fix(check_live_ram): increase /run tmpfs size, if needed

Check the size and available space in /run to enlarge it,
  if needed.
Introduce the check_meminfo() function to replace a less
  versatile sed call.
Also, use local variables.

modules.d/99base/dracut-lib.sh

@@ -1130,6 +1130,18 @@ show_memstats() {
  esac
 }
 
+# parameter: memory_name: example: MemTotal:
+# Check /proc/meminfo
+# echo the field value, if present.
+check_meminfo() {
+ local - m sz
+ set +x
+ while read -r m sz _ || [ "$m" ]; do
+ [ "$m" = "$1" ] && echo "$sz" && return 0
+ done < /proc/meminfo
+ return 1
+}
+
 remove_hostonly_files() {
  rm -fr /etc/cmdline /etc/cmdline.d/*.conf "$hookdir/initqueue/finished"
  if [ -f /lib/dracut/hostonly-files ]; then
@@ -1152,13 +1164,20 @@ load_fstype() {
  modprobe "$1"
 }
 
-# parameter: size of live image
+# parameter: size of live image in MiB
 # calls emergency shell if ram size is too small for the image
+# Increase /run tmpfs size, if needed.
 check_live_ram() {
+ local minmem imgsize memsize runsize runavail
  minmem=$(getarg rd.minmem)
  minmem=${minmem:-1024}
  imgsize=$1
- memsize=$(($(sed -n 's/MemTotal: *\([[:digit:]]*\).*/\1/p' /proc/meminfo) / 1024))
+ memsize=$(($(check_meminfo MemTotal:) >> 10))
+ # shellcheck disable=SC2046
+ set -- $(findmnt -bnro SIZE,AVAIL /run)
+ # bytes to MiB
+ runsize=$(($1 >> 20))
+ runavail=$(($2 >> 20))
 
  if [ -z "$imgsize" ]; then
  warn "Image size could not be determined"
@@ -1174,5 +1193,8 @@ check_live_ram() {
  echo \n/" /usr/bin/dracut-emergency
 
  emergency_shell
+ elif [ $((runavail - imgsize)) -lt "$minmem" ]; then
+ # Increase /run tmpfs size, if needed.
+ mount -o remount,size=$((runsize - runavail + imgsize + minmem))M /run
  fi
 }