def exists(path):
"""Test whether a path exists. Returns False for broken symbolic links"""
try:
os.stat(path)
except OSError:
return False
return True
def isdir(s):
"""Return true if the pathname refers to an existing directory."""
try:
st = os.stat(s)
except OSError:
return False
return stat.S_ISDIR(st.st_mode)
def isfile(path):
"""Test whether a path is a regular file"""
try:
st = os.stat(path)
except OSError:
return False
return stat.S_ISREG(st.st_mode)
def copyfile(src, dst, *, follow_symlinks=True):
"""Copy data from src to dst.
If follow_symlinks is not set and src is a symbolic link, a new
symlink will be created instead of copying the file it points to.
"""
if _samefile(src, dst):
raise SameFileError("{!r} and {!r} are the same file".format(src, dst))
for fn in [src, dst]:
try:
st = os.stat(fn)
except OSError:
# File most likely does not exist
pass
else:
# XXX What about other special files? (sockets, devices...)
if stat.S_ISFIFO(st.st_mode):
raise SpecialFileError("`%s` is a named pipe" % fn)
if not follow_symlinks and os.path.islink(src):
os.symlink(os.readlink(src), dst)
else:
with open(src, 'rb') as fsrc:
with open(dst, 'wb') as fdst:
copyfileobj(fsrc, fdst)
return dst
def checkcache(filename=None):
"""Discard cache entries that are out of date.
(This is not checked upon each call!)"""
if filename is None:
filenames = list(cache.keys())
else:
if filename in cache:
filenames = [filename]
else:
return
for filename in filenames:
entry = cache[filename]
if len(entry) == 1:
# lazy cache entry, leave it lazy.
continue
size, mtime, lines, fullname = entry
if mtime is None:
continue # no-op for files loaded via a __loader__
try:
stat = os.stat(fullname)
except OSError:
del cache[filename]
continue
if size != stat.st_size or mtime != stat.st_mtime:
del cache[filename]
def samefile(f1, f2):
"""Test whether two pathnames reference the same actual file"""
s1 = os.stat(f1)
s2 = os.stat(f2)
return samestat(s1, s2)
def getctime(filename):
"""Return the metadata change time of a file, reported by os.stat()."""
return os.stat(filename).st_ctime
def getatime(filename):
"""Return the last access time of a file, reported by os.stat()."""
return os.stat(filename).st_atime
def getmtime(filename):
"""Return the last modification time of a file, reported by os.stat()."""
return os.stat(filename).st_mtime
def getsize(filename):
"""Return the size of a file, reported by os.stat()."""
return os.stat(filename).st_size
def updatecache(filename, module_globals=None):
"""Update a cache entry and return its list of lines.
If something's wrong, print a message, discard the cache entry,
and return an empty list."""
if filename in cache:
if len(cache[filename]) != 1:
del cache[filename]
if not filename or (filename.startswith('<') and filename.endswith('>')):
return []
fullname = filename
try:
stat = os.stat(fullname)
except OSError:
basename = filename
# Realise a lazy loader based lookup if there is one
# otherwise try to lookup right now.
if lazycache(filename, module_globals):
try:
data = cache[filename][0]()
except (ImportError, OSError):
pass
else:
if data is None:
# No luck, the PEP302 loader cannot find the source
# for this module.
return []
cache[filename] = (
len(data), None,
[line+'\n' for line in data.splitlines()], fullname
)
return cache[filename][2]
# Try looking through the module search path, which is only useful
# when handling a relative filename.
if os.path.isabs(filename):
return []
for dirname in sys.path:
try:
fullname = os.path.join(dirname, basename)
except (TypeError, AttributeError):
# Not sufficiently string-like to do anything useful with.
continue
try:
stat = os.stat(fullname)
break
except OSError:
pass
else:
return []
try:
with tokenize.open(fullname) as fp:
lines = fp.readlines()
except OSError:
return []
if lines and not lines[-1].endswith('\n'):
lines[-1] += '\n'
size, mtime = stat.st_size, stat.st_mtime
cache[filename] = size, mtime, lines, fullname
return lines