path: root/tools/net/ynl/lib/nlspec.py

# SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause

import collections
import importlib
import os
import yaml


# To be loaded dynamically as needed
jsonschema = None


class SpecElement:
    """Netlink spec element.

    Abstract element of the Netlink spec. Implements the dictionary interface
    for access to the raw spec. Supports iterative resolution of dependencies
    across elements and class inheritance levels. The elements of the spec
    may refer to each other, and although loops should be very rare, having
    to maintain correct ordering of instantiation is painful, so the resolve()
    method should be used to perform parts of init which require access to
    other parts of the spec.

    Attributes:
        yaml        raw spec as loaded from the spec file
        family      back reference to the full family

        name        name of the entity as listed in the spec (optional)
        ident_name  name which can be safely used as identifier in code (optional)
    """
    def __init__(self, family, yaml):
        self.yaml = yaml
        self.family = family

        if 'name' in self.yaml:
            self.name = self.yaml['name']
            self.ident_name = self.name.replace('-', '_')

        self._super_resolved = False
        family.add_unresolved(self)

    def __getitem__(self, key):
        return self.yaml[key]

    def __contains__(self, key):
        return key in self.yaml

    def get(self, key, default=None):
        return self.yaml.get(key, default)

    def resolve_up(self, up):
        if not self._super_resolved:
            up.resolve()
            self._super_resolved = True

    def resolve(self):
        pass


class SpecEnumEntry(SpecElement):
    """ Entry within an enum declared in the Netlink spec.

    Attributes:
        doc         documentation string
        enum_set    back reference to the enum
        value       numerical value of this enum (use accessors in most situations!)

    Methods:
        raw_value   raw value, i.e. the id in the enum, unlike user value which is a mask for flags
        user_value   user value, same as raw value for enums, for flags it's the mask
    """
    def __init__(self, enum_set, yaml, prev, value_start):
        if isinstance(yaml, str):
            yaml = {'name': yaml}
        super().__init__(enum_set.family, yaml)

        self.doc = yaml.get('doc', '')
        self.enum_set = enum_set

        if 'value' in yaml:
            self.value = yaml['value']
        elif prev:
            self.value = prev.value + 1
        else:
            self.value = value_start

    def has_doc(self):
        return bool(self.doc)

    def raw_value(self):
        return self.value

    def user_value(self, as_flags=None):
        if self.enum_set['type'] == 'flags' or as_flags:
            return 1 << self.value
        else:
            return self.value


class SpecEnumSet(SpecElement):
    """ Enum type

    Represents an enumeration (list of numerical constants)
    as declared in the "definitions" section of the spec.

    Attributes:
        type            enum or flags
        entries         entries by name
        entries_by_val  entries by value
    Methods:
        get_mask      for flags compute the mask of all defined values
    """
    def __init__(self, family, yaml):
        super().__init__(family, yaml)

        self.type = yaml['type']

        prev_entry = None
        value_start = self.yaml.get('value-start', 0)
        self.entries = dict()
        self.entries_by_val = dict()
        for entry in self.yaml['entries']:
            e = self.new_entry(entry, prev_entry, value_start)
            self.entries[e.name] = e
            self.entries_by_val[e.raw_value()] = e
            prev_entry = e

    def new_entry(self, entry, prev_entry, value_start):
        return SpecEnumEntry(self, entry, prev_entry, value_start)

    def has_doc(self):
        if 'doc' in self.yaml:
            return True
        for entry in self.entries.values():
            if entry.has_doc():
                return True
        return False

    def get_mask(self, as_flags=None):
        mask = 0
        for e in self.entries.values():
            mask += e.user_value(as_flags)
        return mask


class SpecAttr(SpecElement):
    """ Single Netlink attribute type

    Represents a single attribute type within an attr space.

