From 19cccd8a61c73e29314cc55a5dd08004903a24fd Mon Sep 17 00:00:00 2001
From: Chris Hunt <chrahunt@gmail.com>
Date: Sat, 27 Jul 2019 21:08:39 -0400
Subject: [PATCH 1/6] Failing test for local install with socket file.

---
 tests/functional/test_install.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index 6e1e3dd400b..e52407d59d7 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -1,6 +1,8 @@
 import distutils
 import glob
 import os
+import shutil
+import socket
 import sys
 import textwrap
 from os.path import curdir, join, pardir
@@ -488,6 +490,26 @@ def test_install_from_local_directory_with_symlinks_to_directories(
     assert egg_info_folder in result.files_created, str(result)
 
 
+@pytest.mark.skipif("sys.platform == 'win32'")
+def test_install_from_local_directory_with_socket_file(script, data, tmpdir):
+    """
+    Test installing from a local directory containing a socket file.
+    """
+    egg_info_file = (
+        script.site_packages / 'FSPkg-0.1.dev0-py%s.egg-info' % pyversion
+    )
+    package_folder = script.site_packages / 'fspkg'
+    to_copy = data.packages.joinpath("FSPkg")
+    to_install = tmpdir.joinpath("src")
+    shutil.copytree(to_copy, to_install)
+    sock = socket.socket(socket.AF_UNIX)
+    sock.bind(os.path.join(to_install, "example"))
+    result = script.pip("install", to_install, expect_error=False)
+
+    assert package_folder in result.files_created, str(result.stdout)
+    assert egg_info_file in result.files_created, str(result)
+
+
 def test_install_from_local_directory_with_no_setup_py(script, data):
     """
     Test installing from a local directory with no 'setup.py'.

From 761c8fa8d34acb227be4cd94cde52972495fb33a Mon Sep 17 00:00:00 2001
From: Chris Hunt <chrahunt@gmail.com>
Date: Sun, 28 Jul 2019 11:12:33 -0400
Subject: [PATCH 2/6] Ignore errors copying socket files for source installs.

---
 news/5306.bugfix                      |  1 +
 src/pip/_internal/download.py         | 48 +++++++++++-----
 src/pip/_internal/utils/filesystem.py |  6 ++
 tests/functional/test_install.py      | 13 +++--
 tests/lib/filesystem.py               | 47 ++++++++++++++++
 tests/unit/test_download.py           | 80 +++++++++++++++++++++++++++
 tests/unit/test_utils_filesystem.py   | 41 ++++++++++++++
 tox.ini                               |  2 +-
 8 files changed, 216 insertions(+), 22 deletions(-)
 create mode 100644 news/5306.bugfix
 create mode 100644 tests/lib/filesystem.py
 create mode 100644 tests/unit/test_utils_filesystem.py

diff --git a/news/5306.bugfix b/news/5306.bugfix
new file mode 100644
index 00000000000..fe96916d453
--- /dev/null
+++ b/news/5306.bugfix
@@ -0,0 +1 @@
+Ignore errors copying socket files for local source installs.
diff --git a/src/pip/_internal/download.py b/src/pip/_internal/download.py
index 0c6492a8d78..78db4709200 100644
--- a/src/pip/_internal/download.py
+++ b/src/pip/_internal/download.py
@@ -33,7 +33,7 @@
 # Import ssl from compat so the initial import occurs in only one place.
 from pip._internal.utils.compat import HAS_TLS, ssl
 from pip._internal.utils.encoding import auto_decode
-from pip._internal.utils.filesystem import check_path_owner
+from pip._internal.utils.filesystem import check_path_owner, is_socket
 from pip._internal.utils.glibc import libc_ver
 from pip._internal.utils.marker_files import write_delete_marker_file
 from pip._internal.utils.misc import (
@@ -63,7 +63,7 @@
 
 if MYPY_CHECK_RUNNING:
     from typing import (
-        Optional, Tuple, Dict, IO, Text, Union
+        Dict, IO, List, Optional, Text, Tuple, Union
     )
     from optparse import Values
     from pip._internal.models.link import Link
@@ -944,6 +944,36 @@ def unpack_http_url(
             os.unlink(from_path)
 
