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+#
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+# Based on standard python library functions but avoid
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+# repeated stat calls. Its assumed the files will not change from under us
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+# so we can cache stat calls.
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+#
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+
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+import os
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+import errno
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+import stat as statmod
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+
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+class CachedPath(object):
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+ def __init__(self):
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+ self.statcache = {}
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+ self.lstatcache = {}
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+ self.normpathcache = {}
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+ return
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+
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+ def updatecache(self, x):
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+ x = self.normpath(x)
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+ if x in self.statcache:
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+ del self.statcache[x]
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+ if x in self.lstatcache:
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+ del self.lstatcache[x]
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+
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+ def normpath(self, path):
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+ if path in self.normpathcache:
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+ return self.normpathcache[path]
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+ newpath = os.path.normpath(path)
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+ self.normpathcache[path] = newpath
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+ return newpath
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+
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+ def _callstat(self, path):
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+ if path in self.statcache:
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+ return self.statcache[path]
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+ try:
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+ st = os.stat(path)
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+ self.statcache[path] = st
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+ return st
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+ except os.error:
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+ self.statcache[path] = False
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+ return False
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+
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+ # We might as well call lstat and then only
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+ # call stat as well in the symbolic link case
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+ # since this turns out to be much more optimal
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+ # in real world usage of this cache
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+ def callstat(self, path):
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+ path = self.normpath(path)
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+ self.calllstat(path)
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+ return self.statcache[path]
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+
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+ def calllstat(self, path):
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+ path = self.normpath(path)
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+ if path in self.lstatcache:
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+ return self.lstatcache[path]
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+ #bb.error("LStatpath:" + path)
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+ try:
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+ lst = os.lstat(path)
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+ self.lstatcache[path] = lst
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+ if not statmod.S_ISLNK(lst.st_mode):
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+ self.statcache[path] = lst
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+ else:
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+ self._callstat(path)
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+ return lst
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+ except (os.error, AttributeError):
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+ self.lstatcache[path] = False
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+ self.statcache[path] = False
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+ return False
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+
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+ # This follows symbolic links, so both islink() and isdir() can be true
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+ # for the same path ono systems that support symlinks
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+ def isfile(self, path):
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+ """Test whether a path is a regular file"""
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+ st = self.callstat(path)
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+ if not st:
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+ return False
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+ return statmod.S_ISREG(st.st_mode)
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+
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+ # Is a path a directory?
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+ # This follows symbolic links, so both islink() and isdir()
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+ # can be true for the same path on systems that support symlinks
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+ def isdir(self, s):
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+ """Return true if the pathname refers to an existing directory."""
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+ st = self.callstat(s)
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+ if not st:
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+ return False
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+ return statmod.S_ISDIR(st.st_mode)
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+
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+ def islink(self, path):
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+ """Test whether a path is a symbolic link"""
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+ st = self.calllstat(path)
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+ if not st:
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+ return False
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+ return statmod.S_ISLNK(st.st_mode)
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+
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+ # Does a path exist?
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+ # This is false for dangling symbolic links on systems that support them.
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+ def exists(self, path):
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+ """Test whether a path exists. Returns False for broken symbolic links"""
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+ if self.callstat(path):
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+ return True
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+ return False
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+
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+ def lexists(self, path):
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+ """Test whether a path exists. Returns True for broken symbolic links"""
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+ if self.calllstat(path):
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+ return True
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+ return False
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+
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+ def stat(self, path):
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+ return self.callstat(path)
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+
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+ def lstat(self, path):
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+ return self.calllstat(path)
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+
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+ def walk(self, top, topdown=True, onerror=None, followlinks=False):
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+ # Matches os.walk, not os.path.walk()
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+
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+ # We may not have read permission for top, in which case we can't
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+ # get a list of the files the directory contains. os.path.walk
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+ # always suppressed the exception then, rather than blow up for a
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+ # minor reason when (say) a thousand readable directories are still
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+ # left to visit. That logic is copied here.
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+ try:
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+ # Note that listdir and error are globals in this module due
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+ # to earlier import-*.
