summaryrefslogtreecommitdiff
path: root/meta/lib/oe/cachedpath.py
blob: c7860ef4fb11dd109602b3c8b34a824f17fadba9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
#
# Based on standard python library functions but avoid
# repeated stat calls. Its assumed the files will not change from under us
# so we can cache stat calls.
#

import os
import errno
import stat as statmod

class CachedPath(object):
    def __init__(self):
        self.statcache = {}
        self.lstatcache = {}
        self.normpathcache = {}
        return

    def updatecache(self, x):
        x = self.normpath(x)
        if x in self.statcache:
            del self.statcache[x]
        if x in self.lstatcache:
            del self.lstatcache[x]

    def normpath(self, path):
        if path in self.normpathcache:
            return self.normpathcache[path]
        newpath = os.path.normpath(path)
        self.normpathcache[path] = newpath
        return newpath

    def _callstat(self, path):
        if path in self.statcache:
            return self.statcache[path]
        try:
            st = os.stat(path)
            self.statcache[path] = st
            return st
        except os.error:
            self.statcache[path] = False
            return False

    # We might as well call lstat and then only 
    # call stat as well in the symbolic link case
    # since this turns out to be much more optimal
    # in real world usage of this cache
    def callstat(self, path):
        path = self.normpath(path)
        self.calllstat(path)
        return self.statcache[path]

    def calllstat(self, path):
        path = self.normpath(path)
        if path in self.lstatcache:
            return self.lstatcache[path]
        #bb.error("LStatpath:" + path)
        try:
            lst = os.lstat(path)
            self.lstatcache[path] = lst
            if not statmod.S_ISLNK(lst.st_mode):
                self.statcache[path] = lst
            else:
                self._callstat(path)
            return lst
        except (os.error, AttributeError):
            self.lstatcache[path] = False
            self.statcache[path] = False
            return False

    # This follows symbolic links, so both islink() and isdir() can be true
    # for the same path ono systems that support symlinks
    def isfile(self, path):
        """Test whether a path is a regular file"""
        st = self.callstat(path)
        if not st:
            return False
        return statmod.S_ISREG(st.st_mode)

    # Is a path a directory?
    # This follows symbolic links, so both islink() and isdir()
    # can be true for the same path on systems that support symlinks
    def isdir(self, s):
        """Return true if the pathname refers to an existing directory."""
        st = self.callstat(s)
        if not st:
            return False
        return statmod.S_ISDIR(st.st_mode)

    def islink(self, path):
        """Test whether a path is a symbolic link"""
        st = self.calllstat(path)
        if not st:
            return False
        return statmod.S_ISLNK(st.st_mode)

    # Does a path exist?
    # This is false for dangling symbolic links on systems that support them.
    def exists(self, path):
        """Test whether a path exists.  Returns False for broken symbolic links"""
        if self.callstat(path):
            return True
        return False

    def lexists(self, path):
        """Test whether a path exists.  Returns True for broken symbolic links"""
        if self.calllstat(path):
            return True
        return False

    def stat(self, path):
        return self.callstat(path)

    def lstat(self, path):
        return self.calllstat(path)

    def walk(self, top, topdown=True, onerror=None, followlinks=False):
        # Matches os.walk, not os.path.walk()

        # We may not have read permission for top, in which case we can't
        # get a list of the files the directory contains.  os.path.walk
        # always suppressed the exception then, rather than blow up for a
        # minor reason when (say) a thousand readable directories are still
        # left to visit.  That logic is copied here.
        try:
            # Note that listdir and error are globals in this module due
            # to earlier import-*.
            names = os.listdir(top)
        except error as err:
            if onerror is not None:
                onerror(err)
            return

        dirs, nondirs = [], []
        for name in names:
            if self.isdir(os.path.join(top, name)):
                dirs.append(name)
            else:
                nondirs.append(name)

        if topdown:
            yield top, dirs, nondirs
        for name in dirs:
            new_path = os.path.join(top, name)
            if followlinks or not self.islink(new_path):
                for x in self.walk(new_path, topdown, onerror, followlinks):
                    yield x
        if not topdown:
            yield top, dirs, nondirs

    ## realpath() related functions
    def __is_path_below(self, file, root):
        return (file + os.path.sep).startswith(root)

    def __realpath_rel(self, start, rel_path, root, loop_cnt, assume_dir):
        """Calculates real path of symlink 'start' + 'rel_path' below
        'root'; no part of 'start' below 'root' must contain symlinks. """
        have_dir = True

        for d in rel_path.split(os.path.sep):
            if not have_dir and not assume_dir:
                raise OSError(errno.ENOENT, "no such directory %s" % start)

            if d == os.path.pardir: # '..'
                if len(start) >= len(root):
                    # do not follow '..' before root
                    start = os.path.dirname(start)
                else:
                    # emit warning?
                    pass
            else:
                (start, have_dir) = self.__realpath(os.path.join(start, d),
                                                    root, loop_cnt, assume_dir)

            assert(self.__is_path_below(start, root))

        return start

    def __realpath(self, file, root, loop_cnt, assume_dir):
        while self.islink(file) and len(file) >= len(root):
            if loop_cnt == 0:
                raise OSError(errno.ELOOP, file)

            loop_cnt -= 1
            target = os.path.normpath(os.readlink(file))
    
            if not os.path.isabs(target):
                tdir = os.path.dirname(file)
                assert(self.__is_path_below(tdir, root))
            else:
                tdir = root

            file = self.__realpath_rel(tdir, target, root, loop_cnt, assume_dir)

        try:
            is_dir = self.isdir(file)
        except:
            is_dir = False

        return (file, is_dir)

    def realpath(self, file, root, use_physdir = True, loop_cnt = 100, assume_dir = False):
        """ Returns the canonical path of 'file' with assuming a
        toplevel 'root' directory. When 'use_physdir' is set, all
        preceding path components of 'file' will be resolved first;
        this flag should be set unless it is guaranteed that there is
        no symlink in the path. When 'assume_dir' is not set, missing
        path components will raise an ENOENT error"""

        root = os.path.normpath(root)
        file = os.path.normpath(file)

        if not root.endswith(os.path.sep):
            # letting root end with '/' makes some things easier
            root = root + os.path.sep

        if not self.__is_path_below(file, root):
            raise OSError(errno.EINVAL, "file '%s' is not below root" % file)

        try:
            if use_physdir:
                file = self.__realpath_rel(root, file[(len(root) - 1):], root, loop_cnt, assume_dir)
            else:
                file = self.__realpath(file, root, loop_cnt, assume_dir)[0]
        except OSError as e:
            if e.errno == errno.ELOOP:
                # make ELOOP more readable; without catching it, there will
                # be printed a backtrace with 100s of OSError exceptions
                # else
                raise OSError(errno.ELOOP,
                              "too much recursions while resolving '%s'; loop in '%s'" %
                              (file, e.strerror))

            raise

        return file