tools/docs: sphinx-build-wrapper: add a wrapper for sphinx-build

There are too much magic inside docs Makefile to properly run
sphinx-build. Create an ancillary script that contains all
kernel-related sphinx-build call logic currently at Makefile.

Such script is designed to work both as an standalone command
and as part of a Makefile. As such, it properly handles POSIX
jobserver used by GNU make.

On a side note, there was a line number increase due to the
conversion (ignoring comments) is:

 Documentation/Makefile          |  131 +++----------
 tools/docs/sphinx-build-wrapper |  293 +++++++++++++++++++++++++++++++
 2 files changed, 323 insertions(+), 101 deletions(-)

Comments and descriptions adds:
 tools/docs/sphinx-build-wrapper | 261 +++++++++++++++++++++++++++++++-

So, about half of the script are comments/descriptions.

This is because some things are more verbosed on Python and because
it requires reading env vars from Makefile. Besides it, this script
has some extra features that don't exist at the Makefile:

- It can be called directly from command line;
- It properly return PDF build errors.

When running the script alone, it will only take handle sphinx-build
targets. On other words, it won't runn make rustdoc after building
htmlfiles, nor it will run the extra check scripts.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Message-ID: <80ae57b01fcfb1d338d93b8f8e26e57b69b5f16b.1758196090.git.mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 29 insertions, 102 deletions

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 0e8698fa52ef..9ec96ccb3495 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -23,21 +23,22 @@ SPHINXOPTS    =
 SPHINXDIRS    = .
 DOCS_THEME    =
 DOCS_CSS      =
-_SPHINXDIRS   = $(sort $(patsubst $(srctree)/Documentation/%/index.rst,%,$(wildcard $(srctree)/Documentation/*/index.rst)))
 SPHINX_CONF   = conf.py
 PAPER         =
 BUILDDIR      = $(obj)/output
 PDFLATEX      = xelatex
 LATEXOPTS     = -interaction=batchmode -no-shell-escape
 
+PYTHONPYCACHEPREFIX ?= $(abspath $(BUILDDIR)/__pycache__)
+
+# Wrapper for sphinx-build
+
+BUILD_WRAPPER = $(srctree)/tools/docs/sphinx-build-wrapper
+
 # For denylisting "variable font" files
 # Can be overridden by setting as an env variable
 FONTS_CONF_DENY_VF ?= $(HOME)/deny-vf
 
-ifeq ($(findstring 1, $(KBUILD_VERBOSE)),)
-SPHINXOPTS    += "-q"
-endif
-
 # User-friendly check for sphinx-build
 HAVE_SPHINX := $(shell if which $(SPHINXBUILD) >/dev/null 2>&1; then echo 1; else echo 0; fi)
 
@@ -51,66 +52,32 @@ ifeq ($(HAVE_SPHINX),0)
 
 else # HAVE_SPHINX
 
-# User-friendly check for pdflatex and latexmk
-HAVE_PDFLATEX := $(shell if which $(PDFLATEX) >/dev/null 2>&1; then echo 1; else echo 0; fi)
-HAVE_LATEXMK := $(shell if which latexmk >/dev/null 2>&1; then echo 1; else echo 0; fi)
-
-ifeq ($(HAVE_LATEXMK),1)
-	PDFLATEX := latexmk -$(PDFLATEX)
-endif #HAVE_LATEXMK
+# Common documentation targets
+infodocs texinfodocs latexdocs epubdocs xmldocs pdfdocs linkcheckdocs:
+	$(Q)@$(srctree)/tools/docs/sphinx-pre-install --version-check
+	+$(Q)$(PYTHON3) $(BUILD_WRAPPER) $@ \
+		--sphinxdirs="$(SPHINXDIRS)" --conf="$(SPHINX_CONF)" \
+		--builddir="$(BUILDDIR)" --deny-vf=$(FONTS_CONF_DENY_VF) \
+		--theme=$(DOCS_THEME) --css=$(DOCS_CSS) --paper=$(PAPER)
 
