Merge remote-tracking branch 'origin/master' into python3.9

cibuildwheel/__init__.py

@@ -1 +1 @@
-__version__ = '1.4.2'
+__version__ = '1.5.5'

cibuildwheel/__main__.py

@@ -4,6 +4,7 @@ import sys
 import textwrap
 import traceback
 from configparser import ConfigParser
+from pathlib import Path
 
 from typing import Any, Dict, List, Optional, overload
 
@@ -20,6 +21,7 @@ from cibuildwheel.util import (
     BuildSelector,
     DependencyConstraints,
     Unbuffered,
+    resources_dir,
 )
 
 
@@ -114,8 +116,8 @@ def main() -> None:
                   file=sys.stderr)
             exit(2)
 
-    package_dir = args.package_dir
-    output_dir = args.output_dir
+    package_dir = Path(args.package_dir)
+    output_dir = Path(args.output_dir)
 
     if platform == 'linux':
         repair_command_default = 'auditwheel repair -w {dest_dir} {wheel}'
@@ -126,6 +128,7 @@ def main() -> None:
 
     build_config, skip_config = os.environ.get('CIBW_BUILD', '*'), os.environ.get('CIBW_SKIP', '')
     environment_config = get_option_from_environment('CIBW_ENVIRONMENT', platform=platform, default='')
+    before_all = get_option_from_environment('CIBW_BEFORE_ALL', platform=platform, default='')
     before_build = get_option_from_environment('CIBW_BEFORE_BUILD', platform=platform)
     repair_command = get_option_from_environment('CIBW_REPAIR_WHEEL_COMMAND', platform=platform, default=repair_command_default)
     dependency_versions = get_option_from_environment('CIBW_DEPENDENCY_VERSIONS', platform=platform, default='pinned')
@@ -149,7 +152,8 @@ def main() -> None:
     elif dependency_versions == 'latest':
         dependency_constraints = None
     else:
-        dependency_constraints = DependencyConstraints(dependency_versions)
+        dependency_versions_path = Path(dependency_versions)
+        dependency_constraints = DependencyConstraints(dependency_versions_path)
 
     if test_extras:
         test_extras = f'[{test_extras}]'
@@ -163,7 +167,7 @@ def main() -> None:
     # This needs to be passed on to the docker container in linux.py
     os.environ['CIBUILDWHEEL'] = '1'
 
-    if not any(os.path.exists(os.path.join(package_dir, name))
+    if not any((package_dir / name).exists()
                for name in ["setup.py", "setup.cfg", "pyproject.toml"]):
         print('cibuildwheel: Could not find setup.py, setup.cfg or pyproject.toml at root of package', file=sys.stderr)
         exit(2)
@@ -174,9 +178,7 @@ def main() -> None:
 
     manylinux_images: Optional[Dict[str, str]] = None
     if platform == 'linux':
-        pinned_docker_images_file = os.path.join(
-            os.path.dirname(__file__), 'resources', 'pinned_docker_images.cfg'
-        )
+        pinned_docker_images_file = resources_dir / 'pinned_docker_images.cfg'
         all_pinned_docker_images = ConfigParser()
         all_pinned_docker_images.read(pinned_docker_images_file)
         # all_pinned_docker_images looks like a dict of dicts, e.g.
@@ -211,6 +213,7 @@ def main() -> None:
         test_extras=test_extras,
         before_test=before_test,
         before_build=before_build,
+        before_all=before_all,
         build_verbosity=build_verbosity,
         build_selector=build_selector,
         repair_command=repair_command,
@@ -224,8 +227,8 @@ def main() -> None:
 
     print_preamble(platform, build_options)
 
-    if not os.path.exists(output_dir):
-        os.makedirs(output_dir)
+    if not output_dir.exists():
+        output_dir.mkdir(parents=True)
 
     if platform == 'linux':
         cibuildwheel.linux.build(build_options)

cibuildwheel/bashlex_eval.py

@@ -1,17 +1,23 @@
-import shlex
 import subprocess
-
-from typing import Dict, NamedTuple
+from typing import Callable, Dict, List, NamedTuple, Optional, Sequence
 
 import bashlex  # type: ignore
 
+# a function that takes a command and the environment, and returns the result
+EnvironmentExecutor = Callable[[List[str], Dict[str, str]], str]
+
+
+def local_environment_executor(command: List[str], env: Dict[str, str]) -> str:
+    return subprocess.check_output(command, env=env, universal_newlines=True)
+
 
 class NodeExecutionContext(NamedTuple):
     environment: Dict[str, str]
     input: str
+    executor: EnvironmentExecutor
 
 
-def evaluate(value: str, environment: Dict[str, str]) -> str:
+def evaluate(value: str, environment: Dict[str, str], executor: Optional[EnvironmentExecutor] = None) -> str:
     if not value:
         # empty string evaluates to empty string
         # (but trips up bashlex)
@@ -26,7 +32,7 @@ def evaluate(value: str, environment: Dict[str, str]) -> str:
 
     return evaluate_node(
         value_word_node,
-        context=NodeExecutionContext(environment=environment, input=value)
+        context=NodeExecutionContext(environment=environment, input=value, executor=executor or local_environment_executor)
     )
 
 
@@ -34,40 +40,64 @@ def evaluate_node(node: bashlex.ast.node, context: NodeExecutionContext) -> str:
     if node.kind == 'word':
         return evaluate_word_node(node, context=context)
     elif node.kind == 'commandsubstitution':
-        return evaluate_command_node(node.command, context=context)
+        node_result = evaluate_command_node(node.command, context=context)
+        # bash removes training newlines in command substitution
+        return node_result.rstrip()
     elif node.kind == 'parameter':
         return evaluate_parameter_node(node, context=context)
     else:
-        raise ValueError(f'Unsupported bash construct: "{node.word}"')
+        raise ValueError(f'Unsupported bash construct: "{node.kind}"')
 
 
 def evaluate_word_node(node: bashlex.ast.node, context: NodeExecutionContext) -> str:
-    word_start = node.pos[0]
-    word_end = node.pos[1]
-    word_string = context.input[word_start:word_end]
-    letters = list(word_string)
+    value = node.word
 
     for part in node.parts:
-        part_start = part.pos[0] - word_start
-        part_end = part.pos[1] - word_start
+        part_string = context.input[part.pos[0]:part.pos[1]]
+        part_value = evaluate_node(part, context=context)
 
-        # Set all the characters in the part to None
-        for i in range(part_start, part_end):
-            letters[i] = ''
+        if part_string not in value:
+            raise RuntimeError(
+                'bash parse failed. part "{}" not found in "{}". Word was "{}". Full input was "{}"'.format(
+                    part_string, value, node.word, context.input,
+                )
+            )
 
-        letters[part_start] = evaluate_node(part, context=context)
+        value = value.replace(part_string, part_value, 1)
 
-    # remove the None letters and concat
-    value = ''.join(letters)
-
-    # apply bash-like quotes/whitespace treatment
-    return ' '.join(word.strip() for word in shlex.split(value))
+    return value
 
 
 def evaluate_command_node(node: bashlex.ast.node, context: NodeExecutionContext) -> str:
-    words = [evaluate_node(part, context=context) for part in node.parts]
-    command = ' '.join(words)
-    return subprocess.check_output(shlex.split(command), env=context.environment, universal_newlines=True)
+    if any(n.kind == 'operator' for n in node.parts):
+        return evaluate_nodes_as_compound_command(node.parts, context=context)
+    else:
+        return evaluate_nodes_as_simple_command(node.parts, context=context)
+
+
+def evaluate_nodes_as_compound_command(nodes: Sequence[bashlex.ast.node], context: NodeExecutionContext) -> str:
+    # bashlex doesn't support any operators besides ';' inside command
+    # substitutions, so we only need to handle that case. We do so assuming
+    # that `set -o errexit` is on, because it's easier to code!
+
+    result = ''
+    for node in nodes:
+        if node.kind == 'command':
+            result += evaluate_command_node(node, context=context)
+        elif node.kind == 'operator':
+            if node.op == ';':
+                pass
+            else:
+                raise ValueError(f'Unsupported bash operator: "{node.op}"')
+        else:
+            raise ValueError(f'Unsupported bash node in compound command: "{node.kind}"')
+
+    return result
+
+
+def evaluate_nodes_as_simple_command(nodes: List[bashlex.ast.node], context: NodeExecutionContext):
+    command = [evaluate_node(part, context=context) for part in nodes]
+    return context.executor(command, context.environment)
 
 
 def evaluate_parameter_node(node: bashlex.ast.node, context: NodeExecutionContext) -> str:

