1 files changed, 101 insertions, 0 deletions
diff --git a/src/setuptools_scm/_file_finders/__init__.py b/src/setuptools_scm/_file_finders/__init__.py
new file mode 100644
index 0000000..5a7a1c0
--- /dev/null
+++ b/src/setuptools_scm/_file_finders/__init__.py
@@ -0,0 +1,101 @@
+from __future__ import annotations
+
+import itertools
+import os
+from typing import Callable
+
+from typing_extensions import TypeGuard
+
+from setuptools_scm import _types as _t
+from setuptools_scm._entrypoints import iter_entry_points
+from setuptools_scm._trace import trace
+
+
+def scm_find_files(
+    path: _t.PathT,
+    scm_files: set[str],
+    scm_dirs: set[str],
+    force_all_files: bool = False,
+) -> list[str]:
+    """ setuptools compatible file finder that follows symlinks
+
+    - path: the root directory from which to search
+    - scm_files: set of scm controlled files and symlinks
+      (including symlinks to directories)
+    - scm_dirs: set of scm controlled directories
+      (including directories containing no scm controlled files)
+    - force_all_files: ignore ``scm_files`` and ``scm_dirs`` and list everything.
+
+    scm_files and scm_dirs must be absolute with symlinks resolved (realpath),
+    with normalized case (normcase)
+
+    Spec here: http://setuptools.readthedocs.io/en/latest/setuptools.html#\
+        adding-support-for-revision-control-systems
+    """
+    realpath = os.path.normcase(os.path.realpath(path))
+    seen: set[str] = set()
+    res: list[str] = []
+    for dirpath, dirnames, filenames in os.walk(realpath, followlinks=True):
+        # dirpath with symlinks resolved
+        realdirpath = os.path.normcase(os.path.realpath(dirpath))
+
+        def _link_not_in_scm(n: str) -> bool:
+            fn = os.path.join(realdirpath, os.path.normcase(n))
+            return os.path.islink(fn) and fn not in scm_files
+
+        if not force_all_files and realdirpath not in scm_dirs:
+            # directory not in scm, don't walk it's content
+            dirnames[:] = []
+            continue
+        if os.path.islink(dirpath) and not os.path.relpath(
+            realdirpath, realpath
+        ).startswith(os.pardir):
+            # a symlink to a directory not outside path:
+            # we keep it in the result and don't walk its content
+            res.append(os.path.join(path, os.path.relpath(dirpath, path)))
+            dirnames[:] = []
+            continue
+        if realdirpath in seen:
+            # symlink loop protection
+            dirnames[:] = []
+            continue
+        dirnames[:] = [
+            dn for dn in dirnames if force_all_files or not _link_not_in_scm(dn)
+        ]
+        for filename in filenames:
+            if not force_all_files and _link_not_in_scm(filename):
+                continue
+            # dirpath + filename with symlinks preserved
+            fullfilename = os.path.join(dirpath, filename)
+            is_tracked = os.path.normcase(os.path.realpath(fullfilename)) in scm_files
+            if force_all_files or is_tracked:
+                res.append(os.path.join(path, os.path.relpath(fullfilename, realpath)))
+        seen.add(realdirpath)
+    return res
+
+
+def is_toplevel_acceptable(toplevel: str | None) -> TypeGuard[str]:
+    """ """
+    if toplevel is None:
+        return False
+
+    ignored: list[str] = os.environ.get("SETUPTOOLS_SCM_IGNORE_VCS_ROOTS", "").split(
+        os.pathsep
+    )
+    ignored = [os.path.normcase(p) for p in ignored]
+
+    trace(toplevel, ignored)
+
+    return toplevel not in ignored
+
+
+def find_files(path: _t.PathT = "") -> list[str]:
+    for ep in itertools.chain(
+        iter_entry_points("setuptools_scm.files_command"),
+        iter_entry_points("setuptools_scm.files_command_fallback"),
+    ):
+        command: Callable[[_t.PathT], list[str]] = ep.load()
+        res: list[str] = command(path)
+        if res:
+            return res
+    return []