bpo-38144: Add the root_dir and dir_fd parameters in glob.glob(). (GH-16075)

5 files changed, 175 insertions, 47 deletions

diff --git a/Doc/library/glob.rst b/Doc/library/glob.rst
index 92a8c4d..280e9f0 100644
--- a/Doc/library/glob.rst
+++ b/Doc/library/glob.rst
@@ -36,7 +36,7 @@ For example, ``'[?]'`` matches the character ``'?'``.
    The :mod:`pathlib` module offers high-level path objects.
 
 
-.. function:: glob(pathname, *, recursive=False)
+.. function:: glob(pathname, *, root_dir=None, dir_fd=None, recursive=False)
 
    Return a possibly-empty list of path names that match *pathname*, which must be
    a string containing a path specification. *pathname* can be either absolute
@@ -45,6 +45,15 @@ For example, ``'[?]'`` matches the character ``'?'``.
    symlinks are included in the results (as in the shell). Whether or not the
    results are sorted depends on the file system.
 
+   If *root_dir* is not ``None``, it should be a :term:`path-like object`
+   specifying the root directory for searching.  It has the same effect on
+   :func:`glob` as changing the current directory before calling it.  If
+   *pathname* is relative, the result will contain paths relative to
+   *root_dir*.
+
+   This function can support :ref:`paths relative to directory descriptors
+   <dir_fd>` with the *dir_fd* parameter.
+
    .. index::
       single: **; in glob-style wildcards
 
@@ -62,8 +71,11 @@ For example, ``'[?]'`` matches the character ``'?'``.
    .. versionchanged:: 3.5
       Support for recursive globs using "``**``".
 
+   .. versionchanged:: 3.10
+      Added the *root_dir* and *dir_fd* parameters.
+
 
-.. function:: iglob(pathname, *, recursive=False)
+.. function:: iglob(pathname, *, root_dir=None, dir_fd=None, recursive=False)
 
    Return an :term:`iterator` which yields the same values as :func:`glob`
    without actually storing them all simultaneously.
diff --git a/Doc/whatsnew/3.10.rst b/Doc/whatsnew/3.10.rst
index f956ddd..566827b 100644
--- a/Doc/whatsnew/3.10.rst
+++ b/Doc/whatsnew/3.10.rst
@@ -100,6 +100,14 @@ New Modules
 Improved Modules
 ================
 
+glob
+----
+
+Added the *root_dir* and *dir_fd* parameters in :func:`~glob.glob` and
+:func:`~glob.iglob` which allow to specify the root directory for searching.
+(Contributed by Serhiy Storchaka in :issue:`38144`.)
+
+
 Optimizations
 =============
 
diff --git a/Lib/glob.py b/Lib/glob.py
index 0dd2f8b..3c449a9 100644
--- a/Lib/glob.py
+++ b/Lib/glob.py
@@ -3,11 +3,13 @@
 import os
 import re
 import fnmatch
+import itertools
+import stat
 import sys
 
 __all__ = ["glob", "iglob", "escape"]
 
-def glob(pathname, *, recursive=False):
+def glob(pathname, *, root_dir=None, dir_fd=None, recursive=False):
     """Return a list of paths matching a pathname pattern.
 
     The pattern may contain simple shell-style wildcards a la
@@ -18,9 +20,9 @@ def glob(pathname, *, recursive=False):
     If recursive is true, the pattern '**' will match any files and
     zero or more directories and subdirectories.
     """
-    return list(iglob(pathname, recursive=recursive))
+    return list(iglob(pathname, root_dir=root_dir, dir_fd=dir_fd, recursive=recursive))
 
-def iglob(pathname, *, recursive=False):
+def iglob(pathname, *, root_dir=None, dir_fd=None, recursive=False):
     """Return an iterator which yields the paths matching a pathname pattern.
 
