[OE-core] [PATCH 1/2] lib/oe/path.py: support missing directory components in realpath()

[Enrico Scholz]

Some use cases in OE operate on symlinks which dangling path components.
Assume that these are directories instead of raising ENOENT.

Signed-off-by: Enrico Scholz <enrico.scholz at sigma-chemnitz.de>
---
 meta/lib/oe/path.py            | 26 ++++++++++++++------------
 meta/lib/oe/tests/test_path.py | 10 +++++-----
 2 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/meta/lib/oe/path.py b/meta/lib/oe/path.py
index 0b34ceb..faa0f61 100644
--- a/meta/lib/oe/path.py
+++ b/meta/lib/oe/path.py
@@ -168,13 +168,13 @@ def find(dir, **walkoptions):
 def __is_path_below(file, root):
     return (file + os.path.sep).startswith(root)
 
-def __realpath_rel(start, rel_path, root, loop_cnt):
+def __realpath_rel(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:
+        if not have_dir and not assume_dir:
             raise OSError(errno.ENOENT, "no such directory %s" % start)
 
         if d == os.path.pardir: # '..'
@@ -186,13 +186,13 @@ def __realpath_rel(start, rel_path, root, loop_cnt):
                 pass
         else:
             (start, have_dir) = __realpath(os.path.join(start, d),
-                                           root, loop_cnt)
+                                           root, loop_cnt, assume_dir)
 
         assert(__is_path_below(start, root))
 
     return start
 
-def __realpath(file, root, loop_cnt):
+def __realpath(file, root, loop_cnt, assume_dir):
     while os.path.islink(file) and len(file) >= len(root):
         if loop_cnt == 0:
             raise OSError(errno.ELOOP, file)
@@ -206,7 +206,7 @@ def __realpath(file, root, loop_cnt):
         else:
             tdir = root
 
-        file = __realpath_rel(tdir, target, root, loop_cnt)
+        file = __realpath_rel(tdir, target, root, loop_cnt, assume_dir)
 
     try:
         is_dir = os.path.isdir(file)
@@ -215,11 +215,13 @@ def __realpath(file, root, loop_cnt):
 
     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."""
+def realpath(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)
@@ -233,9 +235,9 @@ def realpath(file, root, use_physdir = True, loop_cnt = 100):
 
     try:
         if use_physdir:
-            file = __realpath_rel(root, file[(len(root) - 1):], root, loop_cnt)
+            file = __realpath_rel(root, file[(len(root) - 1):], root, loop_cnt, assume_dir)
         else:
-            file = __realpath(file, root, loop_cnt)[0]
+            file = __realpath(file, root, loop_cnt, assume_dir)[0]
     except OSError, e:
         if e.errno == errno.ELOOP:
             # make ELOOP more readable; without catching it, there will
diff --git a/meta/lib/oe/tests/test_path.py b/meta/lib/oe/tests/test_path.py
index e6aa601..3d41ce1 100644
--- a/meta/lib/oe/tests/test_path.py
+++ b/meta/lib/oe/tests/test_path.py
@@ -25,7 +25,7 @@ class TestRealPath(unittest.TestCase):
         ( "usr/bin/prog-F",  "../../../sbin/prog-F", "/sbin/prog-F" ),
         ( "loop",            "a/loop",               None ),
         ( "a/loop",          "../loop",              None ),
-        ( "b/test",          "file/foo",             None ),
+        ( "b/test",          "file/foo",             "/b/file/foo" ),
     ]
 
     LINKS_PHYS = [
@@ -59,8 +59,9 @@ class TestRealPath(unittest.TestCase):
         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 __realpath(self, file, use_physdir, assume_dir = True):
+        return oe.path.realpath(os.path.join(self.root, file), self.root,
+                                use_physdir, assume_dir = assume_dir)
 
     def test_norm(self):
         for l in self.LINKS:
@@ -85,5 +86,4 @@ class TestRealPath(unittest.TestCase):
     def test_loop(self):
         for e in self.EXCEPTIONS:
             self.assertRaisesRegexp(OSError, r'\[Errno %u\]' % e[1],
-                                    self.__realpath, e[0], False)
-
+                                    self.__realpath, e[0], False, False)
-- 
1.7.11.7