cibuildwheel/docker_container.py

@@ -0,0 +1,192 @@
+import io
+import json
+import os
+import shlex
+import subprocess
+import sys
+import uuid
+from os import PathLike
+from pathlib import Path, PurePath
+from typing import IO, Dict, List, Optional, Sequence, Union
+
+
+class DockerContainer:
+    '''
+    An object that represents a running Docker container.
+
+    Intended for use as a context manager e.g.
+    `with DockerContainer('ubuntu') as docker:`
+
+    A bash shell is running in the remote container. When `call()` is invoked,
+    the command is relayed to the remote shell, and the results are streamed
+    back to cibuildwheel.
+    '''
+    UTILITY_PYTHON = '/opt/python/cp38-cp38/bin/python'
+
+    process: subprocess.Popen
+    bash_stdin: IO[bytes]
+    bash_stdout: IO[bytes]
+
+    def __init__(self, docker_image: str, simulate_32_bit: bool = False, cwd: Optional[Union[str, PathLike]] = None):
+        self.docker_image = docker_image
+        self.simulate_32_bit = simulate_32_bit
+        self.cwd = cwd
+
+    def __enter__(self) -> 'DockerContainer':
+        self.name = f'cibuildwheel-{uuid.uuid4()}'
+        cwd_args = ['-w', str(self.cwd)] if self.cwd else []
+        shell_args = ['linux32', '/bin/bash'] if self.simulate_32_bit else ['/bin/bash']
+        subprocess.run(
+            [
+                'docker', 'create',
+                '--env', 'CIBUILDWHEEL',
+                '--name', self.name,
+                '-i',
+                '-v', '/:/host',  # ignored on CircleCI
+                *cwd_args,
+                self.docker_image,
+                *shell_args
+            ],
+            check=True,
+        )
+        self.process = subprocess.Popen(
+            [
+                'docker', 'start',
+                '--attach', '--interactive',
+                self.name,
+            ],
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+        )
+
+        assert self.process.stdin and self.process.stdout
+        self.bash_stdin = self.process.stdin
+        self.bash_stdout = self.process.stdout
+
+        # run a noop command to block until the container is responding
+        self.call(['/bin/true'])
+
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.bash_stdin.close()
+        self.process.terminate()
+        self.process.wait()
+
+        subprocess.run(['docker', 'rm', '--force', '-v', self.name])
+        self.name = None
+
+    def copy_into(self, from_path: Path, to_path: PurePath) -> None:
+        # `docker cp` causes 'no space left on device' error when
+        # a container is running and the host filesystem is
+        # mounted. https://github.com/moby/moby/issues/38995
+        # Use `docker exec` instead.
+
+        if from_path.is_dir():
+            self.call(['mkdir', '-p', to_path])
+            subprocess.run(
+                f'tar cf - . | docker exec -i {self.name} tar -xC {shell_quote(to_path)} -f -',
+                shell=True,
+                check=True,
+                cwd=from_path)
+        else:
+            subprocess.run(
+                f'cat {shell_quote(from_path)} | docker exec -i {self.name} sh -c "cat > {shell_quote(to_path)}"',
+                shell=True,
+                check=True)
+
+    def copy_out(self, from_path: PurePath, to_path: Path) -> None:
+        # note: we assume from_path is a dir
+        to_path.mkdir(parents=True, exist_ok=True)
+
+        subprocess.run(
+            f'docker exec -i {self.name} tar -cC {shell_quote(from_path)} -f - . | tar -xf -',
+            shell=True,
+            check=True,
+            cwd=to_path
+        )
+
+    def glob(self, path: PurePath, pattern: str) -> List[PurePath]:
+        glob_pattern = os.path.join(str(path), pattern)
+
+        path_strs = json.loads(self.call([
+            self.UTILITY_PYTHON,
+            '-c',
+            f'import sys, json, glob; json.dump(glob.glob({glob_pattern!r}), sys.stdout)'
+        ], capture_output=True))
+
+        return [PurePath(p) for p in path_strs]
+
+    def call(self, args: Sequence[Union[str, PathLike]], env: Dict[str, str] = {},
+             capture_output=False, cwd: Optional[Union[str, PathLike]] = None) -> str:
+        chdir = f'cd {cwd}' if cwd else ''
+        env_assignments = ' '.join(f'{shlex.quote(k)}={shlex.quote(v)}'
+                                   for k, v in env.items())
+        command = ' '.join(shlex.quote(str(a)) for a in args)
+        end_of_message = str(uuid.uuid4())
+
+        # log the command we're executing
+        print(f'    + {command}')
+
+        # Write a command to the remote shell. First we change the
+        # cwd, if that's required. Then, we use the `env` utility to run
+        # `command` inside the specified environment. We use `env` because it
+        # can cope with spaces and strange characters in the name or value.
+        # Finally, the remote shell is told to write a footer - this will show
+        # up in the output so we know when to stop reading, and will include
+        # the returncode of `command`.
+        self.bash_stdin.write(bytes(f'''(
+            {chdir}
+            env {env_assignments} {command}
+            printf "%04d%s\n" $? {end_of_message}
+        )
+        ''', encoding='utf8', errors='surrogateescape'))
+        self.bash_stdin.flush()
+
+        if capture_output:
+            output_io: IO[bytes] = io.BytesIO()
+        else:
+            output_io = sys.stdout.buffer
+
+        while True:
+            line = self.bash_stdout.readline()
+
+            if line.endswith(b'%s\n' % (bytes(end_of_message, encoding='utf8'))):
+                footer_offset = (
+                    len(line)
+                    - 1  # newline character
+                    - len(end_of_message)  # delimiter
+                    - 4  # 4 returncode decimals
+                )
+                returncode_str = line[footer_offset:footer_offset+4]
+                returncode = int(returncode_str)
+                # add the last line to output, without the footer
+                output_io.write(line[0:footer_offset])
+                break
+            else:
+                output_io.write(line)
+
+        if isinstance(output_io, io.BytesIO):
+            output = str(output_io.getvalue(), encoding='utf8', errors='surrogateescape')
+        else:
+            output = ''
+
+        if returncode != 0:
+            raise subprocess.CalledProcessError(returncode, args, output)
+
+        return output
+
+    def get_environment(self) -> Dict[str, str]:
+        return json.loads(self.call([
+            self.UTILITY_PYTHON,
+            '-c',
+            'import sys, json, os; json.dump(os.environ.copy(), sys.stdout)'
+        ], capture_output=True))
+
+    def environment_executor(self, command: List[str], environment: Dict[str, str]) -> str:
+        # used as an EnvironmentExecutor to evaluate commands and capture output
+        return self.call(command, env=environment, capture_output=True)
+
+
+def shell_quote(path: PurePath) -> str:
+    return shlex.quote(str(path))

cibuildwheel/environment.py

@@ -1,6 +1,6 @@
 import bashlex  # type: ignore
 
-from typing import Dict, List
+from typing import Dict, List, Mapping, Optional
 
 from . import bashlex_eval
 
@@ -46,9 +46,9 @@ class EnvironmentAssignment:
         self.name = name
         self.value = value
 
-    def evaluated_value(self, environment: Dict[str, str]) -> str:
+    def evaluated_value(self, environment: Dict[str, str], executor: Optional[bashlex_eval.EnvironmentExecutor] = None) -> str:
         '''Returns the value of this assignment, as evaluated in the environment'''
-        return bashlex_eval.evaluate(self.value, environment=environment)
+        return bashlex_eval.evaluate(self.value, environment=environment, executor=executor)
 
     def as_shell_assignment(self) -> str:
         return f'export {self.name}={self.value}'
@@ -61,11 +61,13 @@ class ParsedEnvironment:
     def __init__(self, assignments: List[EnvironmentAssignment]):
         self.assignments = assignments
 
-    def as_dictionary(self, prev_environment: Dict[str, str]) -> Dict[str, str]:
-        environment = prev_environment.copy()
+    def as_dictionary(self,
+                      prev_environment: Mapping[str, str],
+                      executor: Optional[bashlex_eval.EnvironmentExecutor] = None) -> Dict[str, str]:
+        environment = dict(**prev_environment)
 
         for assignment in self.assignments:
-            value = assignment.evaluated_value(environment=environment)
+            value = assignment.evaluated_value(environment=environment, executor=executor)
             environment[assignment.name] = value
 
         return environment

cibuildwheel/linux.py

@@ -1,26 +1,14 @@
-import os
 import platform
-import shlex
 import subprocess
 import sys
 import textwrap
-import uuid
+from os import PathLike
+from pathlib import Path, PurePath
+from typing import List, NamedTuple, Union
 
-from typing import List, NamedTuple, Optional, Union
-
-from .util import (
-    BuildOptions,
-    BuildSelector,
-    get_build_verbosity_extra_flags,
-    prepare_command,
-)
-
-
-def call(args: List[str], input: Optional[Union[str, bytes]] = None, universal_newlines: bool = False) -> None:
-    print('+ ' + ' '.join(shlex.quote(a) for a in args))
-    subprocess.run(
-        args, input=input, universal_newlines=universal_newlines, check=True
-    )
+from .docker_container import DockerContainer
+from .util import (BuildOptions, BuildSelector,
+                   get_build_verbosity_extra_flags, prepare_command)
 
 
 def matches_platform(identifier: str) -> bool:
@@ -47,42 +35,46 @@ def matches_platform(identifier: str) -> bool:
 class PythonConfiguration(NamedTuple):
     version: str
     identifier: str
-    path: str
+    path_str: str
+
+    @property
+    def path(self):
+        return PurePath(self.path_str)
 
