utils: support use of (GitTree) tree file objects in utils (#3819)

* GitTree: add stat() function

* BaseTree: make walk_files a base tree method

* WorkingTree: add stat() method (wrapper for os.stat)

* utils.fs: support non-working tree for get_mtime_and_size

* utils.fs: add copy_fobj_to_file

* utils: support using tree.open in file_md5

dvc/ignore.py

@@ -139,7 +139,5 @@ class CleanTree(BaseTree):
 
             yield root, dirs, files
 
-    def walk_files(self, top):
-        for root, _, files in self.walk(top):
-            for file in files:
-                yield os.path.join(root, file)
+    def stat(self, path):
+        return self.tree.stat(path)

dvc/scm/git/tree.py

@@ -1,6 +1,7 @@
 import errno
 import io
 import os
+import stat
 
 from dvc.exceptions import DvcException
 from dvc.scm.tree import BaseTree
@@ -87,7 +88,9 @@ class GitTree(BaseTree):
         import git
 
         path = relpath(os.path.realpath(path), self.git.working_dir)
-        assert path.split(os.sep, 1)[0] != ".."
+        if path.split(os.sep, 1)[0] == "..":
+            # path points outside of git repository
+            return None
 
         try:
             tree = self.git.tree(self.rev)
@@ -138,3 +141,40 @@ class GitTree(BaseTree):
             raise OSError(errno.ENOENT, "No such file")
 
         yield from self._walk(tree, topdown=topdown)
+
+    def isexec(self, path):
+        if not self.exists(path):
+            return False
+
+        mode = self.stat(path).st_mode
+        return mode & (stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
+
+    def stat(self, path):
+        import git
+
+        def to_ctime(git_time):
+            sec, nano_sec = git_time
+            return sec + nano_sec / 1000000000
+
+        obj = self.git_object_by_path(path)
+        if obj is None:
+            raise OSError(errno.ENOENT, "No such file")
+        entry = git.index.IndexEntry.from_blob(obj)
+
+        # os.stat_result takes a tuple in the form:
+        #   (mode, ino, dev, nlink, uid, gid, size, atime, mtime, ctime)
+        return os.stat_result(
+            (
+                entry.mode,
+                entry.inode,
+                entry.dev,
+                0,
+                entry.uid,
+                entry.gid,
+                entry.size,
+                # git index has no atime equivalent, use mtime
+                to_ctime(entry.mtime),
+                to_ctime(entry.mtime),
+                to_ctime(entry.ctime),
+            )
+        )

dvc/scm/tree.py

@@ -29,6 +29,11 @@ class BaseTree:
         - it could raise exceptions, there is no onerror argument
         """
 
+    def walk_files(self, top):
+        for root, _, files in self.walk(top):
+            for file in files:
+                yield os.path.join(root, file)
+
 
 class WorkingTree(BaseTree):
     """Proxies the repo file access methods to working tree files"""
@@ -42,6 +47,8 @@ class WorkingTree(BaseTree):
 
     def open(self, path, mode="r", encoding="utf-8"):
         """Open file and return a stream."""
+        if "b" in mode:
+            encoding = None
         return open(path, mode=mode, encoding=encoding)
 
     def exists(self, path):
@@ -76,6 +83,10 @@ class WorkingTree(BaseTree):
         mode = os.stat(path).st_mode
         return mode & (stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
 
+    @staticmethod
+    def stat(path):
+        return os.stat(path)
+
 
 def is_working_tree(tree):
     return isinstance(tree, WorkingTree) or isinstance(

dvc/utils/__init__.py

@@ -27,15 +27,44 @@ def dos2unix(data):
     return data.replace(b"\r\n", b"\n")
 
 
-def file_md5(fname):
+def _fobj_md5(fobj, hash_md5, binary, progress_func=None):
+    while True:
+        data = fobj.read(LOCAL_CHUNK_SIZE)
+        if not data:
+            break
+
+        if binary:
+            chunk = data
+        else:
+            chunk = dos2unix(data)
+
+        hash_md5.update(chunk)
+        if progress_func:
+            progress_func(len(data))
+
+
+def file_md5(fname, tree=None):
     """ get the (md5 hexdigest, md5 digest) of a file """
     from dvc.progress import Tqdm
     from dvc.istextfile import istextfile
 
