docs: Makefile: switch to the new scripts/sphinx-pre-install.py

Now that we have a better, improved Python script, use it when
checking for documentation build dependencies.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/79508fb071512c33e807f5411bbff1904751b5d3.1754992972.git.mchehab+huawei@kernel.org

1 files changed, 1565 insertions, 0 deletions

diff --git a/scripts/sphinx-pre-install b/scripts/sphinx-pre-install
new file mode 100755
index 000000000000..7dfe5c2a6cc2
--- /dev/null
+++ b/scripts/sphinx-pre-install
@@ -0,0 +1,1565 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2017-2025 Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
+#
+# pylint: disable=C0103,C0114,C0115,C0116,C0301,C0302
+# pylint: disable=R0902,R0904,R0911,R0912,R0914,R0915,R1705,R1710,E1121
+
+# Note: this script requires at least Python 3.6 to run.
+# Don't add changes not compatible with it, it is meant to report
+# incompatible python versions.
+
+"""
+Dependency checker for Sphinx documentation Kernel build.
+
+This module provides tools to check for all required dependencies needed to
+build documentation using Sphinx, including system packages, Python modules
+and LaTeX packages for PDF generation.
+
+It detect packages for a subset of Linux distributions used by Kernel
+maintainers, showing hints and missing dependencies.
+
+The main class SphinxDependencyChecker handles the dependency checking logic
+and provides recommendations for installing missing packages. It supports both
+system package installations and  Python virtual environments. By default,
+system pacage install is recommended.
+"""
+
+import argparse
+import os
+import re
+import subprocess
+import sys
+from glob import glob
+
+
+def parse_version(version):
+    """Convert a major.minor.patch version into a tuple"""
+    return tuple(int(x) for x in version.split("."))
+
+
+def ver_str(version):
+    """Returns a version tuple as major.minor.patch"""
+
+    return ".".join([str(x) for x in version])
+
+
+RECOMMENDED_VERSION = parse_version("3.4.3")
+MIN_PYTHON_VERSION = parse_version("3.7")
+
+
+class DepManager:
+    """
+    Manage package dependencies. There are three types of dependencies:
+
+    - System: dependencies required for docs build;
+    - Python: python dependencies for a native distro Sphinx install;
+    - PDF: dependencies needed by PDF builds.
+
+    Each dependency can be mandatory or optional. Not installing an optional
+    dependency won't break the build, but will cause degradation at the
+    docs output.
+    """
+
+    # Internal types of dependencies. Don't use them outside DepManager class.
+    _SYS_TYPE = 0
+    _PHY_TYPE = 1
+    _PDF_TYPE = 2
+
+    # Dependencies visible outside the class.
+    # The keys are tuple with: (type, is_mandatory flag).
+    #
+    # Currently we're not using all optional dep types. Yet, we'll keep all
+    # possible combinations here. They're not many, and that makes easier
+    # if later needed and for the name() method below
+
+    SYSTEM_MANDATORY = (_SYS_TYPE, True)
+    PYTHON_MANDATORY = (_PHY_TYPE, True)
+    PDF_MANDATORY = (_PDF_TYPE, True)
+
+    SYSTEM_OPTIONAL = (_SYS_TYPE, False)
+    PYTHON_OPTIONAL = (_PHY_TYPE, False)
+    PDF_OPTIONAL = (_PDF_TYPE, True)
+
+    def __init__(self, pdf):
+        """
+        Initialize internal vars:
+
+        - missing: missing dependencies list, containing a distro-independent
+                   name for a missing dependency and its type.
+        - missing_pkg: ancillary dict containing missing dependencies in
+                       distro namespace, organized by type.
+        - need: total number of needed dependencies. Never cleaned.
+        - optional: total number of optional dependencies. Never cleaned.
+        - pdf: Is PDF support enabled?
+        """
+        self.missing = {}
+        self.missing_pkg = {}
+        self.need = 0
+        self.optional = 0
+        self.pdf = pdf
+
+    @staticmethod
+    def name(dtype):
+        """
+        Ancillary routine to output a warn/error message reporting
+        missing dependencies.
+        """
+        if dtype[0] == DepManager._SYS_TYPE:
+            msg = "build"
+        elif dtype[0] == DepManager._PHY_TYPE:
+            msg = "Python"
+        else:
+            msg = "PDF"
+
+        if dtype[1]:
+            return f"ERROR: {msg} mandatory deps missing"
+        else:
+            return f"Warning: {msg} optional deps missing"
+
+    @staticmethod
+    def is_optional(dtype):
+        """Ancillary routine to report if a dependency is optional"""
+        return not dtype[1]
+
+    @staticmethod
+    def is_pdf(dtype):
+        """Ancillary routine to report if a dependency is for PDF generation"""
+        if dtype[0] == DepManager._PDF_TYPE:
+            return True
+
+        return False
+
+    def add_package(self, package, dtype):
+        """
+        Add a package at the self.missing() dictionary.
+        Doesn't update missing_pkg.
+        """
+        is_optional = DepManager.is_optional(dtype)
+        self.missing[package] = dtype
+        if is_optional:
+            self.optional += 1
+        else:
+            self.need += 1
+
+    def del_package(self, package):
+        """
+        Remove a package at the self.missing() dictionary.
+        Doesn't update missing_pkg.
+        """
+        if package in self.missing:
+            del self.missing[package]
+
+    def clear_deps(self):
+        """
+        Clear dependencies without changing needed/optional.
+
+        This is an ackward way to have a separate section to recommend
+        a package after system main dependencies.
+
+        TODO: rework the logic to prevent needing it.
+        """
+
+        self.missing = {}
+        self.missing_pkg = {}
+
+    def check_missing(self, progs):
+        """
+        Update self.missing_pkg, using progs dict to convert from the
+        agnostic package name to distro-specific one.
+
+        Returns an string with the packages to be installed, sorted and
+        with eventual duplicates removed.
+        """
+
+        self.missing_pkg = {}
+
+        for prog, dtype in sorted(self.missing.items()):
+            # At least on some LTS distros like CentOS 7, texlive doesn't
+            # provide all packages we need. When such distros are
+            # detected, we have to disable PDF output.
+            #
+            # So, we need to ignore the packages that distros would
+            # need for LaTeX to work
+            if DepManager.is_pdf(dtype) and not self.pdf:
+                self.optional -= 1
+                continue
+
+            if not dtype in self.missing_pkg:
+                self.missing_pkg[dtype] = []
+
+            self.missing_pkg[dtype].append(progs.get(prog, prog))
+
+        install = []
+        for dtype, pkgs in self.missing_pkg.items():
+            install += pkgs
+
+        return " ".join(sorted(set(install)))
+
+    def warn_install(self):
+        """
+        Emit warnings/errors related to missing packages.
