Create disk images without root
`mke2fs` has a `-d` option that allows to populate the newly created filesystem without needing to temporarily mount it. That allows to use `parted` and `mkfs.ext3` on regular files without needing root access.
This commit is contained in:
Eduardo Sánchez Muñoz
fosslinux
parent
67aa2a4826
commit
679f73bbf1
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@ -59,26 +59,16 @@ class Generator():
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# argument matrix ... or we could just use ext3 instead which
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# is effectively universally the same
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if kernel_bootstrap:
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init_path = os.path.join(self.target_dir, 'init')
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self.target_dir = os.path.join(self.target_dir, 'init')
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os.mkdir(self.target_dir)
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os.mkdir(init_path)
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self.target_dir = init_path
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if self.repo_path or self.external_sources:
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target.add_disk("external", filesystem="ext3")
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target.mount_disk("external", "external")
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else:
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if not self.repo_path and not self.external_sources:
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self.external_dir = os.path.join(self.target_dir, 'external')
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elif using_kernel:
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self.target_dir = os.path.join(self.target_dir, 'disk')
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target.add_disk("disk",
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filesystem="ext3",
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size=(str(target_size) + "M") if target_size else "16G",
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bootable=True)
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target.mount_disk("disk", "disk")
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self.external_dir = os.path.join(self.target_dir, 'external')
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os.makedirs(self.external_dir, exist_ok=True)
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os.makedirs(self.external_dir)
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if self.early_preseed:
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# Extract tar containing preseed
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@ -103,10 +93,16 @@ class Generator():
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if kernel_bootstrap:
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self.create_builder_hex0_disk_image(self.target_dir + '.img', target_size)
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if kernel_bootstrap and (self.external_sources or self.repo_path):
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target.umount_disk('external')
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if self.repo_path or self.external_sources:
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mkfs_args = ['-d', os.path.join(target.path, 'external')]
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target.add_disk("external", filesystem="ext3", mkfs_args=mkfs_args)
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elif using_kernel:
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target.umount_disk('disk')
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mkfs_args = ['-d', os.path.join(target.path, 'disk')]
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target.add_disk("disk",
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filesystem="ext3",
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size=(str(target_size) + "M") if target_size else "16G",
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bootable=True,
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mkfs_args=mkfs_args)
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def steps(self):
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"""Copy in steps."""
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@ -8,10 +8,9 @@ Contains a class that represents a target directory
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"""
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import enum
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import getpass
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import os
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from lib.utils import mount, umount, create_disk, run_as_root
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from lib.utils import mount, create_disk
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class TargetType(enum.Enum):
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"""Different types of target dirs we can have"""
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@ -24,7 +23,6 @@ class Target:
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"""
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_disks = {}
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_disk_filesystems = {}
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_mountpoints = {}
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def __init__(self, path="target"):
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@ -34,15 +32,6 @@ class Target:
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if not os.path.exists(self.path):
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os.mkdir(self.path)
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def __del__(self):
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for path in self._mountpoints:
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print(f"Unmounting {path}")
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umount(path)
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for disk in self._disks.values():
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print(f"Detaching {disk}")
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run_as_root("losetup", "-d", disk)
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def tmpfs(self, size="8G"):
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"""Mount a tmpfs"""
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print(f"Mounting tmpfs on {self.path}")
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@ -59,32 +48,13 @@ class Target:
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mkfs_args=None):
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"""Add a disk"""
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disk_path = os.path.join(self.path, f"{name}.img")
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self._disks[name] = create_disk(disk_path,
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tabletype,
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filesystem,
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size,
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bootable,
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mkfs_args)
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self._disk_filesystems[name] = filesystem
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# Allow executing user to access it
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run_as_root("chown", getpass.getuser(), self._disks[name])
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def mount_disk(self, name, mountpoint=None):
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"""Mount the disk"""
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if mountpoint is None:
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mountpoint = f"{name}_mnt"
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mountpoint = os.path.join(self.path, mountpoint)
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os.mkdir(mountpoint)
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mount(self._disks[name] + "p1", mountpoint, self._disk_filesystems[name])
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# Allow executing user to access it
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run_as_root("chown", getpass.getuser(), mountpoint)
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self._mountpoints[name] = mountpoint
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return mountpoint
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def umount_disk(self, name):
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"""Unmount a disk"""
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umount(self._mountpoints[name])
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del self._mountpoints[name]
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create_disk(disk_path,
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tabletype,
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filesystem,
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size,
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bootable,
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mkfs_args)
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self._disks[name] = disk_path
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def get_disk(self, name):
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"""Get the path to a device of a disk"""
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13
lib/utils.py
13
lib/utils.py
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@ -37,16 +37,13 @@ def create_disk(image, disk_type, fs_type, size, bootable=False, mkfs_args=None)
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if mkfs_args is None:
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mkfs_args = []
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run('truncate', '-s', size, image)
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# First find the device we will use, then actually use it
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loop_dev = run_as_root('losetup', '-f', capture_output=True).stdout.decode().strip()
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run_as_root('losetup', '-P', loop_dev, image)
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# Create the partition
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if disk_type != "none":
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run_as_root('parted', '--script', image, 'mklabel', disk_type, 'mkpart',
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'primary', fs_type, '1GiB' if bootable else '1MiB', '100%')
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run_as_root('partprobe', loop_dev)
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run_as_root('mkfs.' + fs_type, loop_dev + "p1", *mkfs_args)
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return loop_dev
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# 1 GiB if bootable, 1 MiB otherwise
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offset = str(1024 * 1024 * (1024 if bootable else 1))
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run('parted', '--script', image, 'mklabel', disk_type, 'mkpart',
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'primary', fs_type, offset + 'B', '100%')
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run('mkfs.' + fs_type, image, '-E', 'offset=' + offset, *mkfs_args)
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def mount(source, target, fs_type, options='', **kwargs):
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"""Mount filesystem"""
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