-    if os.path.exists(fname):
+    if tree:
+        exists_func = tree.exists
+        stat_func = tree.stat
+        open_func = tree.open
+        # assume we don't need to run dos2unix when comparing git blobs
+        binary = True
+    else:
+        exists_func = os.path.exists
+        stat_func = os.stat
+        open_func = open
+        binary = False
+
+    if exists_func(fname):
         hash_md5 = hashlib.md5()
-        binary = not istextfile(fname)
-        size = os.path.getsize(fname)
+        if not binary:
+            binary = not istextfile(fname)
+        size = stat_func(fname).st_size
         no_progress_bar = True
         if size >= LARGE_FILE_SIZE:
             no_progress_bar = False
@@ -52,19 +81,8 @@ def file_md5(fname):
             bytes=True,
             leave=False,
         ) as pbar:
-            with open(fname, "rb") as fobj:
-                while True:
-                    data = fobj.read(LOCAL_CHUNK_SIZE)
-                    if not data:
-                        break
-
-                    if binary:
-                        chunk = data
-                    else:
-                        chunk = dos2unix(data)
-
-                    hash_md5.update(chunk)
-                    pbar.update(len(data))
+            with open_func(fname, "rb") as fobj:
+                _fobj_md5(fobj, hash_md5, binary, pbar.update)
 
         return (hash_md5.hexdigest(), hash_md5.digest())
 

dvc/utils/fs.py

@@ -9,7 +9,6 @@ import nanotime
 from shortuuid import uuid
 
 from dvc.exceptions import DvcException
-from dvc.scm.tree import is_working_tree
 from dvc.system import System
 from dvc.utils import dict_md5
 
@@ -33,14 +32,12 @@ def get_inode(path):
 
 def get_mtime_and_size(path, tree):
 
-    if os.path.isdir(path):
-        assert is_working_tree(tree)
-
+    if tree.isdir(path):
         size = 0
         files_mtimes = {}
         for file_path in tree.walk_files(path):
             try:
-                stats = os.stat(file_path)
+                stats = tree.stat(file_path)
             except OSError as exc:
                 # NOTE: broken symlink case.
                 if exc.errno != errno.ENOENT:
@@ -53,7 +50,7 @@ def get_mtime_and_size(path, tree):
         # max(mtime(f) for f in non_ignored_files)
         mtime = dict_md5(files_mtimes)
     else:
-        base_stat = os.stat(path)
+        base_stat = tree.stat(path)
         size = base_stat.st_size
         mtime = base_stat.st_mtime
         mtime = int(nanotime.timestamp(mtime))
@@ -175,7 +172,6 @@ def copyfile(src, dest, no_progress_bar=False, name=None):
     """Copy file with progress bar"""
     from dvc.exceptions import DvcException
     from dvc.progress import Tqdm
-    from dvc.system import System
 
     name = name if name else os.path.basename(dest)
     total = os.stat(src).st_size
@@ -202,6 +198,12 @@ def copyfile(src, dest, no_progress_bar=False, name=None):
                     fdest_wrapped.write(buf)
 
 
+def copy_fobj_to_file(fsrc, dest):
+    """Copy contents of open file object to destination path."""
+    with open(dest, "wb+") as fdest:
+        shutil.copyfileobj(fsrc, fdest)
+
+
 def walk_files(directory):
     for root, _, files in os.walk(directory):
         for f in files:

tests/unit/utils/test_fs.py

@@ -14,6 +14,7 @@ from dvc.utils import relpath
 from dvc.utils.fs import (
     BasePathNotInCheckedPathException,
     contains_symlink_up_to,
+    copy_fobj_to_file,
     copyfile,
     get_inode,
     get_mtime_and_size,
@@ -260,5 +261,15 @@ def test_copyfile(path, tmp_dir):
         assert filecmp.cmp(src_info, dest_info, shallow=False)
 
 
+def test_copy_fobj_to_file(tmp_dir):
+    tmp_dir.gen({"foo": "foo content"})
+    src = tmp_dir / "foo"
+    dest = "path"
+
+    with open(src, "rb") as fobj:
+        copy_fobj_to_file(fobj, dest)
+    assert filecmp.cmp(src, dest)
+
+
 def test_walk_files(tmp_dir):
     assert list(walk_files(".")) == list(walk_files(tmp_dir))