 
+def _copy_source_tree(source, target):
+    # type: (str, str) -> None
+    def ignore(d, names):
+        # Pulling in those directories can potentially be very slow,
+        # exclude the following directories if they appear in the top
+        # level dir (and only it).
+        # See discussion at https://github.com/pypa/pip/pull/6770
+        return ['.tox', '.nox'] if d == source else []
+
+    try:
+        shutil.copytree(source, target, ignore=ignore, symlinks=True)
+    except shutil.Error as e:
+        errors = e.args[0]  # type: List[Tuple[str, str, shutil.Error]]
+        # Users may have locally-created socket files in the source
+        # directory. Copying socket files is not supported, so we skip errors
+        # related to them, for convenience.
+
+        # Copy list to avoid mutation while iterating.
+        errors_copy = errors[:]
+        for i, err in reversed(list(enumerate(errors_copy))):
+            src, _dest, _error = err
+            if is_socket(src):
+                # Remove errors related to sockets to prevent distractions if
+                # we end up re-raising.
+                errors.pop(i)
+
+        if errors:
+            raise
+
+
 def unpack_file_url(
     link,  # type: Link
     location,  # type: str
@@ -959,21 +989,9 @@ def unpack_file_url(
     link_path = url_to_path(link.url_without_fragment)
     # If it's a url to a local directory
     if is_dir_url(link):
-
-        def ignore(d, names):
-            # Pulling in those directories can potentially be very slow,
-            # exclude the following directories if they appear in the top
-            # level dir (and only it).
-            # See discussion at https://github.com/pypa/pip/pull/6770
-            return ['.tox', '.nox'] if d == link_path else []
-
         if os.path.isdir(location):
             rmtree(location)
-        shutil.copytree(link_path,
-                        location,
-                        symlinks=True,
-                        ignore=ignore)
-
+        _copy_source_tree(link_path, location)
         if download_dir:
             logger.info('Link is a directory, ignoring download_dir')
         return
diff --git a/src/pip/_internal/utils/filesystem.py b/src/pip/_internal/utils/filesystem.py
index 1e6b0338581..1841de92418 100644
--- a/src/pip/_internal/utils/filesystem.py
+++ b/src/pip/_internal/utils/filesystem.py
@@ -1,5 +1,6 @@
 import os
 import os.path
+import stat
 
 from pip._internal.utils.compat import get_path_uid
 
@@ -28,3 +29,8 @@ def check_path_owner(path):
         else:
             previous, path = path, os.path.dirname(path)
     return False  # assume we don't own the path
+
+
+def is_socket(path):
+    # type: (str) -> bool
+    return stat.S_ISSOCK(os.lstat(path).st_mode)
diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index e52407d59d7..40750526c3d 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -2,7 +2,6 @@
 import glob
 import os
 import shutil
-import socket
 import sys
 import textwrap
 from os.path import curdir, join, pardir
@@ -25,6 +24,7 @@
     pyversion_tuple,
     requirements_file,
 )
+from tests.lib.filesystem import make_socket_file
 from tests.lib.local_repos import local_checkout
 from tests.lib.path import Path
 
@@ -496,16 +496,17 @@ def test_install_from_local_directory_with_socket_file(script, data, tmpdir):
     Test installing from a local directory containing a socket file.
     """
     egg_info_file = (
-        script.site_packages / 'FSPkg-0.1.dev0-py%s.egg-info' % pyversion
+        script.site_packages / "FSPkg-0.1.dev0-py%s.egg-info" % pyversion
     )
-    package_folder = script.site_packages / 'fspkg'
+    package_folder = script.site_packages / "fspkg"
     to_copy = data.packages.joinpath("FSPkg")
     to_install = tmpdir.joinpath("src")
+
     shutil.copytree(to_copy, to_install)
-    sock = socket.socket(socket.AF_UNIX)
-    sock.bind(os.path.join(to_install, "example"))
-    result = script.pip("install", to_install, expect_error=False)
+    # Socket file, should be ignored.
+    make_socket_file(os.path.join(to_install, "example"))
 
+    result = script.pip("install", to_install, expect_error=False)
     assert package_folder in result.files_created, str(result.stdout)
     assert egg_info_file in result.files_created, str(result)
 
diff --git a/tests/lib/filesystem.py b/tests/lib/filesystem.py
new file mode 100644
index 00000000000..62f7b07633a
--- /dev/null
+++ b/tests/lib/filesystem.py
@@ -0,0 +1,47 @@
+"""Helpers for filesystem-dependent tests.
+"""
+import os
+import socket
+import subprocess
+import sys
+from functools import partial
+from itertools import chain
+
+from .path import Path
+
+
+def make_socket_file(path):
+    # Socket paths are limited to 108 characters (sometimes less) so we
+    # chdir before creating it and use a relative path name.
+    cwd = os.getcwd()
+    os.chdir(os.path.dirname(path))
+    try:
+        sock = socket.socket(socket.AF_UNIX)
+        sock.bind(os.path.basename(path))
+    finally:
+        os.chdir(cwd)
+
+
+def make_unreadable_file(path):
+    Path(path).touch()
+    os.chmod(path, 0o000)
+    if sys.platform == "win32":
+        username = os.environ["USERNAME"]
+        # Remove "Read Data/List Directory" permission for current user, but
+        # leave everything else.
+        args = ["icacls", path, "/deny", username + ":(RD)"]
+        subprocess.check_call(args)
+
+
+def get_filelist(base):
+    def join(dirpath, dirnames, filenames):
+        relative_dirpath = os.path.relpath(dirpath, base)
+        join_dirpath = partial(os.path.join, relative_dirpath)
+        return chain(
+            (join_dirpath(p) for p in dirnames),
+            (join_dirpath(p) for p in filenames),
+        )
+
+    return set(chain.from_iterable(
+        join(*dirinfo) for dirinfo in os.walk(base)
+    ))
diff --git a/tests/unit/test_download.py b/tests/unit/test_download.py
index f7595f52bcd..52b5864b1ac 100644
--- a/tests/unit/test_download.py
+++ b/tests/unit/test_download.py
@@ -1,6 +1,7 @@
 import functools
 import hashlib
 import os
+import shutil
 import sys
 from io import BytesIO
 from shutil import copy, rmtree
@@ -15,6 +16,7 @@
     MultiDomainBasicAuth,
     PipSession,
     SafeFileCache,
+    _copy_source_tree,
     _download_http_url,
     _get_url_scheme,
     parse_content_disposition,
@@ -28,6 +30,12 @@
 from pip._internal.utils.hashes import Hashes
 from pip._internal.utils.misc import path_to_url
 from tests.lib import create_file
+from tests.lib.filesystem import (
+    get_filelist,
+    make_socket_file,
+    make_unreadable_file,
+)
+from tests.lib.path import Path
 
