nginx-module.eclass: Add NGINX_MOD_CONFIG_DIR, fixup www-nginx/ngx-naxsi

This might be useful for packages having "config" in a non-root
directory. For example, imagine the following directory tree for some
NGINX module:

+--nginx/
|  +--config
|  +--ngx_module.c
|
+--lib/
|  +--defective.c
|
+--README.md

In case defective.c needs to be patched, we need to know both the path
to the config file and the root directory of the module. Without this
patch, we only know the path to config, making it very hard to patch
defective.c

This commit introduces a new variable NGINX_MOD_CONFIG_DIR specifying
the subdirectory of NGINX_MOD_S containing the config script.
NGINX_MOD_S semantics change to "the root directory of the module
sources".

www-nginx/ngx-naxsi was a special case because it is the only module
actually having the config script in a subdirectory of NGINX_MOD_S. This
commit edits its patch and ebuild accordingly.

Signed-off-by: Zurab Kvachadze <zurabid2016@gmail.com>
Part-of: https://github.com/gentoo/gentoo/pull/44576
Signed-off-by: Sam James <sam@gentoo.org>

eclass/nginx-module.eclass

@@ -353,11 +353,21 @@ ngx_mod_link_module() {
 
 # @ECLASS_VARIABLE: NGINX_MOD_S
 # @DESCRIPTION:
-# Holds the path to the module sources directory, used in the
-# nginx-module_src_configure() phase function.  If unset at the time of inherit,
-# defaults to ${S}.
+# Holds the path to the module source directory, used in various phase
+# functions.  If unset at the time of inherit, defaults to ${S}.
 : "${NGINX_MOD_S=${S}}"
 
+# @ECLASS_VARIABLE: NGINX_MOD_CONFIG_DIR
+# @DESCRIPTION:
+# Holds the path of the directory containing the config script relative to the
+# module source directory specified by the ${NGINX_MOD_S} variable.  If unset at
+# the time of inherit, defaults to "" (an empty string, meaning the config
+# script is located at the root of the module source directory).
+#
+# For example, in www-nginx/njs, NGINX_MOD_S="${WORKDIR}/${P}" and
+# NGINX_MOD_CONFIG_DIR="nginx".
+: "${NGINX_MOD_CONFIG_DIR=""}"
+
 # The ${S} variable is set to the path of the directory where the actual build
 # will be performed. In this directory, symbolic links to NGINX's build system
 # and NGINX's headers are created by the nginx-module_src_unpack() phase
@@ -583,7 +593,8 @@ nginx-module_src_unpack() {
 # Then, default_src_prepare() is called.
 nginx-module_src_prepare() {
 	debug-print-function "${FUNCNAME[0]}" "$@"
-	pushd "${NGINX_MOD_S}" >/dev/null || die "pushd failed"
+	pushd "${NGINX_MOD_S}/${NGINX_MOD_CONFIG_DIR}" >/dev/null ||
+		die "pushd failed"
 	# Since NGINX does not guarantee ABI or API stability, we utilise
 	# preprocessor macros that were used to compile NGINX itself, to build third
 	# party modules. As such, we do not want for the dummy preprocessor macros
@@ -610,8 +621,13 @@ nginx-module_src_prepare() {
 		die "sed failed"
 	echo 'mv build/ngx_auto_config.h build/__ngx_gentoo_mod_config.h' \
 		>> config || die "echo failed"
+
+	# cd into module root and apply patches.
+	pushd "${NGINX_MOD_S}" >/dev/null || die "pushd failed"
 	default_src_prepare
 	popd >/dev/null || die "popd failed"
+
+	popd >/dev/null || die "popd failed"
 }
 
 # @FUNCTION: nginx-module_src_configure
@@ -637,7 +653,7 @@ nginx-module_src_configure() {
 		--with-cc-opt="-isystem src/modules"
 		--with-ld-opt="${LDFLAGS}"
 		--builddir=build
-		--add-dynamic-module="${NGINX_MOD_S}"
+		--add-dynamic-module="${NGINX_MOD_S}/${NGINX_MOD_CONFIG_DIR}"
 	)
 
 	# NGINX build system adds directories under src/ to the include path based

www-nginx/ngx-naxsi/files/ngx-naxsi-1.7-use-ngx_module_libs.patch

@@ -14,8 +14,8 @@ Signed-off-by: Zurab Kvachadze <zurabid2016@gmail.com>
 
 diff --git a/naxsi_src/config b/naxsi_src/config
 index 0b8d438..cd27c20 100644
---- a/config
-+++ b/config
+--- a/naxsi_src/config
++++ b/naxsi_src/config
 @@ -49,7 +49,7 @@ if [ "$LIBINJECTION_FOUND" != "0" ]; then
  else
      echo "Using system libinjection"

www-nginx/ngx-naxsi/ngx-naxsi-1.7-r1.ebuild

@@ -4,7 +4,8 @@
 EAPI=8
 
 MY_PN="naxsi"
-NGINX_MOD_S="${WORKDIR}/${MY_PN}-${PV}/naxsi_src"
+NGINX_MOD_S="${WORKDIR}/${MY_PN}-${PV}"
+NGINX_MOD_CONFIG_DIR="naxsi_src"
 
 inherit nginx-module
 
@@ -31,7 +32,7 @@ PATCHES=(
 src_install() {
 	nginx-module_src_install
 	insinto /etc/nginx/naxsi
-	doins -r "${NGINX_MOD_S}"/../naxsi_rules/*
+	doins -r "${NGINX_MOD_S}"/naxsi_rules/*
 	docompress -x "/usr/share/doc/${PF}"
-	dodoc -r "${NGINX_MOD_S}"/../docs/*
+	dodoc -r "${NGINX_MOD_S}"/docs/*
 }