[PATCH v2] pylibfdt: add FdtRo.get_path()

* [PATCH v2] pylibfdt: add FdtRo.get_path()
@ 2022-01-22 10:56 Luca Weiss
       [not found] ` <20220122105653.31219-1-luca-IfPCFPJWly+lVyrhU4qvOw@public.gmane.org>
  0 siblings, 1 reply; 6+ messages in thread
From: Luca Weiss @ 2022-01-22 10:56 UTC (permalink / raw)
  To: devicetree-compiler-u79uwXL29TY76Z2rM5mHXA; +Cc: Luca Weiss

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 in v2:
- dynamically increase size of string buffer until it fits.
  The values are chosen relatively arbitrary, and terminates at lengths
  over than 4096 as I don't expect paths to be longer and there should
  be an exit condition to not eat up RAM in case of some bug.

 pylibfdt/libfdt.i       | 27 +++++++++++++++++++++++++++
 tests/pylibfdt_tests.py |  7 +++++++
 2 files changed, 34 insertions(+)

diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i
index ac70762..d103bb6 100644
--- a/pylibfdt/libfdt.i
+++ b/pylibfdt/libfdt.i
@@ -443,6 +443,28 @@ class FdtRo(object):
         """
         return fdt_get_alias(self._fdt, name)
 
+    def get_path(self, nodeoffset):
+        """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
+        """
+        size = 64
+        while size < 4096:
+            ret, path = fdt_get_path(self._fdt, nodeoffset, size)
+            if ret == -NOSPACE:
+                size += 64
+                continue
+            check_err(ret)
+            return path
+        raise ValueError('Node path is unexpectedly long')
+
     def parent_offset(self, nodeoffset, quiet=()):
         """Get the offset of a node's parent
 
@@ -1115,6 +1137,11 @@ 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..2335a73 100644
--- a/tests/pylibfdt_tests.py
+++ b/tests/pylibfdt_tests.py
@@ -348,6 +348,13 @@ 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))
+
     def testParentOffset(self):
         """Test for the parent_offset() method"""
         self.assertEqual(-libfdt.NOTFOUND,
-- 
2.34.1


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