+        """
+
+        output_msg = ""
+
+        for dtype in sorted(self.missing_pkg.keys()):
+            progs = " ".join(sorted(set(self.missing_pkg[dtype])))
+
+            try:
+                name = DepManager.name(dtype)
+                output_msg += f'{name}:\t{progs}\n'
+            except KeyError:
+                raise KeyError(f"ERROR!!!: invalid dtype for {progs}: {dtype}")
+
+        if output_msg:
+            print(f"\n{output_msg}")
+
+class AncillaryMethods:
+    """
+    Ancillary methods that checks for missing dependencies for different
+    types of types, like binaries, python modules, rpm deps, etc.
+    """
+
+    @staticmethod
+    def which(prog):
+        """
+        Our own implementation of which(). We could instead use
+        shutil.which(), but this function is simple enough.
+        Probably faster to use this implementation than to import shutil.
+        """
+        for path in os.environ.get("PATH", "").split(":"):
+            full_path = os.path.join(path, prog)
+            if os.access(full_path, os.X_OK):
+                return full_path
+
+        return None
+
+    @staticmethod
+    def get_python_version(cmd):
+        """
+        Get python version from a Python binary. As we need to detect if
+        are out there newer python binaries, we can't rely on sys.release here.
+        """
+
+        result = SphinxDependencyChecker.run([cmd, "--version"],
+                                            capture_output=True, text=True)
+        version = result.stdout.strip()
+
+        match = re.search(r"(\d+\.\d+\.\d+)", version)
+        if match:
+            return parse_version(match.group(1))
+
+        print(f"Can't parse version {version}")
+        return (0, 0, 0)
+
+    @staticmethod
+    def find_python():
+        """
+        Detect if are out there any python 3.xy version newer than the
+        current one.
+
+        Note: this routine is limited to up to 2 digits for python3. We
+        may need to update it one day, hopefully on a distant future.
+        """
+        patterns = [
+            "python3.[0-9]",
+            "python3.[0-9][0-9]",
+        ]
+
+        # Seek for a python binary newer than MIN_PYTHON_VERSION
+        for path in os.getenv("PATH", "").split(":"):
+            for pattern in patterns:
+                for cmd in glob(os.path.join(path, pattern)):
+                    if os.path.isfile(cmd) and os.access(cmd, os.X_OK):
+                        version = SphinxDependencyChecker.get_python_version(cmd)
+                        if version >= MIN_PYTHON_VERSION:
+                            return cmd
+
+    @staticmethod
+    def check_python():
+        """
+        Check if the current python binary satisfies our minimal requirement
+        for Sphinx build. If not, re-run with a newer version if found.
+        """
+        cur_ver = sys.version_info[:3]
+        if cur_ver >= MIN_PYTHON_VERSION:
+            ver = ver_str(cur_ver)
+            print(f"Python version: {ver}")
+
+            # This could be useful for debugging purposes
+            if SphinxDependencyChecker.which("docutils"):
+                result = SphinxDependencyChecker.run(["docutils", "--version"],
+                                                    capture_output=True, text=True)
+                ver = result.stdout.strip()
+                match = re.search(r"(\d+\.\d+\.\d+)", ver)
+                if match:
+                    ver = match.group(1)
+
+                print(f"Docutils version: {ver}")
+
+            return
+
+        python_ver = ver_str(cur_ver)
+
+        new_python_cmd = SphinxDependencyChecker.find_python()
+        if not new_python_cmd:
+            print(f"ERROR: Python version {python_ver} is not spported anymore\n")
+            print("       Can't find a new version. This script may fail")
+            return
+
+        # Restart script using the newer version
+        script_path = os.path.abspath(sys.argv[0])
+        args = [new_python_cmd, script_path] + sys.argv[1:]
+
+        print(f"Python {python_ver} not supported. Changing to {new_python_cmd}")
+
+        try:
+            os.execv(new_python_cmd, args)
+        except OSError as e:
+            sys.exit(f"Failed to restart with {new_python_cmd}: {e}")
+
+    @staticmethod
+    def run(*args, **kwargs):
+        """
+        Excecute a command, hiding its output by default.
+        Preserve comatibility with older Python versions.
+        """
+
+        capture_output = kwargs.pop('capture_output', False)
+
+        if capture_output:
+            if 'stdout' not in kwargs:
+                kwargs['stdout'] = subprocess.PIPE
+            if 'stderr' not in kwargs:
+                kwargs['stderr'] = subprocess.PIPE
+        else:
+            if 'stdout' not in kwargs:
+                kwargs['stdout'] = subprocess.DEVNULL
+            if 'stderr' not in kwargs:
+                kwargs['stderr'] = subprocess.DEVNULL
+
+        # Don't break with older Python versions
+        if 'text' in kwargs and sys.version_info < (3, 7):
+            kwargs['universal_newlines'] = kwargs.pop('text')
+
+        return subprocess.run(*args, **kwargs)
+
+class MissingCheckers(AncillaryMethods):
+    """
+    Contains some ancillary checkers for different types of binaries and
+    package managers.
+    """
+
+    def __init__(self, args, texlive):
+        """
+        Initialize its internal variables
+        """
+        self.pdf = args.pdf
+        self.virtualenv = args.virtualenv
+        self.version_check = args.version_check
+        self.texlive = texlive
+
+        self.min_version = (0, 0, 0)
+        self.cur_version = (0, 0, 0)
+
+        self.deps = DepManager(self.pdf)
+
+        self.need_symlink = 0
+        self.need_sphinx = 0
+
+        self.verbose_warn_install = 1
+
+        self.virtenv_dir = ""
+        self.install = ""
+        self.python_cmd = ""
+
+        self.virtenv_prefix = ["sphinx_", "Sphinx_" ]
+
+    def check_missing_file(self, files, package, dtype):
+        """
+        Does the file exists? If not, add it to missing dependencies.
+        """
+        for f in files:
+            if os.path.exists(f):
+                return
+        self.deps.add_package(package, dtype)
+
+    def check_program(self, prog, dtype):
+        """
+        Does the program exists and it is at the PATH?
+        If not, add it to missing dependencies.
+        """
+        found = self.which(prog)
+        if found:
+            return found
+
+        self.deps.add_package(prog, dtype)
+
+        return None
+
+    def check_perl_module(self, prog, dtype):
+        """
+        Does perl have a dependency? Is it available?
+        If not, add it to missing dependencies.
+
+        Right now, we still need Perl for doc build, as it is required
+        by some tools called at docs or kernel build time, like:
+
+            scripts/documentation-file-ref-check
+
+        Also, checkpatch is on Perl.
+        """
+
+        # While testing with lxc download template, one of the
+        # distros (Oracle) didn't have perl - nor even an option to install
+        # before installing oraclelinux-release-el9 package.
+        #
+        # Check it before running an error. If perl is not there,
+        # add it as a mandatory package, as some parts of the doc builder
+        # needs it.