 
 def get_python_configurations(build_selector: BuildSelector) -> List[PythonConfiguration]:
     python_configurations = [
-        PythonConfiguration(version='2.7', identifier='cp27-manylinux_x86_64', path='/opt/python/cp27-cp27m'),
-        PythonConfiguration(version='2.7', identifier='cp27-manylinux_x86_64', path='/opt/python/cp27-cp27mu'),
-        PythonConfiguration(version='3.5', identifier='cp35-manylinux_x86_64', path='/opt/python/cp35-cp35m'),
-        PythonConfiguration(version='3.6', identifier='cp36-manylinux_x86_64', path='/opt/python/cp36-cp36m'),
-        PythonConfiguration(version='3.7', identifier='cp37-manylinux_x86_64', path='/opt/python/cp37-cp37m'),
-        PythonConfiguration(version='3.8', identifier='cp38-manylinux_x86_64', path='/opt/python/cp38-cp38'),
-        PythonConfiguration(version='3.9', identifier='cp39-manylinux_x86_64', path='/opt/python/cp39-cp39'),
-        PythonConfiguration(version='2.7', identifier='cp27-manylinux_i686', path='/opt/python/cp27-cp27m'),
-        PythonConfiguration(version='2.7', identifier='cp27-manylinux_i686', path='/opt/python/cp27-cp27mu'),
-        PythonConfiguration(version='3.5', identifier='cp35-manylinux_i686', path='/opt/python/cp35-cp35m'),
-        PythonConfiguration(version='3.6', identifier='cp36-manylinux_i686', path='/opt/python/cp36-cp36m'),
-        PythonConfiguration(version='3.7', identifier='cp37-manylinux_i686', path='/opt/python/cp37-cp37m'),
-        PythonConfiguration(version='3.8', identifier='cp38-manylinux_i686', path='/opt/python/cp38-cp38'),
-        PythonConfiguration(version='3.9', identifier='cp39-manylinux_i686', path='/opt/python/cp39-cp39'),
-        PythonConfiguration(version='2.7', identifier='pp27-manylinux_x86_64', path='/opt/python/pp27-pypy_73'),
-        PythonConfiguration(version='3.6', identifier='pp36-manylinux_x86_64', path='/opt/python/pp36-pypy36_pp73'),
-        PythonConfiguration(version='3.5', identifier='cp35-manylinux_aarch64', path='/opt/python/cp35-cp35m'),
-        PythonConfiguration(version='3.6', identifier='cp36-manylinux_aarch64', path='/opt/python/cp36-cp36m'),
-        PythonConfiguration(version='3.7', identifier='cp37-manylinux_aarch64', path='/opt/python/cp37-cp37m'),
-        PythonConfiguration(version='3.8', identifier='cp38-manylinux_aarch64', path='/opt/python/cp38-cp38'),
-        PythonConfiguration(version='3.9', identifier='cp39-manylinux_aarch64', path='/opt/python/cp39-cp39'),
-        PythonConfiguration(version='3.5', identifier='cp35-manylinux_ppc64le', path='/opt/python/cp35-cp35m'),
-        PythonConfiguration(version='3.6', identifier='cp36-manylinux_ppc64le', path='/opt/python/cp36-cp36m'),
-        PythonConfiguration(version='3.7', identifier='cp37-manylinux_ppc64le', path='/opt/python/cp37-cp37m'),
-        PythonConfiguration(version='3.8', identifier='cp38-manylinux_ppc64le', path='/opt/python/cp38-cp38'),
-        PythonConfiguration(version='3.9', identifier='cp39-manylinux_ppc64le', path='/opt/python/cp39-cp39'),
-        PythonConfiguration(version='3.5', identifier='cp35-manylinux_s390x', path='/opt/python/cp35-cp35m'),
-        PythonConfiguration(version='3.6', identifier='cp36-manylinux_s390x', path='/opt/python/cp36-cp36m'),
-        PythonConfiguration(version='3.7', identifier='cp37-manylinux_s390x', path='/opt/python/cp37-cp37m'),
-        PythonConfiguration(version='3.8', identifier='cp38-manylinux_s390x', path='/opt/python/cp38-cp38'),
-        PythonConfiguration(version='3.9', identifier='cp39-manylinux_s390x', path='/opt/python/cp39-cp39'),
+        PythonConfiguration(version='2.7', identifier='cp27-manylinux_x86_64', path_str='/opt/python/cp27-cp27m'),
+        PythonConfiguration(version='2.7', identifier='cp27-manylinux_x86_64', path_str='/opt/python/cp27-cp27mu'),
+        PythonConfiguration(version='3.5', identifier='cp35-manylinux_x86_64', path_str='/opt/python/cp35-cp35m'),
+        PythonConfiguration(version='3.6', identifier='cp36-manylinux_x86_64', path_str='/opt/python/cp36-cp36m'),
+        PythonConfiguration(version='3.7', identifier='cp37-manylinux_x86_64', path_str='/opt/python/cp37-cp37m'),
+        PythonConfiguration(version='3.8', identifier='cp38-manylinux_x86_64', path_str='/opt/python/cp38-cp38'),
+        PythonConfiguration(version='3.9', identifier='cp39-manylinux_x86_64', path_str='/opt/python/cp39-cp39'),
+        PythonConfiguration(version='2.7', identifier='cp27-manylinux_i686', path_str='/opt/python/cp27-cp27m'),
+        PythonConfiguration(version='2.7', identifier='cp27-manylinux_i686', path_str='/opt/python/cp27-cp27mu'),
+        PythonConfiguration(version='3.5', identifier='cp35-manylinux_i686', path_str='/opt/python/cp35-cp35m'),
+        PythonConfiguration(version='3.6', identifier='cp36-manylinux_i686', path_str='/opt/python/cp36-cp36m'),
+        PythonConfiguration(version='3.7', identifier='cp37-manylinux_i686', path_str='/opt/python/cp37-cp37m'),
+        PythonConfiguration(version='3.8', identifier='cp38-manylinux_i686', path_str='/opt/python/cp38-cp38'),
+        PythonConfiguration(version='3.9', identifier='cp39-manylinux_i686', path_str='/opt/python/cp39-cp39'),
+        PythonConfiguration(version='2.7', identifier='pp27-manylinux_x86_64', path_str='/opt/python/pp27-pypy_73'),
+        PythonConfiguration(version='3.6', identifier='pp36-manylinux_x86_64', path_str='/opt/python/pp36-pypy36_pp73'),
+        PythonConfiguration(version='3.5', identifier='cp35-manylinux_aarch64', path_str='/opt/python/cp35-cp35m'),
+        PythonConfiguration(version='3.6', identifier='cp36-manylinux_aarch64', path_str='/opt/python/cp36-cp36m'),
+        PythonConfiguration(version='3.7', identifier='cp37-manylinux_aarch64', path_str='/opt/python/cp37-cp37m'),
+        PythonConfiguration(version='3.8', identifier='cp38-manylinux_aarch64', path_str='/opt/python/cp38-cp38'),
+        PythonConfiguration(version='3.9', identifier='cp39-manylinux_aarch64', path_str='/opt/python/cp39-cp39'),
+        PythonConfiguration(version='3.5', identifier='cp35-manylinux_ppc64le', path_str='/opt/python/cp35-cp35m'),
+        PythonConfiguration(version='3.6', identifier='cp36-manylinux_ppc64le', path_str='/opt/python/cp36-cp36m'),
+        PythonConfiguration(version='3.7', identifier='cp37-manylinux_ppc64le', path_str='/opt/python/cp37-cp37m'),
+        PythonConfiguration(version='3.8', identifier='cp38-manylinux_ppc64le', path_str='/opt/python/cp38-cp38'),
+        PythonConfiguration(version='3.9', identifier='cp39-manylinux_ppc64le', path_str='/opt/python/cp39-cp39'),
+        PythonConfiguration(version='3.5', identifier='cp35-manylinux_s390x', path_str='/opt/python/cp35-cp35m'),
+        PythonConfiguration(version='3.6', identifier='cp36-manylinux_s390x', path_str='/opt/python/cp36-cp36m'),
+        PythonConfiguration(version='3.7', identifier='cp37-manylinux_s390x', path_str='/opt/python/cp37-cp37m'),
+        PythonConfiguration(version='3.8', identifier='cp38-manylinux_s390x', path_str='/opt/python/cp38-cp38'),
+        PythonConfiguration(version='3.9', identifier='cp39-manylinux_s390x', path_str='/opt/python/cp39-cp39'),
     ]
     # skip builds as required
     return [c for c in python_configurations if matches_platform(c.identifier) and build_selector(c.identifier)]
@@ -109,193 +101,144 @@ def build(options: BuildOptions) -> None:
         ('pp', 'manylinux_x86_64', options.manylinux_images['pypy_x86_64']),
     ]
 
-    if not os.path.realpath(options.package_dir).startswith(os.path.realpath('.')):
+    cwd = Path.cwd()
+    abs_package_dir = options.package_dir.resolve()
+    if cwd != abs_package_dir and cwd not in abs_package_dir.parents:
         raise Exception('package_dir must be inside the working directory')
 
-    container_package_dir = os.path.join('/project', os.path.relpath(options.package_dir, '.'))
+    container_project_path = PurePath('/project')
+    container_package_dir = container_project_path / abs_package_dir.relative_to(cwd)
+    container_output_dir = PurePath('/output')
 
     for implementation, platform_tag, docker_image in platforms:
         platform_configs = [c for c in python_configurations if c.identifier.startswith(implementation) and c.identifier.endswith(platform_tag)]
         if not platform_configs:
             continue
 
-        shell_cmd = ['linux32', '/bin/bash'] if platform_tag.endswith("i686") else ['/bin/bash']
-
-        container_name = f'cibuildwheel-{uuid.uuid4()}'
-        call(['docker', 'create',
-              '--env', 'CIBUILDWHEEL',
-              '--name', container_name,
-              '-i',
-              '-v', '/:/host',  # ignored on CircleCI
-              docker_image,
-              '/bin/bash'])
-
         try:
-            call(['docker', 'cp', '.', container_name + ':/project'])
+            with DockerContainer(docker_image, simulate_32_bit=platform_tag.endswith('i686'), cwd=container_project_path) as docker:
+                docker.copy_into(Path.cwd(), container_project_path)
 
-            call(['docker', 'start', container_name])
+                if options.before_all:
+                    env = docker.get_environment()
+                    env['PATH'] = f'/opt/python/cp38-cp38:{env["PATH"]}'
+                    env = options.environment.as_dictionary(env, executor=docker.environment_executor)
 
-            for config in platform_configs:
-                if options.dependency_constraints:
-                    constraints_file = options.dependency_constraints.get_for_python_version(config.version)
+                    before_all_prepared = prepare_command(options.before_all, project=container_project_path, package=container_package_dir)
+                    docker.call(['sh', '-c', before_all_prepared], env=env)
 
