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 dracut-lib.sh
  to replace a less versatile sed call.
Also, use local variables,
  use parameter expansion to assign a default value,
  use test exit logic directly, where possible,
  tweak comments,
  and move the check_live_ram() function to img-lib.sh.

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
@@ -1151,28 +1163,3 @@ load_fstype() {
  done < /proc/filesystems
  modprobe "$1"
 }
-
-# parameter: size of live image
-# calls emergency shell if ram size is too small for the image
-check_live_ram() {
- minmem=$(getarg rd.minmem)
- minmem=${minmem:-1024}
- imgsize=$1
- memsize=$(($(sed -n 's/MemTotal: *\([[:digit:]]*\).*/\1/p' /proc/meminfo) / 1024))
-
- if [ -z "$imgsize" ]; then
- warn "Image size could not be determined"
- return 0
- fi
-
- if [ $((memsize - imgsize)) -lt "$minmem" ]; then
- sed -i "N;/and attach it to a bug report./s/echo$/echo\n\
- echo \n\
- echo 'Warning!!!'\n\
- echo 'The memory size of your system is too small for this live image.'\n\
- echo 'Expect killed processes due to out of memory conditions.'\n\
- echo \n/" /usr/bin/dracut-emergency
-
- emergency_shell
- fi
-}

modules.d/99img-lib/img-lib.sh

@@ -106,3 +106,37 @@ unpack_img() {
  }
  fi
 }
+
+# parameter: <size of live image> in MiB
+# Call 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)
+ imgsize=$1
+ memsize=$(($(check_meminfo MemTotal:) >> 10))
+ # shellcheck disable=SC2046
+ set -- $(findmnt -bnro SIZE,AVAIL /run)
+ # bytes to MiB
+ runsize=$(($1 >> 20))
+ runavail=$(($2 >> 20))
+
+ [ "$imgsize" ] || {
+ warn "Image size could not be determined"
+ return 0
+ }
+
+ if [ $((memsize - imgsize)) -lt "${minmem:=1024}" ]; then
+ sed -i "N;/and attach it to a bug report./s/echo$/echo\n\
+ echo \n\
+ echo 'Warning!!!'\n\
+ echo 'The memory size of your system is too small for this live image.'\n\
+ echo 'Expect killed processes due to out of memory conditions.'\n\
+ 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
+}