From 58d9422afe0191276109e2ecaeaec721d8816a88 Mon Sep 17 00:00:00 2001
From: Sam Thursfield <sam.thursfield@codethink.co.uk>
Date: Wed, 8 Nov 2017 17:52:41 +0000
Subject: Add support for building an initramfs

The scripts are taken from
https://gitlab.com/BuildStream/buildstream-tests (branch build-gnome).

Those in turn were taken from
http://git.baserock.org/baserock/baserock/initramfs-scripts.git

We manually set the executable permissions in the init scripts
using chmod, because
https://gitlab.com/BuildStream/buildstream/issues/84
---
 elements/initramfs/initramfs-gz.bst      |  26 ++++++
 elements/initramfs/initramfs-scripts.bst |   6 ++
 elements/initramfs/initramfs.bst         |  12 +++
 files/initramfs-scripts/init             | 132 +++++++++++++++++++++++++++++++
 files/initramfs-scripts/shutdown         |  67 ++++++++++++++++
 5 files changed, 243 insertions(+)
 create mode 100644 elements/initramfs/initramfs-gz.bst
 create mode 100644 elements/initramfs/initramfs-scripts.bst
 create mode 100644 elements/initramfs/initramfs.bst
 create mode 100644 files/initramfs-scripts/init
 create mode 100644 files/initramfs-scripts/shutdown