     The pattern may contain simple shell-style wildcards a la
@@ -31,36 +33,43 @@ def iglob(pathname, *, recursive=False):
     If recursive is true, the pattern '**' will match any files and
     zero or more directories and subdirectories.
     """
-    sys.audit("glob.glob", pathname, recursive)
-    it = _iglob(pathname, recursive, False)
-    if recursive and _isrecursive(pathname):
-        s = next(it)  # skip empty string
-        assert not s
+    if root_dir is not None:
+        root_dir = os.fspath(root_dir)
+    else:
+        root_dir = pathname[:0]
+    it = _iglob(pathname, root_dir, dir_fd, recursive, False)
+    if not pathname or recursive and _isrecursive(pathname[:2]):
+        try:
+            s = next(it)  # skip empty string
+            if s:
+                it = itertools.chain((s,), it)
+        except StopIteration:
+            pass
     return it
 
-def _iglob(pathname, recursive, dironly):
+def _iglob(pathname, root_dir, dir_fd, recursive, dironly):
     dirname, basename = os.path.split(pathname)
     if not has_magic(pathname):
         assert not dironly
         if basename:
-            if os.path.lexists(pathname):
+            if _lexists(_join(root_dir, pathname), dir_fd):
                 yield pathname
         else:
             # Patterns ending with a slash should match only directories
-            if os.path.isdir(dirname):
+            if _isdir(_join(root_dir, dirname), dir_fd):
                 yield pathname
         return
     if not dirname:
         if recursive and _isrecursive(basename):
-            yield from _glob2(dirname, basename, dironly)
+            yield from _glob2(root_dir, basename, dir_fd, dironly)
         else:
-            yield from _glob1(dirname, basename, dironly)
+            yield from _glob1(root_dir, basename, dir_fd, dironly)
         return
     # `os.path.split()` returns the argument itself as a dirname if it is a
     # drive or UNC path.  Prevent an infinite recursion if a drive or UNC path
     # contains magic characters (i.e. r'\\?\C:').
     if dirname != pathname and has_magic(dirname):
-        dirs = _iglob(dirname, recursive, True)
+        dirs = _iglob(dirname, root_dir, dir_fd, recursive, True)
     else:
         dirs = [dirname]
     if has_magic(basename):
@@ -71,76 +80,121 @@ def _iglob(pathname, recursive, dironly):
     else:
         glob_in_dir = _glob0
     for dirname in dirs:
-        for name in glob_in_dir(dirname, basename, dironly):
+        for name in glob_in_dir(_join(root_dir, dirname), basename, dir_fd, dironly):
             yield os.path.join(dirname, name)
 
 # These 2 helper functions non-recursively glob inside a literal directory.
 # They return a list of basenames.  _glob1 accepts a pattern while _glob0
 # takes a literal basename (so it only has to check for its existence).
 
-def _glob1(dirname, pattern, dironly):
-    names = list(_iterdir(dirname, dironly))
+def _glob1(dirname, pattern, dir_fd, dironly):
+    names = list(_iterdir(dirname, dir_fd, dironly))
     if not _ishidden(pattern):
         names = (x for x in names if not _ishidden(x))
     return fnmatch.filter(names, pattern)
 
-def _glob0(dirname, basename, dironly):
-    if not basename:
-        # `os.path.split()` returns an empty basename for paths ending with a
-        # directory separator.  'q*x/' should match only directories.
-        if os.path.isdir(dirname):
+def _glob0(dirname, basename, dir_fd, dironly):
+    if basename:
+        if _lexists(_join(dirname, basename), dir_fd):
             return [basename]
     else:
-        if os.path.lexists(os.path.join(dirname, basename)):
+        # `os.path.split()` returns an empty basename for paths ending with a
+        # directory separator.  'q*x/' should match only directories.
+        if _isdir(dirname, dir_fd):
             return [basename]
     return []
 
 # Following functions are not public but can be used by third-party code.
 
 def glob0(dirname, pattern):
-    return _glob0(dirname, pattern, False)
+    return _glob0(dirname, pattern, None, False)
 
 def glob1(dirname, pattern):
-    return _glob1(dirname, pattern, False)
+    return _glob1(dirname, pattern, None, False)
 
 # This helper function recursively yields relative pathnames inside a literal
 # directory.
 
-def _glob2(dirname, pattern, dironly):
+def _glob2(dirname, pattern, dir_fd, dironly):
     assert _isrecursive(pattern)
     yield pattern[:0]
-    yield from _rlistdir(dirname, dironly)
+    yield from _rlistdir(dirname, dir_fd, dironly)
 
