repofs: use / as root_marker

This makes dvcfs/repofs much easier to work with and allows it to support
isabs/abspath/etc correctly, as previously any full path (with root_marker "")
would be impossible to distinguish from a relative one.

This also detaches external workspaces from the main repo workspace in
DvcFileSystem, which was necessary to be able to distinguish dvcfs abspaths
from local external output paths. Note that currently we still have limited
support for those (e.g. get/api supports them, but import doesn't) and this
change keeps it that way.

dvc/api.py

@@ -19,8 +19,9 @@ def get_url(path, repo=None, rev=None, remote=None):
     directory in the remote storage.
     """
     with Repo.open(repo, rev=rev, subrepos=True, uninitialized=True) as _repo:
+        fs_path = _repo.repo_fs.from_os_path(path)
         with reraise(FileNotFoundError, PathMissingError(path, repo)):
-            info = _repo.repo_fs.info(path)
+            info = _repo.repo_fs.info(fs_path)
 
         dvc_info = info.get("dvc_info")
         if not dvc_info:

dvc/fs/base.py

@@ -83,7 +83,10 @@ def config(self) -> Dict[str, Any]:
     def path(self):
         from .path import Path
 
-        return Path(self.sep)
+        def _getcwd():
+            return self.fs.root_marker
+
+        return Path(self.sep, getcwd=_getcwd)
 
     @classmethod
     def _strip_protocol(cls, path: str) -> str:

dvc/fs/dvc.py

@@ -1,5 +1,4 @@
 import logging
-import os
 import threading
 import typing
 
@@ -22,31 +21,43 @@ class _DvcFileSystem(AbstractFileSystem):  # pylint:disable=abstract-method
         repo: DVC repo.
     """
 
-    def __init__(self, **kwargs):
+    root_marker = "/"
+
+    def __init__(self, workspace=None, **kwargs):
         super().__init__(**kwargs)
         self.repo = kwargs["repo"]
+        self.workspace = workspace or "repo"
+
+    @cached_property
+    def path(self):
+        from .path import Path
+
+        def _getcwd():
+            return self.root_marker
+
+        return Path(self.sep, getcwd=_getcwd)
 
     @property
     def config(self):
         raise NotImplementedError
 
     def _get_key(self, path):
-        from dvc.fs.local import LocalFileSystem
-
-        from . import get_cloud_fs
+        if self.workspace != "repo":
+            from . import get_cloud_fs
 
-        cls, kwargs, fs_path = get_cloud_fs(None, url=path)
-
-        if cls != LocalFileSystem or os.path.isabs(path):
+            cls, kwargs, fs_path = get_cloud_fs(None, url=path)
             fs = cls(**kwargs)
-            return (cls.scheme, *fs.path.parts(fs_path))
+            return (self.workspace, *fs.path.parts(fs_path))
+
+        path = self.path.abspath(path)
+        if path == self.root_marker:
+            return (self.workspace,)
 
-        fs_key = "repo"
-        key = path.split(self.sep)
-        if key == ["."] or key == [""]:
+        key = self.path.relparts(path, self.root_marker)
+        if key == (".") or key == (""):
             key = ()
 
-        return (fs_key, *key)
+        return (self.workspace, *key)
 
     def _get_fs_path(self, path: "AnyPath", remote=None):
         from dvc.config import NoRemoteError

dvc/fs/git.py

@@ -40,6 +40,12 @@ def __init__(
             }
         )
 
+    @cached_property
+    def path(self):
+        from .path import Path
+
+        return Path(self.sep, getcwd=os.getcwd)
+
     @wrap_prop(threading.Lock())
     @cached_property
     def fs(self) -> "FsspecGitFileSystem":

dvc/fs/path.py

@@ -105,7 +105,11 @@ def overlaps(self, left, right):
         return self.isin_or_eq(left, right) or self.isin(right, left)
 
     def relpath(self, path, start):
-        return self.flavour.relpath(path, start=start)
+        if not start:
+            start = "."
+        return self.flavour.relpath(
+            self.abspath(path), start=self.abspath(start)
+        )
 
     def relparts(self, path, base):
         return self.parts(self.relpath(path, base))

dvc/fs/repo.py

@@ -73,6 +73,8 @@ class _RepoFileSystem(AbstractFileSystem):  # pylint:disable=abstract-method
         kwargs: Additional keyword arguments passed to the `DvcFileSystem()`.
     """
 
+    root_marker = "/"
+
     PARAM_REPO_URL = "repo_url"
     PARAM_REPO_ROOT = "repo_root"
     PARAM_REV = "rev"
@@ -103,7 +105,10 @@ def __init__(
         else:
             self.repo_factory = repo_factory
 