-                    # `docker cp` causes 'no space left on device' error when
-                    # a container is running and the host filesystem is
-                    # mounted. https://github.com/moby/moby/issues/38995
-                    # Use `docker exec` instead.
-                    with open(constraints_file, 'rb') as f:
-                        call(
-                            ['docker', 'exec', '-i', container_name, 'sh', '-c', 'cat > /constraints.txt'],
-                            input=f.read(),
-                        )
+                for config in platform_configs:
+                    dependency_constraint_flags: List[Union[str, PathLike]] = []
 
-                call(
-                    ['docker', 'exec', '-i', container_name] + shell_cmd,
-                    universal_newlines=True,
-                    input='''
-                        # give xtrace output an extra level of indent inside docker
-                        PS4='    + '
+                    if options.dependency_constraints:
+                        constraints_file = options.dependency_constraints.get_for_python_version(config.version)
+                        container_constraints_file = PurePath('/constraints.txt')
 
-                        set -o errexit
-                        set -o xtrace
-                        mkdir -p /output
-                        cd /project
+                        docker.copy_into(constraints_file, container_constraints_file)
+                        dependency_constraint_flags = ['-c', container_constraints_file]
 
-                        PYBIN="{config_python_bin}"
+                    env = docker.get_environment()
 
-                        export PATH="$PYBIN:$PATH"
-                        {environment_exports}
+                    # put this config's python top of the list
+                    python_bin = config.path / 'bin'
+                    env['PATH'] = f'{python_bin}:{env["PATH"]}'
 
-                        # check the active python and pip are in PYBIN
-                        if [ "$(which pip)" != "$PYBIN/pip" ]; then
-                        echo "cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it."
-                        exit 1
-                        fi
-                        if [ "$(which python)" != "$PYBIN/python" ]; then
-                        echo "cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it."
-                        exit 1
-                        fi
+                    env = options.environment.as_dictionary(env, executor=docker.environment_executor)
 
-                        if [ ! -z {before_build} ]; then
-                            sh -c {before_build}
-                        fi
+                    # check config python and pip are still on PATH
+                    which_python = docker.call(['which', 'python'], env=env, capture_output=True).strip()
+                    if PurePath(which_python) != python_bin / 'python':
+                        print("cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it.", file=sys.stderr)
+                        exit(1)
 
-                        # Build the wheel
-                        rm -rf /tmp/built_wheel
-                        mkdir /tmp/built_wheel
-                        pip wheel {package_dir} -w /tmp/built_wheel --no-deps {build_verbosity_flag}
-                        built_wheel=(/tmp/built_wheel/*.whl)
+                    which_pip = docker.call(['which', 'pip'], env=env, capture_output=True).strip()
+                    if PurePath(which_pip) != python_bin / 'pip':
+                        print("cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.", file=sys.stderr)
+                        exit(1)
 
-                        # repair the wheel
-                        rm -rf /tmp/repaired_wheels
-                        mkdir /tmp/repaired_wheels
-                        # NOTE: 'built_wheel' here is a bash array of glob matches; "$built_wheel" returns
-                        # the first element
-                        if [[ "$built_wheel" == *none-any.whl ]] || [ -z {repair_command} ]; then
-                            # pure Python wheel or empty repair command
-                            mv "$built_wheel" /tmp/repaired_wheels
-                        else
-                            sh -c {repair_command} repair_command "$built_wheel"
-                        fi
-                        repaired_wheels=(/tmp/repaired_wheels/*.whl)
+                    if options.before_build:
+                        before_build_prepared = prepare_command(options.before_build, project=container_project_path, package=container_package_dir)
+                        docker.call(['sh', '-c', before_build_prepared], env=env)
 
-                        if [ ! -z {test_command} ]; then
-                            # Set up a virtual environment to install and test from, to make sure
-                            # there are no dependencies that were pulled in at build time.
-                            pip install {dependency_install_flags} virtualenv
-                            venv_dir=`mktemp -d`/venv
-                            python -m virtualenv --no-download "$venv_dir"
+                    temp_dir = PurePath('/tmp/cibuildwheel')
+                    built_wheel_dir = temp_dir / 'built_wheel'
+                    docker.call(['rm', '-rf', built_wheel_dir])
+                    docker.call(['mkdir', '-p', built_wheel_dir])
 
-                            # run the tests in a subshell to keep that `activate`
-                            # script from polluting the env
-                            (
-                                source "$venv_dir/bin/activate"
+                    docker.call([
+                        'pip', 'wheel',
+                        container_package_dir,
+                        '-w', built_wheel_dir,
+                        '--no-deps',
+                        *get_build_verbosity_extra_flags(options.build_verbosity)
+                    ], env=env)
 
-                                echo "Running tests using `which python`"
+                    built_wheel = docker.glob(built_wheel_dir, '*.whl')[0]
 
-                                if [ ! -z {before_test} ]; then
-                                    sh -c {before_test}
-                                fi
+                    repaired_wheel_dir = temp_dir / 'repaired_wheel'
+                    docker.call(['rm', '-rf', repaired_wheel_dir])
+                    docker.call(['mkdir', '-p', repaired_wheel_dir])
 
-                                # Install the wheel we just built
-                                # Note: If auditwheel produced two wheels, it's because the earlier produced wheel
-                                # conforms to multiple manylinux standards. These multiple versions of the wheel are
-                                # functionally the same, differing only in name, wheel metadata, and possibly include
-                                # different external shared libraries. so it doesn't matter which one we run the tests on.
-                                # Let's just pick the first one.
-                                pip install "${{repaired_wheels[0]}}"{test_extras}
+                    if built_wheel.name.endswith('none-any.whl') or not options.repair_command:
+                        docker.call(['mv', built_wheel, repaired_wheel_dir])
+                    else:
+                        repair_command_prepared = prepare_command(options.repair_command, wheel=built_wheel, dest_dir=repaired_wheel_dir)
+                        docker.call(['sh', '-c', repair_command_prepared], env=env)
 
-                                # Install any requirements to run the tests
-                                if [ ! -z "{test_requires}" ]; then
-                                    pip install {test_requires}
-                                fi
+                    repaired_wheels = docker.glob(repaired_wheel_dir, '*.whl')
 
-                                # Run the tests from a different directory
-                                pushd $HOME
-                                sh -c {test_command}
-                                popd
-                            )
-                            # exit if tests failed (needed for older bash versions)
-                            if [ $? -ne 0 ]; then
-                              exit 1;
-                            fi
+                    if options.test_command:
+                        # set up a virtual environment to install and test from, to make sure
+                        # there are no dependencies that were pulled in at build time.
+                        docker.call(['pip', 'install', 'virtualenv', *dependency_constraint_flags], env=env)
+                        venv_dir = PurePath(docker.call(['mktemp', '-d'], capture_output=True).strip()) / 'venv'
 
-                            # clean up
-                            rm -rf "$venv_dir"
-                        fi
+                        docker.call(['python', '-m', 'virtualenv', '--no-download', venv_dir], env=env)
 
-                        # we're all done here; move it to output
-                        mv "${{repaired_wheels[@]}}" /output
-                        for repaired_wheel in "${{repaired_wheels[@]}}"; do
-                            chown {uid}:{gid} "/output/$(basename "$repaired_wheel")"
-                        done
-                    '''.format(
-                        config_python_bin=config.path + '/bin',
-                        package_dir=container_package_dir,
-                        test_requires=' '.join(options.test_requires),
-                        test_extras=options.test_extras,
-                        test_command=shlex.quote(
-                            prepare_command(options.test_command, project='/project', package=container_package_dir) if options.test_command else ''
-                        ),
-                        before_build=shlex.quote(
-                            prepare_command(options.before_build, project='/project', package=container_package_dir) if options.before_build else ''
-                        ),
-                        build_verbosity_flag=' '.join(get_build_verbosity_extra_flags(options.build_verbosity)),
-                        repair_command=shlex.quote(
-                            prepare_command(options.repair_command, wheel='"$1"', dest_dir='/tmp/repaired_wheels') if options.repair_command else ''
-                        ),
-                        environment_exports='\n'.join(options.environment.as_shell_commands()),
-                        uid=os.getuid(),
-                        gid=os.getgid(),
-                        before_test=shlex.quote(
-                            prepare_command(options.before_test, project='/project', package=container_package_dir) if options.before_test else ''
-                        ),
-                        dependency_install_flags='-c /constraints.txt' if options.dependency_constraints else '',
-                    )
-                )
+                        virtualenv_env = env.copy()
+                        virtualenv_env['PATH'] = f"{venv_dir / 'bin'}:{virtualenv_env['PATH']}"
 
-            # copy the output back into the host
-            call(['docker', 'cp',
-                  container_name + ':/output/.',
-                  os.path.abspath(options.output_dir)])
+                        if options.before_test:
+                            before_test_prepared = prepare_command(options.before_test, project=container_project_path, package=container_package_dir)
+                            docker.call(['sh', '-c', before_test_prepared], env=virtualenv_env)
+
+                        # Install the wheel we just built
+                        # Note: If auditwheel produced two wheels, it's because the earlier produced wheel
+                        # conforms to multiple manylinux standards. These multiple versions of the wheel are
+                        # functionally the same, differing only in name, wheel metadata, and possibly include
+                        # different external shared libraries. so it doesn't matter which one we run the tests on.
+                        # Let's just pick the first one.
+                        wheel_to_test = repaired_wheels[0]
+                        docker.call(['pip', 'install', str(wheel_to_test) + options.test_extras], env=virtualenv_env)
+
+                        # Install any requirements to run the tests
+                        if options.test_requires:
+                            docker.call(['pip', 'install', *options.test_requires], env=virtualenv_env)
+
+                        # Run the tests from a different directory
+                        test_command_prepared = prepare_command(options.test_command, project=container_project_path, package=container_package_dir)
+                        docker.call(['sh', '-c', test_command_prepared], cwd='/root', env=virtualenv_env)
+
+                        # clean up test environment
+                        docker.call(['rm', '-rf', venv_dir])
+
+                    # move repaired wheels to output
+                    docker.call(['mkdir', '-p', container_output_dir])
+                    docker.call(['mv', *repaired_wheels, container_output_dir])
+
+                # copy the output back into the host
+                docker.copy_out(container_output_dir, options.output_dir)
         except subprocess.CalledProcessError as error:
+            print(f'Command {error.cmd} failed with code {error.returncode}. {error.stdout}')
             troubleshoot(options.package_dir, error)
             exit(1)
-        finally:
-            # Still gets executed, even when 'exit(1)' gets called
-            call(['docker', 'rm', '--force', '-v', container_name])
 
