kernel-install: allow overriding the path to config files

It's pretty hard to write tests without this. I started out by adding separate
variables for each of the files we read, but there's a bunch, and in practice
it's good enough to just override the directory.

2 files changed, 19 insertions, 9 deletions

diff --git a/src/kernel-install/90-loaderentry.install b/src/kernel-install/90-loaderentry.install
index ee55965110..b700a7b2a6 100644
--- a/src/kernel-install/90-loaderentry.install
+++ b/src/kernel-install/90-loaderentry.install
@@ -65,7 +65,11 @@ fi
 SORT_KEY="$IMAGE_ID"
 [ -z "$SORT_KEY" ] && SORT_KEY="$ID"
 
-if [ -f /etc/kernel/cmdline ]; then
+if [ -n "$KERNEL_INSTALL_CONF_ROOT" ]; then
+    if [ -f "$KERNEL_INSTALL_CONF_ROOT/cmdline" ]; then
+        BOOT_OPTIONS="$(tr -s "$IFS" ' ' <"$KERNEL_INSTALL_CONF_ROOT/cmdline")"
+    fi
+elif [ -f /etc/kernel/cmdline ]; then
     BOOT_OPTIONS="$(tr -s "$IFS" ' ' </etc/kernel/cmdline)"
 elif [ -f /usr/lib/kernel/cmdline ]; then
     BOOT_OPTIONS="$(tr -s "$IFS" ' ' </usr/lib/kernel/cmdline)"
@@ -83,10 +87,12 @@ if [ "$ENTRY_TOKEN" = "$MACHINE_ID" ]; then
     BOOT_OPTIONS="$BOOT_OPTIONS systemd.machine_id=$MACHINE_ID"
 fi
 
-if [ -f /etc/kernel/tries ]; then
-    read -r TRIES </etc/kernel/tries
+TRIES_FILE="${KERNEL_INSTALL_CONF_ROOT:-/etc/kernel}/tries"
+
+if [ -f "$TRIES_FILE" ]; then
+    read -r TRIES <"$TRIES_FILE"
     if ! echo "$TRIES" | grep -q '^[0-9][0-9]*$'; then
-        echo "/etc/kernel/tries does not contain an integer." >&2
+        echo "$TRIES_FILE does not contain an integer." >&2
         exit 1
     fi
     LOADER_ENTRY="$BOOT_ROOT/loader/entries/$ENTRY_TOKEN-$KERNEL_VERSION+$TRIES.conf"
diff --git a/src/kernel-install/kernel-install.in b/src/kernel-install/kernel-install.in
index 044ba9f6f2..96595fa295 100755
--- a/src/kernel-install/kernel-install.in
+++ b/src/kernel-install/kernel-install.in
@@ -108,7 +108,9 @@ initrd_generator=
 _MACHINE_ID_SAVED="$MACHINE_ID"
 _BOOT_ROOT_SAVED="$BOOT_ROOT"
 
-if [ -f "/etc/kernel/install.conf" ]; then
+if [ -n "$KERNEL_INSTALL_CONF_ROOT" ]; then
+    install_conf="$KERNEL_INSTALL_CONF_ROOT/install.conf"
+elif [ -f "/etc/kernel/install.conf" ]; then
     install_conf="/etc/kernel/install.conf"
 elif [ -f "/usr/lib/kernel/install.conf" ]; then
     install_conf="/usr/lib/kernel/install.conf"
@@ -116,7 +118,7 @@ else
     install_conf=
 fi
 
-if [ -n "$install_conf" ]; then
+if [ -f "$install_conf" ]; then
     [ "$KERNEL_INSTALL_VERBOSE" -gt 0 ] && echo "Reading $install_conf…"
     # shellcheck source=/dev/null
     . "$install_conf"
@@ -171,10 +173,12 @@ fi
 # $BOOT where we want to place the kernel/initrd and related resources, as well
 # for naming the .conf boot loader spec entry. Typically this is just the
 # machine ID, but it can be anything else, too, if we are told so.
-if [ -z "$ENTRY_TOKEN" ] && [ -f /etc/kernel/entry-token ]; then
-    read -r ENTRY_TOKEN </etc/kernel/entry-token
+ENTRY_TOKEN_FILE="${KERNEL_INSTALL_CONF_ROOT:-/etc/kernel}/entry-token"
+
+if [ -z "$ENTRY_TOKEN" ] && [ -f "$ENTRY_TOKEN_FILE" ]; then
+    read -r ENTRY_TOKEN <"$ENTRY_TOKEN_FILE"
     [ "$KERNEL_INSTALL_VERBOSE" -gt 0 ] && \
-        echo "entry-token \"$ENTRY_TOKEN\" acquired from /etc/kernel/entry-token"
+        echo "entry-token \"$ENTRY_TOKEN\" acquired from $ENTRY_TOKEN_FILE"
 fi
 if [ -z "$ENTRY_TOKEN" ]; then
     # If not configured explicitly, then use a few candidates: the machine ID,