+        if not self.which("perl"):
+            self.deps.add_package("perl", DepManager.SYSTEM_MANDATORY)
+            self.deps.add_package(prog, dtype)
+            return
+
+        try:
+            self.run(["perl", f"-M{prog}", "-e", "1"], check=True)
+        except subprocess.CalledProcessError:
+            self.deps.add_package(prog, dtype)
+
+    def check_python_module(self, module, is_optional=False):
+        """
+        Does a python module exists outside venv? If not, add it to missing
+        dependencies.
+        """
+        if is_optional:
+            dtype = DepManager.PYTHON_OPTIONAL
+        else:
+            dtype = DepManager.PYTHON_MANDATORY
+
+        try:
+            self.run([self.python_cmd, "-c", f"import {module}"], check=True)
+        except subprocess.CalledProcessError:
+            self.deps.add_package(module, dtype)
+
+    def check_rpm_missing(self, pkgs, dtype):
+        """
+        Does a rpm package exists? If not, add it to missing dependencies.
+        """
+        for prog in pkgs:
+            try:
+                self.run(["rpm", "-q", prog], check=True)
+            except subprocess.CalledProcessError:
+                self.deps.add_package(prog, dtype)
+
+    def check_pacman_missing(self, pkgs, dtype):
+        """
+        Does a pacman package exists? If not, add it to missing dependencies.
+        """
+        for prog in pkgs:
+            try:
+                self.run(["pacman", "-Q", prog], check=True)
+            except subprocess.CalledProcessError:
+                self.deps.add_package(prog, dtype)
+
+    def check_missing_tex(self, is_optional=False):
+        """
+        Does a LaTeX package exists? If not, add it to missing dependencies.
+        """
+        if is_optional:
+            dtype = DepManager.PDF_OPTIONAL
+        else:
+            dtype = DepManager.PDF_MANDATORY
+
+        kpsewhich = self.which("kpsewhich")
+        for prog, package in self.texlive.items():
+
+            # If kpsewhich is not there, just add it to deps
+            if not kpsewhich:
+                self.deps.add_package(package, dtype)
+                continue
+
+            # Check if the package is needed
+            try:
+                result = self.run(
+                    [kpsewhich, prog], stdout=subprocess.PIPE, text=True, check=True
+                )
+
+                # Didn't find. Add it
+                if not result.stdout.strip():
+                    self.deps.add_package(package, dtype)
+
+            except subprocess.CalledProcessError:
+                # kpsewhich returned an error. Add it, just in case
+                self.deps.add_package(package, dtype)
+
+    def get_sphinx_fname(self):
+        """
+        Gets the binary filename for sphinx-build.
+        """
+        if "SPHINXBUILD" in os.environ:
+            return os.environ["SPHINXBUILD"]
+
+        fname = "sphinx-build"
+        if self.which(fname):
+            return fname
+
+        fname = "sphinx-build-3"
+        if self.which(fname):
+            self.need_symlink = 1
+            return fname
+
+        return ""
+
+    def get_sphinx_version(self, cmd):
+        """
+        Gets sphinx-build version.
+        """
+        try:
+            result = self.run([cmd, "--version"],
+                              stdout=subprocess.PIPE,
+                              stderr=subprocess.STDOUT,
+                              text=True, check=True)
+        except (subprocess.CalledProcessError, FileNotFoundError):
+            return None
+
+        for line in result.stdout.split("\n"):
+            match = re.match(r"^sphinx-build\s+([\d\.]+)(?:\+(?:/[\da-f]+)|b\d+)?\s*$", line)
+            if match:
+                return parse_version(match.group(1))
+
+            match = re.match(r"^Sphinx.*\s+([\d\.]+)\s*$", line)
+            if match:
+                return parse_version(match.group(1))
+
+    def check_sphinx(self, conf):
+        """
+        Checks Sphinx minimal requirements
+        """
+        try:
+            with open(conf, "r", encoding="utf-8") as f:
+                for line in f:
+                    match = re.match(r"^\s*needs_sphinx\s*=\s*[\'\"]([\d\.]+)[\'\"]", line)
+                    if match:
+                        self.min_version = parse_version(match.group(1))
+                        break
+        except IOError:
+            sys.exit(f"Can't open {conf}")
+
+        if not self.min_version:
+            sys.exit(f"Can't get needs_sphinx version from {conf}")
+
+        self.virtenv_dir = self.virtenv_prefix[0] + "latest"
+
+        sphinx = self.get_sphinx_fname()
+        if not sphinx:
+            self.need_sphinx = 1
+            return
+
+        self.cur_version = self.get_sphinx_version(sphinx)
+        if not self.cur_version:
+            sys.exit(f"{sphinx} didn't return its version")
+
+        if self.cur_version < self.min_version:
+            curver = ver_str(self.cur_version)
+            minver = ver_str(self.min_version)
+
+            print(f"ERROR: Sphinx version is {curver}. It should be >= {minver}")
+            self.need_sphinx = 1
+            return
+
+        # On version check mode, just assume Sphinx has all mandatory deps
+        if self.version_check and self.cur_version >= RECOMMENDED_VERSION:
+            sys.exit(0)
+
+    def catcheck(self, filename):
+        """
+        Reads a file if it exists, returning as string.
+        If not found, returns an empty string.
+        """
+        if os.path.exists(filename):
+            with open(filename, "r", encoding="utf-8") as f:
+                return f.read().strip()
+        return ""
+
+    def get_system_release(self):
+        """
+        Determine the system type. There's no unique way that would work
+        with all distros with a minimal package install. So, several
+        methods are used here.
+
+        By default, it will use lsb_release function. If not available, it will
+        fail back to reading the known different places where the distro name
+        is stored.
+
+        Several modern distros now have /etc/os-release, which usually have
+        a decent coverage.
+        """
+
+        system_release = ""
+
+        if self.which("lsb_release"):
+            result = self.run(["lsb_release", "-d"], capture_output=True, text=True)
+            system_release = result.stdout.replace("Description:", "").strip()
+
+        release_files = [
+            "/etc/system-release",
+            "/etc/redhat-release",
+            "/etc/lsb-release",
+            "/etc/gentoo-release",
+        ]
+
+        if not system_release:
+            for f in release_files:
+                system_release = self.catcheck(f)
+                if system_release:
+                    break
+
+        # This seems more common than LSB these days
+        if not system_release:
+            os_var = {}
+            try:
+                with open("/etc/os-release", "r", encoding="utf-8") as f:
+                    for line in f:
+                        match = re.match(r"^([\w\d\_]+)=\"?([^\"]*)\"?\n", line)
+                        if match:
+                            os_var[match.group(1)] = match.group(2)
+
+                system_release = os_var.get("NAME", "")
+                if "VERSION_ID" in os_var:
+                    system_release += " " + os_var["VERSION_ID"]
+                elif "VERSION" in os_var:
+                    system_release += " " + os_var["VERSION"]
+            except IOError:
+                pass
+
+        if not system_release:
+            system_release = self.catcheck("/etc/issue")
+
+        system_release = system_release.strip()
+
+        return system_release
+
+class SphinxDependencyChecker(MissingCheckers):
+    """
+    Main class for checking Sphinx documentation build dependencies.
