[PATCH v7 11/13] Add dracut module helper

["'Quirin Gylstorff' via isar-users" <isar-users@googlegroups.com>]

From: Quirin Gylstorff <quirin.gylstorff@siemens.com>

This adds a helper class similar to initramfs-hook to generate a dracut
module based on dpkg-raw.

Signed-off-by: Quirin Gylstorff <quirin.gylstorff@siemens.com>
---
 meta/classes-recipe/dracut-module.bbclass     | 87 +++++++++++++++++++
 .../dracut-module/files/module-setup.sh.tmpl  | 42 +++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 meta/classes-recipe/dracut-module.bbclass
 create mode 100644 meta/recipes-initramfs/dracut-module/files/module-setup.sh.tmpl

diff --git a/meta/classes-recipe/dracut-module.bbclass b/meta/classes-recipe/dracut-module.bbclass
new file mode 100644
index 00000000..364fb5b4
--- /dev/null
+++ b/meta/classes-recipe/dracut-module.bbclass
@@ -0,0 +1,87 @@
+#
+# Copyright (c) Siemens AG, 2025
+#
+# Authors:
+#  Quirin Gylstorff <quirin.gylstorff@siemens.com>
+#
+# SPDX-License-Identifier: MIT
+#
+
+inherit dpkg-raw
+
+FILESPATH:append = ":${LAYERDIR_core}/recipes-initramfs/dracut-module/files"
+
+DPKG_ARCH = "all"
+
+DRACUT_MODULE_SETUP = "module-setup.sh"
+SRC_URI:append = "file://${DRACUT_MODULE_SETUP}.tmpl"
+
+DRACUT_MODULE_NO ??= "50"
+DRACUT_MODULE_NAME ?= "${@ d.getVar('PN')[7:] if d.getVar('PN').startswith('dracut-') else d.getVAR('PN')}"
+
+DEBIAN_DEPENDS = "dracut-core"
+DRACUT_MODULE_PATH = "${D}/usr/lib/dracut/modules.d/${DRACUT_MODULE_NO}${DRACUT_MODULE_NAME}/"
+
+DRACUT_REQUIRED_BINARIES ??= ""
+DRACUT_MODULE_DEPENDENCIES ??= ""
+DRACUT_CHECK_CONTENT_FILE_NAME ??= ""
+DRACUT_DEPENDS_CONTENT_FILE_NAME ??= ""
+DRACUT_CMDLINE_CONTENT_FILE_NAME ??= ""
+DRACUT_INSTALL_CONTENT_FILE_NAME ??= ""
+DRACUT_INSTALLKERNEL_CONTENT_FILE_NAME ??= ""
+
+def add_file_if_variable_is_set(d, variable_name, prefix):
+    variable = d.getVar(variable_name) or ''
+    if variable:
+        return f"{prefix}{variable}"
+    return ''
+
+def replace_marker_with_file_content(template_file, content_file, marker):
+    with open(template_file, 'r') as template_fd:
+        tmpl_content = template_fd.read()
+
+    with open(content_file, 'r') as content_fd:
+        content = content_fd.read()
+
+    new_tpml_content = tmpl_content.replace(marker, content)
+    with open(template_file, 'w') as tmpl_fd:
+        tmpl_fd.write(new_tpml_content)
+
+SRC_URI:append = " ${@ add_file_if_variable_is_set(d, 'DRACUT_CHECK_CONTENT_FILE_NAME', 'file://')} \
+            ${@ add_file_if_variable_is_set(d, 'DRACUT_DEPENDS_CONTENT_FILE_NAME', 'file://')} \
+            ${@ add_file_if_variable_is_set(d, 'DRACUT_CMDLINE_CONTENT_FILE_NAME', 'file://')} \
+            ${@ add_file_if_variable_is_set(d, 'DRACUT_INSTALL_CONTENT_FILE_NAME', 'file://')} \
+            ${@ add_file_if_variable_is_set(d, 'DRACUT_INSTALLKERNEL_CONTENT_FILE_NAME', 'file://')}"
+
+TEMPLATE_FILES:append = " \
+    ${DRACUT_MODULE_SETUP}.tmpl \
+    "
+
+TEMPLATE_VARS:append = " \
+    DRACUT_REQUIRED_BINARIES \
+    DRACUT_MODULE_DEPENDENCIES \
+    "
+python do_add_additional_dracut_configuration() {
+    workdir = os.path.normpath(d.getVar('WORKDIR'))
+    module_setup = d.getVar('DRACUT_MODULE_SETUP')
+    module_setup_tpml = f"{module_setup}.tmpl"
+    content_file_name_to_marker = {
+        "DRACUT_CHECK_CONTENT_FILE_NAME" : "# ISAR_DRACUT_CHECK",
+        "DRACUT_DEPENDS_CONTENT_FILE_NAME" : "# ISAR_DRACUT_DEPENDS",
+        "DRACUT_CMDLINE_CONTENT_FILE_NAME" : "# ISAR_DRACUT_CMDLINE",
+        "DRACUT_INSTALL_CONTENT_FILE_NAME" : "# ISAR_DRACUT_INSTALL",
+        "DRACUT_INSTALLKERNEL_CONTENT_FILE_NAME" : "# ISAR_DRACUT_KERNELINSTALL"
+    }
+
+    for var_name, marker in content_file_name_to_marker.items():
+        file_name = d.getVar(var_name) or ''
+        if file_name:
+            replace_marker_with_file_content(f"{workdir}/{module_setup_tpml}",
+                f"{workdir}/{file_name}", marker)
+}
+addtask add_additional_dracut_configuration before do_transform_template after do_patch
+
+do_install[cleandirs] += "${DRACUT_MODULE_PATH}"
+do_install:append() {
+    install -m 770 ${WORKDIR}/${DRACUT_MODULE_SETUP} ${DRACUT_MODULE_PATH}
+}
diff --git a/meta/recipes-initramfs/dracut-module/files/module-setup.sh.tmpl b/meta/recipes-initramfs/dracut-module/files/module-setup.sh.tmpl
new file mode 100644
index 00000000..be0f4c54
--- /dev/null
+++ b/meta/recipes-initramfs/dracut-module/files/module-setup.sh.tmpl
@@ -0,0 +1,42 @@
+#!/bin/bash
+
+# called by dracut
+check() {
+
+    # If the binary(s) requirements are not fulfilled the module can't be installed.
+    require_binaries \
+        ${DRACUT_REQUIRED_BINARIES} \
+        || return 1
+    # ISAR_DRACUT_CHECK
+    return 0
+
+}
+
+# Module dependency requirements.
+depends() {
+    echo "${DRACUT_MODULE_DEPENDENCIES}"
+    # ISAR_DRACUT_DEPENDS
+    return 0
+
+}
+installkernel() {
+    # ISAR_DRACUT_KERNELINSTALL
+    return 0
+}
+
+cmdline() {
+    # ISAR_DRACUT_CMDLINE
+    return 0
+}
+
+install() {
+    for executable in ${DRACUT_REQUIRED_BINARIES}; do
+        if exec_path=$(command -v $executable 2>/dev/null); then
+            inst_binary "$exec_path"
+        else
+            echo "(ERROR): Unable to copy $executable" >&2
+            exit 1
+        fi
+    done
+    # ISAR_DRACUT_INSTALL
+}
-- 
2.51.0

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