-# Internal variables.
-PAPEROPT_a4     = -D latex_elements.papersize=a4paper
-PAPEROPT_letter = -D latex_elements.papersize=letterpaper
-ALLSPHINXOPTS   = -D kerneldoc_srctree=$(srctree) -D kerneldoc_bin=$(KERNELDOC)
-ALLSPHINXOPTS   += $(PAPEROPT_$(PAPER)) $(SPHINXOPTS)
-ifneq ($(wildcard $(srctree)/.config),)
-ifeq ($(CONFIG_RUST),y)
-	# Let Sphinx know we will include rustdoc
-	ALLSPHINXOPTS   +=  -t rustdoc
-endif
+# Special handling for pdfdocs
+ifneq ($(shell which $(PDFLATEX) >/dev/null 2>&1; echo $$?),0)
+pdfdocs:
+	$(warning The '$(PDFLATEX)' command was not found. Make sure you have it installed and in PATH to produce PDF output.)
+	@echo "  SKIP    Sphinx $@ target."
 endif
-# the i18n builder cannot share the environment and doctrees with the others
-I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
-
-# commands; the 'cmd' from scripts/Kbuild.include is not *loopable*
-loop_cmd = $(echo-cmd) $(cmd_$(1)) || exit;
-
-# $2 sphinx builder e.g. "html"
-# $3 name of the build subfolder / e.g. "userspace-api/media", used as:
-#    * dest folder relative to $(BUILDDIR) and
-#    * cache folder relative to $(BUILDDIR)/.doctrees
-# $4 dest subfolder e.g. "man" for man pages at userspace-api/media/man
-# $5 reST source folder relative to $(src),
-#    e.g. "userspace-api/media" for the linux-tv book-set at ./Documentation/userspace-api/media
-
-PYTHONPYCACHEPREFIX ?= $(abspath $(BUILDDIR)/__pycache__)
-
-quiet_cmd_sphinx = SPHINX  $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
-      cmd_sphinx = \
-	PYTHONPYCACHEPREFIX="$(PYTHONPYCACHEPREFIX)" \
-	BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(src)/$5/$(SPHINX_CONF)) \
-	$(PYTHON3) $(srctree)/scripts/jobserver-exec \
-	$(CONFIG_SHELL) $(srctree)/Documentation/sphinx/parallel-wrapper.sh \
-	$(SPHINXBUILD) \
-	-b $2 \
-	-c $(abspath $(src)) \
-	-d $(abspath $(BUILDDIR)/.doctrees/$3) \
-	-D version=$(KERNELVERSION) -D release=$(KERNELRELEASE) \
-	$(ALLSPHINXOPTS) \
-	$(abspath $(src)/$5) \
-	$(abspath $(BUILDDIR)/$3/$4) && \
-	if [ "x$(DOCS_CSS)" != "x" ]; then \
-		cp $(if $(patsubst /%,,$(DOCS_CSS)),$(abspath $(srctree)/$(DOCS_CSS)),$(DOCS_CSS)) $(BUILDDIR)/$3/_static/; \
-	fi
-
-htmldocs:
-	@$(srctree)/tools/docs/sphinx-pre-install --version-check
-	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var)))
 
 htmldocs-redirects: $(srctree)/Documentation/.renames.txt
 	@tools/docs/gen-redirects.py --output $(BUILDDIR) < $<
 
+# HTML main logic is identical to other targets. However, if rust is enabled,
+# an extra step at the end is required to generate rustdoc.
+htmldocs:
+	$(Q)@$(srctree)/tools/docs/sphinx-pre-install --version-check
+	+$(Q)$(PYTHON3) $(BUILD_WRAPPER) $@ \
+		--sphinxdirs="$(SPHINXDIRS)" --conf="$(SPHINX_CONF)" \
+		--builddir="$(BUILDDIR)" \
+		--theme=$(DOCS_THEME) --css=$(DOCS_CSS) --paper=$(PAPER)
 # If Rust support is available and .config exists, add rustdoc generated contents.
 # If there are any, the errors from this make rustdoc will be displayed but
 # won't stop the execution of htmldocs
@@ -121,49 +88,6 @@ ifeq ($(CONFIG_RUST),y)
 endif
 endif
 
-texinfodocs:
-	@$(srctree)/tools/docs/sphinx-pre-install --version-check
-	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,texinfo,$(var),texinfo,$(var)))
-
-# Note: the 'info' Make target is generated by sphinx itself when
-# running the texinfodocs target define above.
-infodocs: texinfodocs
-	$(MAKE) -C $(BUILDDIR)/texinfo info
-
-linkcheckdocs:
-	@$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var)))
-
-latexdocs:
-	@$(srctree)/tools/docs/sphinx-pre-install --version-check
-	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,latex,$(var),latex,$(var)))
-
-ifeq ($(HAVE_PDFLATEX),0)
-
-pdfdocs:
-	$(warning The '$(PDFLATEX)' command was not found. Make sure you have it installed and in PATH to produce PDF output.)
-	@echo "  SKIP    Sphinx $@ target."
-
-else # HAVE_PDFLATEX
-
-pdfdocs: DENY_VF = XDG_CONFIG_HOME=$(FONTS_CONF_DENY_VF)
-pdfdocs: latexdocs
-	@$(srctree)/tools/docs/sphinx-pre-install --version-check
-	$(foreach var,$(SPHINXDIRS), \
-	   $(MAKE) PDFLATEX="$(PDFLATEX)" LATEXOPTS="$(LATEXOPTS)" $(DENY_VF) -C $(BUILDDIR)/$(var)/latex || $(PYTHON3) $(srctree)/tools/docs/check-variable-fonts.py || exit; \
-	   mkdir -p $(BUILDDIR)/$(var)/pdf; \
-	   mv $(subst .tex,.pdf,$(wildcard $(BUILDDIR)/$(var)/latex/*.tex)) $(BUILDDIR)/$(var)/pdf/; \
-	)
-
-endif # HAVE_PDFLATEX
-
-epubdocs:
-	@$(srctree)/tools/docs/sphinx-pre-install --version-check
-	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,epub,$(var),epub,$(var)))
-
-xmldocs:
-	@$(srctree)/tools/docs/sphinx-pre-install --version-check
-	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,xml,$(var),xml,$(var)))
-
 endif # HAVE_SPHINX
 
 # The following targets are independent of HAVE_SPHINX, and the rules should
@@ -175,6 +99,9 @@ refcheckdocs:
 cleandocs:
 	$(Q)rm -rf $(BUILDDIR)
 
+# Used only on help
+_SPHINXDIRS   = $(sort $(patsubst $(srctree)/Documentation/%/index.rst,%,$(wildcard $(srctree)/Documentation/*/index.rst)))
+
 dochelp:
 	@echo  ' Linux kernel internal documentation in different formats from ReST:'
 	@echo  '  htmldocs        - HTML'