| commit | ad8bf9f9aa39625d732b7db16badecc0842750e2 | [log] [tgz] |
|---|---|---|
| author | Pierre-Clément Tosi <ptosi@google.com> | Thu Aug 31 13:39:18 2023 +0100 |
| committer | David Gibson <david@gibson.dropbear.id.au> | Mon Sep 04 15:27:55 2023 +1000 |
| tree | 0c77b9276260f8815706d77dd4d25d8212722a27 | |
| parent | 6c5e189fb9527c4f69f8bd80e34eb24878795c47 [diff] |
libfdt: Fix fdt_appendprop_addrrange documentation
According to the documentation, the function should default to the very
common property name <reg> when none is "specified". However, neither
passing NULL (ends up calling strlen(NULL) and segfaults) nor ""
(appends a property with an empty name) implements this behavior.
Furthermore, the test case supposed to cover this default value actually
passes the value to the function, somewhat defeating its own purpose:
/* 2. default property name */
// ...
err = fdt_appendprop_addrrange(fdt, 0, offset, "reg", addr, size);
if (err)
FAIL("Failed to set \"reg\": %s", fdt_strerror(err));
check_getprop_addrrange(fdt, 0, offset, "reg", 1);
Finally, nothing in the implementation of the function seems to attempt
to cover that use-case.
As the feature can't ever have been used by clients and as the resulting
reduced readability of the caller seems (IMO) to outweigh any potential
benefit this API would bring, remove the erroneous documentation instead
of trying to fix the function.
Reported-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
Message-ID: <20230831123918.rf54emwkzgtcb7aw@google.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The source tree contains the Device Tree Compiler (dtc) toolchain for working with device tree source and binary files and also libfdt, a utility library for reading and manipulating the binary format.
dtc and libfdt are maintained by:
A Python library wrapping libfdt is also available. To build this you will need to install swig and Python development files. On Debian distributions:
$ sudo apt-get install swig python3-dev
The library provides an Fdt class which you can use like this:
$ PYTHONPATH=../pylibfdt python3
>>> import libfdt
>>> fdt = libfdt.Fdt(open('test_tree1.dtb', mode='rb').read())
>>> node = fdt.path_offset('/subnode@1')
>>> print(node)
124
>>> prop_offset = fdt.first_property_offset(node)
>>> prop = fdt.get_property_by_offset(prop_offset)
>>> print('%s=%s' % (prop.name, prop.as_str()))
compatible=subnode1
>>> node2 = fdt.path_offset('/')
>>> print(fdt.getprop(node2, 'compatible').as_str())
test_tree1
You will find tests in tests/pylibfdt_tests.py showing how to use each method. Help is available using the Python help command, e.g.:
$ cd pylibfdt $ python3 -c "import libfdt; help(libfdt)"
If you add new features, please check code coverage:
$ sudo apt-get install python3-coverage $ cd tests # It's just 'coverage' on most other distributions $ python3-coverage run pylibfdt_tests.py $ python3-coverage html # Open 'htmlcov/index.html' in your browser
The library can be installed with pip from a local source tree:
$ pip install . [--user|--prefix=/path/to/install_dir]
Or directly from a remote git repo:
$ pip install git+git://git.kernel.org/pub/scm/utils/dtc/dtc.git@main
The install depends on libfdt shared library being installed on the host system first. Generally, using --user or --prefix is not necessary and pip will use the default location for the Python installation which varies if the user is root or not.
You can also install everything via make if you like, but pip is recommended.
To install both libfdt and pylibfdt you can use:
$ make install [PREFIX=/path/to/install_dir]
To disable building the python library, even if swig and Python are available, use:
$ make NO_PYTHON=1
More work remains to support all of libfdt, including access to numeric values.