2457635bac
Rather than relying on the offset parameter, simply run mkfs on the loopback device which is anyway being set up. This also allows us not to specify the size explicitly. Before this patch mkfs would complain (uneccesarily) about the backing file containing a partition table. This is a false positive as the partition table is in the region of the file before the passed offset. Signed-off-by: Tom Gundersen <teg@jklm.no>
110 lines
4.2 KiB
Python
Executable file
110 lines
4.2 KiB
Python
Executable file
#!/usr/bin/python3
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import contextlib
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import json
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import os
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import socket
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import shutil
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import subprocess
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import sys
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import tempfile
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import osbuild.remoteloop as remoteloop
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@contextlib.contextmanager
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def mount(source):
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with tempfile.TemporaryDirectory(prefix="osbuild-mnt") as dest:
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subprocess.run(["mount", source, dest], check=True)
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try:
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yield dest
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finally:
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subprocess.run(["umount", "-R", dest], check=True)
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def main(tree, output_dir, options, loop_client):
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fmt = options["format"]
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filename = options["filename"]
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ptuuid = options["ptuuid"]
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root_fs_uuid = options["root_fs_uuid"]
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size = options["size"]
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# sfdisk works on sectors of 512 bytes and ignores excess space - be explicit about this
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if size % 512 != 0:
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raise ValueError("`size` must be a multiple of sector size (512)")
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if fmt not in ["raw", "qcow2", "vdi", "vmdk"]:
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raise ValueError("`format` must be one of raw, qcow, vdi, vmdk")
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image = "/var/tmp/osbuild-image.raw"
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grub2_core = "/var/tmp/grub2-core.img"
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# Create an empty image file
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subprocess.run(["truncate", "--size", str(size), image], check=True)
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# Set up the partition table of the image
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partition_table = f"label: mbr\nlabel-id: {ptuuid}\nbootable, type=83"
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subprocess.run(["sfdisk", "-q", image], input=partition_table, encoding='utf-8', check=True)
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r = subprocess.run(["sfdisk", "--json", image], stdout=subprocess.PIPE, encoding='utf-8', check=True)
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partition_table = json.loads(r.stdout)
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partition = partition_table["partitiontable"]["partitions"][0]
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partition_offset = partition["start"] * 512
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partition_size = partition["size"] * 512
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# Create the level-2 bootloader
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# The purpose of this is to find the grub modules and configuration
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# to be able to start the level-3 bootloader. It contains the modules
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# necessary to do this, but nothing else.
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subprocess.run(["grub2-mkimage",
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"--verbose",
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"--directory", "/usr/lib/grub/i386-pc",
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"--prefix", "(,msdos1)/boot/grub2",
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"--format", "i386-pc",
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"--compression", "auto",
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"--output", grub2_core,
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"part_msdos", "ext2", "biosdisk"],
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check=True)
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assert os.path.getsize(grub2_core) < partition_offset - 512
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with open(image, "rb+") as image_f:
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# Install the level-1 bootloader into the start of the MBR
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# The purpose of this is simply to jump into the level-2 bootloader.
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with open("/usr/lib/grub/i386-pc/boot.img", "rb") as boot_f:
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# The boot.img file is 512 bytes, but we must only copy the first 440
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# bytes, as these contain the bootstrapping code. The rest of the
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# first sector contains the partition table, and must not be
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# overwritten.
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image_f.write(boot_f.read(440))
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# Install the level-2 bootloader into the space after the MBR, before
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# the first partition.
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with open(grub2_core, "rb") as core_f:
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image_f.seek(512)
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shutil.copyfileobj(core_f, image_f)
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with loop_client.device(image, partition_offset, partition_size) as loop:
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# Populate the first partition of the image with an ext4 fs
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subprocess.run(["mkfs.ext4", "-U", root_fs_uuid, loop],
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input="y", encoding='utf-8', check=True)
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# Copy the tree into the target image
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with mount(loop) as mountpoint:
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subprocess.run(["cp", "-a", f"{tree}/.", mountpoint], check=True)
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extra_args = []
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# raw and vdi don't suppport compression
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if fmt not in ("raw", "vdi"):
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extra_args.append("-c")
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subprocess.run(["qemu-img", "convert", "-O", fmt, *extra_args, image, f"{output_dir}/{filename}"], check=True)
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if __name__ == '__main__':
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args = json.load(sys.stdin)
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with socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM) as sock:
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sock.setsockopt(socket.SOL_SOCKET, socket.SO_PASSCRED, 1)
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sock.connect("/run/osbuild/api/remoteloop")
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ret = main(args["tree"], args["output_dir"], args["options"], remoteloop.LoopClient(sock))
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sys.exit(ret)
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