feat: Add crc32 filter (#5062)

* feat: Add crc32 filter

Compute CRC32 checksum of a string and return its hex representation. Can be
use to create short checksums.

Signed-off-by: Julien Riou <julien@riou.xyz>

* Update license lines

* Improve string check of a crc32 value

Signed-off-by: Julien Riou <julien@riou.xyz>

Signed-off-by: Julien Riou <julien@riou.xyz>
Co-authored-by: Felix Fontein <felix@fontein.de>

plugins/filter/crc32.py

@@ -0,0 +1,64 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2022, Julien Riou <julien@riou.xyz>
+# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+from ansible.errors import AnsibleFilterError
+from ansible.module_utils.common.text.converters import to_bytes
+from ansible.module_utils.common.collections import is_string
+
+try:
+    from zlib import crc32
+    HAS_ZLIB = True
+except ImportError:
+    HAS_ZLIB = False
+
+
+DOCUMENTATION = '''
+  name: crc32
+  short_description: Generate a CRC32 checksum
+  version_added: 5.4.0
+  description:
+    - Checksum a string using CRC32 algorithm and return its hexadecimal representation.
+  options:
+    _input:
+      description:
+        - The string to checksum.
+      type: string
+      required: true
+  author:
+    - Julien Riou
+'''
+
+EXAMPLES = '''
+  - name: Checksum a test string
+    ansible.builtin.debug:
+      msg: "{{ 'test' | community.general.crc32 }}"
+'''
+
+RETURN = '''
+  _value:
+    description: CRC32 checksum.
+    type: string
+'''
+
+
+def crc32s(value):
+    if not is_string(value):
+        raise AnsibleFilterError('Invalid value type (%s) for crc32 (%r)' %
+                                 (type(value), value))
+
+    if not HAS_ZLIB:
+        raise AnsibleFilterError('Failed to import zlib module')
+
+    data = to_bytes(value, errors='surrogate_or_strict')
+    return "{0:x}".format(crc32(data) & 0xffffffff)
+
+
+class FilterModule:
+    def filters(self):
+        return {
+            'crc32': crc32s,
+        }