+
+    - Check for missing system packages;
+    - Check for missing Python modules;
+    - Check for missing LaTeX packages needed by PDF generation;
+    - Propose Sphinx install via Python Virtual environment;
+    - Propose Sphinx install via distro-specific package install.
+    """
+    def __init__(self, args):
+        """Initialize checker variables"""
+
+        # List of required texlive packages on Fedora and OpenSuse
+        texlive = {
+            "amsfonts.sty":       "texlive-amsfonts",
+            "amsmath.sty":        "texlive-amsmath",
+            "amssymb.sty":        "texlive-amsfonts",
+            "amsthm.sty":         "texlive-amscls",
+            "anyfontsize.sty":    "texlive-anyfontsize",
+            "atbegshi.sty":       "texlive-oberdiek",
+            "bm.sty":             "texlive-tools",
+            "capt-of.sty":        "texlive-capt-of",
+            "cmap.sty":           "texlive-cmap",
+            "ctexhook.sty":       "texlive-ctex",
+            "ecrm1000.tfm":       "texlive-ec",
+            "eqparbox.sty":       "texlive-eqparbox",
+            "eu1enc.def":         "texlive-euenc",
+            "fancybox.sty":       "texlive-fancybox",
+            "fancyvrb.sty":       "texlive-fancyvrb",
+            "float.sty":          "texlive-float",
+            "fncychap.sty":       "texlive-fncychap",
+            "footnote.sty":       "texlive-mdwtools",
+            "framed.sty":         "texlive-framed",
+            "luatex85.sty":       "texlive-luatex85",
+            "multirow.sty":       "texlive-multirow",
+            "needspace.sty":      "texlive-needspace",
+            "palatino.sty":       "texlive-psnfss",
+            "parskip.sty":        "texlive-parskip",
+            "polyglossia.sty":    "texlive-polyglossia",
+            "tabulary.sty":       "texlive-tabulary",
+            "threeparttable.sty": "texlive-threeparttable",
+            "titlesec.sty":       "texlive-titlesec",
+            "ucs.sty":            "texlive-ucs",
+            "upquote.sty":        "texlive-upquote",
+            "wrapfig.sty":        "texlive-wrapfig",
+        }
+
+        super().__init__(args, texlive)
+
+        self.need_pip = 0
+        self.rec_sphinx_upgrade = 0
+
+        self.system_release = self.get_system_release()
+        self.activate_cmd = ""
+
+        # Some distros may not have a Sphinx shipped package compatible with
+        # our minimal requirements
+        self.package_supported = True
+
+        # Recommend a new python version
+        self.recommend_python = None
+
+        # Certain hints are meant to be shown only once
+        self.distro_msg = None
+
+        self.latest_avail_ver = (0, 0, 0)
+        self.venv_ver = (0, 0, 0)
+
+        prefix = os.environ.get("srctree", ".") + "/"
+
+        self.conf = prefix + "Documentation/conf.py"
+        self.requirement_file = prefix + "Documentation/sphinx/requirements.txt"
+
+    def get_install_progs(self, progs, cmd, extra=None):
+        """
+        Check for missing dependencies using the provided program mapping.
+
+        The actual distro-specific programs are mapped via progs argument.
+        """
+        install = self.deps.check_missing(progs)
+
+        if self.verbose_warn_install:
+            self.deps.warn_install()
+
+        if not install:
+            return
+
+        if cmd:
+            if self.verbose_warn_install:
+                msg = "You should run:"
+            else:
+                msg = ""
+
+            if extra:
+                msg += "\n\t" + extra.replace("\n", "\n\t")
+
+            return(msg + "\n\tsudo " + cmd + " " + install)
+
+        return None
+
+    #
+    # Distro-specific hints methods
+    #
+
+    def give_debian_hints(self):
+        """
+        Provide package installation hints for Debian-based distros.
+        """
+        progs = {
+            "Pod::Usage":    "perl-modules",
+            "convert":       "imagemagick",
+            "dot":           "graphviz",
+            "ensurepip":     "python3-venv",
+            "python-sphinx": "python3-sphinx",
+            "rsvg-convert":  "librsvg2-bin",
+            "virtualenv":    "virtualenv",
+            "xelatex":       "texlive-xetex",
+            "yaml":          "python3-yaml",
+        }
+
+        if self.pdf:
+            pdf_pkgs = {
+                "texlive-lang-chinese": [
+                    "/usr/share/texlive/texmf-dist/tex/latex/ctex/ctexhook.sty",
+                ],
+                "fonts-dejavu": [
+                    "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
+                ],
+                "fonts-noto-cjk": [
+                    "/usr/share/fonts/noto-cjk/NotoSansCJK-Regular.ttc",
+                    "/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc",
+                    "/usr/share/fonts/opentype/noto/NotoSerifCJK-Regular.ttc",
+                ],
+            }
+
+            for package, files in pdf_pkgs.items():
+                self.check_missing_file(files, package, DepManager.PDF_MANDATORY)
+
+            self.check_program("dvipng", DepManager.PDF_MANDATORY)
+
+        return self.get_install_progs(progs, "apt-get install")
+
+    def give_redhat_hints(self):
+        """
+        Provide package installation hints for RedHat-based distros
+        (Fedora, RHEL and RHEL-based variants).
+        """
+        progs = {
+            "Pod::Usage":       "perl-Pod-Usage",
+            "convert":          "ImageMagick",
+            "dot":              "graphviz",
+            "python-sphinx":    "python3-sphinx",
+            "rsvg-convert":     "librsvg2-tools",
+            "virtualenv":       "python3-virtualenv",
+            "xelatex":          "texlive-xetex-bin",
+            "yaml":             "python3-pyyaml",
+        }
+
+        fedora_tex_pkgs = [
+            "dejavu-sans-fonts",
+            "dejavu-sans-mono-fonts",
+            "dejavu-serif-fonts",
+            "texlive-collection-fontsrecommended",
+            "texlive-collection-latex",
+            "texlive-xecjk",
+        ]
+
+        fedora = False
+        rel = None
+
+        match = re.search(r"(release|Linux)\s+(\d+)", self.system_release)
+        if match:
+            rel = int(match.group(2))
+
+        if not rel:
+            print("Couldn't identify release number")
+            noto_sans_redhat = None
+            self.pdf = False
+        elif re.search("Fedora", self.system_release):
+            # Fedora 38 and upper use this CJK font
+
+            noto_sans_redhat = "google-noto-sans-cjk-fonts"
+            fedora = True
+        else:
+            # Almalinux, CentOS, RHEL, ...