 
 @pytest.fixture(scope="function")
@@ -334,6 +342,78 @@ def test_url_to_path_path_to_url_symmetry_win():
     assert url_to_path(path_to_url(unc_path)) == unc_path
 
 
+@pytest.fixture
+def clean_project(tmpdir_factory, data):
+    tmpdir = Path(str(tmpdir_factory.mktemp("clean_project")))
+    new_project_dir = tmpdir.joinpath("FSPkg")
+    path = data.packages.joinpath("FSPkg")
+    shutil.copytree(path, new_project_dir)
+    return new_project_dir
+
+
+def test_copy_source_tree(clean_project, tmpdir):
+    target = tmpdir.joinpath("target")
+    expected_files = get_filelist(clean_project)
+    assert len(expected_files) == 3
+
+    _copy_source_tree(clean_project, target)
+
+    copied_files = get_filelist(target)
+    assert expected_files == copied_files
+
+
+@pytest.mark.skipif("sys.platform == 'win32'")
+def test_copy_source_tree_with_socket(clean_project, tmpdir):
+    target = tmpdir.joinpath("target")
+    expected_files = get_filelist(clean_project)
+    make_socket_file(clean_project.joinpath("aaa"))
+
+    _copy_source_tree(clean_project, target)
+
+    copied_files = get_filelist(target)
+    assert expected_files == copied_files
+
+
+@pytest.mark.skipif("sys.platform == 'win32'")
+def test_copy_source_tree_with_socket_fails_with_no_socket_error(
+    clean_project, tmpdir
+):
+    target = tmpdir.joinpath("target")
+    expected_files = get_filelist(clean_project)
+    make_socket_file(clean_project.joinpath("aaa"))
+    unreadable_file = clean_project.joinpath("bbb")
+    make_unreadable_file(unreadable_file)
+
+    with pytest.raises(shutil.Error) as e:
+        _copy_source_tree(clean_project, target)
+
+    errored_files = [err[0] for err in e.value.args[0]]
+    assert len(errored_files) == 1
+    assert unreadable_file in errored_files
+
+    copied_files = get_filelist(target)
+    # Even with errors, all files should have been copied.
+    assert expected_files == copied_files
+
+
+def test_copy_source_tree_with_unreadable_dir_fails(clean_project, tmpdir):
+    target = tmpdir.joinpath("target")
+    expected_files = get_filelist(clean_project)
+    unreadable_file = clean_project.joinpath("bbb")
+    make_unreadable_file(unreadable_file)
+
+    with pytest.raises(shutil.Error) as e:
+        _copy_source_tree(clean_project, target)
+
+    errored_files = [err[0] for err in e.value.args[0]]
+    assert len(errored_files) == 1
+    assert unreadable_file in errored_files
+
+    copied_files = get_filelist(target)
+    # Even with errors, all files should have been copied.
+    assert expected_files == copied_files
+
+
 class Test_unpack_file_url(object):
 
     def prep(self, tmpdir, data):
diff --git a/tests/unit/test_utils_filesystem.py b/tests/unit/test_utils_filesystem.py
new file mode 100644
index 00000000000..533340f24d3
--- /dev/null
+++ b/tests/unit/test_utils_filesystem.py
@@ -0,0 +1,41 @@
+import os
+
+import pytest
+
+from pip._internal.utils.filesystem import is_socket
+
+from ..lib.filesystem import make_socket_file
+from ..lib.path import Path
+
+
+def make_file(path):
+    Path(path).touch()
+
+
+def make_valid_symlink(path):
+    target = path + "1"
+    make_file(target)
+    os.symlink(target, path)
+
+
+def make_broken_symlink(path):
+    os.symlink("foo", path)
+
+
+def make_dir(path):
+    os.mkdir(path)
+
+
+@pytest.mark.skipif("sys.platform == 'win32'")
+@pytest.mark.parametrize("create,result", [
+    (make_socket_file, True),
+    (make_file, False),
+    (make_valid_symlink, False),
+    (make_broken_symlink, False),
+    (make_dir, False),
+])
+def test_is_socket(create, result, tmpdir):
+    target = tmpdir.joinpath("target")
+    create(target)
+    assert os.path.lexists(target)
+    assert is_socket(target) == result
diff --git a/tox.ini b/tox.ini
index fc1f3bd98ce..3dd128c9135 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,7 +10,7 @@ envlist =
 pip = python {toxinidir}/tools/tox_pip.py
 
 [testenv]
-passenv = CI GIT_SSL_CAINFO
+passenv = CI GIT_SSL_CAINFO USERNAME
 setenv =
     # This is required in order to get UTF-8 output inside of the subprocesses
     # that our tests use.