 
-def troubleshoot(package_dir: str, error: Exception) -> None:
+def troubleshoot(package_dir: Path, error: Exception) -> None:
     if (isinstance(error, subprocess.CalledProcessError) and 'exec' in error.cmd):
         # the bash script failed
         print('Checking for common errors...')
-        so_files = []
-        for root, dirs, files in os.walk(package_dir):
-            for name in files:
-                _, ext = os.path.splitext(name)
-                if ext == '.so':
-                    so_files.append(os.path.join(root, name))
+        so_files = list(package_dir.glob('**/*.so'))
 
         if so_files:
             print(textwrap.dedent('''
@@ -309,5 +252,5 @@ def troubleshoot(package_dir: str, error: Exception) -> None:
             '''))
 
             print('  Files detected:')
-            print('\n'.join(['    ' + f for f in so_files]))
+            print('\n'.join([f'    {f}' for f in so_files]))
             print('')

cibuildwheel/macos.py

@@ -4,27 +4,22 @@ import shutil
 import subprocess
 import sys
 import tempfile
-from glob import glob
-
-from typing import Dict, List, Optional, NamedTuple, Union
+from os import PathLike
+from pathlib import Path
+from typing import Dict, List, NamedTuple, Optional, Sequence, Union
 
 from .environment import ParsedEnvironment
-from .util import (
-    BuildOptions,
-    BuildSelector,
-    download,
-    get_build_verbosity_extra_flags,
-    get_pip_script,
-    prepare_command,
-)
+from .util import (BuildOptions, BuildSelector, download,
+                   get_build_verbosity_extra_flags, get_pip_script,
+                   prepare_command)
 
 
-def call(args: Union[str, List[str]], env: Optional[Dict[str, str]] = None, cwd: Optional[str] = None, shell: bool = False) -> int:
+def call(args: Union[str, Sequence[Union[str, PathLike]]], env: Optional[Dict[str, str]] = None, cwd: Optional[str] = None, shell: bool = False) -> int:
     # print the command executing for the logs
     if shell:
         print(f'+ {args}')
     else:
-        print('+ ' + ' '.join(shlex.quote(a) for a in args))
+        print('+ ' + ' '.join(shlex.quote(str(a)) for a in args))
 
     return subprocess.check_call(args, env=env, cwd=cwd, shell=shell)
 
@@ -41,8 +36,8 @@ def get_python_configurations(build_selector: BuildSelector) -> List[PythonConfi
         PythonConfiguration(version='2.7', identifier='cp27-macosx_x86_64', url='https://www.python.org/ftp/python/2.7.18/python-2.7.18-macosx10.9.pkg'),
         PythonConfiguration(version='3.5', identifier='cp35-macosx_x86_64', url='https://www.python.org/ftp/python/3.5.4/python-3.5.4-macosx10.6.pkg'),
         PythonConfiguration(version='3.6', identifier='cp36-macosx_x86_64', url='https://www.python.org/ftp/python/3.6.8/python-3.6.8-macosx10.9.pkg'),
-        PythonConfiguration(version='3.7', identifier='cp37-macosx_x86_64', url='https://www.python.org/ftp/python/3.7.7/python-3.7.7-macosx10.9.pkg'),
-        PythonConfiguration(version='3.8', identifier='cp38-macosx_x86_64', url='https://www.python.org/ftp/python/3.8.3/python-3.8.3-macosx10.9.pkg'),
+        PythonConfiguration(version='3.7', identifier='cp37-macosx_x86_64', url='https://www.python.org/ftp/python/3.7.8/python-3.7.8-macosx10.9.pkg'),
+        PythonConfiguration(version='3.8', identifier='cp38-macosx_x86_64', url='https://www.python.org/ftp/python/3.8.4/python-3.8.4-macosx10.9.pkg'),
         PythonConfiguration(version='3.9', identifier='cp39-macosx_x86_64', url='https://www.python.org/ftp/python/3.9.0/python-3.9.0b3-macosx10.9.pkg'),
         # PyPy
         PythonConfiguration(version='2.7', identifier='pp27-macosx_x86_64', url='https://downloads.python.org/pypy/pypy2.7-v7.3.1-osx64.tar.bz2'),
@@ -53,41 +48,41 @@ def get_python_configurations(build_selector: BuildSelector) -> List[PythonConfi
     return [c for c in python_configurations if build_selector(c.identifier)]
 
 
-SYMLINKS_DIR = '/tmp/cibw_bin'
+SYMLINKS_DIR = Path('/tmp/cibw_bin')
 
 
-def make_symlinks(installation_bin_path: str, python_executable: str, pip_executable: str) -> None:
-    assert os.path.exists(os.path.join(installation_bin_path, python_executable))
+def make_symlinks(installation_bin_path: Path, python_executable: str, pip_executable: str) -> None:
+    assert (installation_bin_path / python_executable).exists()
 
     # Python bin folders on Mac don't symlink `python3` to `python`, and neither
     # does PyPy for `pypy` or `pypy3`, so we do that so `python` and `pip` always
     # point to the active configuration.
-    if os.path.exists(SYMLINKS_DIR):
+    if SYMLINKS_DIR.exists():
         shutil.rmtree(SYMLINKS_DIR)
-    os.makedirs(SYMLINKS_DIR)
+    SYMLINKS_DIR.mkdir(parents=True)
 
-    os.symlink(os.path.join(installation_bin_path, python_executable), os.path.join(SYMLINKS_DIR, 'python'))
-    os.symlink(os.path.join(installation_bin_path, python_executable + '-config'), os.path.join(SYMLINKS_DIR, 'python-config'))
-    os.symlink(os.path.join(installation_bin_path, pip_executable), os.path.join(SYMLINKS_DIR, 'pip'))
+    (SYMLINKS_DIR / 'python').symlink_to(installation_bin_path / python_executable)
+    (SYMLINKS_DIR / 'python-config').symlink_to(installation_bin_path / (python_executable + '-config'))
+    (SYMLINKS_DIR / 'pip').symlink_to(installation_bin_path / pip_executable)
 
 
-def install_cpython(version: str, url: str) -> str:
+def install_cpython(version: str, url: str) -> Path:
     installed_system_packages = subprocess.check_output(['pkgutil', '--pkgs'], universal_newlines=True).splitlines()
 
     # if this version of python isn't installed, get it from python.org and install
     python_package_identifier = f'org.python.Python.PythonFramework-{version}'
     if python_package_identifier not in installed_system_packages:
         # download the pkg
-        download(url, '/tmp/Python.pkg')
+        download(url, Path('/tmp/Python.pkg'))
         # install
         call(['sudo', 'installer', '-pkg', '/tmp/Python.pkg', '-target', '/'])
         # patch open ssl
         if version == '3.5':
             open_ssl_patch_url = f'https://github.com/mayeut/patch-macos-python-openssl/releases/download/v1.0.2u/patch-macos-python-{version}-openssl-v1.0.2u.tar.gz'
-            download(open_ssl_patch_url, '/tmp/python-patch.tar.gz')
+            download(open_ssl_patch_url, Path('/tmp/python-patch.tar.gz'))
             call(['sudo', 'tar', '-C', f'/Library/Frameworks/Python.framework/Versions/{version}/', '-xmf', '/tmp/python-patch.tar.gz'])
 
-    installation_bin_path = f'/Library/Frameworks/Python.framework/Versions/{version}/bin'
+    installation_bin_path = Path(f'/Library/Frameworks/Python.framework/Versions/{version}/bin')
     python_executable = 'python3' if version[0] == '3' else 'python'
     pip_executable = 'pip3' if version[0] == '3' else 'pip'
     make_symlinks(installation_bin_path, python_executable, pip_executable)
@@ -95,16 +90,18 @@ def install_cpython(version: str, url: str) -> str:
     return installation_bin_path
 
 
-def install_pypy(version: str, url: str) -> str:
+def install_pypy(version: str, url: str) -> Path:
     pypy_tar_bz2 = url.rsplit('/', 1)[-1]
-    assert pypy_tar_bz2.endswith(".tar.bz2")
-    pypy_base_filename = os.path.splitext(os.path.splitext(pypy_tar_bz2)[0])[0]
-    installation_path = os.path.join('/tmp', pypy_base_filename)
-    if not os.path.exists(installation_path):
-        download(url, os.path.join("/tmp", pypy_tar_bz2))
-        call(['tar', '-C', '/tmp', '-xf', os.path.join("/tmp", pypy_tar_bz2)])
+    extension = ".tar.bz2"
+    assert pypy_tar_bz2.endswith(extension)
+    pypy_base_filename = pypy_tar_bz2[:-len(extension)]
+    installation_path = Path('/tmp') / pypy_base_filename
+    if not installation_path.exists():
+        downloaded_tar_bz2 = Path("/tmp") / pypy_tar_bz2
+        download(url, downloaded_tar_bz2)
+        call(['tar', '-C', '/tmp', '-xf', downloaded_tar_bz2])
 
