.github/workflows/valid-xml.yml

#                          __  __            _
#                       ___\ \/ /_ __   __ _| |_
#                      / _ \\  /| '_ \ / _` | __|
#                     |  __//  \| |_) | (_| | |_
#                      \___/_/\_\ .__/ \__,_|\__|
#                               |_| XML parser
#
# Copyright (c) 2021-2025 Sebastian Pipping <sebastian@pipping.org>
# Copyright (c) 2023      Joyce Brum <joycebrum@google.com>
# Licensed under the MIT license:
#
# Permission is  hereby granted,  free of charge,  to any  person obtaining
# a  copy  of  this  software   and  associated  documentation  files  (the
# "Software"),  to  deal in  the  Software  without restriction,  including
# without  limitation the  rights  to use,  copy,  modify, merge,  publish,
# distribute, sublicense, and/or sell copies of the Software, and to permit
# persons  to whom  the Software  is  furnished to  do so,  subject to  the
# following conditions:
#
# The above copyright  notice and this permission notice  shall be included
# in all copies or substantial portions of the Software.
#
# THE  SOFTWARE  IS  PROVIDED  "AS  IS",  WITHOUT  WARRANTY  OF  ANY  KIND,
# EXPRESS  OR IMPLIED,  INCLUDING  BUT  NOT LIMITED  TO  THE WARRANTIES  OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
# NO EVENT SHALL THE AUTHORS OR  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
# DAMAGES OR  OTHER LIABILITY, WHETHER  IN AN  ACTION OF CONTRACT,  TORT OR
# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
# USE OR OTHER DEALINGS IN THE SOFTWARE.

name: Ensure well-formed and valid XML

on:
  pull_request:
  push:
  schedule:
    - cron: '0 2 * * 5'  # Every Friday at 2am
  workflow_dispatch:

permissions:
  contents: read

jobs:
  checks:
    name: Ensure well-formed and valid XML
    runs-on: ubuntu-22.04
    steps:
    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8  # v5.0.0

    - name: Install build dependencies
      run: |-
        set -x
        sudo apt-get update
        sudo apt-get install --yes --no-install-recommends -V \
            docbook \
            libxml2-utils \
            w3c-sgml-lib

    - name: Ensure well-formed and valid XML
      run: |
        set -x

        # Target offline validation rather than online (for robust CI)
        sed 's,http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd,file:///usr/share/sgml/docbook/dtd/4.2/docbookx.dtd,' -i expat/doc/xmlwf.xml
        sed 's,http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd,file:///usr/share/xml/w3c-sgml-lib/schema/dtd/REC-xhtml1-20020801/xhtml1-strict.dtd,' -i expat/doc/reference.html

        # We're using unshare(1) to take internet access away forcefully
        # so that we'll notice whenever our all-offline validation stops being all-offline
        unshare --map-root-user --net -- xmllint --nonet --noout --valid expat/doc/reference.html
        unshare --map-root-user --net -- xmllint --nonet --noout --valid expat/doc/xmlwf.xml