 # If dironly is false, yields all file names inside a directory.
 # If dironly is true, yields only directory names.
-def _iterdir(dirname, dironly):
-    if not dirname:
-        if isinstance(dirname, bytes):
-            dirname = bytes(os.curdir, 'ASCII')
-        else:
-            dirname = os.curdir
+def _iterdir(dirname, dir_fd, dironly):
     try:
-        with os.scandir(dirname) as it:
-            for entry in it:
-                try:
-                    if not dironly or entry.is_dir():
-                        yield entry.name
-                except OSError:
-                    pass
+        fd = None
+        fsencode = None
+        if dir_fd is not None:
+            if dirname:
+                fd = arg = os.open(dirname, _dir_open_flags, dir_fd=dir_fd)
+            else:
+                arg = dir_fd
+            if isinstance(dirname, bytes):
+                fsencode = os.fsencode
+        elif dirname:
+            arg = dirname
+        elif isinstance(dirname, bytes):
+            arg = bytes(os.curdir, 'ASCII')
+        else:
+            arg = os.curdir
+        try:
+            with os.scandir(arg) as it:
+                for entry in it:
+                    try:
+                        if not dironly or entry.is_dir():
+                            if fsencode is not None:
+                                yield fsencode(entry.name)
+                            else:
+                                yield entry.name
+                    except OSError:
+                        pass
+        finally:
+            if fd is not None:
+                os.close(fd)
     except OSError:
         return
 
 # Recursively yields relative pathnames inside a literal directory.
-def _rlistdir(dirname, dironly):
-    names = list(_iterdir(dirname, dironly))
+def _rlistdir(dirname, dir_fd, dironly):
+    names = list(_iterdir(dirname, dir_fd, dironly))
     for x in names:
         if not _ishidden(x):
             yield x
-            path = os.path.join(dirname, x) if dirname else x
-            for y in _rlistdir(path, dironly):
-                yield os.path.join(x, y)
+            path = _join(dirname, x) if dirname else x
+            for y in _rlistdir(path, dir_fd, dironly):
+                yield _join(x, y)
 
 
+def _lexists(pathname, dir_fd):
+    # Same as os.path.lexists(), but with dir_fd
+    if dir_fd is None:
+        return os.path.lexists(pathname)
+    try:
+        os.lstat(pathname, dir_fd=dir_fd)
+    except (OSError, ValueError):
+        return False
+    else:
+        return True
+
+def _isdir(pathname, dir_fd):
+    # Same as os.path.isdir(), but with dir_fd
+    if dir_fd is None:
+        return os.path.isdir(pathname)
+    try:
+        st = os.stat(pathname, dir_fd=dir_fd)
+    except (OSError, ValueError):
+        return False
+    else:
+        return stat.S_ISDIR(st.st_mode)
+
+def _join(dirname, basename):
+    # It is common if dirname or basename is empty
+    if not dirname or not basename:
+        return dirname or basename
+    return os.path.join(dirname, basename)
+
 magic_check = re.compile('([*?[])')
 magic_check_bytes = re.compile(b'([*?[])')
 
@@ -171,3 +225,6 @@ def escape(pathname):
     else:
         pathname = magic_check.sub(r'[\1]', pathname)
     return drive + pathname
+
+
+_dir_open_flags = os.O_RDONLY | getattr(os, 'O_DIRECTORY', 0)
diff --git a/Lib/test/test_glob.py b/Lib/test/test_glob.py
index cba8c7c..f815852 100644
--- a/Lib/test/test_glob.py
+++ b/Lib/test/test_glob.py
@@ -9,6 +9,7 @@ from test.support import (TESTFN, skip_unless_symlink,
 
 
 class GlobTests(unittest.TestCase):
+    dir_fd = None
 
     def norm(self, *parts):
         return os.path.normpath(os.path.join(self.tempdir, *parts))
@@ -38,8 +39,14 @@ class GlobTests(unittest.TestCase):
             os.symlink(self.norm('broken'), self.norm('sym1'))
             os.symlink('broken', self.norm('sym2'))
             os.symlink(os.path.join('a', 'bcd'), self.norm('sym3'))
+        if {os.open, os.stat} <= os.supports_dir_fd and os.scandir in os.supports_fd:
+            self.dir_fd = os.open(self.tempdir, os.O_RDONLY | os.O_DIRECTORY)
+        else:
+            self.dir_fd = None
 