-    installation_bin_path = os.path.join(installation_path, 'bin')
+    installation_bin_path = installation_path / 'bin'
     python_executable = 'pypy3' if version[0] == '3' else 'pypy'
     pip_executable = 'pip3' if version[0] == '3' else 'pip'
     make_symlinks(installation_bin_path, python_executable, pip_executable)
@@ -112,7 +109,9 @@ def install_pypy(version: str, url: str) -> str:
     return installation_bin_path
 
 
-def setup_python(python_configuration: PythonConfiguration, dependency_constraint_flags: List[str], environment: ParsedEnvironment) -> Dict[str, str]:
+def setup_python(python_configuration: PythonConfiguration,
+                 dependency_constraint_flags: Sequence[Union[str, PathLike]],
+                 environment: ParsedEnvironment) -> Dict[str, str]:
     if python_configuration.identifier.startswith('cp'):
         installation_bin_path = install_cpython(python_configuration.version, python_configuration.url)
     elif python_configuration.identifier.startswith('pp'):
@@ -122,8 +121,8 @@ def setup_python(python_configuration: PythonConfiguration, dependency_constrain
 
     env = os.environ.copy()
     env['PATH'] = os.pathsep.join([
-        SYMLINKS_DIR,
-        installation_bin_path,
+        str(SYMLINKS_DIR),
+        str(installation_bin_path),
         env['PATH'],
     ])
 
@@ -145,15 +144,15 @@ def setup_python(python_configuration: PythonConfiguration, dependency_constrain
         exit(1)
 
     # install pip & wheel
-    call(['python', get_pip_script] + dependency_constraint_flags, env=env, cwd="/tmp")
-    assert os.path.exists(os.path.join(installation_bin_path, 'pip'))
+    call(['python', get_pip_script, *dependency_constraint_flags], env=env, cwd="/tmp")
+    assert (installation_bin_path / 'pip').exists()
     call(['which', 'pip'], env=env)
     call(['pip', '--version'], env=env)
     which_pip = subprocess.check_output(['which', 'pip'], env=env, universal_newlines=True).strip()
     if which_pip != '/tmp/cibw_bin/pip':
         print("cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.", file=sys.stderr)
         exit(1)
-    call(['pip', 'install', '--upgrade', 'setuptools', 'wheel', 'delocate'] + dependency_constraint_flags, env=env)
+    call(['pip', 'install', '--upgrade', 'setuptools', 'wheel', 'delocate', *dependency_constraint_flags], env=env)
 
     # Set MACOSX_DEPLOYMENT_TARGET to 10.9, if the user didn't set it.
     # CPython 3.5 defaults to 10.6, and pypy defaults to 10.7, causing
@@ -171,14 +170,19 @@ def setup_python(python_configuration: PythonConfiguration, dependency_constrain
 
 
 def build(options: BuildOptions) -> None:
-    temp_dir = tempfile.mkdtemp(prefix='cibuildwheel')
-    built_wheel_dir = os.path.join(temp_dir, 'built_wheel')
-    repaired_wheel_dir = os.path.join(temp_dir, 'repaired_wheel')
+    temp_dir = Path(tempfile.mkdtemp(prefix='cibuildwheel'))
+    built_wheel_dir = temp_dir / 'built_wheel'
+    repaired_wheel_dir = temp_dir / 'repaired_wheel'
+
+    if options.before_all:
+        env = options.environment.as_dictionary(prev_environment=os.environ)
+        before_all_prepared = prepare_command(options.before_all, project='.', package=options.package_dir)
+        call([before_all_prepared], shell=True, env=env)
 
     python_configurations = get_python_configurations(options.build_selector)
 
     for config in python_configurations:
-        dependency_constraint_flags = []
+        dependency_constraint_flags: Sequence[Union[str, PathLike]] = []
         if options.dependency_constraints:
             dependency_constraint_flags = [
                 '-c', options.dependency_constraints.get_for_python_version(config.version)
@@ -192,31 +196,39 @@ def build(options: BuildOptions) -> None:
             call(before_build_prepared, env=env, shell=True)
 
         # build the wheel
-        if os.path.exists(built_wheel_dir):
+        if built_wheel_dir.exists():
             shutil.rmtree(built_wheel_dir)
-        os.makedirs(built_wheel_dir)
-        # os.path.abspath is need. Without it pip wheel may try to fetch package from pypi.org
+        built_wheel_dir.mkdir(parents=True)
+
+        # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
         # see https://github.com/joerick/cibuildwheel/pull/369
-        call(['pip', 'wheel', os.path.abspath(options.package_dir), '-w', built_wheel_dir, '--no-deps'] + get_build_verbosity_extra_flags(options.build_verbosity), env=env)
-        built_wheel = glob(os.path.join(built_wheel_dir, '*.whl'))[0]
+        call([
+            'pip', 'wheel',
+            options.package_dir.resolve(),
+            '-w', built_wheel_dir,
+            '--no-deps',
+            *get_build_verbosity_extra_flags(options.build_verbosity)
+        ], env=env)
+
+        built_wheel = next(built_wheel_dir.glob('*.whl'))
 
         # repair the wheel
-        if os.path.exists(repaired_wheel_dir):
+        if repaired_wheel_dir.exists():
             shutil.rmtree(repaired_wheel_dir)
-        os.makedirs(repaired_wheel_dir)
-        if built_wheel.endswith('none-any.whl') or not options.repair_command:
+        repaired_wheel_dir.mkdir(parents=True)
+        if built_wheel.name.endswith('none-any.whl') or not options.repair_command:
             # pure Python wheel or empty repair command
-            shutil.move(built_wheel, repaired_wheel_dir)
+            shutil.move(str(built_wheel), repaired_wheel_dir)
         else:
             repair_command_prepared = prepare_command(options.repair_command, wheel=built_wheel, dest_dir=repaired_wheel_dir)
             call(repair_command_prepared, env=env, shell=True)
-        repaired_wheel = glob(os.path.join(repaired_wheel_dir, '*.whl'))[0]
+        repaired_wheel = next(repaired_wheel_dir.glob('*.whl'))
 
         if options.test_command:
             # set up a virtual environment to install and test from, to make sure
             # there are no dependencies that were pulled in at build time.
-            call(['pip', 'install', 'virtualenv'] + dependency_constraint_flags, env=env)
-            venv_dir = tempfile.mkdtemp()
+            call(['pip', 'install', 'virtualenv', *dependency_constraint_flags], env=env)
+            venv_dir = Path(tempfile.mkdtemp())
 
             # Use --no-download to ensure determinism by using seed libraries
             # built into virtualenv
@@ -224,7 +236,7 @@ def build(options: BuildOptions) -> None:
 
             virtualenv_env = env.copy()
             virtualenv_env['PATH'] = os.pathsep.join([
-                os.path.join(venv_dir, 'bin'),
+                str(venv_dir / 'bin'),
                 virtualenv_env['PATH'],
             ])
 
@@ -236,7 +248,7 @@ def build(options: BuildOptions) -> None:
                 call(before_test_prepared, env=virtualenv_env, shell=True)
 
             # install the wheel
-            call(['pip', 'install', repaired_wheel + options.test_extras], env=virtualenv_env)
+            call(['pip', 'install', str(repaired_wheel) + options.test_extras], env=virtualenv_env)
 
             # test the wheel
             if options.test_requires:
@@ -247,8 +259,8 @@ def build(options: BuildOptions) -> None:
             # and not the repo code)
             test_command_prepared = prepare_command(
                 options.test_command,
-                project=os.path.abspath('.'),
-                package=os.path.abspath(options.package_dir)
+                project=Path('.').resolve(),
+                package=options.package_dir.resolve()
             )
             call(test_command_prepared, cwd=os.environ['HOME'], env=virtualenv_env, shell=True)
 
@@ -256,5 +268,4 @@ def build(options: BuildOptions) -> None:
             shutil.rmtree(venv_dir)
 
         # we're all done here; move it to output (overwrite existing)
-        dst = os.path.join(options.output_dir, os.path.basename(repaired_wheel))
-        shutil.move(repaired_wheel, dst)
+        shutil.move(str(repaired_wheel), options.output_dir)

cibuildwheel/util.py

@@ -1,14 +1,15 @@
 import os
 import urllib.request
 from fnmatch import fnmatch
+from pathlib import Path
 from time import sleep
 
-from typing import Dict, List, NamedTuple, Optional
+from typing import Dict, List, NamedTuple, Optional, Union
 
 from .environment import ParsedEnvironment
 
 
-def prepare_command(command: str, **kwargs: str) -> str:
+def prepare_command(command: str, **kwargs: Union[str, os.PathLike]) -> str:
     '''
     Preprocesses a command by expanding variables like {python}.
 
@@ -58,11 +59,11 @@ class Unbuffered:
         return getattr(self.stream, attr)
 
 
-def download(url: str, dest: str) -> None:
-    print('+ Download ' + url + ' to ' + dest)
-    dest_dir = os.path.dirname(dest)
-    if not os.path.exists(dest_dir):
-        os.makedirs(dest_dir)
+def download(url: str, dest: Path) -> None:
+    print(f'+ Download {url} to {dest}')
+    dest_dir = dest.parent
+    if not dest_dir.exists():
+        dest_dir.mkdir(parents=True)
 
     repeat_num = 3
     for i in range(repeat_num):
@@ -76,42 +77,42 @@ def download(url: str, dest: str) -> None:
         break
 
     try:
-        with open(dest, 'wb') as file:
-            file.write(response.read())
+        dest.write_bytes(response.read())
     finally:
         response.close()
 
 
 class DependencyConstraints:
-    def __init__(self, base_file_path: str):
-        assert os.path.exists(base_file_path)
-        self.base_file_path = os.path.abspath(base_file_path)
+    def __init__(self, base_file_path: Path):
+        assert base_file_path.exists()
+        self.base_file_path = base_file_path.resolve()
 
     @staticmethod
     def with_defaults() -> 'DependencyConstraints':
         return DependencyConstraints(
-            base_file_path=os.path.join(os.path.dirname(__file__), 'resources', 'constraints.txt')
+            base_file_path=resources_dir / 'constraints.txt'
         )
 
-    def get_for_python_version(self, version: str) -> str:
+    def get_for_python_version(self, version: str) -> Path:
         version_parts = version.split('.')
 
