On Wed, Jun 06, 2018 at 03:37:06PM -0600, Simon Glass wrote:
> It is common to want to set a property to a nul-terminated string in a
> device tree. Add python methods to handle this.
>
> Signed-off-by: Simon Glass <sjg@xxxxxxxxxxxx>
> ---
>
> Changes in v2:
> - Add support for unicode strings
> - Check for invalid embedded nul characters in as_str()
> - Check for nul termination in as_str()
> - Make the as_str() function a non-member of Property
>
> pylibfdt/libfdt.i | 30 ++++++++++++++++++++++++++++++
> tests/pylibfdt_tests.py | 27 +++++++++++++++++++++++++++
> 2 files changed, 57 insertions(+)
>
> diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i
> index 0eefc5a..ae63263 100644
> --- a/pylibfdt/libfdt.i
> +++ b/pylibfdt/libfdt.i
> @@ -170,6 +170,14 @@ def as_uint64(bytes):
> def as_int64(bytes):
> return as_cell(bytes, 'q')
>
> +def as_str(self):
> + """Unicode is supposed by decoding from UTF-8"""
> + if self[-1] != 0:
> + raise ValueError('Property lacks nul termination')
> + if 0 in self[:-1]:
> + raise ValueError('Property contains embedded nul characters')
> + return self[:-1].decode('utf-8')
As mentioned elsehwere, I've changed my mind and I think this would be
better as a Property method.
>
> class Fdt:
> """Device tree class, supporting all operations
> @@ -601,6 +609,28 @@ class Fdt:
> return check_err(fdt_setprop_u64(self._fdt, nodeoffset, prop_name, val),
> quiet)
>
> + def setprop_str(self, nodeoffset, prop_name, val, quiet=()):
> + """Set the string value of a property
> +
> + The property is set to the string, with a nul terminator added
> +
> + Args:
> + nodeoffset: Node offset containing the property to create/update
> + prop_name: Name of property
> + val: Value to write (string without nul terminator). Unicode is
> + supposed by encoding to UTF-8
> + quiet: Errors to ignore (empty to raise on all errors)
> +
> + Returns:
> + Error code, or 0 if OK
> +
> + Raises:
> + FdtException if no parent found or other error occurs
> + """
> + val = (val + '\0').encode('utf-8')
Logically, adding the \0 should be done *after* the utf-8 encoding.
> + return check_err(fdt_setprop(self._fdt, nodeoffset, prop_name,
> + val, len(val)), quiet)
> +
> def delprop(self, nodeoffset, prop_name):
> """Delete a property from a node
>
> diff --git a/tests/pylibfdt_tests.py b/tests/pylibfdt_tests.py
> index 2badef2..738210f 100644
> --- a/tests/pylibfdt_tests.py
> +++ b/tests/pylibfdt_tests.py
> @@ -68,6 +68,8 @@ TEST_VALUE64_1L = 0x01abcdef
> TEST_VALUE64_1 = (TEST_VALUE64_1H << 32) | TEST_VALUE64_1L
>
> TEST_STRING_1 = 'hello world'
> +TEST_STRING_2 = 'hi world'
> +TEST_STRING_3 = u'unicode ' + unichr(467)
>
>
> def get_err(err_code):
> @@ -441,6 +443,31 @@ class PyLibfdtTests(unittest.TestCase):
> self.assertEquals(struct.pack('>Q', TEST_VALUE64_1),
> self.fdt.getprop(node, prop))
>
> + def testSetPropStr(self):
> + """Test that we can set a property to a particular string"""
> + node = 0
> + prop = 'prop-str'
> + self.assertEquals(TEST_STRING_1,
> + libfdt.as_str(self.fdt.getprop(node, prop)))
> + self.fdt.setprop_str(node, prop, TEST_STRING_2)
> + self.assertEquals(TEST_STRING_2,
> + libfdt.as_str(self.fdt.getprop(node, prop)))
> + with self.assertRaises(ValueError) as e:
> + libfdt.as_str(self.fdt.getprop(node, 'prop-int'))
> + self.assertIn('lacks nul termination', str(e.exception))
> +
> + node2 = self.fdt.path_offset('/subnode@1/subsubnode')
> + with self.assertRaises(ValueError) as e:
> + libfdt.as_str(self.fdt.getprop(node2, 'compatible'))
> + self.assertIn('embedded nul', str(e.exception))
> +
> + # Expand the device tree so we now have room
> + self.fdt.resize(self.fdt.totalsize() + 50)
> + prop = 'prop-unicode'
> + self.fdt.setprop_str(node, prop, TEST_STRING_3)
> + self.assertEquals(TEST_STRING_3,
> + libfdt.as_str(self.fdt.getprop(node, prop)))
> +
>
> if __name__ == "__main__":
> unittest.main()
--
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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