overlay: Move our bash modifications to a separate package

The new coreos-base/misc-files package will contain the compatibility
symlinks and other files we added as modifications to Gentoo
ebuilds. Now we will be moving the app-shells/bash package to
portage-stable, so move our bashrc snippet and symlink creation to the
new package.

sdk_container/src/third_party/coreos-overlay/app-shells/bash/files/dot-bashrc

@@ -16,12 +16,3 @@ fi
 
 
 # Put your fun stuff here.
-
-alias_bcc_tool() {
-    local tool="${1}"
-        alias iovisor-${tool}="docker run --rm -it -v /lib/modules:/lib/modules -v /sys/kernel/debug:/sys/kernel/debug -v /sys/fs/cgroup:/sys/fs/cgroup -v /sys/fs/bpf:/sys/fs/bpf --privileged --net host --pid host quay.io/iovisor/bcc /usr/share/bcc/tools/${tool}"
-}
-
-bcc_debug_toolset=( tcpretrans tcpconnect tcpaccept biolatency )
-
-for t in "${bcc_debug_toolset[@]}"; do alias_bcc_tool "${t}"; done

sdk_container/src/third_party/coreos-overlay/coreos-base/coreos/coreos-0.0.1.ebuild

@@ -113,6 +113,7 @@ RDEPEND="${RDEPEND}
 	coreos-base/afterburn
 	coreos-base/coreos-cloudinit
 	coreos-base/coreos-init
+	coreos-base/misc-files
 	coreos-base/update-ssh-keys
 	coreos-base/update_engine
 	dev-db/etcdctl

sdk_container/src/third_party/coreos-overlay/coreos-base/misc-files/files/99-flatcar-bcc

@@ -0,0 +1,5 @@
+for iovisor_bcc_tool in tcpretrans tcpconnect tcpaccept biolatency; do
+    alias "iovisor-${iovisor_bcc_tool}=docker run --rm -it -v /lib/modules:/lib/modules -v /sys/kernel/debug:/sys/kernel/debug -v /sys/fs/cgroup:/sys/fs/cgroup -v /sys/fs/bpf:/sys/fs/bpf --privileged --net host --pid host quay.io/iovisor/bcc /usr/share/bcc/tools/${iovisor_bcc_tool}"
+done
+
+unset -v iovisor_bcc_tool

sdk_container/src/third_party/coreos-overlay/coreos-base/misc-files/metadata.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+</pkgmetadata>

sdk_container/src/third_party/coreos-overlay/coreos-base/misc-files/misc-files-0.ebuild

@@ -0,0 +1,60 @@
+# Copyright (c) 2023 The Flatcar Maintainers.
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+DESCRIPTION='Flatcar miscellaneous files'
+HOMEPAGE='https://www.flatcar.org/'
+
+LICENSE='Apache-2.0'
+SLOT='0'
+KEYWORDS='amd64 arm64'
+
+# No source directory.
+S="${WORKDIR}"
+
+# Versions listed below are version of packages that shedded the
+# modifications in their ebuilds.
+RDEPEND="
+	>=app-shells/bash-5.2_p15-r2
+"
+
+src_compile() {
+    # An empty file for temporary symlink destinations under
+    # /usr/share/flatcar/etc.
+    touch "${T}/empty-file"
+}
+
+src_install() {
+    # Use absolute paths to be clear about what locations are used. The
+    # dosym below will make relative paths out of them.
+    #
+    # For files inside /usr/share/flatcar/etc the ebuild will create empty
+    # files to avoid having dangling symlinks. During the assembly of the
+    # image, the /usr/share/flatcar/etc directory will be removed, and
+    # /etc will be moved in its place.
+    #
+    # These links exist because old installations can still have
+    # references to `/usr/share/(bash|skel)`.
+    local -A compat_symlinks
+    compat_symlinks=(
+        ['/usr/share/bash/bash_logout']='/usr/share/flatcar/etc/bash/bash_logout'
+        ['/usr/share/bash/bashrc']='/usr/share/flatcar/etc/bash/bashrc'
+        ['/usr/share/skel/.bash_logout']='/usr/share/flatcar/etc/skel/.bash_logout'
+        ['/usr/share/skel/.bash_profile']='/usr/share/flatcar/etc/skel/.bash_profile'
+        ['/usr/share/skel/.bashrc']='/usr/share/flatcar/etc/skel/.bashrc'
+    )
+
+    local link target
+    for link in "${!compat_symlinks[@]}"; do
+        target=${compat_symlinks["${link}"]}
+        dosym -r "${target}" "${link}"
+        if [[ "${target}" = /usr/share/flatcar/etc/* ]]; then
+            insinto "${target%/*}"
+            newins "${T}/empty-file" "${target##*/}"
+        fi
+    done
+
+    insinto '/etc/bash/bashrc.d'
+    doins "${FILESDIR}/99-flatcar-bcc"
+}