init: primitive parsing of the command line

2 files changed, 31 insertions, 3 deletions

diff --git a/rc.boot b/rc.boot
index e0d9951..7d12a78 100755
--- a/rc.boot
+++ b/rc.boot
@@ -38,6 +38,10 @@ out "Mounting pseudo filesystems..."; {
     mnt /dev/shm -o mode=1777,nosuid,nodev        -nt tmpfs      shm
 }
 
+out "Parsing kernel commandline..."; {
+    parse_cmdline
+}
+
 [ "$dmesg_level" ] && {
     out "Setting dmesg level..."
     dmesg -n$dmesg_level
@@ -55,12 +59,14 @@ out "Remounting rootfs as read-only..."; {
     mount -o remount,ro / || shell
 }
 
-out "Checking filesystems..."; {
-    fsck -ATat noopts=_netdev
+[ "$FASTBOOT" = 1 ] || {
+    out "Checking filesystems..."
+    fsck "-ATat${FORCEFSCK}" noopts=_netdev
     [ $? -gt 1 ] && shell
 }
 
-out "Mounting rootfs read-write..."; {
+[ "$RO" = "1" ] || {
+    out "Mounting rootfs read-write..."
     mount -o remount,rw / || shell
 }
 
diff --git a/rc.lib b/rc.lib
index e0ee61f..7d5068d 100644
--- a/rc.lib
+++ b/rc.lib
@@ -39,3 +39,25 @@ random() {
     esac
 }
 
+parse_cmdline() {
+    # This is a primitive way of parsing kernel command line
+    # options. Before now, carbs-init ignored these options
+    # set by the user. More will be added as needed. Init scripts
+    # don't need to handle most of the command line options
+    # as the kernel deals with most of them, but not things
+    # such as mount options.
+    [ -r /proc/cmdline ] || {
+        err "Kernel command line options cannot be parsed"
+        shell
+    }
+
+    # We want to read words instead of lines here.
+    # shellcheck disable=2013
+    for arg in $(cat /proc/cmdline); do
+        case "$arg" in
+            ro) RO=1 ;;
+            forcefsck) FORCEFSCK="-f" ;;
+            fastboot)  FASTBOOT=1 ;;
+        esac
+    done
+}