Re: [PATCH v4 1/7] initramfs-hook: Add infrastructure to ease writing hooks

["'Jan Kiszka' via isar-users" <isar-users@googlegroups.com>]

On 16.11.24 12:12, 'Jan Kiszka' via isar-users wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> This recipe include shall simplify writing of initramfs hooks. It
> provides the usual headers for the installation hook as well as the boot
> scripts, allow to generate that code that installs executables and
> modules into the image, but also supports expanding the scripts with own
> snippets.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  .../initramfs-hook/files/hook-header.tmpl     | 39 ++++++++++
>  .../initramfs-hook/files/script-header.tmpl   | 26 +++++++
>  .../recipes-initramfs/initramfs-hook/hook.inc | 76 +++++++++++++++++++
>  3 files changed, 141 insertions(+)
>  create mode 100644 meta/recipes-initramfs/initramfs-hook/files/hook-header.tmpl
>  create mode 100644 meta/recipes-initramfs/initramfs-hook/files/script-header.tmpl
>  create mode 100644 meta/recipes-initramfs/initramfs-hook/hook.inc
> 
> diff --git a/meta/recipes-initramfs/initramfs-hook/files/hook-header.tmpl b/meta/recipes-initramfs/initramfs-hook/files/hook-header.tmpl
> new file mode 100644
> index 00000000..ee30d691
> --- /dev/null
> +++ b/meta/recipes-initramfs/initramfs-hook/files/hook-header.tmpl
> @@ -0,0 +1,39 @@
> +#!/bin/sh
> +#
> +# Copyright (c) Siemens AG, 2024
> +#
> +# Authors:
> +#  Jan Kiszka <jan.kiszka@siemens.com>
> +#
> +# SPDX-License-Identifier: MIT
> +#
> +
> +set -e
> +
> +prereqs()
> +{
> +	echo "${HOOK_PREREQ}"
> +}
> +
> +case $1 in
> +prereqs)
> +	prereqs
> +	exit 0
> +	;;
> +esac
> +
> +. /usr/share/initramfs-tools/hook-functions
> +
> +for module in ${HOOK_ADD_MODULES}; do
> +	manual_add_modules $module
> +done
> +
> +for executable in ${HOOK_COPY_EXECS}; do
> +	if exec_path=$(command -v $executable 2>/dev/null); then
> +		copy_exec "$exec_path"
> +	else
> +		echo "(ERROR): Unable to copy $executable" >&2
> +		exit 1
> +	fi
> +done
> +
> diff --git a/meta/recipes-initramfs/initramfs-hook/files/script-header.tmpl b/meta/recipes-initramfs/initramfs-hook/files/script-header.tmpl
> new file mode 100644
> index 00000000..faa1a644
> --- /dev/null
> +++ b/meta/recipes-initramfs/initramfs-hook/files/script-header.tmpl
> @@ -0,0 +1,26 @@
> +#!/bin/sh
> +#
> +# Copyright (c) Siemens AG, 2024
> +#
> +# Authors:
> +#  Jan Kiszka <jan.kiszka@siemens.com>
> +#
> +# SPDX-License-Identifier: MIT
> +#
> +
> +set -e
> +
> +prereqs()
> +{
> +	echo "${SCRIPT_PREREQ}"
> +}
> +
> +case $1 in
> +prereqs)
> +	prereqs
> +	exit 0
> +	;;
> +esac
> +
> +. /scripts/functions
> +
> diff --git a/meta/recipes-initramfs/initramfs-hook/hook.inc b/meta/recipes-initramfs/initramfs-hook/hook.inc
> new file mode 100644
> index 00000000..b0e7c66c
> --- /dev/null
> +++ b/meta/recipes-initramfs/initramfs-hook/hook.inc
> @@ -0,0 +1,76 @@
> +#
> +# Copyright (c) Siemens AG, 2024
> +#
> +# Authors:
> +#  Jan Kiszka <jan.kiszka@siemens.com>
> +#
> +# SPDX-License-Identifier: MIT
> +#
> +
> +FILESPATH:append := ":${FILE_DIRNAME}/files"
> +
> +inherit dpkg-raw
> +
> +SRC_URI = " \
> +    file://hook-header.tmpl \
> +    file://script-header.tmpl"
> +
> +TEMPLATE_FILES = " \
> +    hook-header.tmpl \
> +    script-header.tmpl"
> +
> +TEMPLATE_VARS:append = " \
> +    HOOK_PREREQ \
> +    HOOK_ADD_MODULES \
> +    HOOK_COPY_EXECS \
> +    SCRIPT_PREREQ"
> +
> +HOOK_PREREQ ?= ""
> +HOOK_ADD_MODULES ?= ""
> +HOOK_COPY_EXECS ?= ""
> +SCRIPT_PREREQ ?= ""
> +
> +DEBIAN_DEPENDS = "initramfs-tools"
> +
> +def get_initramfs_hook_name(d):
> +    name = d.getVar('BPN')
> +    if name.startswith("initramfs-"):
> +        name = name[10:]
> +    if name.endswith("-hook"):
> +        name = name[:-5]
> +    return name
> +
> +INITRAMFS_HOOK_NAME ?= "${@get_initramfs_hook_name(d)}"
> +
> +do_install() {
> +	if [ -f "${WORKDIR}/hook" ] || [ -n "${HOOK_COPY_EXECS}" ] || \
> +	   [ -n "${HOOK_ADD_MODULES}" ]; then
> +		rm -rf "${D}/usr/share/initramfs-tools/hooks"
> +		install -d -m 0755 "${D}/usr/share/initramfs-tools/hooks"
> +
> +		install -m 0755 "${WORKDIR}/hook-header" \
> +			"${D}/usr/share/initramfs-tools/hooks/${INITRAMFS_HOOK_NAME}"
> +		if [ -f "${WORKDIR}/hook" ]; then
> +			cat "${WORKDIR}/hook" >> \
> +			    "${D}/usr/share/initramfs-tools/hooks/${INITRAMFS_HOOK_NAME}"
> +		else
> +			echo "exit 0" >> \
> +			    "${D}/usr/share/initramfs-tools/hooks/${INITRAMFS_HOOK_NAME}"
> +		fi
> +	fi
> +
> +	for script in init-top init-premount local-top nfs-top local-block \
> +		      local-premount nfs-premount local-bottom nfs-bottom \
> +		      init-bottom; do
> +		if [ ! -f "${WORKDIR}/$script" ]; then
> +			continue
> +		fi
> +
> +		rm -rf "${D}/usr/share/initramfs-tools/scripts/$script"
> +		install -d -m 0755 "${D}/usr/share/initramfs-tools/scripts/$script"
> +		install -m 0755 "${WORKDIR}/script-header" \
> +			"${D}/usr/share/initramfs-tools/scripts/$script/${INITRAMFS_HOOK_NAME}"
> +		cat "${WORKDIR}/$script" >> \
> +		    "${D}/usr/share/initramfs-tools/scripts/$script/${INITRAMFS_HOOK_NAME}"
> +	done
> +}

OK, will need v5: Unconditionally adding a script header is too
inflexible. There are cases where the users are better of providing a
complete script themselves, e.g. when the PREREQ are function-generated
or when there are multiple boot scripts at multiple stages in the same
recipe with different PREREQs. We need an opt-out.

Jan

-- 
Siemens AG, Technology
Linux Expert Center

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