mkarchiso: split out build mode specific checks from _validate_options to _validate_requirements_buildmode_*

The bootstrap build mode does not use packages.${arch}, ${bootmodes[@]} or $airootfs_image_type so there's no need to validate them.
Requirements common to iso and netboot are checked with the _validate_common_requirements_buildmode_iso_netboot function.

Fixes #149.

* Rename _validate_requirements_buildmode_all to _validate_common_requirements_buildmode_all to prevent potential conflicts since we are using _validate_requirements_buildmode_${_buildmode} to run the functions.
* Improve searching in an array. See https://stackoverflow.com/a/15394738.

$pkg_list_from_file and $bootstrap_pkg_list_from_file are arrays, they must be referenced as such. Fixes https://bugs.archlinux.org/task/71852.

Remove quotes from arithmetic expressions.

Add new -G option to set gpg's --sender. This allows to see who signed the rootfs image without needing to import the gpg key from the keyring in initramfs.

* Add --batch, since gpg is run in a script.
* Add --no-armor (this is the default). Armored output provides no benifit here.
* Add --no-include-key-block (this is the default). There is no need to have the gpg key in the signature. The mkinitcpio hook will verify the signature against the included keyring.

Remove the output files before running gpg. Otherwise gpg --batch will fail if they exist.

Fixes #147.

This could prevent a few issues when creating an image file when re-running mkarchiso after a failure.

Remove useless test before running rm -f. The command will always succeed.

mkfs.ext4 with its -d option can "copy the contents of the given directory into the root directory of the filesystem".
This allows to get rid of the last directly used mount and umount commands in mkarchiso.

Additionally try to make the ext4 image somewhat reproducible by setting E2FSPROGS_FAKE_TIME to SOURCE_DATE_EPOCH, clearing the UUID and using a reproducible hash seed.
See https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/commit/?id=e1f7100643a46456be107b33098f6034b0835e6d .

Place mkfs.ext4 options in an array to avoid duplicating the command.

Related to #40.

archiso/mkarchiso:
Do not run `_build_iso_base` with `_run_once`, as it sets variables which are important to functions that are called
after it.

* Merge _make_efi_dir_on_iso9660 into _make_bootmode_uefi-x64.systemd-boot.eltorito since it's specific to that boot mode.
* Split off FAT image creation into _make_efibootimg, so it can be reused by other functions.
* Add/improve comments to better document what the script does.

LC_ALL overrides LANG and all LC_* variables, so use it instead.
See https://www.gnu.org/software/gettext/manual/html_node/Locale-Environment-Variables.html#Locale-Environment-Variables .

Alternative to 3d6651ab which caused issues.

Fixes https://bugs.archlinux.org/task/70580 .

This reverts commit 3d6651ab.

A missing $PATH breaks scripts that do not hardcode binary paths.
Fixes https://bugs.archlinux.org/task/71416 .

archiso/mkarchiso:
Generalize the handling of ucode files (e.g. copying, signing, size calculation) by introducing the global readonly
array of expected ucode names instead of hardcoding them in various functions.
When making use of ucode files in `_make_boot_on_iso9660()`, `_make_bootmode_uef-x86.systemd-boot.esp()` and
`_sign_netboot_artifacts()` create a list of files that is guaranteed to contain existing files.

Fixes #132

Use the new, prettier short URLs.

Fixes #138

Environment variables can interfere with the commands in chroot.
This causes issues when the environment variables specify a path that does not exist inside the chroot, e.g. if TMPDIR is set to a custom value.

Fixes https://bugs.archlinux.org/task/70580 .

archiso/mkarchiso:
Change `_make_pkglist()` to also generate the package list when using the netboot build mode.

archiso/mkarchiso:
Implement a buildmode to export artifacts required for netboot with IPXE.
When providing the buildmode 'netboot' via profiledef.sh or the `-m` option, all targets necessary to create an ISO
medium are built, but the components required for netboot are exported to the output dir.
Optionally, it is possible to provide a set of certificates for codsigning using the `-c` option, where the first file
is considered as the signer certificate and the second as the key.

