Handles FileNotFoundError exception in shadow.info

Musl libc getspnam implementation returns ENOENT when user is not found
Changing the linux_shadow.info to deal with FileNotFoundError, allowing
the user.present state to work in musl based systems, like the Alpine
Linux.

changelog/50979.fixed

@@ -0,0 +1 @@
+Allow user.present to work on Alpine Linux by fixing linux_shadow.info

salt/modules/linux_shadow.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Manage the shadow file on Linux systems
 
@@ -8,21 +7,16 @@ Manage the shadow file on Linux systems
     *'shadow.info' is not available*), see :ref:`here
     <module-provider-override>`.
 """
-from __future__ import absolute_import, print_function, unicode_literals
 
 import datetime
 import functools
 import logging
-
-# Import python libs
 import os
 
-# Import salt libs
 import salt.utils.data
 import salt.utils.files
 import salt.utils.stringutils
 from salt.exceptions import CommandExecutionError
-from salt.ext import six
 from salt.ext.six.moves import range
 
 try:
@@ -93,7 +87,7 @@ def info(name, root=None):
             "inact": data.sp_inact,
             "expire": data.sp_expire,
         }
-    except KeyError:
+    except (KeyError, FileNotFoundError):
         return {
             "name": "",
             "passwd": "",
@@ -385,7 +379,7 @@ def set_password(name, password, use_usermod=False, root=None):
         # ALT Linux uses tcb to store password hashes. More information found
         # in manpage (http://docs.altlinux.org/manpages/tcb.5.html)
         if __grains__["os"] == "ALT":
-            s_file = "/etc/tcb/{0}/shadow".format(name)
+            s_file = "/etc/tcb/{}/shadow".format(name)
         else:
             s_file = "/etc/shadow"
         if root:
@@ -396,9 +390,7 @@ def set_password(name, password, use_usermod=False, root=None):
             return ret
         lines = []
         user_found = False
-        lstchg = six.text_type(
-            (datetime.datetime.today() - datetime.datetime(1970, 1, 1)).days
-        )
+        lstchg = str((datetime.datetime.today() - datetime.datetime(1970, 1, 1)).days)
         with salt.utils.files.fopen(s_file, "rb") as fp_:
             for line in fp_:
                 line = salt.utils.stringutils.to_unicode(line)

tests/unit/modules/test_linux_shadow.py

@@ -2,6 +2,7 @@
     :codeauthor: Erik Johnson <erik@saltstack.com>
 """
 
+import spwd
 import textwrap
 
 import pytest
@@ -143,6 +144,57 @@ class LinuxShadowTest(TestCase, LoaderModuleMockMixin):
         # Make sure we wrote the correct info
         assert filehandles[1].write_calls[0].split(":")[:2] == [user, password]
 
+    def test_info(self):
+        """
+        Test if info shows the correct user information
+        """
+
+        # First test is with a succesful call
+        expected_result = [
+            ("expire", -1),
+            ("inact", -1),
+            ("lstchg", 31337),
+            ("max", 99999),
+            ("min", 0),
+            ("name", "foo"),
+            ("passwd", _HASHES["sha512"]["pw_hash"]),
+            ("warn", 7),
+        ]
+        getspnam_return = spwd.struct_spwd(
+            ["foo", _HASHES["sha512"]["pw_hash"], 31337, 0, 99999, 7, -1, -1, -1]
+        )
+        with patch("spwd.getspnam", return_value=getspnam_return):
+            result = shadow.info("foo")
+            self.assertEqual(
+                expected_result, sorted(result.items(), key=lambda x: x[0])
+            )
+
+        # The next two is for a non-existent user
+        expected_result = [
+            ("expire", ""),
+            ("inact", ""),
+            ("lstchg", ""),
+            ("max", ""),
+            ("min", ""),
+            ("name", ""),
+            ("passwd", ""),
+            ("warn", ""),
+        ]
+        # We get KeyError exception for non-existent users in glibc based systems
+        getspnam_return = KeyError
+        with patch("spwd.getspnam", side_effect=getspnam_return):
+            result = shadow.info("foo")
+            self.assertEqual(
+                expected_result, sorted(result.items(), key=lambda x: x[0])
+            )
+        # And FileNotFoundError in musl based systems
+        getspnam_return = FileNotFoundError
+        with patch("spwd.getspnam", side_effect=getspnam_return):
+            result = shadow.info("foo")
+            self.assertEqual(
+                expected_result, sorted(result.items(), key=lambda x: x[0])
+            )
+
     @pytest.mark.skip_if_not_root
     def test_list_users(self):
         """