         # try to find a version-specific dependency file e.g. if
         # ./constraints.txt is the base, look for ./constraints-python27.txt
-        base, ext = os.path.splitext(self.base_file_path)
-        specific = base + f'-python{version_parts[0]}{version_parts[1]}'
-        specific_file_path = specific + ext
-        if os.path.exists(specific_file_path):
+        specific_stem = self.base_file_path.stem + f'-python{version_parts[0]}{version_parts[1]}'
+        specific_name = specific_stem + self.base_file_path.suffix
+        specific_file_path = self.base_file_path.with_name(specific_name)
+        if specific_file_path.exists():
             return specific_file_path
         else:
             return self.base_file_path
 
 
 class BuildOptions(NamedTuple):
-    package_dir: str
-    output_dir: str
+    package_dir: Path
+    output_dir: Path
     build_selector: BuildSelector
     environment: ParsedEnvironment
+    before_all: str
     before_build: Optional[str]
     repair_command: str
     manylinux_images: Optional[Dict[str, str]]
@@ -123,5 +124,5 @@ class BuildOptions(NamedTuple):
     build_verbosity: int
 
 
-resources_dir = os.path.abspath(os.path.join(os.path.dirname(__file__), 'resources'))
-get_pip_script = os.path.join(resources_dir, 'get-pip.py')
+resources_dir = Path(__file__).resolve().parent / 'resources'
+get_pip_script = resources_dir / 'get-pip.py'

cibuildwheel/windows.py

@@ -3,29 +3,32 @@ import shutil
 import subprocess
 import sys
 import tempfile
-from glob import glob
+from os import PathLike
+from pathlib import Path
+from typing import Dict, List, NamedTuple, Optional, Sequence, Union
 from zipfile import ZipFile
-
-from typing import Dict, List, Optional, NamedTuple
+import toml
 
 from .environment import ParsedEnvironment
-from .util import (
-    BuildOptions,
-    BuildSelector,
-    download,
-    get_build_verbosity_extra_flags,
-    get_pip_script,
-    prepare_command,
-)
+from .util import (BuildOptions, BuildSelector, download,
+                   get_build_verbosity_extra_flags, get_pip_script,
+                   prepare_command)
 
-
-IS_RUNNING_ON_AZURE = os.path.exists('C:\\hostedtoolcache')
+IS_RUNNING_ON_AZURE = Path('C:\\hostedtoolcache').exists()
 IS_RUNNING_ON_TRAVIS = os.environ.get('TRAVIS_OS_NAME') == 'windows'
 
 
-def shell(args: List[str], env: Optional[Dict[str, str]] = None, cwd: Optional[str] = None) -> int:
-    print('+ ' + ' '.join(args))
-    return subprocess.check_call(' '.join(args), env=env, cwd=cwd, shell=True)
+def call(args: Sequence[Union[str, PathLike]], env: Optional[Dict[str, str]] = None,
+         cwd: Optional[str] = None) -> None:
+    print('+ ' + ' '.join(str(a) for a in args))
+    # we use shell=True here, even though we don't need a shell due to a bug
+    # https://bugs.python.org/issue8557
+    subprocess.check_call([str(a) for a in args], env=env, cwd=cwd, shell=True)
+
+
+def shell(command: str, env: Optional[Dict[str, str]] = None, cwd: Optional[str] = None) -> None:
+    print(f'+ {command}')
+    subprocess.check_call(command, env=env, cwd=cwd, shell=True)
 
 
 def get_nuget_args(version: str, arch: str) -> List[str]:
@@ -51,10 +54,10 @@ def get_python_configurations(build_selector: BuildSelector) -> List[PythonConfi
         PythonConfiguration(version='3.5.4', arch='64', identifier='cp35-win_amd64', url=None),
         PythonConfiguration(version='3.6.8', arch='32', identifier='cp36-win32', url=None),
         PythonConfiguration(version='3.6.8', arch='64', identifier='cp36-win_amd64', url=None),
-        PythonConfiguration(version='3.7.7', arch='32', identifier='cp37-win32', url=None),
-        PythonConfiguration(version='3.7.7', arch='64', identifier='cp37-win_amd64', url=None),
-        PythonConfiguration(version='3.8.3', arch='32', identifier='cp38-win32', url=None),
-        PythonConfiguration(version='3.8.3', arch='64', identifier='cp38-win_amd64', url=None),
+        PythonConfiguration(version='3.7.8', arch='32', identifier='cp37-win32', url=None),
+        PythonConfiguration(version='3.7.8', arch='64', identifier='cp37-win_amd64', url=None),
+        PythonConfiguration(version='3.8.4', arch='32', identifier='cp38-win32', url=None),
+        PythonConfiguration(version='3.8.4', arch='64', identifier='cp38-win_amd64', url=None),
         PythonConfiguration(version='3.9.0-b3', arch='32', identifier='cp39-win32', url=None),
         PythonConfiguration(version='3.9.0-b3', arch='64', identifier='cp39-win_amd64', url=None),
         # PyPy
@@ -73,36 +76,38 @@ def get_python_configurations(build_selector: BuildSelector) -> List[PythonConfi
     return python_configurations
 
 
-def extract_zip(zip_src: str, dest: str) -> None:
+def extract_zip(zip_src: Path, dest: Path) -> None:
     with ZipFile(zip_src) as zip:
         zip.extractall(dest)
 
 
-def install_cpython(version: str, arch: str, nuget: str) -> str:
+def install_cpython(version: str, arch: str, nuget: Path) -> Path:
     nuget_args = get_nuget_args(version, arch)
-    installation_path = os.path.join(nuget_args[-1], nuget_args[0] + '.' + version, 'tools')
-    shell([nuget, 'install'] + nuget_args)
+    installation_path = Path(nuget_args[-1]) / (nuget_args[0] + '.' + version) / 'tools'
+    call([nuget, 'install', *nuget_args])
     return installation_path
 
 
-def install_pypy(version: str, arch: str, url: str) -> str:
+def install_pypy(version: str, arch: str, url: str) -> Path:
     assert arch == '32'
     # Inside the PyPy zip file is a directory with the same name
     zip_filename = url.rsplit('/', 1)[-1]
-    installation_path = os.path.join('C:\\cibw', os.path.splitext(zip_filename)[0])
-    if not os.path.exists(installation_path):
-        pypy_zip = os.path.join('C:\\cibw', zip_filename)
+    extension = ".zip"
+    assert zip_filename.endswith(extension)
+    installation_path = Path('C:\\cibw') / zip_filename[:-len(extension)]
+    if not installation_path.exists():
+        pypy_zip = Path('C:\\cibw') / zip_filename
         download(url, pypy_zip)
         # Extract to the parent directory because the zip file still contains a directory
-        extract_zip(pypy_zip, os.path.dirname(installation_path))
+        extract_zip(pypy_zip, installation_path.parent)
         pypy_exe = 'pypy3.exe' if version[0] == '3' else 'pypy.exe'
-        shell(['mklink', os.path.join(installation_path, 'python.exe'), os.path.join(installation_path, pypy_exe)])
+        (installation_path / 'python.exe').symlink_to(installation_path / pypy_exe)
     return installation_path
 
 
-def setup_python(python_configuration: PythonConfiguration, dependency_constraint_flags: List[str], environment: ParsedEnvironment) -> Dict[str, str]:
-    nuget = 'C:\\cibw\\nuget.exe'
-    if not os.path.exists(nuget):
+def setup_python(python_configuration: PythonConfiguration, dependency_constraint_flags: Sequence[Union[str, PathLike]], environment: ParsedEnvironment) -> Dict[str, str]:
+    nuget = Path('C:\\cibw\\nuget.exe')
+    if not nuget.exists():
         download('https://dist.nuget.org/win-x86-commandline/latest/nuget.exe', nuget)
 
     if python_configuration.identifier.startswith('cp'):
@@ -113,58 +118,88 @@ def setup_python(python_configuration: PythonConfiguration, dependency_constrain
     else:
         raise ValueError("Unknown Python implementation")
 
-    assert os.path.exists(os.path.join(installation_path, 'python.exe'))
+    assert (installation_path / 'python.exe').exists()
 
     # set up PATH and environment variables for run_with_env
     env = os.environ.copy()
     env['PYTHON_VERSION'] = python_configuration.version
     env['PYTHON_ARCH'] = python_configuration.arch
     env['PATH'] = os.pathsep.join([
-        installation_path,
-        os.path.join(installation_path, 'Scripts'),
+        str(installation_path),
+        str(installation_path / 'Scripts'),
         env['PATH']
     ])
     # update env with results from CIBW_ENVIRONMENT
     env = environment.as_dictionary(prev_environment=env)
 
     # for the logs - check we're running the right version of python
-    shell(['where', 'python'], env=env)
-    shell(['python', '--version'], env=env)
-    shell(['python', '-c', '"import struct; print(struct.calcsize(\'P\') * 8)"'], env=env)
+    call(['where', 'python'], env=env)
+    call(['python', '--version'], env=env)
+    call(['python', '-c', '"import struct; print(struct.calcsize(\'P\') * 8)"'], env=env)
     where_python = subprocess.check_output(['where', 'python'], env=env, universal_newlines=True).splitlines()[0].strip()
-    if where_python != os.path.join(installation_path, 'python.exe'):
+    if where_python != str(installation_path / 'python.exe'):
         print("cibuildwheel: python available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert python above it.", file=sys.stderr)
         exit(1)
 
