# ----------------------------------------------------------------------------
# Copyright (c) 2016-2020, QIIME 2 development team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file LICENSE, distributed with this software.
# ----------------------------------------------------------------------------
import os
import sys
import errno
import shutil
import threading
import contextlib
_REDIRECTED_STDIO_LOCK = threading.Lock()
@contextlib.contextmanager
def redirected_stdio(stdout=None, stderr=None):
with _REDIRECTED_STDIO_LOCK:
if stdout is not None:
with _redirected_fd(to=stdout, stdio=sys.stdout):
if stderr is not None:
with _redirected_fd(to=stderr, stdio=sys.stderr):
yield
else:
yield
elif stderr is not None:
with _redirected_fd(to=stderr, stdio=sys.stderr):
yield
else:
yield
# Taken whole-sale from: http://stackoverflow.com/a/22434262/579416
@contextlib.contextmanager
def _redirected_fd(to=os.devnull, stdio=None):
if stdio is None:
stdio = sys.stdout
stdio_fd = _get_fileno(stdio)
# copy stdio_fd before it is overwritten
# NOTE: `copied` is inheritable on Windows when duplicating a standard
# stream
with os.fdopen(os.dup(stdio_fd), 'wb') as copied:
stdio.flush() # flush library buffers that dup2 knows nothing about
try:
os.dup2(_get_fileno(to), stdio_fd) # $ exec >&to
except ValueError: # filename
with open(to, 'wb') as to_file:
os.dup2(to_file.fileno(), stdio_fd) # $ exec > to
try:
yield stdio # allow code to be run with the redirected stdio
finally:
# restore stdio to its previous value
# NOTE: dup2 makes stdio_fd inheritable unconditionally
stdio.flush()
os.dup2(copied.fileno(), stdio_fd) # $ exec >&copied
def _get_fileno(file_or_fd):
fd = getattr(file_or_fd, 'fileno', lambda: file_or_fd)()
if not isinstance(fd, int):
raise ValueError("Expected a file (`.fileno()`) or a file descriptor")
return fd
def duplicate(src, dst):
"""Alternative to shutil.copyfile, this will use os.link when possible.
See shutil.copyfile for documention. Only `src` and `dst` are supported.
Unlike copyfile, this will not overwrite the destination if it exists.
"""
if os.path.isdir(src):
# os.link will give a permission error
raise OSError(errno.EISDIR, "Is a directory", src)
if os.path.isdir(dst):
# os.link will give a FileExists error
raise OSError(errno.EISDIR, "Is a directory", dst)
if os.path.exists(dst):
# shutil.copyfile will overwrite the existing file
raise OSError(errno.EEXIST, "File exists", src, "File exists", dst)
try:
os.link(src, dst)
except OSError as e:
if e.errno == errno.EXDEV: # Invalid cross-device link
shutil.copyfile(src, dst)
elif e.errno == errno.EPERM: # Permissions/ownership error
shutil.copyfile(src, dst)
else:
raise
