first draft symlinks

.gitignore

@@ -8,6 +8,7 @@ datastore_server/source/core-plugins
 openbis/source/core-plugins
 */bin/*
 **/.DS_Store
+*__pycache__/
 *$py.class
 **/.pydevproject
 **/.shredder

pybis/src/python/pybis/dataset.py

@@ -162,6 +162,9 @@ class DataSet(
             return self.data['physicalData']['status']
         except Exception:
             return None
+    @property
+    def sftp_path(self):
+        return os.path(self.experiment.identifier[1:], self.permId)
 
     def archive(self, remove_from_data_store=True):
         fetchopts = {

pybis/src/python/pybis/utils.py

@@ -255,3 +255,47 @@ def extract_userId(user):
         return str(user)
 
 
+def check_symlink(target_dir: str) -> Path:
+    # there are several options: basically resolvable symlink, non-resolvable symlink, does not exist at all or exists but it is not a symlink
+
+    target_dir_path = Path(target_dir)
+
+    if target_dir_path.is_symlink() and target_dir_path.exists():
+        return target_dir_path.resolve()
+    elif target_dir_path.is_symlink() and not target_dir_path.exists():
+        raise FileNotFoundError(
+            f"target_dir={target_dir} is non-resolvable symlink. No such file or directory: {target_dir_path.resolve()}"
+        )
+    elif not target_dir_path.is_symlink() and not target_dir_path.exists():
+        raise FileNotFoundError(f"target_dir={target_dir} does not exist")
+    else:
+        raise ValueError(f"target_dir={target_dir} exists but it is not a symlink")
+
+
+def create_symlink(
+    target_dir: str, source_dir: str, mountpoint: str, replace_if_symlink: bool = True
+):
+    # Path(mountpoint,ds.experiment.identifier[1:],ds.permId)
+    # replace_if_symlink will replace the the target_dir in case it is an existing symlink
+
+    mountpoint_path = Path(mountpoint)
+
+    # check mountpoint
+    if not mountpoint_path.is_mount():
+        if not mountpoint_path.exists():
+            raise FileNotFoundError(f"mountpoint={mountpoint} does not exist")
+        else:
+            raise ValueError(f"mountpoint={mountpoint} exists but it is not a mount")
+
+    # join mountpoint and source_dir
+    # if source_dir is absolute we have to remove "/" to be able to join it with mountpoint
+    # I did not find any way to achieve this in case they are pathlib.Path
+    if source_dir[0] == "/":
+        source_dir = source_dir[1:]
+    source_dir_path = Path(mountpoint, source_dir)
+
+    target_dir_path = Path(target_dir)
+    if target_dir_path.is_symlink() and replace_if_symlink:
+        target_dir_path.unlink()
+
+    target_dir_path.symlink_to(source_dir_path, target_is_directory=True)
\ No newline at end of file