-        self.path = Path(self.sep)
+        def _getcwd():
+            return self.root_marker
+
+        self.path = Path(self.sep, getcwd=_getcwd)
         self.repo = repo
         self.hash_jobs = repo.fs.hash_jobs
         self._traverse_subrepos = subrepos
@@ -258,17 +263,7 @@ def _get_fs_pair(
         """
         Returns a pair of fss based on repo the path falls in, using prefix.
         """
-        from dvc.utils import as_posix
-
-        if os.path.isabs(path):
-            if self.repo.fs.path.isin_or_eq(path, self.repo.root_dir):
-                path = self.repo.fs.path.relpath(path, self.repo.root_dir)
-            else:
-                return None, None, self.repo.dvcfs, path
-
-        path = as_posix(path)
-
-        parts = self.path.parts(path)
+        parts = self.path.relparts(path, self.root_marker)
         if parts and parts[0] == os.curdir:
             parts = parts[1:]
 
@@ -461,3 +456,11 @@ def repo_url(self):
     @property
     def config(self):
         return self.fs.config
+
+    def from_os_path(self, path):
+        from dvc.utils import as_posix
+
+        if os.path.isabs(path):
+            path = os.path.relpath(path, self.repo.root_dir)
+
+        return as_posix(path)

dvc/repo/__init__.py

@@ -491,12 +491,22 @@ def index_db_dir(self):
     @contextmanager
     def open_by_relpath(self, path, remote=None, mode="r", encoding=None):
         """Opens a specified resource as a file descriptor"""
+        from dvc.fs.dvc import DvcFileSystem
         from dvc.fs.repo import RepoFileSystem
 
-        fs = RepoFileSystem(repo=self, subrepos=True)
+        if os.path.isabs(path):
+            fs = DvcFileSystem(repo=self, workspace="local")
+            fs_path = path
+        else:
+            fs = RepoFileSystem(repo=self, subrepos=True)
+            fs_path = fs.from_os_path(path)
+
         try:
             with fs.open(
-                path, mode=mode, encoding=encoding, remote=remote
+                fs_path,
+                mode=mode,
+                encoding=encoding,
+                remote=remote,
             ) as fobj:
                 yield fobj
         except FileNotFoundError as exc:

dvc/repo/collect.py

@@ -1,5 +1,4 @@
 import logging
-import os
 from typing import TYPE_CHECKING, Callable, Iterable, List, Tuple
 
 from dvc.types import AnyPath
@@ -34,8 +33,8 @@ def _collect_paths(
     from dvc.fs.repo import RepoFileSystem
     from dvc.utils import relpath
 
-    fs_paths = [os.path.abspath(target) for target in targets]
     fs = RepoFileSystem(repo=repo)
+    fs_paths = [fs.from_os_path(target) for target in targets]
 
     target_paths: StrPaths = []
     for fs_path in fs_paths:
@@ -60,10 +59,11 @@ def _filter_duplicates(
     fs_res_paths = fs_paths
 
     for out in outs:
-        if out.fs_path in fs_paths:
+        fs_path = out.repo.repo_fs.from_os_path(out.fs_path)
+        if fs_path in fs_paths:
             res_outs.append(out)
             # MUTATING THE SAME LIST!!
-            fs_res_paths.remove(out.fs_path)
+            fs_res_paths.remove(fs_path)
 
     return res_outs, fs_res_paths
 

dvc/repo/diff.py

@@ -186,8 +186,9 @@ def _dir_output_paths(fs, fs_path, obj, targets=None):
 
 def _filter_missing(repo_fs, paths):
     for path in paths:
+        fs_path = repo_fs.from_os_path(path)
         try:
-            info = repo_fs.info(path)
+            info = repo_fs.info(fs_path)
             dvc_info = info.get("dvc_info")
             if (
                 dvc_info

dvc/repo/get.py

@@ -50,14 +50,26 @@ def get(url, path, out=None, rev=None, jobs=None):
         with external_repo(
             url=url, rev=rev, cache_dir=tmp_dir, cache_types=cache_types
         ) as repo:
-            fs = repo.repo_fs
+
+            if os.path.isabs(path):
+                from dvc.fs.dvc import DvcFileSystem
+
+                fs = DvcFileSystem(repo=repo, workspace="local")
+                fs_path = path
+            else:
+                fs = repo.repo_fs
+                fs_path = fs.from_os_path(path)
+
             with FsspecCallback.as_tqdm_callback(
                 total=-1,
                 desc=f"Downloading {fs.path.name(path)}",
                 unit="files",
             ) as cb:
                 fs.get(
-                    path, os.path.abspath(out), batch_size=jobs, callback=cb
+                    fs_path,
+                    os.path.abspath(out),
+                    batch_size=jobs,
+                    callback=cb,
                 )
     finally:
         remove(tmp_dir)

dvc/repo/ls.py

@@ -45,8 +45,10 @@ def ls(url, path=None, rev=None, recursive=None, dvc_only=False):
 
