We want to use use the 'du' option '--apparent-size' which is a
GNU coreutils extension. GNU coreutils is a build dependency so
we know it is available. With this commit we first try to pick up
du as 'gdu', and if that fails, try 'du' instead.
There was previously a case where the build-image-qemu.sh script
decided to mount an existing disk image, but without creating the
memory disk device and recording its /dev file name.
After this commit, We create the memory disk device just before
it is used to mount the disk image.
Having lots of small files in Base/ may require more inodes in the
ext2 filesystem than the format utility sets aside by default. Let's
make a more educated guess since we have a rough idea of how many
inodes we need by counting files and directories.
This adds support for re-using and re-sizing existing disk images.
Disk images are checked with e2fsck prior to re-use and a new disk
image is automatically created when that check fails.
realpath(1) is specific to coreutils and its behavior can be had
with readlink -f
Create the Toolchain Build directory if it doesn't exist before
calling readlink, since realpath(3) on at least OpenBSD will error
on a non-existent path
In the GNU coreutils version of chown, ":" is a valid argument
(the command will result in a no-op), but POSIX chown does not
consider that valid.
If the user who ran build-image-*.sh was root, SUDO_UID and SUDO_GID
would not be set and, if the version of chown installed on the system
did not allow passing just a ":" as argument, the script would fail.
Let's default the value of SUDO_UID and SUDO_GID to 0 just in case.
