[oe-commits] Enrico Scholz : lib: implemented oe.path.realpath()
git at git.openembedded.org
git at git.openembedded.org
Mon Feb 11 14:45:50 UTC 2013
Module: openembedded-core.git
Branch: master
Commit: 76e0bd7f8e3a3bd052a6e329f88e2d8099e899c4
URL: http://git.openembedded.org/?p=openembedded-core.git&a=commit;h=76e0bd7f8e3a3bd052a6e329f88e2d8099e899c4
Author: Enrico Scholz <enrico.scholz at sigma-chemnitz.de>
Date: Sun Feb 10 13:41:46 2013 +0100
lib: implemented oe.path.realpath()
Various parts of the buildsystem have to work with symlinks. Resolving
them is not trivial because they are always relative to a sysroot
directory.
Patch adds a function which returns the destination of a symlink by
assuming a given path as the / toplevel directory. A testsuite was
added too.
Signed-off-by: Enrico Scholz <enrico.scholz at sigma-chemnitz.de>
Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
meta/lib/oe/path.py | 87 +++++++++++++++++++++++++++++++++++++++
meta/lib/oe/tests/test_path.py | 89 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 176 insertions(+), 0 deletions(-)
diff --git a/meta/lib/oe/path.py b/meta/lib/oe/path.py
index ea58bed..0b34ceb 100644
--- a/meta/lib/oe/path.py
+++ b/meta/lib/oe/path.py
@@ -2,6 +2,7 @@ import errno
import glob
import shutil
import subprocess
+import os.path
def join(*paths):
"""Like os.path.join but doesn't treat absolute RHS specially"""
@@ -161,3 +162,89 @@ def find(dir, **walkoptions):
for root, dirs, files in os.walk(dir, **walkoptions):
for file in files:
yield os.path.join(root, file)
+
+
+## realpath() related functions
+def __is_path_below(file, root):
+ return (file + os.path.sep).startswith(root)
+
+def __realpath_rel(start, rel_path, root, loop_cnt):
+ """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:
+ 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) = __realpath(os.path.join(start, d),
+ root, loop_cnt)
+
+ assert(__is_path_below(start, root))
+
+ return start
+
+def __realpath(file, root, loop_cnt):
+ while os.path.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(__is_path_below(tdir, root))
+ else:
+ tdir = root
+
+ file = __realpath_rel(tdir, target, root, loop_cnt)
+
+ try:
+ is_dir = os.path.isdir(file)
+ except:
+ is_dir = false
+
+ return (file, is_dir)
+
+def realpath(file, root, use_physdir = True, loop_cnt = 100):
+ """ 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."""
+
+ 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 __is_path_below(file, root):
+ raise OSError(errno.EINVAL, "file '%s' is not below root" % file)
+
+ try:
+ if use_physdir:
+ file = __realpath_rel(root, file[(len(root) - 1):], root, loop_cnt)
+ else:
+ file = __realpath(file, root, loop_cnt)[0]
+ except OSError, 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
diff --git a/meta/lib/oe/tests/test_path.py b/meta/lib/oe/tests/test_path.py
new file mode 100644
index 0000000..e6aa601
--- /dev/null
+++ b/meta/lib/oe/tests/test_path.py
@@ -0,0 +1,89 @@
+import unittest
+import oe, oe.path
+import tempfile
+import os
+import errno
+import shutil
+
+class TestRealPath(unittest.TestCase):
+ DIRS = [ "a", "b", "etc", "sbin", "usr", "usr/bin", "usr/binX", "usr/sbin", "usr/include", "usr/include/gdbm" ]
+ FILES = [ "etc/passwd", "b/file" ]
+ LINKS = [
+ ( "bin", "/usr/bin", "/usr/bin" ),
+ ( "binX", "usr/binX", "/usr/binX" ),
+ ( "c", "broken", "/broken" ),
+ ( "etc/passwd-1", "passwd", "/etc/passwd" ),
+ ( "etc/passwd-2", "passwd-1", "/etc/passwd" ),
+ ( "etc/passwd-3", "/etc/passwd-1", "/etc/passwd" ),
+ ( "etc/shadow-1", "/etc/shadow", "/etc/shadow" ),
+ ( "etc/shadow-2", "/etc/shadow-1", "/etc/shadow" ),
+ ( "prog-A", "bin/prog-A", "/usr/bin/prog-A" ),
+ ( "prog-B", "/bin/prog-B", "/usr/bin/prog-B" ),
+ ( "usr/bin/prog-C", "../../sbin/prog-C", "/sbin/prog-C" ),
+ ( "usr/bin/prog-D", "/sbin/prog-D", "/sbin/prog-D" ),
+ ( "usr/binX/prog-E", "../sbin/prog-E", None ),
+ ( "usr/bin/prog-F", "../../../sbin/prog-F", "/sbin/prog-F" ),
+ ( "loop", "a/loop", None ),
+ ( "a/loop", "../loop", None ),
+ ( "b/test", "file/foo", None ),
+ ]
+
+ LINKS_PHYS = [
+ ( "./", "/", "" ),
+ ( "binX/prog-E", "/usr/sbin/prog-E", "/sbin/prog-E" ),
+ ]
+
+ EXCEPTIONS = [
+ ( "loop", errno.ELOOP ),
+ ( "b/test", errno.ENOENT ),
+ ]
+
+ def __del__(self):
+ try:
+ #os.system("tree -F %s" % self.tmpdir)
+ shutil.rmtree(self.tmpdir)
+ except:
+ pass
+
+ def setUp(self):
+ self.tmpdir = tempfile.mkdtemp(prefix = "oe-test_path")
+ self.root = os.path.join(self.tmpdir, "R")
+
+ os.mkdir(os.path.join(self.tmpdir, "_real"))
+ os.symlink("_real", self.root)
+
+ for d in self.DIRS:
+ os.mkdir(os.path.join(self.root, d))
+ for f in self.FILES:
+ file(os.path.join(self.root, f), "w")
+ for l in self.LINKS:
+ os.symlink(l[1], os.path.join(self.root, l[0]))
+
+ def __realpath(self, file, use_physdir):
+ return oe.path.realpath(os.path.join(self.root, file), self.root, use_physdir)
+
+ def test_norm(self):
+ for l in self.LINKS:
+ if l[2] == None:
+ continue
+
+ target_p = self.__realpath(l[0], True)
+ target_l = self.__realpath(l[0], False)
+
+ if l[2] != False:
+ self.assertEqual(target_p, target_l)
+ self.assertEqual(l[2], target_p[len(self.root):])
+
+ def test_phys(self):
+ for l in self.LINKS_PHYS:
+ target_p = self.__realpath(l[0], True)
+ target_l = self.__realpath(l[0], False)
+
+ self.assertEqual(l[1], target_p[len(self.root):])
+ self.assertEqual(l[2], target_l[len(self.root):])
+
+ def test_loop(self):
+ for e in self.EXCEPTIONS:
+ self.assertRaisesRegexp(OSError, r'\[Errno %u\]' % e[1],
+ self.__realpath, e[0], False)
+
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