     def tearDown(self):
+        if self.dir_fd is not None:
+            os.close(self.dir_fd)
         shutil.rmtree(self.tempdir)
 
     def glob(self, *parts, **kwargs):
@@ -53,6 +60,41 @@ class GlobTests(unittest.TestCase):
         bres = [os.fsencode(x) for x in res]
         self.assertCountEqual(glob.glob(os.fsencode(p), **kwargs), bres)
         self.assertCountEqual(glob.iglob(os.fsencode(p), **kwargs), bres)
+
+        with change_cwd(self.tempdir):
+            res2 = glob.glob(pattern, **kwargs)
+            for x in res2:
+                self.assertFalse(os.path.isabs(x), x)
+            if pattern == '**' or pattern == '**' + os.sep:
+                expected = res[1:]
+            else:
+                expected = res
+            self.assertCountEqual([os.path.join(self.tempdir, x) for x in res2],
+                                  expected)
+            self.assertCountEqual(glob.iglob(pattern, **kwargs), res2)
+            bpattern = os.fsencode(pattern)
+            bres2 = [os.fsencode(x) for x in res2]
+            self.assertCountEqual(glob.glob(bpattern, **kwargs), bres2)
+            self.assertCountEqual(glob.iglob(bpattern, **kwargs), bres2)
+
+        self.assertCountEqual(glob.glob(pattern, root_dir=self.tempdir, **kwargs), res2)
+        self.assertCountEqual(glob.iglob(pattern, root_dir=self.tempdir, **kwargs), res2)
+        btempdir = os.fsencode(self.tempdir)
+        self.assertCountEqual(
+            glob.glob(bpattern, root_dir=btempdir, **kwargs), bres2)
+        self.assertCountEqual(
+            glob.iglob(bpattern, root_dir=btempdir, **kwargs), bres2)
+
+        if self.dir_fd is not None:
+            self.assertCountEqual(
+                glob.glob(pattern, dir_fd=self.dir_fd, **kwargs), res2)
+            self.assertCountEqual(
+                glob.iglob(pattern, dir_fd=self.dir_fd, **kwargs), res2)
+            self.assertCountEqual(
+                glob.glob(bpattern, dir_fd=self.dir_fd, **kwargs), bres2)
+            self.assertCountEqual(
+                glob.iglob(bpattern, dir_fd=self.dir_fd, **kwargs), bres2)
+
         return res
 
     def assertSequencesEqual_noorder(self, l1, l2):
@@ -78,6 +120,14 @@ class GlobTests(unittest.TestCase):
         res = glob.glob(os.path.join(os.fsencode(os.curdir), b'*'))
         self.assertEqual({type(r) for r in res}, {bytes})
 
+    def test_glob_empty_pattern(self):
+        self.assertEqual(glob.glob(''), [])
+        self.assertEqual(glob.glob(b''), [])
+        self.assertEqual(glob.glob('', root_dir=self.tempdir), [])
+        self.assertEqual(glob.glob(b'', root_dir=os.fsencode(self.tempdir)), [])
+        self.assertEqual(glob.glob('', dir_fd=self.dir_fd), [])
+        self.assertEqual(glob.glob(b'', dir_fd=self.dir_fd), [])
+
     def test_glob_one_directory(self):
         eq = self.assertSequencesEqual_noorder
         eq(self.glob('a*'), map(self.norm, ['a', 'aab', 'aaa']))
diff --git a/Misc/NEWS.d/next/Library/2019-09-12-21-34-03.bpo-38144.8uQCdd.rst b/Misc/NEWS.d/next/Library/2019-09-12-21-34-03.bpo-38144.8uQCdd.rst
new file mode 100644
index 0000000..2c335bf
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-09-12-21-34-03.bpo-38144.8uQCdd.rst
@@ -0,0 +1 @@
+Added the *root_dir* and *dir_fd* parameters in :func:`glob.glob`.