From 44be331a97d0b410d2d64d5d4813a63143f7508e Mon Sep 17 00:00:00 2001
From: Leonard Crestez <cdleonard@gmail.com>
Date: Tue, 1 Sep 2020 07:02:27 +0300
Subject: [PATCH] Initial symlink creation support

Implemented only in OSFS but with tests in FSTestCases

Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
---
 fs/base.py   | 17 +++++++++++++++++
 fs/osfs.py   |  6 ++++++
 fs/test.py   | 32 ++++++++++++++++++++++++++++++++
 fs/wrapfs.py |  4 ++++
 4 files changed, 59 insertions(+)

diff --git a/fs/base.py b/fs/base.py
index a4b7aefb..40f39ad7 100644
--- a/fs/base.py
+++ b/fs/base.py
@@ -310,6 +310,21 @@ def setinfo(self, path, info):
 
         """
 
+    def symlink(self, src, dst):
+        # type: (Text, Text) -> None
+        """Create a symbolic link pointing to src named dst.
+
+        Arguments:
+            src (str): Path to target
+            dst (str): Path to symlink
+
+        Raises:
+            fs.errors.ResourceNotFound: If ``path`` does not exist
+                on the filesystem
+            NotImplementedError: If not supported by underlying filesystem.
+        """
+        raise NotImplementedError()
+
     # ---------------------------------------------------------------- #
     # Optional methods                                                 #
     # Filesystems *may* implement these methods.                       #
@@ -709,6 +724,8 @@ def getmeta(self, namespace="standard"):
         read_only           `True` if this filesystem is read only.
         supports_rename     `True` if this filesystem supports an
                             `os.rename` operation.
+        symlink             `True` if this filesystem supports an
+                            `os.symlink` operation.
         =================== ============================================
 
         Most builtin filesystems will provide all these keys, and third-
diff --git a/fs/osfs.py b/fs/osfs.py
index ec68d0ad..96f4ea67 100644
--- a/fs/osfs.py
+++ b/fs/osfs.py
@@ -146,6 +146,7 @@ def __init__(
             "thread_safe": True,
             "unicode_paths": os.path.supports_unicode_filenames,
             "virtual": False,
+            "symlink": bool(getattr(os, 'symlink', None)),
         }
 
         try:
@@ -676,3 +677,8 @@ def validatepath(self, path):
                     " env var); {error}".format(path=path, error=error),
             )
         return super(OSFS, self).validatepath(path)
+
+    def symlink(self, src, dst):
+        _dst = self._to_sys_path(self.validatepath(dst))
+        with convert_os_errors("symlink", _dst):
+            return os.symlink(src, _dst)
diff --git a/fs/test.py b/fs/test.py
index 53ed290e..d46a1650 100644
--- a/fs/test.py
+++ b/fs/test.py
@@ -1852,3 +1852,35 @@ def test_hash(self):
             self.assertEqual(
                 foo_fs.hash("hashme.txt", "md5"), "9fff4bb103ab8ce4619064109c54cb9c"
             )
+
+    def test_create_symlink(self):
+        if not self.fs.getmeta().get("symlink", False):
+            raise unittest.SkipTest("the filesystem does not support symlinks.")
+        self.fs.writetext('a', 'hello')
+        self.fs.symlink('a', 'b')
+        info = self.fs.getinfo('b', namespaces=['link'])
+        self.assertTrue(info.is_link)
+        self.assertEqual(info.target, 'a')
+        read_text = self.fs.readtext('b', 'utf8')
+        self.assertEqual('hello', read_text)
+
+    def test_create_symlink_dir(self):
+        if not self.fs.getmeta().get("symlink", False):
+            raise unittest.SkipTest("the filesystem does not support symlinks.")
+        self.fs.makedirs('a1/a2')
+        self.fs.writetext('a1/a2/file.txt', 'hello')
+        self.fs.makedir('b1')
+        self.fs.symlink('../a1/a2', 'b1/b2')
+        b1 = self.fs.opendir('b1')
+        self.assertTrue(b1.islink('b2'))
+        b2 = b1.opendir('b2')
+        self.assertEqual('hello', b2.readtext('file.txt', 'utf8'))
+
+    def test_create_symlink_target_exists(self):
+        # Check it behaves like os.symlink and ln -T:
+        # if target is directory don't create inside directory
+        if not self.fs.getmeta().get("symlink", False):
+            raise unittest.SkipTest("the filesystem does not support symlinks.")
+        self.fs.makedir('dst')
+        with self.assertRaises(errors.FileExists):
+            self.fs.symlink('src', 'dst')
diff --git a/fs/wrapfs.py b/fs/wrapfs.py
index c09e9cf3..c27575e0 100644
--- a/fs/wrapfs.py
+++ b/fs/wrapfs.py
@@ -538,3 +538,7 @@ def hash(self, path, name):
     def walk(self):
         # type: () -> BoundWalker
         return self._wrap_fs.walker_class.bind(self)
+
+    def symlink(self, src, dst):
+        _fs, _dst = self.delegate_path(dst)
+        return _fs.symlink(src, _dst)