     # make sure pip is installed
-    if not os.path.exists(os.path.join(installation_path, 'Scripts', 'pip.exe')):
-        shell(['python', get_pip_script] + dependency_constraint_flags, env=env, cwd="C:\\cibw")
-    assert os.path.exists(os.path.join(installation_path, 'Scripts', 'pip.exe'))
+    if not (installation_path / 'Scripts' / 'pip.exe').exists():
+        call(['python', get_pip_script, *dependency_constraint_flags], env=env, cwd="C:\\cibw")
+    assert (installation_path / 'Scripts' / 'pip.exe').exists()
     where_pip = subprocess.check_output(['where', 'pip'], env=env, universal_newlines=True).splitlines()[0].strip()
-    if where_pip.strip() != os.path.join(installation_path, 'Scripts', 'pip.exe'):
+    if where_pip.strip() != str(installation_path / 'Scripts' / 'pip.exe'):
         print("cibuildwheel: pip available on PATH doesn't match our installed instance. If you have modified PATH, ensure that you don't overwrite cibuildwheel's entry or insert pip above it.", file=sys.stderr)
         exit(1)
 
     # prepare the Python environment
-    shell(['python', '-m', 'pip', 'install', '--upgrade', 'pip'] + dependency_constraint_flags, env=env)
-    shell(['pip', '--version'], env=env)
-    shell(['pip', 'install', '--upgrade', 'setuptools', 'wheel'] + dependency_constraint_flags, env=env)
+    call(['python', '-m', 'pip', 'install', '--upgrade', 'pip', *dependency_constraint_flags], env=env)
+    call(['pip', '--version'], env=env)
+    call(['pip', 'install', '--upgrade', 'setuptools', 'wheel', *dependency_constraint_flags], env=env)
 
     return env
 
 
+def pep_518_cp35_workaround(package_dir: Path, env: Dict[str, str]) -> None:
+    """
+    Python 3.5 PEP 518 hack (see https://github.com/pypa/pip/issues/8392#issuecomment-639563494)
+    Basically, nuget's Python is an embedded Python distribution, which is not supported by pip.
+    Before version 3.6, there was no way to disable the "embedded" behavior, including the ignoring
+    of environment variables, including the ones pip uses to setup PEP 518 builds.
+
+    The fix here is as suggested in that issue; we manually setup the PEP 518 requirements. Since we
+    are in a fresh environment (except for pinned cibuildweel dependencies), the build is already
+    mostly "isolated".
+    """
+
+    pyproject_path = package_dir / 'pyproject.toml'
+
+    if pyproject_path.exists():
+        data = toml.load(pyproject_path)
+        requirements = (
+            data['build-system'].get('requires', [])
+            if 'build-system' in data
+            else []
+        )
+        if requirements:
+            shell(['pip', 'install'] + requirements, env=env)
+
+
 def build(options: BuildOptions) -> None:
-    temp_dir = tempfile.mkdtemp(prefix='cibuildwheel')
-    built_wheel_dir = os.path.join(temp_dir, 'built_wheel')
-    repaired_wheel_dir = os.path.join(temp_dir, 'repaired_wheel')
+    temp_dir = Path(tempfile.mkdtemp(prefix='cibuildwheel'))
+    built_wheel_dir = temp_dir / 'built_wheel'
+    repaired_wheel_dir = temp_dir / 'repaired_wheel'
 
     # install nuget as best way to provide python
-    nuget = 'C:\\cibw\\nuget.exe'
+    nuget = Path('C:\\cibw\\nuget.exe')
     download('https://dist.nuget.org/win-x86-commandline/latest/nuget.exe', nuget)
 
+    if options.before_all:
+        env = options.environment.as_dictionary(prev_environment=os.environ)
+        before_all_prepared = prepare_command(options.before_all, project='.', package=options.package_dir)
+        shell(before_all_prepared, env=env)
+
     python_configurations = get_python_configurations(options.build_selector)
     for config in python_configurations:
-        dependency_constraint_flags = []
+        dependency_constraint_flags: Sequence[Union[str, PathLike]] = []
         if options.dependency_constraints:
             dependency_constraint_flags = [
                 '-c', options.dependency_constraints.get_for_python_version(config.version)
@@ -176,47 +211,59 @@ def build(options: BuildOptions) -> None:
         # run the before_build command
         if options.before_build:
             before_build_prepared = prepare_command(options.before_build, project='.', package=options.package_dir)
-            shell([before_build_prepared], env=env)
+            shell(before_build_prepared, env=env)
+
+        # activate the PEP 518 patch if on Windows Python 3.5
+        # (will only have an effect if PEP 517 builds are used):
+        if config.version.startswith('3.5'):
+            pep_518_cp35_workaround(options.package_dir, env)
 
         # build the wheel
-        if os.path.exists(built_wheel_dir):
+        if built_wheel_dir.exists():
             shutil.rmtree(built_wheel_dir)
-        os.makedirs(built_wheel_dir)
-        # os.path.abspath is need. Without it pip wheel may try to fetch package from pypi.org
+        built_wheel_dir.mkdir(parents=True)
+        # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
         # see https://github.com/joerick/cibuildwheel/pull/369
-        shell(['pip', 'wheel', os.path.abspath(options.package_dir), '-w', built_wheel_dir, '--no-deps'] + get_build_verbosity_extra_flags(options.build_verbosity), env=env)
-        built_wheel = glob(os.path.join(built_wheel_dir, '*.whl'))[0]
+        call([
+            'pip', 'wheel',
+            options.package_dir.resolve(),
+            '-w', built_wheel_dir,
+            '--no-deps',
+            *get_build_verbosity_extra_flags(options.build_verbosity)
+        ], env=env)
+
+        built_wheel = next(built_wheel_dir.glob('*.whl'))
 
         # repair the wheel
-        if os.path.exists(repaired_wheel_dir):
+        if repaired_wheel_dir.exists():
             shutil.rmtree(repaired_wheel_dir)
-        os.makedirs(repaired_wheel_dir)
-        if built_wheel.endswith('none-any.whl') or not options.repair_command:
+        repaired_wheel_dir.mkdir(parents=True)
+        if built_wheel.name.endswith('none-any.whl') or not options.repair_command:
             # pure Python wheel or empty repair command
-            shutil.move(built_wheel, repaired_wheel_dir)
+            shutil.move(str(built_wheel), repaired_wheel_dir)
         else:
             repair_command_prepared = prepare_command(options.repair_command, wheel=built_wheel, dest_dir=repaired_wheel_dir)
-            shell([repair_command_prepared], env=env)
-        repaired_wheel = glob(os.path.join(repaired_wheel_dir, '*.whl'))[0]
+            shell(repair_command_prepared, env=env)
+        repaired_wheel = next(repaired_wheel_dir.glob('*.whl'))
 
         if options.test_command:
             # set up a virtual environment to install and test from, to make sure
             # there are no dependencies that were pulled in at build time.
-            shell(['pip', 'install', 'virtualenv'] + dependency_constraint_flags, env=env)
-            venv_dir = tempfile.mkdtemp()
+            call(['pip', 'install', 'virtualenv', *dependency_constraint_flags], env=env)
+            venv_dir = Path(tempfile.mkdtemp())
 
             # Use --no-download to ensure determinism by using seed libraries
             # built into virtualenv
-            shell(['python', '-m', 'virtualenv', '--no-download', venv_dir], env=env)
+            call(['python', '-m', 'virtualenv', '--no-download', venv_dir], env=env)
 
             virtualenv_env = env.copy()
             virtualenv_env['PATH'] = os.pathsep.join([
-                os.path.join(venv_dir, 'Scripts'),
+                str(venv_dir / 'Scripts'),
                 virtualenv_env['PATH'],
             ])
 
             # check that we are using the Python from the virtual environment
-            shell(['which', 'python'], env=virtualenv_env)
+            call(['which', 'python'], env=virtualenv_env)
 
             if options.before_test:
                 before_test_prepared = prepare_command(
@@ -224,30 +271,27 @@ def build(options: BuildOptions) -> None:
                     project='.',
                     package=options.package_dir
                 )
-                shell([before_test_prepared], env=virtualenv_env)
+                shell(before_test_prepared, env=virtualenv_env)
 
             # install the wheel
-            shell(['pip', 'install', repaired_wheel + options.test_extras], env=virtualenv_env)
+            call(['pip', 'install', str(repaired_wheel) + options.test_extras], env=virtualenv_env)
 
             # test the wheel
             if options.test_requires:
-                shell(['pip', 'install'] + options.test_requires, env=virtualenv_env)
+                call(['pip', 'install'] + options.test_requires, env=virtualenv_env)
 
             # run the tests from c:\, with an absolute path in the command
             # (this ensures that Python runs the tests against the installed wheel
             # and not the repo code)
             test_command_prepared = prepare_command(
                 options.test_command,
-                project=os.path.abspath('.'),
-                package=os.path.abspath(options.package_dir)
+                project=Path('.').resolve(),
+                package=options.package_dir.resolve()
             )
-            shell([test_command_prepared], cwd='c:\\', env=virtualenv_env)
+            shell(test_command_prepared, cwd='c:\\', env=virtualenv_env)
 
             # clean up
             shutil.rmtree(venv_dir)
 
         # we're all done here; move it to output (remove if already exists)
-        dst = os.path.join(options.output_dir, os.path.basename(repaired_wheel))
-        if os.path.isfile(dst):
-            os.remove(dst)
-        shutil.move(repaired_wheel, dst)
+        shutil.move(str(repaired_wheel), options.output_dir)