From 3e043acb1a7be2cf72932bd97b653f15b7ce7580 Mon Sep 17 00:00:00 2001
From: Chris Hunt <chrahunt@gmail.com>
Date: Tue, 6 Aug 2019 21:28:55 -0400
Subject: [PATCH 3/6] Address review comments.

---
 src/pip/_internal/download.py         | 50 +++++++++++++++++----------
 src/pip/_internal/utils/filesystem.py | 30 ++++++++++++++++
 tests/functional/test_install.py      |  6 ++--
 tests/unit/test_download.py           | 15 +++++---
 tests/unit/test_utils_filesystem.py   | 30 +++++++++++++++-
 5 files changed, 105 insertions(+), 26 deletions(-)

diff --git a/src/pip/_internal/download.py b/src/pip/_internal/download.py
index 78db4709200..fa6b61859f1 100644
--- a/src/pip/_internal/download.py
+++ b/src/pip/_internal/download.py
@@ -33,7 +33,7 @@
 # Import ssl from compat so the initial import occurs in only one place.
 from pip._internal.utils.compat import HAS_TLS, ssl
 from pip._internal.utils.encoding import auto_decode
-from pip._internal.utils.filesystem import check_path_owner, is_socket
+from pip._internal.utils.filesystem import check_path_owner, copytree
 from pip._internal.utils.glibc import libc_ver
 from pip._internal.utils.marker_files import write_delete_marker_file
 from pip._internal.utils.misc import (
@@ -49,6 +49,7 @@
     format_size,
     get_installed_version,
     netloc_has_port,
+    path_to_display,
     path_to_url,
     remove_auth_from_url,
     rmtree,
@@ -63,7 +64,7 @@
 
 if MYPY_CHECK_RUNNING:
     from typing import (
-        Dict, IO, List, Optional, Text, Tuple, Union
+        Dict, IO, Optional, Text, Tuple, Union
     )
     from optparse import Values
     from pip._internal.models.link import Link
@@ -953,25 +954,36 @@ def ignore(d, names):
         # See discussion at https://github.com/pypa/pip/pull/6770
         return ['.tox', '.nox'] if d == source else []
 
+    def ignore_special_file_errors(error_details):
+        # Copying special files is not supported, so we skip errors related to
+        # them. This is a convenience to support users that may have tools
+        # creating e.g. socket files in their source directory.
+        src, dest, error = error_details
+
+        if not isinstance(error, shutil.SpecialFileError):
+            # Then it is some other kind of error that we do want to report.
+            return True
+
+        # SpecialFileError may be raised due to either the source or
+        # destination. If the destination was the cause then we would actually
+        # care, but since the destination directory is deleted prior to
+        # copy we ignore all of them assuming it is caused by the source.
+        logger.warning(
+            "Ignoring special file error '%s' encountered copying %s to %s.",
+            str(error),
+            path_to_display(src),
+            path_to_display(dest),
+        )
+
     try:
-        shutil.copytree(source, target, ignore=ignore, symlinks=True)
+        copytree(source, target, ignore=ignore, symlinks=True)
     except shutil.Error as e:
-        errors = e.args[0]  # type: List[Tuple[str, str, shutil.Error]]
-        # Users may have locally-created socket files in the source
-        # directory. Copying socket files is not supported, so we skip errors
-        # related to them, for convenience.
-
-        # Copy list to avoid mutation while iterating.
-        errors_copy = errors[:]
-        for i, err in reversed(list(enumerate(errors_copy))):
-            src, _dest, _error = err
-            if is_socket(src):
-                # Remove errors related to sockets to prevent distractions if
-                # we end up re-raising.
-                errors.pop(i)
-
-        if errors:
-            raise
+        errors = e.args[0]
+        normal_file_errors = list(
+            filter(ignore_special_file_errors, errors)
+        )
+        if normal_file_errors:
+            raise shutil.Error(normal_file_errors)
 
 
 def unpack_file_url(
diff --git a/src/pip/_internal/utils/filesystem.py b/src/pip/_internal/utils/filesystem.py
index 1841de92418..a9719701f49 100644
--- a/src/pip/_internal/utils/filesystem.py
+++ b/src/pip/_internal/utils/filesystem.py
@@ -1,5 +1,6 @@
 import os
 import os.path
+import shutil
 import stat
 
 from pip._internal.utils.compat import get_path_uid
@@ -31,6 +32,35 @@ def check_path_owner(path):
     return False  # assume we don't own the path
 
 
+def copytree(*args, **kwargs):
+    """Wrap shutil.copytree() to map errors copying socket file to
+    SpecialFileError.
+
+    See also https://bugs.python.org/issue37700.
+    """
+    def to_correct_error(src, dest, error):
+        for f in [src, dest]:
+            try:
+                if is_socket(f):
+                    new_error = shutil.SpecialFileError("`%s` is a socket" % f)
+                    return (src, dest, new_error)
+            except OSError:
+                # An error has already occurred. Another error here is not
+                # a problem and we can ignore it.
+                pass
+
+        return (src, dest, error)
+
+    try:
+        shutil.copytree(*args, **kwargs)
+    except shutil.Error as e:
+        errors = e.args[0]
+        new_errors = [
+            to_correct_error(src, dest, error) for src, dest, error in errors
+        ]
+        raise shutil.Error(new_errors)
+
+
 def is_socket(path):
     # type: (str) -> bool
     return stat.S_ISSOCK(os.lstat(path).st_mode)
diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index 40750526c3d..963e94d56eb 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -504,11 +504,13 @@ def test_install_from_local_directory_with_socket_file(script, data, tmpdir):
 
     shutil.copytree(to_copy, to_install)
     # Socket file, should be ignored.
-    make_socket_file(os.path.join(to_install, "example"))
+    socket_file_path = os.path.join(to_install, "example")
+    make_socket_file(socket_file_path)
 