+
+            # at least up to version 9 (and Fedora < 38), that's the CJK font
+            noto_sans_redhat = "google-noto-sans-cjk-ttc-fonts"
+
+            progs["virtualenv"] = "python-virtualenv"
+
+            if not rel or rel < 8:
+                print("ERROR: Distro not supported. Too old?")
+                return
+
+            # RHEL 8 uses Python 3.6, which is not compatible with
+            # the build system anymore. Suggest Python 3.11
+            if rel == 8:
+                self.deps.add_package("python39", DepManager.SYSTEM_MANDATORY)
+                self.recommend_python = True
+
+            if not self.distro_msg:
+                self.distro_msg = \
+                    "Note: RHEL-based distros typically require extra repositories.\n" \
+                    "For most, enabling epel and crb are enough:\n" \
+                    "\tsudo dnf install -y epel-release\n" \
+                    "\tsudo dnf config-manager --set-enabled crb\n" \
+                    "Yet, some may have other required repositories. Those commands could be useful:\n" \
+                    "\tsudo dnf repolist all\n" \
+                    "\tsudo dnf repoquery --available --info <pkgs>\n" \
+                    "\tsudo dnf config-manager --set-enabled '*' # enable all - probably not what you want"
+
+        if self.pdf:
+            pdf_pkgs = [
+                "/usr/share/fonts/google-noto-cjk/NotoSansCJK-Regular.ttc",
+                "/usr/share/fonts/google-noto-sans-cjk-fonts/NotoSansCJK-Regular.ttc",
+            ]
+
+            self.check_missing_file(pdf_pkgs, noto_sans_redhat, DepManager.PDF_MANDATORY)
+
+            self.check_rpm_missing(fedora_tex_pkgs, DepManager.PDF_MANDATORY)
+
+            self.check_missing_tex(DepManager.PDF_MANDATORY)
+
+            # There's no texlive-ctex on RHEL 8 repositories. This will
+            # likely affect CJK pdf build only.
+            if not fedora and rel == 8:
+                self.deps.del_package("texlive-ctex")
+
+        return self.get_install_progs(progs, "dnf install")
+
+    def give_opensuse_hints(self):
+        """
+        Provide package installation hints for openSUSE-based distros
+        (Leap and Tumbleweed).
+        """
+        progs = {
+            "Pod::Usage":    "perl-Pod-Usage",
+            "convert":       "ImageMagick",
+            "dot":           "graphviz",
+            "python-sphinx": "python3-sphinx",
+            "virtualenv":    "python3-virtualenv",
+            "xelatex":       "texlive-xetex-bin",
+            "yaml":          "python3-pyyaml",
+        }
+
+        suse_tex_pkgs = [
+            "texlive-babel-english",
+            "texlive-caption",
+            "texlive-colortbl",
+            "texlive-courier",
+            "texlive-dvips",
+            "texlive-helvetic",
+            "texlive-makeindex",
+            "texlive-metafont",
+            "texlive-metapost",
+            "texlive-palatino",
+            "texlive-preview",
+            "texlive-times",
+            "texlive-zapfchan",
+            "texlive-zapfding",
+        ]
+
+        progs["latexmk"] = "texlive-latexmk-bin"
+
+        match = re.search(r"(Leap)\s+(\d+).(\d)", self.system_release)
+        if match:
+            rel = int(match.group(2))
+
+            # Leap 15.x uses Python 3.6, which is not compatible with
+            # the build system anymore. Suggest Python 3.11
+            if rel == 15:
+                if not self.which(self.python_cmd):
+                    self.recommend_python = True
+                    self.deps.add_package(self.python_cmd, DepManager.SYSTEM_MANDATORY)
+
+                progs.update({
+                    "python-sphinx": "python311-Sphinx",
+                    "virtualenv":    "python311-virtualenv",
+                    "yaml":          "python311-PyYAML",
+                })
+        else:
+            # Tumbleweed defaults to Python 3.11
+
+            progs.update({
+                "python-sphinx": "python313-Sphinx",
+                "virtualenv":    "python313-virtualenv",
+                "yaml":          "python313-PyYAML",
+            })
+
+        # FIXME: add support for installing CJK fonts
+        #
+        # I tried hard, but was unable to find a way to install
+        # "Noto Sans CJK SC" on openSUSE
+
+        if self.pdf:
+            self.check_rpm_missing(suse_tex_pkgs, DepManager.PDF_MANDATORY)
+        if self.pdf:
+            self.check_missing_tex()
+
+        return self.get_install_progs(progs, "zypper install --no-recommends")
+
+    def give_mageia_hints(self):
+        """
+        Provide package installation hints for Mageia and OpenMandriva.
+        """
+        progs = {
+            "Pod::Usage":    "perl-Pod-Usage",
+            "convert":       "ImageMagick",
+            "dot":           "graphviz",
+            "python-sphinx": "python3-sphinx",
+            "rsvg-convert":  "librsvg2",
+            "virtualenv":    "python3-virtualenv",
+            "xelatex":       "texlive",
+            "yaml":          "python3-yaml",
+        }
+
+        tex_pkgs = [
+            "texlive-fontsextra",
+        ]
+
+        if re.search(r"OpenMandriva", self.system_release):
+            packager_cmd = "dnf install"
+            noto_sans = "noto-sans-cjk-fonts"
+            tex_pkgs = ["texlive-collection-fontsextra"]
+
+            # Tested on OpenMandriva Lx 4.3
+            progs["convert"] = "imagemagick"
+            progs["yaml"] = "python-pyyaml"
+
+        else:
+            packager_cmd = "urpmi"
+            noto_sans = "google-noto-sans-cjk-ttc-fonts"
+
+        progs["latexmk"] = "texlive-collection-basic"
+
+        if self.pdf:
+            pdf_pkgs = [
+                "/usr/share/fonts/google-noto-cjk/NotoSansCJK-Regular.ttc",
+                "/usr/share/fonts/TTF/NotoSans-Regular.ttf",
+            ]
+
+            self.check_missing_file(pdf_pkgs, noto_sans, DepManager.PDF_MANDATORY)
+            self.check_rpm_missing(tex_pkgs, DepManager.PDF_MANDATORY)
+
+        return self.get_install_progs(progs, packager_cmd)
+
+    def give_arch_linux_hints(self):
+        """
+        Provide package installation hints for ArchLinux.