 
 def _ls(fs, path, recursive=None, dvc_only=False):
+    fs_path = fs.from_os_path(path)
+
     try:
-        fs_path = fs.info(path)["name"]
+        fs_path = fs.info(fs_path)["name"]
     except FileNotFoundError:
         return {}
 

dvc/repo/metrics/show.py

@@ -24,11 +24,11 @@ def _to_fs_paths(metrics: List[Output]) -> StrPaths:
     result = []
     for out in metrics:
         if out.metric:
-            result.append(out.fs_path)
+            result.append(out.repo.repo_fs.from_os_path(out.fs_path))
         elif out.live:
             fs_path = summary_fs_path(out)
             if fs_path:
-                result.append(fs_path)
+                result.append(out.repo.repo_fs.from_os_path(fs_path))
     return result
 
 
@@ -78,12 +78,16 @@ def _read_metric(path, fs, rev, **kwargs):
 def _read_metrics(repo, metrics, rev, onerror=None):
     fs = RepoFileSystem(repo=repo)
 
+    relpath = ""
+    if repo.root_dir != repo.fs.path.getcwd():
+        relpath = repo.fs.path.relpath(repo.root_dir, repo.fs.path.getcwd())
+
     res = {}
     for metric in metrics:
         if not fs.isfile(metric):
             continue
 
-        res[os.path.relpath(metric, os.getcwd())] = _read_metric(
+        res[os.path.join(relpath, *fs.path.parts(metric))] = _read_metric(
             metric, fs, rev, onerror=onerror
         )
 

dvc/repo/plots/__init__.py

@@ -251,7 +251,10 @@ def _collect_plots(
         recursive=recursive,
     )
 
-    result = {plot.fs_path: _plot_props(plot) for plot in plots}
+    result = {
+        repo.repo_fs.from_os_path(plot.fs_path): _plot_props(plot)
+        for plot in plots
+    }
     result.update({fs_path: {} for fs_path in fs_paths})
     return result
 

tests/unit/fs/test_dvc.py

@@ -15,6 +15,7 @@
     [
         ("", ("repo",)),
         (".", ("repo",)),
+        ("/", ("repo",)),
         ("foo", ("repo", "foo")),
         ("dir/foo", ("repo", "dir", "foo")),
     ],

tests/unit/fs/test_repo.py

@@ -474,16 +474,16 @@ def test_repo_fs_no_subrepos(tmp_dir, dvc, scm):
     dvc._reset()
     fs = RepoFileSystem(repo=dvc)
     expected = [
-        ".dvcignore",
-        ".gitignore",
-        "lorem",
-        "lorem.dvc",
-        "dir",
-        "dir/repo.txt",
+        "/.dvcignore",
+        "/.gitignore",
+        "/lorem",
+        "/lorem.dvc",
+        "/dir",
+        "/dir/repo.txt",
     ]
 
     actual = []
-    for root, dirs, files in fs.walk("", dvcfiles=True):
+    for root, dirs, files in fs.walk("/", dvcfiles=True):
         for entry in dirs + files:
             actual.append(posixpath.join(root, entry))
 
@@ -657,9 +657,9 @@ def dvc_structure(suffix):
 
         if traverse_subrepos or repo_dir == tmp_dir:
             repo_dir_path = (
-                repo_dir.relative_to(tmp_dir).as_posix()
+                "/" + repo_dir.relative_to(tmp_dir).as_posix()
                 if repo_dir != tmp_dir
-                else ""
+                else "/"
             )
             expected[repo_dir_path] = set(
                 scm_files.keys() | dvc_files.keys() | extras
@@ -675,13 +675,13 @@ def dvc_structure(suffix):
 
     if traverse_subrepos:
         # update subrepos
-        expected[""].update(["subrepo1", "subrepo2"])
-        expected["subrepo1"].add("subrepo3")
+        expected["/"].update(["subrepo1", "subrepo2"])
+        expected["/subrepo1"].add("subrepo3")
 
     actual = {}
     fs = RepoFileSystem(repo=dvc)
     for root, dirs, files in fs.walk(
-        "", ignore_subrepos=not traverse_subrepos
+        "/", ignore_subrepos=not traverse_subrepos
     ):
         actual[root] = set(dirs + files)
     assert expected == actual

tests/unit/fs/test_repo_info.py

@@ -137,10 +137,3 @@ def test_info_on_subrepos(make_tmp_dir, tmp_dir, dvc, scm, repo_fs):
         assert info["repo"].root_dir == str(
             subrepo
         ), f"repo root didn't match for {path}"
-
-    # supports external outputs on top-level DVC repo
-    external_dir = make_tmp_dir("external-output")
-    external_dir.gen("bar", "bar")
-    dvc.add(str(external_dir / "bar"), external=True)
-    info = repo_fs.info((external_dir / "bar").fs_path)
-    assert info["repo"].root_dir == str(tmp_dir)