core: add options to delegate BPFFS token creation

Add four new options BPFDelegate{Commands,Maps,Programs,Attachments}=
in order to delegate to a BPFFS instance the permission to create tokens.

The value is a list of options taken from:
https://github.com/torvalds/linux/blob/v6.14/include/uapi/linux/bpf.h#L922-L1121
The special value "any" means to allow every possible values.

More informations about BPF tokens here:
https://lwn.net/Articles/947173/

src/basic/generate-bpf-delegate-configs.py

@@ -0,0 +1,76 @@
+#!/usr/bin/env python3
+
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+# Convert the bpf_{cmd,map_type,prog_type,attach_type} enums into a string
+# array to be used as configuration options
+
+import re
+import sys
+
+
+def print_usage_and_exit() -> None:
+    print(f'Usage: {sys.argv[0]} <code|doc> <header>')
+    sys.exit(1)
+
+
+if len(sys.argv) != 3:
+    print_usage_and_exit()
+
+output = sys.argv[1]
+header = sys.argv[2]
+
+if output not in ['code', 'doc']:
+    print(f'Invalid format: {format}')
+    print_usage_and_exit()
+
+with open(header) as file:
+    inEnum = False
+    enumValues: list[str] = []
+    enumName = ''
+
+    if output == 'doc':
+        print("""\
+<?xml version="1.0"?>
+<!DOCTYPE bpf-delegates PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
+<para>
+""")
+
+    for line in file:
+        line = line.strip()
+
+        if inEnum:
+            # Inside an enum definition
+            if re.match(r'^\s*}', line):
+                # End of an enum definition
+                inEnum = False
+                # Print the enum values as a static const char* array
+                if output == 'code':
+                    print(f'static const char* const {enumName}_table[] = {{')
+                else:
+                    print(f'<para id="{enumName}">')
+                for enumValue in enumValues:
+                    words = enumValue.split('_')
+                    enumValue = words[0] + ''.join(word.capitalize() for word in words[1:])
+                    if output == 'code':
+                        print(f'\t"{enumValue}",')
+                    else:
+                        print(f'<literal>{enumValue}</literal>')
+                if output == 'code':
+                    print('};')
+                else:
+                    print('</para>')
+                enumValues = []
+            else:
+                # Collect enum values
+                match = re.fullmatch(r'(\w+)\b,', line)
+                if match and len(match.groups()) > 0 and not match[1].startswith('__'):
+                    enumValues.append(match[1])
+        elif match := re.match(r'^\s*enum\s+bpf_(cmd|map_type|prog_type|attach_type)+\s*{', line):
+            # Start of a new enum
+            inEnum = True
+            enumName = 'bpf_delegate_' + match[1]
+
+    if output == 'doc':
+        print('</para>')

src/basic/meson.build

@@ -273,8 +273,17 @@ filesystem_switch_case_inc = custom_target(
                    '@INPUT@'],
         capture : true)
 
-generated_sources += [filesystem_list_inc, filesystem_switch_case_inc, filesystems_gperf_h]
-basic_sources += [filesystem_list_inc, filesystem_switch_case_inc, filesystems_gperf_h]
+generate_bpf_delegate_configs = find_program('generate-bpf-delegate-configs.py')
+bpf_delegate_configs_inc = custom_target(
+        input : files('include/linux/bpf.h'),
+        output : 'bpf-delegate-configs.inc',
+        command : [generate_bpf_delegate_configs,
+                   'code',
+                   '@INPUT@'],
+        capture : true)
+
+generated_sources += [filesystem_list_inc, filesystem_switch_case_inc, filesystems_gperf_h, bpf_delegate_configs_inc]
+basic_sources += [filesystem_list_inc, filesystem_switch_case_inc, filesystems_gperf_h, bpf_delegate_configs_inc]
 
 libbasic_static = static_library(
         'basic',