-    result = script.pip("install", to_install, expect_error=False)
+    result = script.pip("install", "--verbose", to_install, expect_error=False)
     assert package_folder in result.files_created, str(result.stdout)
     assert egg_info_file in result.files_created, str(result)
+    assert str(socket_file_path) in result.stderr
 
 
 def test_install_from_local_directory_with_no_setup_py(script, data):
diff --git a/tests/unit/test_download.py b/tests/unit/test_download.py
index 52b5864b1ac..ee8720dea58 100644
--- a/tests/unit/test_download.py
+++ b/tests/unit/test_download.py
@@ -363,16 +363,23 @@ def test_copy_source_tree(clean_project, tmpdir):
 
 
 @pytest.mark.skipif("sys.platform == 'win32'")
-def test_copy_source_tree_with_socket(clean_project, tmpdir):
+def test_copy_source_tree_with_socket(clean_project, tmpdir, caplog):
     target = tmpdir.joinpath("target")
     expected_files = get_filelist(clean_project)
-    make_socket_file(clean_project.joinpath("aaa"))
+    socket_path = str(clean_project.joinpath("aaa"))
+    make_socket_file(socket_path)
 
     _copy_source_tree(clean_project, target)
 
     copied_files = get_filelist(target)
     assert expected_files == copied_files
 
+    # Warning should have been logged.
+    assert len(caplog.records) == 1
+    record = caplog.records[0]
+    assert record.levelname == 'WARNING'
+    assert socket_path in record.message
+
 
 @pytest.mark.skipif("sys.platform == 'win32'")
 def test_copy_source_tree_with_socket_fails_with_no_socket_error(
@@ -392,7 +399,7 @@ def test_copy_source_tree_with_socket_fails_with_no_socket_error(
     assert unreadable_file in errored_files
 
     copied_files = get_filelist(target)
-    # Even with errors, all files should have been copied.
+    # All files without errors should have been copied.
     assert expected_files == copied_files
 
 
@@ -410,7 +417,7 @@ def test_copy_source_tree_with_unreadable_dir_fails(clean_project, tmpdir):
     assert unreadable_file in errored_files
 
     copied_files = get_filelist(target)
-    # Even with errors, all files should have been copied.
+    # All files without errors should have been copied.
     assert expected_files == copied_files
 
 
diff --git a/tests/unit/test_utils_filesystem.py b/tests/unit/test_utils_filesystem.py
index 533340f24d3..a3ca40326db 100644
--- a/tests/unit/test_utils_filesystem.py
+++ b/tests/unit/test_utils_filesystem.py
@@ -1,8 +1,9 @@
 import os
+import shutil
 
 import pytest
 
-from pip._internal.utils.filesystem import is_socket
+from pip._internal.utils.filesystem import copytree, is_socket
 
 from ..lib.filesystem import make_socket_file
 from ..lib.path import Path
@@ -39,3 +40,30 @@ def test_is_socket(create, result, tmpdir):
     create(target)
     assert os.path.lexists(target)
     assert is_socket(target) == result
+
+
+@pytest.mark.skipif("sys.platform == 'win32'")
+def test_copytree_maps_socket_errors(tmpdir):
+    src_dir = tmpdir.joinpath("src")
+    make_dir(src_dir)
+    make_file(src_dir.joinpath("a"))
+    socket_src = src_dir.joinpath("b")
+    make_socket_file(socket_src)
+    make_file(src_dir.joinpath("c"))
+
+    dest_dir = tmpdir.joinpath("dest")
+    socket_dest = dest_dir.joinpath("b")
+
+    with pytest.raises(shutil.Error) as e:
+        copytree(src_dir, dest_dir)
+
+    errors = e.value.args[0]
+    assert len(errors) == 1
+    src, dest, error = errors[0]
+    assert src == str(socket_src)
+    assert dest == str(socket_dest)
+    assert isinstance(error, shutil.SpecialFileError)
+
+    assert dest_dir.joinpath("a").exists()
+    assert not socket_dest.exists()
+    assert dest_dir.joinpath("c").exists()

From 64fbe1ffa54ddb01100efc42e497d85bc002e3ac Mon Sep 17 00:00:00 2001
From: Chris Hunt <chrahunt@gmail.com>
Date: Wed, 7 Aug 2019 19:58:08 -0400
Subject: [PATCH 4/6] Python 3-only implementation.

