1 files changed, 112 insertions, 0 deletions
diff --git a/modules/fs/path.inc b/modules/fs/path.inc
new file mode 100644
index 0000000..f3a041b
--- /dev/null
+++ b/modules/fs/path.inc
@@ -0,0 +1,112 @@
+#!/bin/ash
+
+DM_STATE_FILE="/run/openslx/dmsetup.state"
+readonly DM_STATE_FILE
+
+# Return the device corresponding to the given path, or
+# empty if it's not mounted from a device (tmpfs, cifs, ...)
+fs_path_getdev() {
+	local _dev
+	_dev="$( df -P "$1" | awk '$1 ~ "^/dev/" {print $1}' )"
+	[ -n "$_dev" ] || return 1
+	[ -b "$_dev" ] || return 1
+	printf "%s" "$_dev"
+}
+
+# Return base mount point of given path
+# eg. call with "/mnt/nfs/temp/data", returns "/mnt/nfs"
+fs_path_getmountpoint() {
+	local _mp
+	_mp="$( df -P "$1" | awk '$6 ~ "^/" {print $6}' )"
+	[ -n "$_mp" ] || return 1
+	[ -d "$_mp" ] || return 1
+	printf "%s" "$_mp"
+}
+
+# Get fstype of given directory
+fs_path_gettype() {
+	local _mp
+	_mp="$( df -P "$1" | awk '$6 ~ "^/" {print $6}' )"
+	[ -n "$_mp" ] || return 1
+	[ -d "$_mp" ] || return 1
+	awk '$2 == "'"$_mp"'" {print $3}' '/proc/mounts'
+}
+
+# Helper to check whether given directory resides in RAM, either
+# by being mounted as tmpfs or not mounted at all in which case
+# we assume the same. Returns 0 if so, 1 if otherwise backed,
+# 2 when errors occur.
+fs_path_isvolatile() {
+	[ -z "$1" ] && return 2
+	local _dev _mp
+	_dev="$(fs_path_getdev "$1")"
+	[ -z "$_dev" ] && return 0 # No result, assume tmpfs
+	[ "$_dev" = "${_dev#/dev/zram}" ] || return 0 # zram is in RAM, like tmpfs
+	[ "$_dev" != "${_dev#/dev/mapper/}" ] || return 1 # Doesn't start with /dev/mapper, assume some kind of storage
+	[ -s "$DM_STATE_FILE" ] || return 2 # No point in continuing
+	_mp="$(fs_path_getmountpoint "$1")"
+	[ -z "$_mp" ] && return 2
+	# it is a device mapper device, check if it was setup in dracut's initramfs.
+	grep -qE "^$( regex_escape "${_dev}" )\s+$( regex_escape "${_mp}" )\s+type=0" "$DM_STATE_FILE"
+}
+
+# Return free/total space at given path, in KiB.
+# If the given path is backed by a thin pool, snapshot, etc.
+# it returns a conservative estimate, considering the remaining
+# space of the backing device.
+# Returns "<free> <total>"
+fs_path_space() {
+	[ -z "$1" ] && return 1
+	local _free _total _dev _type _id _name _bs _tmp _tfree _ttotal
+	_type="$( fs_path_gettype "$1" )"
+	[ -z "$_type" ] && return 1
+	_free="$( df -P "$1" | awk '$6 ~ "^/" {print $4 " " $2}' )"
+	case "$_type" in # EASY!
+		tmpfs|nfs*|cifs)
+		printf "%s" "$_free"
+		return
+	esac
+	_dev="$( fs_path_getdev "$1" )"
+	if [ "$_dev" = "${_dev#/dev/mapper/}" ]; then # does *NOT* start with /dev/mapper, assume not device mapped
+		# In case we start using aufs again, check if it needs special handling...
+		printf "%s" "$_free"
+		return
+	fi
+	# Split, since we might need to do Min()
+	_total="${_free#* }"
+	_free="${_free% *}"
+	_type="$( dmsetup status "$_dev" | awk '{print $3}' )"
+	_tfree=0
+	_ttotal=0
+	case "$_type" in
+		snapshot)
+			# Field 4 is used/total in sectors of 512 byte, so divide by two for KiB
+			_tmp="$( dmsetup status "$_dev" | awk '{split($4, a, "/"); print (a[2] - a[1]) / 2 " " a[2] / 2}' )"
+			_tfree="${_tmp% *}"
+			_ttotal="${_tmp#* }"
+			;;
+		thin)
+			# Determine matching pool
+			_id="$( dmsetup table "$_dev" | awk '{print $4}' )"
+			if [ -n "$_id" ]; then
+				_name="$( cat "/sys/dev/block/${_id}/dm/name" )"
+				if [ -n "$_name" ]; then
+					# Get data block size (in sectors of 512 byte)
+					_bs="$( dmsetup table "$_name" | awk '{print $6}' )"
+					if [ "$_bs" -gt 0 ]; then
+						# Field 6 is used/total (in data blocks), so transform into KiB
+						_tmp="$( dmsetup status "$_name" | awk -v "bs=$_bs" '{split($6, a, "/"); print ((a[2] - a[1]) / 2) * bs " " (a[2] / 2) * bs}' )"
+						_tfree="${_tmp% *}"
+						_ttotal="${_tmp#* }"
+					fi
+				fi
+			fi
+			;;
+	esac
+	if [ "$_tfree" -ge 0 ] && [ "$_ttotal" -gt 0 ]; then
+		[ "$_tfree" -lt "$_free" ] && _free="$_tfree"
+		[ "$_ttotal" -lt "$_total" ] && _total="$_ttotal"
+	fi
+	printf "%s" "$_free $_total"
+}
+