+        """
+        progs = {
+            "convert":      "imagemagick",
+            "dot":          "graphviz",
+            "latexmk":      "texlive-core",
+            "rsvg-convert": "extra/librsvg",
+            "virtualenv":   "python-virtualenv",
+            "xelatex":      "texlive-xetex",
+            "yaml":         "python-yaml",
+        }
+
+        archlinux_tex_pkgs = [
+            "texlive-core",
+            "texlive-latexextra",
+            "ttf-dejavu",
+        ]
+
+        if self.pdf:
+            self.check_pacman_missing(archlinux_tex_pkgs,
+                                      DepManager.PDF_MANDATORY)
+
+            self.check_missing_file(["/usr/share/fonts/noto-cjk/NotoSansCJK-Regular.ttc"],
+                                    "noto-fonts-cjk",
+                                    DepManager.PDF_MANDATORY)
+
+
+        return self.get_install_progs(progs, "pacman -S")
+
+    def give_gentoo_hints(self):
+        """
+        Provide package installation hints for Gentoo.
+        """
+        progs = {
+            "convert":       "media-gfx/imagemagick",
+            "dot":           "media-gfx/graphviz",
+            "rsvg-convert":  "gnome-base/librsvg",
+            "virtualenv":    "dev-python/virtualenv",
+            "xelatex":       "dev-texlive/texlive-xetex media-fonts/dejavu",
+            "yaml":          "dev-python/pyyaml",
+            "python-sphinx": "dev-python/sphinx",
+        }
+
+        if self.pdf:
+            pdf_pkgs = {
+                "media-fonts/dejavu": [
+                    "/usr/share/fonts/dejavu/DejaVuSans.ttf",
+                ],
+                "media-fonts/noto-cjk": [
+                    "/usr/share/fonts/noto-cjk/NotoSansCJKsc-Regular.otf",
+                    "/usr/share/fonts/noto-cjk/NotoSerifCJK-Regular.ttc",
+                ],
+            }
+            for package, files in pdf_pkgs.items():
+                self.check_missing_file(files, package, DepManager.PDF_MANDATORY)
+
+        # Handling dependencies is a nightmare, as Gentoo refuses to emerge
+        # some packages if there's no package.use file describing them.
+        # To make it worse, compilation flags shall also be present there
+        # for some packages. If USE is not perfect, error/warning messages
+        #   like those are shown:
+        #
+        #   !!! The following binary packages have been ignored due to non matching USE:
+        #
+        #    =media-gfx/graphviz-12.2.1-r1 X pdf -python_single_target_python3_13 qt6 svg
+        #    =media-gfx/graphviz-12.2.1-r1 X pdf python_single_target_python3_12 -python_single_target_python3_13 qt6 svg
+        #    =media-gfx/graphviz-12.2.1-r1 X pdf qt6 svg
+        #    =media-gfx/graphviz-12.2.1-r1 X pdf -python_single_target_python3_10 qt6 svg
+        #    =media-gfx/graphviz-12.2.1-r1 X pdf -python_single_target_python3_10 python_single_target_python3_12 -python_single_target_python3_13 qt6 svg
+        #    =media-fonts/noto-cjk-20190416 X
+        #    =app-text/texlive-core-2024-r1 X cjk -xetex
+        #    =app-text/texlive-core-2024-r1 X -xetex
+        #    =app-text/texlive-core-2024-r1 -xetex
+        #    =dev-libs/zziplib-0.13.79-r1 sdl
+        #
+        # And will ignore such packages, installing the remaining ones. That
+        # affects mostly the image extension and PDF generation.
+
+        # Package dependencies and the minimal needed args:
+        portages = {
+            "graphviz": "media-gfx/graphviz",
+            "imagemagick": "media-gfx/imagemagick",
+            "media-libs": "media-libs/harfbuzz icu",
+            "media-fonts": "media-fonts/noto-cjk",
+            "texlive": "app-text/texlive-core xetex",
+            "zziblib": "dev-libs/zziplib sdl",
+        }
+
+        extra_cmds = ""
+        if not self.distro_msg:
+            self.distro_msg = "Note: Gentoo requires package.use to be adjusted before emerging packages"
+
+            use_base = "/etc/portage/package.use"
+            files = glob(f"{use_base}/*")
+
+            for fname, portage in portages.items():
+                install = False
+
+                while install is False:
+                    if not files:
+                        # No files under package.usage. Install all
+                        install = True
+                        break
+
+                    args = portage.split(" ")
+
+                    name = args.pop(0)
+
+                    cmd = ["grep", "-l", "-E", rf"^{name}\b" ] + files
+                    result = self.run(cmd, stdout=subprocess.PIPE, text=True)
+                    if result.returncode or not result.stdout.strip():
+                        # File containing portage name not found
+                        install = True
+                        break
+
+                    # Ensure that needed USE flags are present
+                    if args:
+                        match_fname = result.stdout.strip()
+                        with open(match_fname, 'r', encoding='utf8',
+                                errors='backslashreplace') as fp:
+                            for line in fp:
+                                for arg in args:
+                                    if arg.startswith("-"):
+                                        continue
+
+                                if not re.search(rf"\s*{arg}\b", line):
+                                    # Needed file argument not found
+                                    install = True
+                                    break
+
+                    # Everything looks ok, don't install
+                    break
+
+                # emit a code to setup missing USE
+                if install:
+                    extra_cmds += (f"sudo su -c 'echo \"{portage}\" > {use_base}/{fname}'\n")
+
+        # Now, we can use emerge and let it respect USE
+        return self.get_install_progs(progs,
+                                      "emerge --ask --changed-use --binpkg-respect-use=y",
+                                      extra_cmds)
+
+    def get_install(self):
+        """
+        OS-specific hints logic. Seeks for a hinter. If found, use it to
+        provide package-manager specific install commands.
+
+        Otherwise, outputs install instructions for the meta-packages.
+
+        Returns a string with the command to be executed to install the
+        the needed packages, if distro found. Otherwise, return just a
+        list of packages that require installation.
+        """
+        os_hints = {
+            re.compile("Red Hat Enterprise Linux"):   self.give_redhat_hints,
+            re.compile("Fedora"):                     self.give_redhat_hints,
+            re.compile("AlmaLinux"):                  self.give_redhat_hints,
+            re.compile("Amazon Linux"):               self.give_redhat_hints,
+            re.compile("CentOS"):                     self.give_redhat_hints,
+            re.compile("openEuler"):                  self.give_redhat_hints,
+            re.compile("Oracle Linux Server"):        self.give_redhat_hints,
+            re.compile("Rocky Linux"):                self.give_redhat_hints,
+            re.compile("Springdale Open Enterprise"): self.give_redhat_hints,
+
+            re.compile("Ubuntu"):                     self.give_debian_hints,
+            re.compile("Debian"):                     self.give_debian_hints,
+            re.compile("Devuan"):                     self.give_debian_hints,
+            re.compile("Kali"):                       self.give_debian_hints,
+            re.compile("Mint"):                       self.give_debian_hints,
+
+            re.compile("openSUSE"):                   self.give_opensuse_hints,
+
+            re.compile("Mageia"):                     self.give_mageia_hints,
+            re.compile("OpenMandriva"):               self.give_mageia_hints,
+
+            re.compile("Arch Linux"):                 self.give_arch_linux_hints,
+            re.compile("Gentoo"):                     self.give_gentoo_hints,
+        }
+
+        # If the OS is detected, use per-OS hint logic
+        for regex, os_hint in os_hints.items():
+            if regex.search(self.system_release):
+                return os_hint()
+
+        #
+        # Fall-back to generic hint code for other distros
+        # That's far from ideal, specially for LaTeX dependencies.