---
 src/pip/_internal/download.py         | 60 ++++++++++++++-------------
 src/pip/_internal/utils/filesystem.py | 29 ++++++-------
 tests/functional/test_install.py      |  2 +-
 tests/unit/test_download.py           |  4 +-
 tests/unit/test_utils_filesystem.py   | 45 +++++++++-----------
 5 files changed, 66 insertions(+), 74 deletions(-)

diff --git a/src/pip/_internal/download.py b/src/pip/_internal/download.py
index fa6b61859f1..29013df3cfa 100644
--- a/src/pip/_internal/download.py
+++ b/src/pip/_internal/download.py
@@ -21,6 +21,7 @@
 from pip._vendor.requests.models import CONTENT_CHUNK_SIZE, Response
 from pip._vendor.requests.structures import CaseInsensitiveDict
 from pip._vendor.requests.utils import get_netrc_auth
+from pip._vendor.six import PY2
 # NOTE: XMLRPC Client is not annotated in typeshed as on 2017-07-17, which is
 #       why we ignore the type on this import
 from pip._vendor.six.moves import xmlrpc_client  # type: ignore
@@ -33,7 +34,7 @@
 # Import ssl from compat so the initial import occurs in only one place.
 from pip._internal.utils.compat import HAS_TLS, ssl
 from pip._internal.utils.encoding import auto_decode
-from pip._internal.utils.filesystem import check_path_owner, copytree
+from pip._internal.utils.filesystem import check_path_owner, copy2_fixed
 from pip._internal.utils.glibc import libc_ver
 from pip._internal.utils.marker_files import write_delete_marker_file
 from pip._internal.utils.misc import (
@@ -945,45 +946,48 @@ def unpack_http_url(
             os.unlink(from_path)
 
 
-def _copy_source_tree(source, target):
+def _copy2_ignoring_special_files(src, dest):
     # type: (str, str) -> None
-    def ignore(d, names):
-        # Pulling in those directories can potentially be very slow,
-        # exclude the following directories if they appear in the top
-        # level dir (and only it).
-        # See discussion at https://github.com/pypa/pip/pull/6770
-        return ['.tox', '.nox'] if d == source else []
-
-    def ignore_special_file_errors(error_details):
-        # Copying special files is not supported, so we skip errors related to
-        # them. This is a convenience to support users that may have tools
-        # creating e.g. socket files in their source directory.
-        src, dest, error = error_details
-
-        if not isinstance(error, shutil.SpecialFileError):
-            # Then it is some other kind of error that we do want to report.
-            return True
-
+    """Copying special files is not supported, but as a convenience to users
+    we skip errors copying them. This supports tools that may create e.g.
+    socket files in the project source directory.
+    """
+    try:
+        copy2_fixed(src, dest)
+    except shutil.SpecialFileError as e:
         # SpecialFileError may be raised due to either the source or
         # destination. If the destination was the cause then we would actually
         # care, but since the destination directory is deleted prior to
         # copy we ignore all of them assuming it is caused by the source.
         logger.warning(
             "Ignoring special file error '%s' encountered copying %s to %s.",
-            str(error),
+            str(e),
             path_to_display(src),
             path_to_display(dest),
         )
 
-    try:
-        copytree(source, target, ignore=ignore, symlinks=True)
-    except shutil.Error as e:
-        errors = e.args[0]
-        normal_file_errors = list(
-            filter(ignore_special_file_errors, errors)
+
+def _copy_source_tree(source, target):
+    # type: (str, str) -> None
+    def ignore(d, names):
+        # Pulling in those directories can potentially be very slow,
+        # exclude the following directories if they appear in the top
+        # level dir (and only it).
+        # See discussion at https://github.com/pypa/pip/pull/6770
+        return ['.tox', '.nox'] if d == source else []
+
+    if PY2:
+        # Python 2 does not support copy_function, so we let errors for
+        # uncopyable special files propagate.
+        shutil.copytree(source, target, ignore=ignore, symlinks=True)
+    else:
+        shutil.copytree(
+            source,
+            target,
+            copy_function=_copy2_ignoring_special_files,
+            ignore=ignore,
+            symlinks=True
         )
-        if normal_file_errors:
-            raise shutil.Error(normal_file_errors)
 
 
 def unpack_file_url(
diff --git a/src/pip/_internal/utils/filesystem.py b/src/pip/_internal/utils/filesystem.py
index a9719701f49..c5233ebbc71 100644
--- a/src/pip/_internal/utils/filesystem.py
+++ b/src/pip/_internal/utils/filesystem.py
@@ -32,33 +32,28 @@ def check_path_owner(path):
     return False  # assume we don't own the path
 
 
-def copytree(*args, **kwargs):
-    """Wrap shutil.copytree() to map errors copying socket file to
-    SpecialFileError.
+def copy2_fixed(src, dest):
+    # type: (str, str) -> None
+    """Wrap shutil.copy2() but map errors copying socket files to
+    SpecialFileError as expected.
 
