image: T4516: Added system image tools

This commit adds the whole set of system image tools written from the scratch in
Python that allows performing all the operations on images:

* check information
* perform installation and deletion
* versions management

Also, it contains a new service that will update the GRUB menu and keep tracking
its version in the future.

WARNING: The commit contains non-reversible changes. Because of boot menu
changes, it will not be possible to manage images from older VyOS versions after
an update.

(cherry picked from commit 8f94262e8fa2477700c50303ea6e2c6ddad72adb)

1 files changed, 197 insertions, 0 deletions

diff --git a/python/vyos/system/image.py b/python/vyos/system/image.py
new file mode 100644
index 000000000..b77c3563f
--- /dev/null
+++ b/python/vyos/system/image.py
@@ -0,0 +1,197 @@
+# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+from pathlib import Path
+from re import compile as re_compile
+from tempfile import TemporaryDirectory
+from typing import TypedDict
+
+from vyos import version
+from vyos.system import disk, grub
+
+# Define variables
+GRUB_DIR_MAIN: str = '/boot/grub'
+GRUB_DIR_VYOS: str = f'{GRUB_DIR_MAIN}/grub.cfg.d'
+CFG_VYOS_VARS: str = f'{GRUB_DIR_VYOS}/20-vyos-defaults-autoload.cfg'
+GRUB_DIR_VYOS_VERS: str = f'{GRUB_DIR_VYOS}/vyos-versions'
+# prepare regexes
+REGEX_KERNEL_CMDLINE: str = r'^BOOT_IMAGE=/(?P<boot_type>boot|live)/((?P<image_version>.+)/)?vmlinuz.*$'
+
+
+# structures definitions
+class ImageDetails(TypedDict):
+    name: str
+    version: str
+    disk_ro: int
+    disk_rw: int
+    disk_total: int
+
+
+class BootDetails(TypedDict):
+    image_default: str
+    image_running: str
+    images_available: list[str]
+    console_type: str
+    console_num: int
+
+
+def bootmode_detect() -> str:
+    """Detect system boot mode
+
+    Returns:
+        str: 'bios' or 'efi'
+    """
+    if Path('/sys/firmware/efi/').exists():
+        return 'efi'
+    else:
+        return 'bios'
+
+
+def get_version(image_name: str, root_dir: str) -> str:
+    """Extract version name from rootfs based on image name
+
+    Args:
+        image_name (str): a name of image (from boot menu)
+        root_dir (str): a root directory of persistence storage
+
+    Returns:
+        str: version name
+    """
+    squashfs_file: str = next(
+        Path(f'{root_dir}/boot/{image_name}').glob('*.squashfs')).as_posix()
+    with TemporaryDirectory() as squashfs_mounted:
+        disk.partition_mount(squashfs_file, squashfs_mounted, 'squashfs')
+        version_file: str = Path(
+            f'{squashfs_mounted}/opt/vyatta/etc/version').read_text()
+        disk.partition_umount(squashfs_file)
+        version_name: str = version_file.lstrip('Version: ').strip()
+
+    return version_name
+
+
+def get_details(image_name: str, root_dir: str = '') -> ImageDetails:
+    """Return information about image
+
+    Args:
+        image_name (str): a name of an image
+        root_dir (str, optional): an optional path to the root directory.
+        Defaults to ''.
+
+    Returns:
+        ImageDetails: a dictionary with details about an image (name, size)
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    image_version: str = get_version(image_name, root_dir)
+
+    image_path: Path = Path(f'{root_dir}/boot/{image_name}')
+    image_path_rw: Path = Path(f'{root_dir}/boot/{image_name}/rw')
+
+    image_disk_ro: int = int()
+    for item in image_path.iterdir():
+        if not item.is_symlink():
+            image_disk_ro += item.stat().st_size
+
+    image_disk_rw: int = int()
+    for item in image_path_rw.rglob('*'):
+        if not item.is_symlink():
+            image_disk_rw += item.stat().st_size
+
+    image_details: ImageDetails = {
+        'name': image_name,
+        'version': image_version,
+        'disk_ro': image_disk_ro,
+        'disk_rw': image_disk_rw,
+        'disk_total': image_disk_ro + image_disk_rw
+    }
+
+    return image_details
+
+
+def get_running_image() -> str:
+    """Find currently running image name
+
+    Returns:
+        str: image name
+    """
+    running_image: str = ''
+    regex_filter = re_compile(REGEX_KERNEL_CMDLINE)
+    cmdline: str = Path('/proc/cmdline').read_text()
+    running_image_result = regex_filter.match(cmdline)
+    if running_image_result:
+        running_image: str = running_image_result.groupdict().get(
+            'image_version', '')
+    # we need to have a fallbak for live systems
+    if not running_image:
+        running_image: str = version.get_version()
+
+    return running_image
+
+
+def get_default_image(root_dir: str = '') -> str:
+    """Get default boot entry
+
+    Args:
+        root_dir (str, optional): an optional path to the root directory.
+        Defaults to empty.
+    Returns:
+        str: a version name
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    vars_file: str = f'{root_dir}/{CFG_VYOS_VARS}'
+    vars_current: dict[str, str] = grub.vars_read(vars_file)
+    default_uuid: str = vars_current.get('default', '')
+    if default_uuid:
+        images_list: list[str] = grub.version_list(root_dir)
+        for image_name in images_list:
+            if default_uuid == grub.gen_version_uuid(image_name):
+                return image_name
+        return ''
+    else:
+        return ''
+
+
+def validate_name(image_name: str) -> bool:
+    """Validate image name
+
+    Args:
+        image_name (str): suggested image name
+
+    Returns:
+        bool: validation result
+    """
+    regex_filter = re_compile(r'^[\w\.+-]{1,32}$')
+    if regex_filter.match(image_name):
+        return True
+    return False
+
+
+def is_live_boot() -> bool:
+    """Detect live booted system
+
+    Returns:
+        bool: True if the system currently booted in live mode
+    """
+    regex_filter = re_compile(REGEX_KERNEL_CMDLINE)
+    cmdline: str = Path('/proc/cmdline').read_text()
+    running_image_result = regex_filter.match(cmdline)
+    if running_image_result:
+        boot_type: str = running_image_result.groupdict().get('boot_type', '')
+        if boot_type == 'live':
+            return True
+    return False