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+ names = os.listdir(top)
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+ except error, err:
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+ if onerror is not None:
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+ onerror(err)
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+ return
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+
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+ dirs, nondirs = [], []
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+ for name in names:
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+ if self.isdir(os.path.join(top, name)):
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+ dirs.append(name)
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+ else:
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+ nondirs.append(name)
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+
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+ if topdown:
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+ yield top, dirs, nondirs
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+ for name in dirs:
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+ new_path = os.path.join(top, name)
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+ if followlinks or not self.islink(new_path):
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+ for x in self.walk(new_path, topdown, onerror, followlinks):
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+ yield x
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+ if not topdown:
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+ yield top, dirs, nondirs
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+
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+ ## realpath() related functions
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+ def __is_path_below(self, file, root):
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+ return (file + os.path.sep).startswith(root)
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+
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+ def __realpath_rel(self, start, rel_path, root, loop_cnt, assume_dir):
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+ """Calculates real path of symlink 'start' + 'rel_path' below
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+ 'root'; no part of 'start' below 'root' must contain symlinks. """
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+ have_dir = True
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+
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+ for d in rel_path.split(os.path.sep):
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+ if not have_dir and not assume_dir:
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+ raise OSError(errno.ENOENT, "no such directory %s" % start)
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+
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+ if d == os.path.pardir: # '..'
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+ if len(start) >= len(root):
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+ # do not follow '..' before root
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+ start = os.path.dirname(start)
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+ else:
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+ # emit warning?
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+ pass
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+ else:
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+ (start, have_dir) = self.__realpath(os.path.join(start, d),
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+ root, loop_cnt, assume_dir)
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+
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+ assert(self.__is_path_below(start, root))
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+
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+ return start
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+
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+ def __realpath(self, file, root, loop_cnt, assume_dir):
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+ while self.islink(file) and len(file) >= len(root):
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+ if loop_cnt == 0:
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+ raise OSError(errno.ELOOP, file)
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+
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+ loop_cnt -= 1
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+ target = os.path.normpath(os.readlink(file))
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+
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+ if not os.path.isabs(target):
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+ tdir = os.path.dirname(file)
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+ assert(self.__is_path_below(tdir, root))
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+ else:
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+ tdir = root
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+
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+ file = self.__realpath_rel(tdir, target, root, loop_cnt, assume_dir)
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+
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+ try:
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+ is_dir = self.isdir(file)
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+ except:
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+ is_dir = False
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+
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+ return (file, is_dir)
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+
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+ def realpath(self, file, root, use_physdir = True, loop_cnt = 100, assume_dir = False):
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+ """ Returns the canonical path of 'file' with assuming a
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+ toplevel 'root' directory. When 'use_physdir' is set, all
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+ preceding path components of 'file' will be resolved first;
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+ this flag should be set unless it is guaranteed that there is
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+ no symlink in the path. When 'assume_dir' is not set, missing
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+ path components will raise an ENOENT error"""
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+
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+ root = os.path.normpath(root)
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+ file = os.path.normpath(file)
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+
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+ if not root.endswith(os.path.sep):
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+ # letting root end with '/' makes some things easier
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+ root = root + os.path.sep
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+
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+ if not self.__is_path_below(file, root):
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+ raise OSError(errno.EINVAL, "file '%s' is not below root" % file)
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+
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+ try:
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+ if use_physdir:
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+ file = self.__realpath_rel(root, file[(len(root) - 1):], root, loop_cnt, assume_dir)
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+ else:
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+ file = self.__realpath(file, root, loop_cnt, assume_dir)[0]
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+ except OSError, e:
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+ if e.errno == errno.ELOOP:
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+ # make ELOOP more readable; without catching it, there will
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+ # be printed a backtrace with 100s of OSError exceptions
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+ # else
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+ raise OSError(errno.ELOOP,
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+ "too much recursions while resolving '%s'; loop in '%s'" %
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+ (file, e.strerror))
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+
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+ raise
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+
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+ return file
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