Add `_export_netboot_artifacts()` to copy build artifacts to the output directory.
Add `_sign_netboot_artifacts()` to codesign the netboot artifacts in the work directory.
Add `_validate_requirements_buildmode_netboot()` to check for openssl.
Add `_build_iso_base()` to implement common function calls between the 'iso' and the 'netboot' buildmodes.
Add `_build_buildmode_netboot()` to make use of `_build_iso_base()`, (optionally) `_sign_netboot_artifacts()` and
`_export_netboot_artifacts()`.
Change `_build_buildmode_iso()` to make use of `_build_iso_base()`.
Add `-c` as an option to mkarchiso to read in a list of file names.
Unify the output of `_usage()` by using the same definition style for lists of strings provided to options that accept
them (e.g. `-c`, `-m`, `-p`).

Closes #128

archiso/mkarchiso:
Introduce a buildmodes array, that can be used to build towards more than one output artifact type.
Add a buildmode for building a bootstrap image (a compressed file containing a very minimal Arch installation).
The buildmodes can be set either using a `buildmodes` array in a `profiledef.sh` or by using the `-m` option flag to
mkarchiso and providing a space delimited, quoted list.
The 'iso' buildmode is always the default if no buildmodes are setup.
Implement building a bootstrap image, when using the 'bootstrap' `buildmode`, which uses a profile's
'bootstrap_packages.$arch' file to install packages using pacstrap and compressing it to a bootstrap image.
The name of the output file is currently constructed from the `iso_name` value by appending `-bootstrap`.

Replace the uses of `airootfs_dir` with the more generic `pacstrap_dir`, as the location denotes where pacstrap is
being used.
Replace uses of `img_name` with `image_name` and removing it from the global scope, so that it can be overridden per
each buildmode.
Rename `_cleanup_airootfs_dir()` to `_cleanup_pacstrap_dir()`.
Make `_run_once()` more generic by prepending the state files with a string defined by `run_once_mode`.
Add `_validate_requirements_buildmode_all()`, `_validate_requirements_buildmode_bootstrap()` and
`_validate_requirements_buildmode_iso()` to validate the general requirements of the different buildmodes.
Add `_build_bootstrap_image()` to generate the bootstrap image using bsdtar.
Rename `_build_iso()` to `_build_iso_image()` to fit the naming of the respective bootstrap function.
Extend `_read_profile()` to include the reading of bootstrap image specific packages from a file.
Extend `_validate_options()` to include testing of the bootstrap packages and running of validation functions for all
buildmodes.
Change `_set_overrides()` to override the buildmodes if they are specified via the `-m` option flag.
Change `_make_version()` to be used generically in all buildmodes.
Change `_make_pkglist()` to be used generically in all buildmodes.
Rename `_build_profile()` to `_build_buildmode_iso()` and set local variables that are specific to the buildmode, such
as `image_name`, `pacstrap_dir`, `run_once_mode` , `buildmode_packages` and `buildmode_pkg_list`.
Add `_build_buildmode_bootstrap()` and set local variables that are specific to the buildmode, such as `image_name`,
`pacstrap_dir`, `run_once_mode` , `buildmode_packages` and `buildmode_pkg_list`.
Add the `-m` option flag to the list of flags.

Closes #127

archiso/mkarchiso:
Change the help output to reflect that the `-g` option is generically signing a rootfs (which may be e.g. squashfs or
erofs).
Change the output of `_mksignature()` to be more generic, as it signs any type of understood rootfs image (which may be
e.g. squashfs or erofs).

archiso/mkarchiso:
Force the file extension in use for the PGP signatures of the rootfs to always be .sig.
When gnupg's 'armor' configuration option is used, the output otherwise defaults to using .asc.
As the verification hook in mkinitcpio-archiso expects the .sig file extension, verifying the rootfs will fail in that
scenario.

Use the gzip option -n/--no-name to prevent saving the original file name and timestamp.

