[elbe-devel] [PATCH] filesystem: make Filesyste.realpath() handle absolute paths in links
Olivier Dion
dion at linutronix.de
Mon Jun 17 18:43:45 CEST 2019
I've wrote a dozen of cases .. It cover them all .. I hope it does for
you too. Commit is pushed on devel/dion/issue-199
Signed-off-by: Olivier Dion <dion at linutronix.de>
---
elbepack/filesystem.py | 44 ++++++++++++++++++++++++++++++++++----------
1 file changed, 34 insertions(+), 10 deletions(-)
diff --git a/elbepack/filesystem.py b/elbepack/filesystem.py
index 4c925d1c..450f1524 100644
--- a/elbepack/filesystem.py
+++ b/elbepack/filesystem.py
@@ -85,26 +85,50 @@ class Filesystem(object):
os.makedirs(self.fname(path))
def realpath(self, path):
- if path[0] != os.sep:
- path = os.sep + path
+
path = path.split(os.sep)
path.reverse()
+ following = []
real_path = [self.path]
+
while path:
candidate = path.pop()
+
+ # Don't care
if candidate == '' or candidate == os.curdir:
continue
- elif candidate == os.pardir:
+
+ # Can't go out of RFS
+ if candidate == os.pardir:
+ if following:
+ following.pop()
if len(real_path) > 1:
real_path.pop()
- else:
+ continue
+
+ parent = os.sep.join(real_path)
+ new_path = os.path.join(parent, candidate)
+ if not os.path.islink(new_path):
+ if following:
+ following.pop()
real_path.append(candidate)
- new_path = os.sep.join(real_path)
- if os.path.islink(new_path):
- elements = os.readlink(new_path)
- for element in reversed(elements.split(os.sep)):
- path.append(element)
- real_path.pop()
+ continue
+
+ # Circular loop; Don't follow it
+ if new_path in following:
+ real_path.append(candidate)
+ continue
+
+ following.append(new_path)
+ link = os.readlink(new_path)
+
+ # Reset root for absolute link
+ if os.path.isabs(link):
+ real_path = [self.path]
+
+ for element in reversed(link.split(os.sep)):
+ path.append(element)
+
return os.sep.join(real_path)
def symlink(self, src, path, allow_exists=False):
--
2.11.0Signed-off-by: Olivier Dion <dion at linutronix.de>
---
elbepack/filesystem.py | 44 ++++++++++++++++++++++++++++++++++----------
1 file changed, 34 insertions(+), 10 deletions(-)
diff --git a/elbepack/filesystem.py b/elbepack/filesystem.py
index 4c925d1c..450f1524 100644
--- a/elbepack/filesystem.py
+++ b/elbepack/filesystem.py
@@ -85,26 +85,50 @@ class Filesystem(object):
os.makedirs(self.fname(path))
def realpath(self, path):
- if path[0] != os.sep:
- path = os.sep + path
+
path = path.split(os.sep)
path.reverse()
+ following = []
real_path = [self.path]
+
while path:
candidate = path.pop()
+
+ # Don't care
if candidate == '' or candidate == os.curdir:
continue
- elif candidate == os.pardir:
+
+ # Can't go out of RFS
+ if candidate == os.pardir:
+ if following:
+ following.pop()
if len(real_path) > 1:
real_path.pop()
- else:
+ continue
+
+ parent = os.sep.join(real_path)
+ new_path = os.path.join(parent, candidate)
+ if not os.path.islink(new_path):
+ if following:
+ following.pop()
real_path.append(candidate)
- new_path = os.sep.join(real_path)
- if os.path.islink(new_path):
- elements = os.readlink(new_path)
- for element in reversed(elements.split(os.sep)):
- path.append(element)
- real_path.pop()
+ continue
+
+ # Circular loop; Don't follow it
+ if new_path in following:
+ real_path.append(candidate)
+ continue
+
+ following.append(new_path)
+ link = os.readlink(new_path)
+
+ # Reset root for absolute link
+ if os.path.isabs(link):
+ real_path = [self.path]
+
+ for element in reversed(link.split(os.sep)):
+ path.append(element)
+
return os.sep.join(real_path)
def symlink(self, src, path, allow_exists=False):
--
2.11.0
On 2019-06-14T17:29:35+0200, Torben Hohn wrote:
> the realpath() implementation is still not correct.
> but i like the approach.
> please finish it. and fold my patch into it.
> On Fri, Jun 14, 2019 at 05:28:04PM +0200, Torben Hohn wrote:
> > the current implementation fails for absolute links:
> >
> > >>> from elbepack import filesystem
> > >>> f = filesystem.Filesystem('xxx')
> > >>> f.mkdir_p('/usr/bin')
> > >>> f.symlink('/usr/bin/vim', '/usr/bin/omg')
> > >>> f.realpath('/usr/bin/omg')
> > '/home/torbenh/elbe/elbe/xxx/usr/bin/usr/bin/vim'
> > >>>
> >
> > handle it by "initialising" path again, when an absolute path
> > is returned from os.readlink()
> >
> > this still lacks catching recursive links, and i think, that .. is
> > not evaluated properly in any case.
> >
> > Signed-off-by: Torben Hohn <torben.hohn at linutronix.de>
> > ---
> > elbepack/filesystem.py | 11 ++++++++---
> > 1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/elbepack/filesystem.py b/elbepack/filesystem.py
> > index 4c925d1c6..91dbe0879 100644
> > --- a/elbepack/filesystem.py
> > +++ b/elbepack/filesystem.py
> > @@ -102,9 +102,14 @@ class Filesystem(object):
> > new_path = os.sep.join(real_path)
> > if os.path.islink(new_path):
> > elements = os.readlink(new_path)
> > - for element in reversed(elements.split(os.sep)):
> > - path.append(element)
> > - real_path.pop()
> > + if os.path.isabs(elements):
> > + path = elements.split(os.sep)
> > + path.reverse()
> > + real_path = [self.path]
> > + else:
> > + for element in reversed(elements.split(os.sep)):
> > + path.append(element)
> > + real_path.pop()
> > return os.sep.join(real_path)
> >
> > def symlink(self, src, path, allow_exists=False):
> > --
> > 2.11.0
> >
> >
> > _______________________________________________
> > elbe-devel mailing list
> > elbe-devel at linutronix.de
> > https://lists.linutronix.de/mailman/listinfo/elbe-devel
> --
> Torben Hohn
> Linutronix GmbH | Bahnhofstrasse 3 | D-88690 Uhldingen-Mühlhofen
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--
Olivier Dion
Linutronix GmbH | Bahnhofstrasse 3 | D-88690 Uhldingen-Mühlhofen
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