    Attributes:
        type          string, attribute type
        value         numerical ID when serialized
        attr_set      Attribute Set containing this attr
        is_multi      bool, attr may repeat multiple times
        struct_name   string, name of struct definition
        sub_type      string, name of sub type
        len           integer, optional byte length of binary types
        display_hint  string, hint to help choose format specifier
                      when displaying the value
        sub_message   string, name of sub message type
        selector      string, name of attribute used to select
                      sub-message type

        is_auto_scalar bool, attr is a variable-size scalar
    """
    def __init__(self, family, attr_set, yaml, value):
        super().__init__(family, yaml)

        self.type = yaml['type']
        self.value = value
        self.attr_set = attr_set
        self.is_multi = yaml.get('multi-attr', False)
        self.struct_name = yaml.get('struct')
        self.sub_type = yaml.get('sub-type')
        self.byte_order = yaml.get('byte-order')
        self.len = yaml.get('len')
        self.display_hint = yaml.get('display-hint')
        self.sub_message = yaml.get('sub-message')
        self.selector = yaml.get('selector')

        self.is_auto_scalar = self.type == "sint" or self.type == "uint"


class SpecAttrSet(SpecElement):
    """ Netlink Attribute Set class.

    Represents a ID space of attributes within Netlink.

    Note that unlike other elements, which expose contents of the raw spec
    via the dictionary interface Attribute Set exposes attributes by name.

    Attributes:
        attrs      ordered dict of all attributes (indexed by name)
        attrs_by_val  ordered dict of all attributes (indexed by value)
        subset_of  parent set if this is a subset, otherwise None
    """
    def __init__(self, family, yaml):
        super().__init__(family, yaml)

        self.subset_of = self.yaml.get('subset-of', None)

        self.attrs = collections.OrderedDict()
        self.attrs_by_val = collections.OrderedDict()

        if self.subset_of is None:
            val = 1
            for elem in self.yaml['attributes']:
                if 'value' in elem:
                    val = elem['value']

                attr = self.new_attr(elem, val)
                self.attrs[attr.name] = attr
                self.attrs_by_val[attr.value] = attr
                val += 1
        else:
            real_set = family.attr_sets[self.subset_of]
            for elem in self.yaml['attributes']:
                attr = real_set[elem['name']]
                self.attrs[attr.name] = attr
                self.attrs_by_val[attr.value] = attr

    def new_attr(self, elem, value):
        return SpecAttr(self.family, self, elem, value)

    def __getitem__(self, key):
        return self.attrs[key]

    def __contains__(self, key):
        return key in self.attrs

    def __iter__(self):
        yield from self.attrs

    def items(self):
        return self.attrs.items()


class SpecStructMember(SpecElement):
    """Struct member attribute

    Represents a single struct member attribute.

    Attributes:
        type        string, type of the member attribute
        byte_order  string or None for native byte order
        enum        string, name of the enum definition
        len         integer, optional byte length of binary types
        display_hint  string, hint to help choose format specifier
                      when displaying the value
        struct      string, name of nested struct type
    """
    def __init__(self, family, yaml):
        super().__init__(family, yaml)
        self.type = yaml['type']
        self.byte_order = yaml.get('byte-order')
        self.enum = yaml.get('enum')
        self.len = yaml.get('len')
        self.display_hint = yaml.get('display-hint')
        self.struct = yaml.get('struct')


class SpecStruct(SpecElement):
    """Netlink struct type

    Represents a C struct definition.

    Attributes:
        members   ordered list of struct members
    """
    def __init__(self, family, yaml):
        super().__init__(family, yaml)

        self.members = []
        for member in yaml.get('members', []):
            self.members.append(self.new_member(family, member))

    def new_member(self, family, elem):
        return SpecStructMember(family, elem)

    def __iter__(self):
        yield from self.members

    def items(self):
        return self.members.items()


class SpecSubMessage(SpecElement):
    """ Netlink sub-message definition

    Represents a set of sub-message formats for polymorphic nlattrs
    that contain type-specific sub messages.

    Attributes:
        name     string, name of sub-message definition
        formats  dict of sub-message formats indexed by match value
    """
    def __init__(self, family, yaml):
        super().