Fixes #104.

mkarchiso: make sure to remove potentially preexisting files from $airootfs_dir before creating them with output redirection

mkarchiso creates "${airootfs_dir}/etc/machine-id" by using output redirection. If this file is an existing symlink, then the printf output would be written to the symlink target. It can be a big issue in case the symlink resolves to a path outside ${airootfs_dir}.

Fixes #121.

This provides the ISO version information in the os-release file.

* IMAGE_ID is set to the value of $iso_name.
* IMAGE_VERSION is set to the value of $iso_version.

Implements #116.

mkarchiso: use -isohybrid-gpt-basdat instead of -appended_part_as_gpt for ISOs that will support BIOS booting

Some hardware, like Lenovo Thinkpad T420, will not BIOS boot if the disk has a valid GPT.
See https://bbs.archlinux.org/viewtopic.php?id=264096 .

Instead of a valid GPT, change to a valid MBR and invalid GPT similar to what was used before 729d16b4. That layout, despite having crazy partition tables, boots everywhere.
The difference is that -append_partition is still kept and specified before -isohybrid-gpt-basdat. Thus the appended partition will be listed as EFI system partition in MBR and as Microsoft basic partition in the invalid GPT.

Fixes #102.

Remove hardcoded '-comp xz', it prevents using mksquashfs defaults.

Fixes #112.

Michael Gilchrist authored Mar 21, 2021 and David Runge committed Mar 21, 2021

- if a folder listed in the associative array ends with a "/",
  recursively apply chmod and chown.

EROFS, like Squashfs, is a read-only file system. It can be used to store airootfs in an image file.
Its advantage is the support for POSIX ACLs. EROFS downside is that currently it only supports LZ4 compression (LZMA support is not yet fully implemented).

A difference from Squashfs is that, EROFS stores change time (ctime) not modification time (mtime). The reverse is true for Squashfs.

Implements #59

- Apply overrides before validating the options.
- Parse all paths with realpath. Fixes #84 .

To date the iso version was used for iso volume information and iso file name.
In my custom builds I do use it a lot more:

* Inside the root fs: The system knows about its own version. I use this to:
  -> report the version to a server (poor man's inventory)
  -> let the system update itself

* On the iso fs: The files are served via rsync, running systems transfer
  version file first to check for available update.

* A grub environment file on the iso fs: Booting the iso from grub allows
  to create cow directory per version:

    loopback loop archlinux.iso
    load_env -f (loop)/arch/grubenv
    linux (loop)/arch/boot/x86_64/vmlinuz-linux ... \
        cow_directory=archlinux/${VERSION} ...

So let's just create these files.

archiso/mkarchiso:
Make sure to always compare absolute paths in `_make_custom_airootfs()` (as `realpath` is used).
Remove `echo` calls that prevent the setting of actual file ownerships and modes.

configs/releng/profiledef.sh:
Set file mode of /root/.automated_script.sh to 755.

Fixes #82

This gets rid of the duplicate ldlinux.c32 and the useless isolinux.cfg which only points to syslinux.cfg.

Implements #46 .

profiledef.sh can now contain an associative array called file_permissions which can be used to set custom ownership and mode of custom airootfs files. The array's keys contain the path and the value is a colon separated list of owner UID, owner GID and access mode.
For example:

    file_permissions=(
      ["/etc/shadow"]="0:0:400"
    )

This means that mkarchiso now copies airootfs files (and directores) without permissions and anything that should be owned by a user other than root and/or if the mode should be something other than 644 for files and 755 for directories must to be listed in ${file_permission[@]} in profiledef.sh.

Fixes #61 .

archiso/mkarchiso:
Guard the call to `_mksignature()` in `_prepare_airootfs_image()` by an if statement.
Using the `&&` logic leads to `_prepare_airootfs_image()` evaluating to false if `$gpg_key` is not set.

Add `_msg_info()` calls to `_set_override()` which prevent the function from evaluating to false if no override is
being done. Additionally this is great for debugging purposes.

Add `_msg_info()` calls to `_read_profile()` (which is great for debugging purposes).

Fixes #81