[LTP] [PATCH v2 1/2] doc/Makefile: Allow to create and use .venv

[Petr Vorel]

This is an optional target (not run by default).
If .venv exists, it's used in other targets.

This helps to use virtualenv for development, but avoid using it by
default (readthedoc uses container with virtualenv, creating it would be
waste of time).

Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
v1: https://patchwork.ozlabs.org/project/ltp/patch/20250206143421.1571918-4-pvorel@suse.cz/

Changes v1->v2:
* virtualenv is optional
* use variables

 doc/Makefile | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/doc/Makefile b/doc/Makefile
index a07df04d5c..909d9687b8 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -5,14 +5,26 @@ top_srcdir		?= ..
 
 include $(top_srcdir)/include/mk/env_pre.mk
 
+PYTHON := python3
+VENV_DIR := .venv
+VENV_CMD := . $(VENV_DIR)/bin/activate
+RUN_VENV := if [ -d $(VENV_DIR) ]; then $(VENV_CMD); fi
+
+# install sphinx only if needed
+INSTALL_SPHINX := $(shell $(PYTHON) -c "import sphinx" 2>/dev/null && echo ":" || echo "pip install sphinx")
+
+$(VENV_DIR):
+	$(PYTHON) -m virtualenv $(VENV_DIR)
+	$(VENV_CMD) && pip install -r requirements.txt && $(INSTALL_SPHINX)
+
 ${abs_top_builddir}/metadata/ltp.json:
 	$(MAKE) -C ${abs_top_builddir}/metadata
 
 all: ${abs_top_builddir}/metadata/ltp.json
-	sphinx-build -b html . html
+	$(RUN_VENV); sphinx-build -b html . html
 
 spelling:
-	sphinx-build -b spelling -d build/doctree . build/spelling
+	$(RUN_VENV); sphinx-build -b spelling -d build/doctree . build/spelling
 
 clean:
-	rm -rf html/ build/ _static/syscalls.rst _static/tests.rst syscalls.tbl
+	rm -rf html/ build/ _static/syscalls.rst _static/tests.rst syscalls.tbl $(VENV_DIR)
-- 
2.47.2