__dyn_install: improve reporting of build and image sizes

Prior to this commit, the reported sizes would look like:

 * Final size of build directory: 34942 KiB
 * Final size of installed tree: 5627 KiB

Because the sizes aren't aligned, it is hard to (visually) compare them.
On top of this, because the numbers are sometimes bigger, print a human
friendly size after the KiB size if applicable, like so:

 * Final size of build directory: 1906 KiB (1.8 MiB)
 * Final size of installed tree:     7 KiB

It should be noted that in case both sizes have a human-readable
variant, they are also aligned.

The helper functions are defined and used in a subshell to avoid
pollution of the caller's environment.

Reviewed-by: Zac Medico <zmedico@gentoo.org>

1 files changed, 49 insertions, 4 deletions

diff --git a/bin/phase-functions.sh b/bin/phase-functions.sh
index dfd8733c8..ce174ba91 100644
--- a/bin/phase-functions.sh
+++ b/bin/phase-functions.sh
@@ -598,10 +598,55 @@ __dyn_install() {
 
 	# record build & installed size in build log
 	if type -P du &>/dev/null; then
-		local sz=( $(du -ks "${WORKDIR}") )
-		einfo "Final size of build directory: ${sz[0]} KiB"
-		sz=( $(du -ks "${D}") )
-		einfo "Final size of installed tree: ${sz[0]} KiB"
+		local nsz=( $(du -ks "${WORKDIR}") )
+		local isz=( $(du -ks "${D}") )
+
+		# subshell to avoid polluting the caller env with the helper
+		# functions below
+		(
+			# align $1 to the right to the width of the widest of $1 and $2
+			padl() {
+				local s1=$1
+				local s2=$2
+				local width=${#s1}
+				[[ ${#s2} -gt ${width} ]] && width=${#s2}
+				printf "%*s" ${width} "${s1}"
+			}
+
+			# transform number in KiB into MiB, GiB or TiB based on size
+			human() {
+				local s1=$1
+				local units=( KiB MiB GiB TiB )
+
+				s1=$((s1 * 10))
+				while [[ ${s1} -gt 10240 && ${#units[@]} -gt 1 ]] ; do
+					s1=$((s1 / 1024 ))
+					units=( ${units[@]:1} )
+				done
+
+				local r=${s1: -1}
+				s1=$((s1 / 10))
+				printf "%s.%s %s" "${s1}" "${r}" "${units[0]}"
+			}
+
+			size() {
+				local s1=$1
+				local s2=$2
+				local out="$(padl "${s1}" "${s2}") KiB"
+
+				if [[ ${s1} -gt 1024 ]] ; then
+					s1=$(human ${s1})
+					if [[ ${s2} -gt 1024 ]] ; then
+						s2=$(human ${s2})
+						s1=$(padl ${s1} ${s2})
+					fi
+					out+=" (${s1})"
+				fi
+				echo "${out}"
+			}
+			einfo "Final size of build directory: $(size ${nsz[0]} ${isz[0]})"
+			einfo "Final size of installed tree:  $(size ${isz[0]} ${nsz[0]})"
+		)
 		__vecho
 	fi