+        #
+        progs = {"sphinx-build": "sphinx"}
+        if self.pdf:
+            self.check_missing_tex()
+
+        self.distro_msg = \
+            f"I don't know distro {self.system_release}.\n" \
+            "So, I can't provide you a hint with the install procedure.\n" \
+            "There are likely missing dependencies.\n"
+
+        return self.get_install_progs(progs, None)
+
+    #
+    # Common dependencies
+    #
+    def deactivate_help(self):
+        """
+        Print a helper message to disable a virtual environment.
+        """
+
+        print("\n    If you want to exit the virtualenv, you can use:")
+        print("\tdeactivate")
+
+    def get_virtenv(self):
+        """
+        Give a hint about how to activate an already-existing virtual
+        environment containing sphinx-build.
+
+        Returns a tuble with (activate_cmd_path, sphinx_version) with
+        the newest available virtual env.
+        """
+
+        cwd = os.getcwd()
+
+        activates = []
+
+        # Add all sphinx prefixes with possible version numbers
+        for p in self.virtenv_prefix:
+            activates += glob(f"{cwd}/{p}[0-9]*/bin/activate")
+
+        activates.sort(reverse=True, key=str.lower)
+
+        # Place sphinx_latest first, if it exists
+        for p in self.virtenv_prefix:
+            activates = glob(f"{cwd}/{p}*latest/bin/activate") + activates
+
+        ver = (0, 0, 0)
+        for f in activates:
+            # Discard too old Sphinx virtual environments
+            match = re.search(r"(\d+)\.(\d+)\.(\d+)", f)
+            if match:
+                ver = (int(match.group(1)), int(match.group(2)), int(match.group(3)))
+
+                if ver < self.min_version:
+                    continue
+
+            sphinx_cmd = f.replace("activate", "sphinx-build")
+            if not os.path.isfile(sphinx_cmd):
+                continue
+
+            ver = self.get_sphinx_version(sphinx_cmd)
+
+            if not ver:
+                venv_dir = f.replace("/bin/activate", "")
+                print(f"Warning: virtual environment {venv_dir} is not working.\n" \
+                      "Python version upgrade? Remove it with:\n\n" \
+                      "\trm -rf {venv_dir}\n\n")
+            else:
+                if self.need_sphinx and ver >= self.min_version:
+                    return (f, ver)
+                elif parse_version(ver) > self.cur_version:
+                    return (f, ver)
+
+        return ("", ver)
+
+    def recommend_sphinx_upgrade(self):
+        """
+        Check if Sphinx needs to be upgraded.
+
+        Returns a tuple with the higest available Sphinx version if found.
+        Otherwise, returns None to indicate either that no upgrade is needed
+        or no venv was found.
+        """
+
+        # Avoid running sphinx-builds from venv if cur_version is good
+        if self.cur_version and self.cur_version >= RECOMMENDED_VERSION:
+            self.latest_avail_ver = self.cur_version
+            return None
+
+        # Get the highest version from sphinx_*/bin/sphinx-build and the
+        # corresponding command to activate the venv/virtenv
+        self.activate_cmd, self.venv_ver = self.get_virtenv()
+
+        # Store the highest version from Sphinx existing virtualenvs
+        if self.activate_cmd and self.venv_ver > self.cur_version:
+            self.latest_avail_ver = self.venv_ver
+        else:
+            if self.cur_version:
+                self.latest_avail_ver = self.cur_version
+            else:
+                self.latest_avail_ver = (0, 0, 0)
+
+        # As we don't know package version of Sphinx, and there's no
+        # virtual environments, don't check if upgrades are needed
+        if not self.virtualenv:
+            if not self.latest_avail_ver:
+                return None
+
+            return self.latest_avail_ver
+
+        # Either there are already a virtual env or a new one should be created
+        self.need_pip = 1
+
+        if not self.latest_avail_ver:
+            return None
+
+        # Return if the reason is due to an upgrade or not
+        if self.latest_avail_ver != (0, 0, 0):
+            if self.latest_avail_ver < RECOMMENDED_VERSION:
+                self.rec_sphinx_upgrade = 1
+
+        return self.latest_avail_ver
+
+    def recommend_package(self):
+        """
+        Recommend installing Sphinx as a distro-specific package.
+        """
+
+        print("\n2) As a package with:")
+
+        old_need = self.deps.need
+        old_optional = self.deps.optional
+
+        self.pdf = False
+        self.deps.optional = 0
+        old_verbose = self.verbose_warn_install
+        self.verbose_warn_install = 0
+
+        self.deps.clear_deps()
+
+        self.deps.add_package("python-sphinx", DepManager.PYTHON_MANDATORY)
+
+        cmd = self.get_install()
+        if cmd:
+            print(cmd)
+
+        self.deps.need = old_need
+        self.deps.optional = old_optional
+        self.verbose_warn_install = old_verbose
+
+    def recommend_sphinx_version(self, virtualenv_cmd):
+        """
+        Provide recommendations for installing or upgrading Sphinx based
+        on current version.
+
+        The logic here is complex, as it have to deal with different versions:
+
+        - minimal supported version;
+        - minimal PDF version;
+        - recommended version.
+
+        It also needs to work fine with both distro's package and
+        venv/virtualenv
+        """
+
+        if self.recommend_python:
+            print("\nPython version is incompatible with doc build.\n" \
+                  "Please upgrade it and re-run.\n")
+            return
+
+
+        # Version is OK. Nothing to do.
+        if self.cur_version != (0, 0, 0) and self.cur_version >= RECOMMENDED_VERSION:
+            return
+
+        if self.latest_avail_ver:
+            latest_avail_ver = ver_str(self.latest_avail_ver)
+
+        if not self.need_sphinx:
+            # sphinx-build is present and its version is >= $min_version
+
+            # only recommend enabling a newer virtenv version if makes sense.
+            if self.latest_avail_ver and self.latest_avail_ver > self.cur_version:
+                print(f"\nYou may also use the newer Sphinx version {latest_avail_ver} with:")
+                if f"{self.virtenv_prefix}" in os.getcwd():
+                    print("\tdeactivate")
+                print(f"\t. {self.activate_cmd}")
+                self.deactivate_help()
+                return
+
+            if self.latest_avail_ver and self.latest_avail_ver >= RECOMMENDED_VERSION:
+                return
+
+        if not self.virtualenv:
+            # No sphinx either via package or via virtenv. As we can't
+            # Compare the versions here, just return, recommending the
+            # user to install it from the package distro.
