Re: [PATCH v4] pylibfdt: add FdtRo.get_path()

[Luca Weiss <luca-IfPCFPJWly+lVyrhU4qvOw@public.gmane.org>]

Hi Simon and David,

On Mittwoch, 20. April 2022 04:56:15 CEST David Gibson wrote:
> On Tue, Apr 19, 2022 at 03:54:07PM -0600, Simon Glass wrote:
> > Hi Luca,
> > 
> > On Tue, 19 Apr 2022 at 13:49, Luca Weiss <luca-IfPCFPJWly+lVyrhU4qvOw@public.gmane.org> wrote:
> > > Add a new Python method wrapping fdt_get_path() from the C API.
> > > 
> > > Also add a test for the new method.
> > > 
> > > Signed-off-by: Luca Weiss <luca-IfPCFPJWly+lVyrhU4qvOw@public.gmane.org>
> > > ---
> > > Changes since v3:
> > > * add quiet parameter
> > > * return integer error when error is quieted
> > > 
> > > Changes since v2:
> > > * Remove arbitrary size limit
> > > * Change size calculation to increase exponentially
> > > * Add test to verify we still get exceptions with bad parameters
> > > 
> > >  pylibfdt/libfdt.i       | 28 ++++++++++++++++++++++++++++
> > >  tests/pylibfdt_tests.py | 13 +++++++++++++
> > >  2 files changed, 41 insertions(+)
> > 
> > Reviewed-by: Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> > 
> > You don't check for when it is output of space, but I think that is
> > OK.
> 
> Right, a testcase for that would be good, but it can be a follow up.

I don't quite understand what you mean "is output of space".

Maybe you mean a test for when the string is longer than 1024 characters 
("size = 1024") so the size increase gets triggered?

If yes, then I did test that manually before by setting the value absurdly 
low. Not sure how to properly check that in the tests though. Add a node with 
a super long name into the test dtb?

> 
> Applied.

Thanks!

Regards
Luca

> 
> > > diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i
> > > index ac70762..f9f7e7e 100644
> > > --- a/pylibfdt/libfdt.i
> > > +++ b/pylibfdt/libfdt.i
> > > 
> > > @@ -443,6 +443,29 @@ class FdtRo(object):
> > >          """
> > >          return fdt_get_alias(self._fdt, name)
> > > 
> > > +    def get_path(self, nodeoffset, quiet=()):
> > > +        """Get the full path of a node
> > > +
> > > +        Args:
> > > +            nodeoffset: Node offset to check
> > > +
> > > +        Returns:
> > > +            Full path to the node
> > > +
> > > +        Raises:
> > > +            FdtException if an error occurs
> > > +        """
> > > +        size = 1024
> > > +        while True:
> > > +            ret, path = fdt_get_path(self._fdt, nodeoffset, size)
> > > +            if ret == -NOSPACE:
> > > +                size = size * 2
> > > +                continue
> > > +            err = check_err(ret, quiet)
> > > +            if err:
> > > +                return err
> > > +            return path
> > > +
> > > 
> > >      def parent_offset(self, nodeoffset, quiet=()):
> > >          """Get the offset of a node's parent
> > > 
> > > @@ -1115,6 +1138,11 @@ typedef uint32_t fdt32_t;
> > > 
> > >          }
> > >  
> > >  }
> > > 
> > > +%include "cstring.i"
> > > +
> > > +%cstring_output_maxsize(char *buf, int buflen);
> > > +int fdt_get_path(const void *fdt, int nodeoffset, char *buf, int
> > > buflen);
> > > +
> > > 
> > >  /* We have both struct fdt_property and a function fdt_property() */
> > >  %warnfilter(302) fdt_property;
> > > 
> > > diff --git a/tests/pylibfdt_tests.py b/tests/pylibfdt_tests.py
> > > index 5479363..68d6aaa 100644
> > > --- a/tests/pylibfdt_tests.py
> > > +++ b/tests/pylibfdt_tests.py
> > > 
> > > @@ -348,6 +348,19 @@ class PyLibfdtBasicTests(unittest.TestCase):
> > >          self.assertEqual("/subnode@1/subsubnode",
> > >          self.fdt3.get_alias('ss1'))
> > >          self.assertEqual("/subnode@1/subsubnode/subsubsubnode",
> > >          self.fdt3.get_alias('sss1'))> > 
> > > +    def testGetPath(self):
> > > +        """Test for the get_path() method"""
> > > +        node = self.fdt.path_offset('/subnode@1')
> > > +        node2 = self.fdt.path_offset('/subnode@1/subsubnode')
> > > +        self.assertEqual("/subnode@1", self.fdt.get_path(node))
> > > +        self.assertEqual("/subnode@1/subsubnode",
> > > self.fdt.get_path(node2)) +
> > > +        with self.assertRaises(FdtException) as e:
> > > +            self.fdt.get_path(-1)
> > > +        self.assertEqual(e.exception.err, -libfdt.BADOFFSET)
> > > +
> > > +        self.assertEqual(-libfdt.BADOFFSET, self.fdt.get_path(-1,
> > > quiet=(libfdt.BADOFFSET,))) +
> > > 
> > >      def testParentOffset(self):
> > >          """Test for the parent_offset() method"""
> > >          self.assertEqual(-libfdt.NOTFOUND,
> > 
> > Regards,
> > Simon