Re: [PATCH 3/4] pylibfdt: add FdtRo.get_path()

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Sat, Dec 25, 2021 at 02:25:57PM +0100, Luca Weiss 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>
> ---
>  pylibfdt/libfdt.i       | 21 +++++++++++++++++++++
>  tests/pylibfdt_tests.py | 12 ++++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i
> index ac70762..5434d48 100644
> --- a/pylibfdt/libfdt.i
> +++ b/pylibfdt/libfdt.i
> @@ -443,6 +443,22 @@ class FdtRo(object):
>          """
>          return fdt_get_alias(self._fdt, name)
>  
> +    def get_path(self, nodeoffset, size=128):

Having an explicit max buffer size here makes for a very un-Pythonic
interface.  The python interface really needs to re-allocate and retry
automatically until it gets the full result.

Whether you implement that in Python code or in the C wrapper is up to
you.

> +        """Get the full path of a node
> +
> +        Args:
> +            nodeoffset: Node offset to check
> +
> +        Returns:
> +            Full path to the node
> +
> +        Raises:
> +            FdtException if the path is longer than 'size' or other error occurs
> +        """
> +        ret, path = fdt_get_path(self._fdt, nodeoffset, size)
> +        check_err(ret)
> +        return path
> +
>      def parent_offset(self, nodeoffset, quiet=()):
>          """Get the offset of a node's parent
>  
> @@ -1115,6 +1131,11 @@ 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..bcd3daa 100644
> --- a/tests/pylibfdt_tests.py
> +++ b/tests/pylibfdt_tests.py
> @@ -348,6 +348,18 @@ 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", self.fdt.get_path(node, 16))
> +        self.assertEqual("/subnode@1/subsubnode", self.fdt.get_path(node2))
> +
> +        with self.assertRaises(FdtException) as e:
> +            self.fdt.get_path(node2, 16)
> +        self.assertEqual(e.exception.err, -libfdt.NOSPACE)
> +
>      def testParentOffset(self):
>          """Test for the parent_offset() method"""
>          self.assertEqual(-libfdt.NOTFOUND,

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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