diff --git a/elements/initramfs/initramfs-gz.bst b/elements/initramfs/initramfs-gz.bst
new file mode 100644
index 00000000..383e9603
--- /dev/null
+++ b/elements/initramfs/initramfs-gz.bst
@@ -0,0 +1,26 @@
+kind: script
+description: The compressed initramfs
+
+depends:
+- filename: initramfs/initramfs.bst
+  type: build
+- filename: gnu-toolchain.bst
+  type: build
+
+variables:
+  cwd: "%{build-root}"
+
+config:
+  layout:
+  - element: gnu-toolchain.bst
+    destination: /
+  - element: initramfs/initramfs.bst
+    destination: "%{build-root}"
+
+  commands:
+  - mkdir -p %{install-root}/boot
+  # We need to ensure exec permissions here.
+  # See: https://gitlab.com/BuildStream/buildstream/issues/84
+  - chmod +x ./sbin/init ./sbin/shutdown
+  - (find . -print0 | cpio -0 -H newc -o) |
+    gzip -c > %{install-root}/boot/initramfs.gz
diff --git a/elements/initramfs/initramfs-scripts.bst b/elements/initramfs/initramfs-scripts.bst
new file mode 100644
index 00000000..536a3302
--- /dev/null
+++ b/elements/initramfs/initramfs-scripts.bst
@@ -0,0 +1,6 @@
+kind: import
+
+sources:
+- kind: local
+  path: files/initramfs-scripts
+  directory: /sbin
diff --git a/elements/initramfs/initramfs.bst b/elements/initramfs/initramfs.bst
new file mode 100644
index 00000000..15ef4c0d
--- /dev/null
+++ b/elements/initramfs/initramfs.bst
@@ -0,0 +1,12 @@
+kind: compose
+description: Initramfs composition
+
+depends:
+- filename: gnu-toolchain.bst
+  type: build
+- filename: initramfs/initramfs-scripts.bst
+  type: build
+
+config:
+  include:
+  - runtime
diff --git a/files/initramfs-scripts/init b/files/initramfs-scripts/init
new file mode 100644
index 00000000..d1d1042b
--- /dev/null
+++ b/files/initramfs-scripts/init
@@ -0,0 +1,132 @@
+#!/bin/sh
+trap 'exec /bin/sh' INT EXIT
+
+# We need proc for reading the kernel command line
+mount -n -t proc none /proc
+
+set -- $(cat /proc/cmdline)
+
+# We don't want to leave mount points around
+umount /proc
+
+rootwait=true # defaults to off in the kernel, I think it's more useful on
+for arg; do
+    case "$arg" in
+    root=LABEL=*)
+        if [ x"$root_type" != x ]; then
+            echo "Warning, multiple root= specified, using latest."
+        fi
+        root_type=label
+        root="${arg#root=LABEL=}"
+        ;;
+    root=UUID=*)
+        if [ x"$root_type" != x ]; then
+            echo "Warning, multiple root= specified, using latest."
+        fi
+        root_type=uuid
+        root="${arg#root=UUID=}"
+        ;;
+    root=*)
+        if [ x"$root_type" != x ]; then
+            echo "Warning, multiple root= specified, using latest."
+        fi
+        root_type=disk
+        root="${arg#root=}"
+        ;;
+    rootflags=*)
+        if [ x"$rootflags" != x ]; then
+            echo "Warning, multiple rootflags= specified, using latest."
+        fi
+        rootflags=",${arg#rootflags=}"
+        ;;
+    rootfstype=*)
+        if [ x"$rootfstype" != x ]; then
+            echo "Warning, multiple rootfstype= specified, using latest."
+        fi
+        rootfstype="${arg#rootfstype=}"
+        ;;
+    rootdelay=*)
+        if [ x"$rootdelay" != x ]; then
+            echo "Warning, multiple rootdelay= specified, using latest."
+        fi
+        rootdelay="${arg#rootdelay=}"
+        ;;
+    rootwait)
+        rootwait=true
+        ;;
+    norootwait)
+        rootwait=false
+        ;;
+    ro)
+        ro=ro
+        ;;
+    rw)
+        ro=rw
+        ;;
+    init=*)
+        init="${arg#init=}"
+        ;;
+    esac
+done
+
+
+if [ x"$rootdelay" != x ]; then
+    sleep "$rootdelay"
+fi
+
+if [ x"$rootfstype" = x ]; then
+    # Warn that busybox may not be able to auto-detect rootfs type
+    cat <<\EOF
+Warning, rootfs type not specified, auto-detection of type is slow and
+may fail. Please add rootfstype=$type to kernel command line.
+EOF
+fi
+
+mount -n -t devtmpfs devtmpfs /dev
+
+while true; do
+    case "$root_type" in
+    disk)
+        if mount -n -t "${rootfstype}" -o "${ro-rw}""$rootflags" "$root" /mnt; then
+            break
+        else
+            echo disk $root not found
+            blkid
+        fi
+        ;;
+    label)
+        disk="$(findfs LABEL="$root")"
+        if [ x"$disk" = x ]; then
+            echo disk with label $root not found
+            blkid
+        else
+            mount -n -t "${rootfstype}" -o "${ro-rw}""$rootflags" "$disk" /mnt && break
+        fi
+        ;;
+    uuid)
+        disk="$(findfs UUID="$root")"
+        if [ x"$disk" = x ]; then
+            echo disk with UUID $root not found
+            blkid
+        else
+            mount -n -t "${rootfstype}" -o "${ro-rw}""$rootflags" "$disk" /mnt && break
+        fi
+        ;;
+    '')
+        echo "Error, no root specified"
+        exit 1
+        ;;
+    esac
+    if "$rootwait"; then
+        echo Trying again in 0.5 seconds
+        sleep 0.5
+    fi
+done
+umount -n /dev
+
+# We dont create any static device nodes while building,
+# device nodes will be created by systemd but before that
+# we at least need the console
+mknod -m 0600 /mnt/dev/console c 5 1
+
+exec switch_root -c /dev/console /mnt "${init-/sbin/init}"
diff --git a/files/initramfs-scripts/shutdown b/files/initramfs-scripts/shutdown
new file mode 100644
index 00000000..0065bcc8
--- /dev/null
+++ b/files/initramfs-scripts/shutdown
@@ -0,0 +1,67 @@
+#!/bin/sh
+
+fail(){
+    echo "$@" >&2
+    # The behaviour on failure of systemd when shutting down without a
+    # shutdownramfs is to freeze if it fails, but the behaviour of an initramfs
+    # on failure is to drop you into a recovery shell. The latter seems more
+    # useful.
+    exec /bin/sh
+}
+
+startswith(){
+    # Filter out lines that don't start with $1
+    # grep ^EXPR is usually sufficient, but would require escaping of EXPR.
+    # Instead this compares the line to the line with its prefix stripped,
+    # so if the line is different, then it started with that prefix.
+    # It's ugly, but is less logic than escaping the regular expression and
+    # using grep, more reliable than not making any effort to escape, and
+    # less surprising than requiring the parameter to be pre-escaped.
+    while read -r line; do
+        if [ "${line#"$1"}" != "$line" ]; then
+            printf '%s\n' "$line"
+        fi
+    done
+}
+
+recursive_umount(){
+    # Recursively unmount every mountpoint under $1.
+    # This works by filtering to select mountpoints from mountinfo that start
+    # with the absolute path of the directory given.
+    # It unmounts in reverse-order, so that it may unmount dependent mounts
+    # first, and it has to handle the paths having octal escape sequences.
+    set -- "$(readlink -f "$1")"
+    cut -d' ' -f5 /proc/self/mountinfo | startswith "$1" \
+        | sort -r | while read -r mp; do
+        umount "$(echo -e "$mp")"
+    done
+}
+
+# Give the rootfs another chance to write its state to disk.
+sync
+
+# Kill any http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons/
+# as we don't have any facility to cleanly shut them down in this initramfs.
+killall5
+
+# Recursively unmount the old root, so they have a chance of performing
+# unmount-time cleanup.
+recursive_umount /oldroot
+
+case "$1" in
+reboot|poweroff|halt)
+        if ! "$1" -f; then
+            fail "$1 command failed"
+        fi
+        ;;
+kexec)
+        # probably don't have this, but we'll try anyway
+        if ! kexec -e; then
+            fail "$1 command failed"
+        fi
+        ;;
+*)
+        fail "Unrecognized shutdown verb $1"
+        ;;
+esac
+
-- 
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