Properly work with isfile/isdir/islink

* add islink
* add symlink (`os.symlink` mimic)
* add chmod (`os.chmod` mimic)

Signed-off-by: Aleksei Stepanov <penguinolog@gmail.com>

Author: penguinolog

doc/source/SSHClient.rst

@@ -337,31 +337,39 @@ API: SSHClient and SSHAuth.
 
         Open file on remote using SFTP session.
 
+        :param path: filesystem object path
         :type path: ``str``
+        :param mode: open file mode ('t' is not supported)
         :type mode: ``str``
+        :return: file.open() stream
+        :rtype: ``paramiko.SFTPFile``
 
     .. py:method:: exists(path)
 
         Check for file existence using SFTP session.
 
+        :param path: filesystem object path
         :type path: ``str``
+        :return: path is valid (object exists)
         :rtype: ``bool``
 
     .. py:method:: stat(path)
 
         Get stat info for path with following symlinks.
 
+        :param path: filesystem object path
         :type path: ``str``
+        :return: stat like information for remote path
         :rtype: ``paramiko.sftp_attr.SFTPAttributes``
 
     .. py:method:: utime(path, times=None):
 
         Set atime, mtime.
 
         :param path: filesystem object path
-        :type path: str
+        :type path: ``str``
         :param times: (atime, mtime)
-        :type times: typing.Optional[typing.Tuple[int, int]]
+        :type times: ``typing.Optional[typing.Tuple[int, int]]``
         :rtype: None
 
         .. versionadded:: 1.0.0
@@ -370,16 +378,47 @@ API: SSHClient and SSHAuth.
 
         Check, that path is file using SFTP session.
 
+        :param path: remote path to validate
         :type path: ``str``
+        :return: path is file
         :rtype: ``bool``
 
     .. py:method:: isdir(path)
 
         Check, that path is directory using SFTP session.
 
+        :param path: remote path to validate
+        :type path: ``str``
+        :return: path is directory
+        :rtype: ``bool``
+
+    .. py:method:: islink(path)
+
+        Check, that path is symlink using SFTP session.
+
+        :param path: remote path to validate
         :type path: ``str``
+        :return: path is symlink
         :rtype: ``bool``
 
+    .. py:method:: symlink(source, dest)
+
+        Produce symbolic link like `os.symlink`.
+
+        :param source: source path
+        :type source: ``str``
+        :param dest: source path
+        :type dest: ``str``
+
+    .. py:method:: chmod(path, mode)
+
+        Change the mode (permissions) of a file like `os.chmod`.
+
+        :param path: filesystem object path
+        :type path: ``str``
+        :param mode: new permissions
+        :type mode: ``int``
+
     **Non standard methods:**
 
     .. py:method:: mkdir(path)

exec_helpers/_ssh_client_base.py

@@ -987,7 +987,7 @@ def isfile(self, path: str) -> bool:
         """
         try:
             attrs: paramiko.sftp_attr.SFTPAttributes = self._sftp.lstat(path)
-            return attrs.st_mode & stat.S_IFREG != 0  # type: ignore
+            return stat.S_ISREG(attrs.st_mode)
         except IOError:
             return False
 
@@ -1001,6 +1001,40 @@ def isdir(self, path: str) -> bool:
         """
         try:
             attrs: paramiko.sftp_attr.SFTPAttributes = self._sftp.lstat(path)
-            return attrs.st_mode & stat.S_IFDIR != 0  # type: ignore
+            return stat.S_ISDIR(attrs.st_mode)
         except IOError:
             return False
+
+    def islink(self, path: str) -> bool:
+        """Check, that path is symlink using SFTP session.
+
+        :param path: remote path to validate
+        :type path: str
+        :return: path is symlink
+        :rtype: bool
+        """
+        try:
+            attrs: paramiko.sftp_attr.SFTPAttributes = self._sftp.lstat(path)
+            return stat.S_ISLNK(attrs.st_mode)
+        except IOError:
+            return False
+
+    def symlink(self, source: str, dest: str) -> None:
+        """Produce symbolic link like `os.symlink`.
+
+        :param source: source path
+        :type source: str
+        :param dest: source path
+        :type dest: str
+        """
+        self._sftp.symlink(source, dest)  # pragma: no cover
+
+    def chmod(self, path: str, mode: int) -> None:
+        """Change the mode (permissions) of a file like `os.chmod`.
+
+        :param path: filesystem object path
+        :type path: str
+        :param mode: new permissions
+        :type mode: int
+        """
+        self._sftp.chmod(path, mode)  # pragma: no cover

setup.py

@@ -155,7 +155,7 @@ def get_simple_vars_from_src(src):
                     str, bytes,
                     int, float, complex,
                     list, set, dict, tuple,
-                    None,
+                    None, bool, Ellipsis
                 ]
             ]
 
@@ -189,7 +189,10 @@ def get_simple_vars_from_src(src):
     >>> get_simple_vars_from_src(multiple_assign)
     OrderedDict([('e', 1), ('f', 1), ('g', 1)])
     """
-    ast_data = (ast.Str, ast.Num, ast.List, ast.Set, ast.Dict, ast.Tuple, ast.Bytes, ast.NameConstant)
+    if sys.version_info[:2] < (3, 8):
+        ast_data = (ast.Str, ast.Num, ast.List, ast.Set, ast.Dict, ast.Tuple, ast.Bytes, ast.NameConstant, ast.Ellipsis)
+    else:
+        ast_data = ast.Constant
 
     tree = ast.parse(src)
 
@@ -221,6 +224,7 @@ def get_simple_vars_from_src(src):
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3.6",
     "Programming Language :: Python :: 3.7",
+    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
 ]

test/test_sftp.py

@@ -158,6 +158,38 @@ def __init__(self, mode):
         self.assertFalse(result)
         lstat.assert_called_once_with(dst)
 
+    def test_islink(self, client, *args):
+        class Attrs:
+            def __init__(self, mode):
+                self.st_mode = mode
+
+        ssh, _sftp = self.prepare_sftp_file_tests(client)
+        lstat = mock.Mock()
+        _sftp.attach_mock(lstat, "lstat")
+        lstat.return_value = Attrs(stat.S_IFLNK)
+        dst = "/etc/passwd"
+
+        # noinspection PyTypeChecker
+        result = ssh.islink(dst)
+        self.assertTrue(result)
+        lstat.assert_called_once_with(dst)
+
+        # Negative scenario
+        lstat.reset_mock()
+        lstat.return_value = Attrs(stat.S_IFREG)
+
+        # noinspection PyTypeChecker
+        result = ssh.islink(dst)
+        self.assertFalse(result)
+        lstat.assert_called_once_with(dst)
+
+        lstat.reset_mock()
+        lstat.side_effect = IOError
+        # noinspection PyTypeChecker
+        result = ssh.islink(dst)
+        self.assertFalse(result)
+        lstat.assert_called_once_with(dst)
+
     @mock.patch("exec_helpers.ssh_client.SSHClient.exists")
     @mock.patch("exec_helpers.ssh_client.SSHClient.execute")
     def test_mkdir(self, execute, exists, *args):