Add image size report

In the common case of not specifying a size, we are already running
"du" over the image to figure out how big it is.  Leverage that by
saving it's output and displaying a pruned list of big files when
requested.

We add a flag to show a summarised option (files >10MiB) and another
to show full output, should you wish that level of detail.

"Invocation" documentation is updated (and formatted a little better
while we're here).

Change-Id: I255800790a62fed1c82fcd311f1cc29c9867766d

bin/disk-image-create

@@ -306,12 +306,50 @@ unmount_image
 mv $TMP_BUILD_DIR/mnt $TMP_BUILD_DIR/built
 
 if [ -n "$DIB_IMAGE_SIZE" ]; then
-  du_size=$(echo "$DIB_IMAGE_SIZE" | awk '{printf("%d\n",$1 * 1024 *1024)}')
+    du_size=$(echo "$DIB_IMAGE_SIZE" | awk '{printf("%d\n",$1 * 1024 *1024)}')
 else
-  # in kb*0.60 - underreport to get a slightly bigger device
-  du_size=$(sudo du --block-size=600 -x -s ${TMP_BUILD_DIR}/built |\
-            awk ' { print $1 }')
+    du_output=$(sudo du -a -c -x ${TMP_BUILD_DIR}/built)
+
+    # the last line is the total size from "-c".
+    # scale this by 0.6 to create a slightly bigger image
+    du_size=$(echo "$du_output" | tail -n1 | cut -f1 | \
+                     awk '{print int($1 / 0.6)}')
 fi
+
+if [[ "${DIB_SHOW_IMAGE_USAGE:-0}" != 0 ]]; then
+    xtrace=$(set +o | grep xtrace)
+    set +o xtrace
+
+    if [ -z "$du_output" ]; then
+        du_output=$(sudo du -a -c -x ${TMP_BUILD_DIR}/built)
+    fi
+
+    # by default show the 10MiB and greater files & directories -- a
+    # dir with lots of little files will still show up, but this helps
+    # signal:noise ratio
+    if [[ ${DIB_SHOW_IMAGE_USAGE_FULL:-0} == 0 ]]; then
+        # numfmt will start giving a decimal place when < 10MiB
+        du_output_limit="| egrep 'MiB|GiB|TiB|PiB' | grep -v '\..MiB'"
+        echo "================================="
+        echo "Image size report (files > 10MiB)"
+        echo "================================="
+    else
+        du_output_limit=""
+        echo "================="
+        echo "Image size report"
+        echo "================="
+    fi
+
+    echo "$du_output" | sort -nr | \
+        numfmt --to=iec-i --padding=7 --suffix=B --field=1 --from-unit=1024 \
+               $du_output_limit
+    echo
+    echo "===== end image size report ====="
+    echo
+
+    $xtrace
+fi
+
 if [ "$FS_TYPE" = "ext4" ] ; then
   # Very conservative to handle images being resized a lot
   # We set journal size to 64M so our journal is large enough when we

doc/source/developer/invocation.rst

@@ -1,19 +1,29 @@
 Invocation
 ==========
 
-The scripts can generally just be run. Options can be set on the command line
-or by exporting variables to override those present in lib/img-defaults. -h to
-get help.
-The image building scripts expect to be able to invoke commands with sudo, so if you
-want them to run non-interactively, you should either run them as root, with
-sudo -E, or allow your build user to run any sudo command without password.
+The scripts can generally just be run. Options can be set on the
+command line or by exporting variables to override those present in
+lib/img-defaults. -h to get help.
 
-Using the variable ELEMENTS\_PATH will allow to specify multiple elements locations.
-It's a colon (:) separated path list, and it will work in a first path/element found,
-first served approach. The included elements tree is used when no path is supplied,
-and is added to the end of the path if a path is supplied.
+The image building scripts expect to be able to invoke commands with
+sudo, so if you want them to run non-interactively, you should either
+run them as root, with sudo -E, or allow your build user to run any
+sudo command without password.
 
-By default, the image building scripts will not overwrite existing disk images,
-allowing you to compare the newly built image with the existing one. To change
-that behaviour, set the variable OVERWRITE\_OLD\_IMAGE to any value that isn't
-0.
+Using the variable ``ELEMENTS_PATH`` will allow to specify multiple
+elements locations.  It is a colon (:) separated path list, and it
+will work in a first path/element found, first served approach. The
+included elements tree is used when no path is supplied, and is added
+to the end of the path if a path is supplied.
+
+By default, the image building scripts will not overwrite existing
+disk images, allowing you to compare the newly built image with the
+existing one. To change that behaviour, set the variable
+``OVERWRITE_OLD_IMAGE`` to any value that isn't ``0``.
+
+Setting the variable ``DIB_SHOW_IMAGE_USAGE`` will print out a
+summarised disk-usage report for the final image of files and
+directories over 10MiB in size.  Setting ``DIB_SHOW_IMAGE_USAGE_FULL``
+will show all files and directories.  These settings can be useful
+additions to the logs in automated build situations where debugging
+image-growth may be important.