+            if not self.latest_avail_ver or self.latest_avail_ver == (0, 0, 0):
+                return
+
+            # User doesn't want a virtenv recommendation, but he already
+            # installed one via virtenv with a newer version.
+            # So, print commands to enable it
+            if self.latest_avail_ver > self.cur_version:
+                print(f"\nYou may also use the Sphinx virtualenv version {latest_avail_ver} with:")
+                if f"{self.virtenv_prefix}" in os.getcwd():
+                    print("\tdeactivate")
+                print(f"\t. {self.activate_cmd}")
+                self.deactivate_help()
+                return
+            print("\n")
+        else:
+            if self.need_sphinx:
+                self.deps.need += 1
+
+        # Suggest newer versions if current ones are too old
+        if self.latest_avail_ver and self.latest_avail_ver >= self.min_version:
+            if self.latest_avail_ver >= RECOMMENDED_VERSION:
+                print(f"\nNeed to activate Sphinx (version {latest_avail_ver}) on virtualenv with:")
+                print(f"\t. {self.activate_cmd}")
+                self.deactivate_help()
+                return
+
+            # Version is above the minimal required one, but may be
+            # below the recommended one. So, print warnings/notes
+            if self.latest_avail_ver < RECOMMENDED_VERSION:
+                print(f"Warning: It is recommended at least Sphinx version {RECOMMENDED_VERSION}.")
+
+        # At this point, either it needs Sphinx or upgrade is recommended,
+        # both via pip
+
+        if self.rec_sphinx_upgrade:
+            if not self.virtualenv:
+                print("Instead of install/upgrade Python Sphinx pkg, you could use pip/pypi with:\n\n")
+            else:
+                print("To upgrade Sphinx, use:\n\n")
+        else:
+            print("\nSphinx needs to be installed either:\n1) via pip/pypi with:\n")
+
+        if not virtualenv_cmd:
+            print("   Currently not possible.\n")
+            print("   Please upgrade Python to a newer version and run this script again")
+        else:
+            print(f"\t{virtualenv_cmd} {self.virtenv_dir}")
+            print(f"\t. {self.virtenv_dir}/bin/activate")
+            print(f"\tpip install -r {self.requirement_file}")
+            self.deactivate_help()
+
+        if self.package_supported:
+            self.recommend_package()
+
+        print("\n" \
+              "   Please note that Sphinx currentlys produce false-positive\n" \
+              "   warnings when the same name is used for more than one type (functions,\n" \
+              "   structs, enums,...). This is known Sphinx bug. For more details, see:\n" \
+              "\thttps://github.com/sphinx-doc/sphinx/pull/8313")
+
+    def check_needs(self):
+        """
+        Main method that checks needed dependencies and provides
+        recommendations.
+        """
+        self.python_cmd = sys.executable
+
+        # Check if Sphinx is already accessible from current environment
+        self.check_sphinx(self.conf)
+
+        if self.system_release:
+            print(f"Detected OS: {self.system_release}.")
+        else:
+            print("Unknown OS")
+        if self.cur_version != (0, 0, 0):
+            ver = ver_str(self.cur_version)
+            print(f"Sphinx version: {ver}\n")
+
+        # Check the type of virtual env, depending on Python version
+        virtualenv_cmd = None
+
+        if sys.version_info < MIN_PYTHON_VERSION:
+            min_ver = ver_str(MIN_PYTHON_VERSION)
+            print(f"ERROR: at least python {min_ver} is required to build the kernel docs")
+            self.need_sphinx = 1
+
+        self.venv_ver = self.recommend_sphinx_upgrade()
+
+        if self.need_pip:
+            if sys.version_info < MIN_PYTHON_VERSION:
+                self.need_pip = False
+                print("Warning: python version is not supported.")
+
+            else:
+                virtualenv_cmd = f"{self.python_cmd} -m venv"
+                self.check_python_module("ensurepip")
+
+        # Check for needed programs/tools
+        self.check_perl_module("Pod::Usage", DepManager.SYSTEM_MANDATORY)
+
+        self.check_program("make", DepManager.SYSTEM_MANDATORY)
+        self.check_program("gcc", DepManager.SYSTEM_MANDATORY)
+
+        self.check_program("dot", DepManager.SYSTEM_OPTIONAL)
+        self.check_program("convert", DepManager.SYSTEM_OPTIONAL)
+
+        self.check_python_module("yaml")
+
+        if self.pdf:
+            self.check_program("xelatex", DepManager.PDF_MANDATORY)
+            self.check_program("rsvg-convert", DepManager.PDF_MANDATORY)
+            self.check_program("latexmk", DepManager.PDF_MANDATORY)
+
+        # Do distro-specific checks and output distro-install commands
+        cmd = self.get_install()
+        if cmd:
+            print(cmd)
+
+        # If distro requires some special instructions, print here.
+        # Please notice that get_install() needs to be called first.
+        if self.distro_msg:
+            print("\n" + self.distro_msg)
+
+        if not self.python_cmd:
+            if self.need == 1:
+                sys.exit("Can't build as 1 mandatory dependency is missing")
+            elif self.need:
+                sys.exit(f"Can't build as {self.need} mandatory dependencies are missing")
+
+        # Check if sphinx-build is called sphinx-build-3
+        if self.need_symlink:
+            sphinx_path = self.which("sphinx-build-3")
+            if sphinx_path:
+                print(f"\tsudo ln -sf {sphinx_path} /usr/bin/sphinx-build\n")
+
+        self.recommend_sphinx_version(virtualenv_cmd)
+        print("")
+
+        if not self.deps.optional:
+            print("All optional dependencies are met.")
+
+        if self.deps.need == 1:
+            sys.exit("Can't build as 1 mandatory dependency is missing")
+        elif self.deps.need:
+            sys.exit(f"Can't build as {self.deps.need} mandatory dependencies are missing")
+
+        print("Needed package dependencies are met.")
+
+DESCRIPTION = """
+Process some flags related to Sphinx installation and documentation build.
+"""
+
+
+def main():
+    """Main function"""
+    parser = argparse.ArgumentParser(description=DESCRIPTION)
+
+    parser.add_argument(
+        "--no-virtualenv",
+        action="store_false",
+        dest="virtualenv",
+        help="Recommend installing Sphinx instead of using a virtualenv",
+    )
+
+    parser.add_argument(
+        "--no-pdf",
+        action="store_false",
+        dest="pdf",
+        help="Don't check for dependencies required to build PDF docs",
+    )
+
+    parser.add_argument(
+        "--version-check",
+        action="store_true",
+        dest="version_check",
+        help="If version is compatible, don't check for missing dependencies",
+    )
+
+    args = parser.parse_args()
+
+    checker = SphinxDependencyChecker(args)
+
+    checker.check_python()
+    checker.check_needs()
+
+# Call main if not used as module
+if __name__ == "__main__":
+    main()