            # shlex.split on python-2.6 needs bytes.  On python-3.x it needs text
+            args = shlex.split(to_native(b_shebang[2:], errors='surrogate_or_strict'))
+
+            # _get_shebang() takes text strings
+            args = [to_text(a, errors='surrogate_or_strict') for a in args]
             interpreter = args[0]
-            interpreter = to_bytes(interpreter)
+            b_new_shebang = to_bytes(_get_shebang(interpreter, task_vars, templar, args[1:])[0],
+                                     errors='surrogate_or_strict', nonstring='passthru')
 
-            new_shebang = to_bytes(_get_shebang(interpreter, task_vars, templar, args[1:])[0], errors='surrogate_or_strict', nonstring='passthru')
-            if new_shebang:
-                lines[0] = shebang = new_shebang
+            if b_new_shebang:
+                b_lines[0] = b_shebang = b_new_shebang
 
-            if os.path.basename(interpreter).startswith(b'python'):
-                lines.insert(1, to_bytes(ENCODING_STRING))
+            if os.path.basename(interpreter).startswith(u'python'):
+                b_lines.insert(1, b_ENCODING_STRING)
+
+            shebang = to_text(b_shebang, nonstring='passthru', errors='surrogate_or_strict')
         else:
             # No shebang, assume a binary module?
             pass
 
-        b_module_data = b"\n".join(lines)
-    else:
-        shebang = to_bytes(shebang, errors='surrogate_or_strict')
+        b_module_data = b"\n".join(b_lines)
 
-    return (b_module_data, module_style, to_text(shebang, nonstring='passthru'))
+    return (b_module_data, module_style, shebang)