     See also https://bugs.python.org/issue37700.
     """
-    def to_correct_error(src, dest, error):
+    try:
+        shutil.copy2(src, dest)
+    except (OSError, IOError):
         for f in [src, dest]:
             try:
-                if is_socket(f):
-                    new_error = shutil.SpecialFileError("`%s` is a socket" % f)
-                    return (src, dest, new_error)
+                is_socket_file = is_socket(f)
             except OSError:
                 # An error has already occurred. Another error here is not
                 # a problem and we can ignore it.
                 pass
+            else:
+                if is_socket_file:
+                    raise shutil.SpecialFileError("`%s` is a socket" % f)
 
-        return (src, dest, error)
-
-    try:
-        shutil.copytree(*args, **kwargs)
-    except shutil.Error as e:
-        errors = e.args[0]
-        new_errors = [
-            to_correct_error(src, dest, error) for src, dest, error in errors
-        ]
-        raise shutil.Error(new_errors)
+        raise
 
 
 def is_socket(path):
diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index 963e94d56eb..3151b77bb30 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -490,7 +490,7 @@ def test_install_from_local_directory_with_symlinks_to_directories(
     assert egg_info_folder in result.files_created, str(result)
 
 
-@pytest.mark.skipif("sys.platform == 'win32'")
+@pytest.mark.skipif("sys.platform == 'win32' or sys.version_info < (3,)")
 def test_install_from_local_directory_with_socket_file(script, data, tmpdir):
     """
     Test installing from a local directory containing a socket file.
diff --git a/tests/unit/test_download.py b/tests/unit/test_download.py
index ee8720dea58..22eb9576d44 100644
--- a/tests/unit/test_download.py
+++ b/tests/unit/test_download.py
@@ -362,7 +362,7 @@ def test_copy_source_tree(clean_project, tmpdir):
     assert expected_files == copied_files
 
 
-@pytest.mark.skipif("sys.platform == 'win32'")
+@pytest.mark.skipif("sys.platform == 'win32' or sys.version_info < (3,)")
 def test_copy_source_tree_with_socket(clean_project, tmpdir, caplog):
     target = tmpdir.joinpath("target")
     expected_files = get_filelist(clean_project)
@@ -381,7 +381,7 @@ def test_copy_source_tree_with_socket(clean_project, tmpdir, caplog):
     assert socket_path in record.message
 
 
-@pytest.mark.skipif("sys.platform == 'win32'")
+@pytest.mark.skipif("sys.platform == 'win32' or sys.version_info < (3,)")
 def test_copy_source_tree_with_socket_fails_with_no_socket_error(
     clean_project, tmpdir
 ):
diff --git a/tests/unit/test_utils_filesystem.py b/tests/unit/test_utils_filesystem.py
index a3ca40326db..b7da0de266d 100644
--- a/tests/unit/test_utils_filesystem.py
+++ b/tests/unit/test_utils_filesystem.py
@@ -3,9 +3,9 @@
 
 import pytest
 
-from pip._internal.utils.filesystem import copytree, is_socket
+from pip._internal.utils.filesystem import copy2_fixed, is_socket
 
-from ..lib.filesystem import make_socket_file
+from ..lib.filesystem import make_socket_file, make_unreadable_file
 from ..lib.path import Path
 
 
@@ -27,7 +27,10 @@ def make_dir(path):
     os.mkdir(path)
 
 
-@pytest.mark.skipif("sys.platform == 'win32'")
+skip_on_windows = pytest.mark.skipif("sys.platform == 'win32'")
+
+
+@skip_on_windows
 @pytest.mark.parametrize("create,result", [
     (make_socket_file, True),
     (make_file, False),
@@ -42,28 +45,18 @@ def test_is_socket(create, result, tmpdir):
     assert is_socket(target) == result
 
 
-@pytest.mark.skipif("sys.platform == 'win32'")
-def test_copytree_maps_socket_errors(tmpdir):
-    src_dir = tmpdir.joinpath("src")
-    make_dir(src_dir)
-    make_file(src_dir.joinpath("a"))
-    socket_src = src_dir.joinpath("b")
-    make_socket_file(socket_src)
-    make_file(src_dir.joinpath("c"))
-
-    dest_dir = tmpdir.joinpath("dest")
-    socket_dest = dest_dir.joinpath("b")
-
-    with pytest.raises(shutil.Error) as e:
-        copytree(src_dir, dest_dir)
+@pytest.mark.parametrize("create,error_type", [
+    pytest.param(
+        make_socket_file, shutil.SpecialFileError, marks=skip_on_windows
+    ),
+    (make_unreadable_file, OSError),
+])
+def test_copy2_fixed_raises_appropriate_errors(create, error_type, tmpdir):
+    src = tmpdir.joinpath("src")
+    create(src)
+    dest = tmpdir.joinpath("dest")
 
-    errors = e.value.args[0]
-    assert len(errors) == 1
-    src, dest, error = errors[0]
-    assert src == str(socket_src)
-    assert dest == str(socket_dest)
-    assert isinstance(error, shutil.SpecialFileError)
+    with pytest.raises(error_type):
+        copy2_fixed(src, dest)
 
-    assert dest_dir.joinpath("a").exists()
-    assert not socket_dest.exists()
-    assert dest_dir.joinpath("c").exists()
+    assert not dest.exists()

From ce6f64a94637ca4dfbf4280b860234a3f55fc1ad Mon Sep 17 00:00:00 2001
From: Chris Hunt <chrahunt@gmail.com>
Date: Fri, 9 Aug 2019 19:33:51 -0400
Subject: [PATCH 5/6] Construct copytree keyword arguments instead of using
 separate calls.

---
 src/pip/_internal/download.py | 45 +++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/src/pip/_internal/download.py b/src/pip/_internal/download.py
index 29013df3cfa..abff7bbc98e 100644
--- a/src/pip/_internal/download.py
+++ b/src/pip/_internal/download.py
@@ -65,15 +65,38 @@
 
 if MYPY_CHECK_RUNNING:
     from typing import (
-        Dict, IO, Optional, Text, Tuple, Union
+        Callable, Dict, List, IO, Optional, Text, Tuple, Union
     )
     from optparse import Values
+
+    from mypy_extensions import TypedDict
+
     from pip._internal.models.link import Link
     from pip._internal.utils.hashes import Hashes
     from pip._internal.vcs.versioncontrol import AuthInfo, VersionControl
 
     Credentials = Tuple[str, str, str]
 
+    if PY2:
+        CopytreeKwargs = TypedDict(
+            'CopytreeKwargs',
+            {
+                'ignore': Callable[[str, List[str]], List[str]],
+                'symlinks': bool,
+            },
+            total=False,
+        )
+    else:
+        CopytreeKwargs = TypedDict(
+            'CopytreeKwargs', {
+                'copy_function': Callable[[str, str], None],
+                'ignore': Callable[[str, List[str]], List[str]],
+                'ignore_dangling_symlinks': bool,
+                'symlinks': bool,
+            },
+            total=False,
+        )
+
 
 __all__ = ['get_file_content',
            'is_url', 'url_to_path', 'path_to_url',
@@ -976,18 +999,14 @@ def ignore(d, names):
         # See discussion at https://github.com/pypa/pip/pull/6770
         return ['.tox', '.nox'] if d == source else []
 
-    if PY2:
-        # Python 2 does not support copy_function, so we let errors for
-        # uncopyable special files propagate.
-        shutil.copytree(source, target, ignore=ignore, symlinks=True)
-    else:
-        shutil.copytree(
-            source,
-            target,
-            copy_function=_copy2_ignoring_special_files,
-            ignore=ignore,
-            symlinks=True
-        )
+    kwargs = dict(ignore=ignore, symlinks=True)  # type: CopytreeKwargs
+
+    if not PY2:
+        # Python 2 does not support copy_function, so we only ignore
+        # errors on special file copy in Python 3.
+        kwargs['copy_function'] = _copy2_ignoring_special_files
+
+    shutil.copytree(source, target, **kwargs)
 
 
 def unpack_file_url(

From a7dbd12d7bfa02eadb772515c552ac9e3c24c9a0 Mon Sep 17 00:00:00 2001
From: Chris Hunt <chrahunt@gmail.com>
Date: Sun, 11 Aug 2019 15:09:33 -0400
Subject: [PATCH 6/6] Relative import to absolute import, and update news

---
 news/5306.bugfix                    | 2 +-
 src/pip/_internal/download.py       | 3 ++-
 tests/lib/filesystem.py             | 1 +
 tests/unit/test_utils_filesystem.py | 5 ++---
 tox.ini                             | 1 +
 5 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/news/5306.bugfix b/news/5306.bugfix
index fe96916d453..bf040a95fcf 100644
--- a/news/5306.bugfix
+++ b/news/5306.bugfix
@@ -1 +1 @@
-Ignore errors copying socket files for local source installs.
+Ignore errors copying socket files for local source installs (in Python 3).
diff --git a/src/pip/_internal/download.py b/src/pip/_internal/download.py
index abff7bbc98e..81d443ddf49 100644
--- a/src/pip/_internal/download.py
+++ b/src/pip/_internal/download.py
@@ -88,7 +88,8 @@
         )
     else:
         CopytreeKwargs = TypedDict(
-            'CopytreeKwargs', {
+            'CopytreeKwargs',
+            {
                 'copy_function': Callable[[str, str], None],
                 'ignore': Callable[[str, List[str]], List[str]],
                 'ignore_dangling_symlinks': bool,
diff --git a/tests/lib/filesystem.py b/tests/lib/filesystem.py
index 62f7b07633a..dc14b323e33 100644
--- a/tests/lib/filesystem.py
+++ b/tests/lib/filesystem.py
@@ -26,6 +26,7 @@ def make_unreadable_file(path):
     Path(path).touch()
     os.chmod(path, 0o000)
     if sys.platform == "win32":
+        # Once we drop PY2 we can use `os.getlogin()` instead.
         username = os.environ["USERNAME"]
         # Remove "Read Data/List Directory" permission for current user, but
         # leave everything else.
diff --git a/tests/unit/test_utils_filesystem.py b/tests/unit/test_utils_filesystem.py
index b7da0de266d..3ef814dce4b 100644
--- a/tests/unit/test_utils_filesystem.py
+++ b/tests/unit/test_utils_filesystem.py
@@ -4,9 +4,8 @@
 import pytest
 
 from pip._internal.utils.filesystem import copy2_fixed, is_socket
-
-from ..lib.filesystem import make_socket_file, make_unreadable_file
-from ..lib.path import Path
+from tests.lib.filesystem import make_socket_file, make_unreadable_file
+from tests.lib.path import Path
 
 
 def make_file(path):
diff --git a/tox.ini b/tox.ini
index 3dd128c9135..608d491e3fe 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,6 +10,7 @@ envlist =
 pip = python {toxinidir}/tools/tox_pip.py
 
 [testenv]
+# Remove USERNAME once we drop PY2.
 passenv = CI GIT_SSL_CAINFO USERNAME
 setenv =
     # This is required in order to get UTF-8 output inside of the subprocesses