mirror of
https://github.com/GNS3/gns3-server
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293 lines
11 KiB
Python
293 lines
11 KiB
Python
#
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# Copyright (C) 2014 GNS3 Technologies Inc.
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import os
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import hashlib
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import stat
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import aiofiles
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import shutil
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from typing import AsyncGenerator
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from ..config import Config
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from . import force_unix_path
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import gns3server.db.models as models
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from gns3server.db.repositories.images import ImagesRepository
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import logging
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log = logging.getLogger(__name__)
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def list_images(image_type):
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"""
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Scan directories for available image for a given type.
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:param image_type: image type (dynamips, qemu, iou)
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"""
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files = set()
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images = []
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server_config = Config.instance().settings.Server
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general_images_directory = os.path.expanduser(server_config.images_path)
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# Subfolder of the general_images_directory specific to this VM type
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default_directory = default_images_directory(image_type)
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for directory in images_directories(image_type):
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# We limit recursion to path outside the default images directory
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# the reason is in the default directory manage file organization and
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# it should be flatten to keep things simple
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recurse = True
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if os.path.commonprefix([directory, general_images_directory]) == general_images_directory:
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recurse = False
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directory = os.path.normpath(directory)
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for root, _, filenames in _os_walk(directory, recurse=recurse):
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for filename in filenames:
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path = os.path.join(root, filename)
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if filename not in files:
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if filename.endswith(".md5sum") or filename.startswith("."):
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continue
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elif (
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((filename.endswith(".image") or filename.endswith(".bin")) and image_type == "dynamips")
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or ((filename.endswith(".bin") or filename.startswith("i86bi")) and image_type == "iou")
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or (not filename.endswith(".bin") and not filename.endswith(".image") and image_type == "qemu")
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):
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files.add(filename)
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# It the image is located in the standard directory the path is relative
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if os.path.commonprefix([root, default_directory]) != default_directory:
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path = os.path.join(root, filename)
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else:
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path = os.path.relpath(os.path.join(root, filename), default_directory)
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try:
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if image_type in ["dynamips", "iou"]:
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with open(os.path.join(root, filename), "rb") as f:
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# read the first 7 bytes of the file.
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elf_header_start = f.read(7)
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# valid IOS images must start with the ELF magic number, be 32-bit, big endian and have an ELF version of 1
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if (
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not elf_header_start == b"\x7fELF\x01\x02\x01"
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and not elf_header_start == b"\x7fELF\x01\x01\x01"
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):
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continue
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images.append(
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{
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"filename": filename,
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"path": force_unix_path(path),
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"md5sum": md5sum(os.path.join(root, filename)),
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"filesize": os.stat(os.path.join(root, filename)).st_size,
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}
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)
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except OSError as e:
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log.warning(f"Can't add image {path}: {str(e)}")
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return images
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def _os_walk(directory, recurse=True, **kwargs):
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"""
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Work like os.walk but if recurse is False just list current directory
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"""
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if recurse:
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for root, dirs, files in os.walk(directory, **kwargs):
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yield root, dirs, files
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else:
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files = []
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for filename in os.listdir(directory):
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if os.path.isfile(os.path.join(directory, filename)):
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files.append(filename)
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yield directory, [], files
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def default_images_directory(image_type):
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"""
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:returns: Return the default directory for an image type.
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"""
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server_config = Config.instance().settings.Server
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img_dir = os.path.expanduser(server_config.images_path)
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if image_type == "qemu":
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return os.path.join(img_dir, "QEMU")
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elif image_type == "iou":
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return os.path.join(img_dir, "IOU")
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elif image_type == "dynamips" or image_type == "ios":
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return os.path.join(img_dir, "IOS")
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else:
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raise NotImplementedError(f"%s node type is not supported", image_type)
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def images_directories(type):
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"""
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Return all directories where we will look for images
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by priority
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:param type: Type of emulator
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"""
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server_config = Config.instance().settings.Server
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paths = []
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img_dir = os.path.expanduser(server_config.images_path)
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type_img_directory = default_images_directory(type)
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try:
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os.makedirs(type_img_directory, exist_ok=True)
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paths.append(type_img_directory)
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except (OSError, PermissionError):
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pass
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for directory in server_config.additional_images_paths:
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paths.append(directory)
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# Compatibility with old topologies we look in parent directory
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paths.append(img_dir)
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# Return only the existing paths
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return [force_unix_path(p) for p in paths if os.path.exists(p)]
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def md5sum(path, working_dir=None, stopped_event=None):
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"""
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Return the md5sum of an image and cache it on disk
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:param path: Path to the image
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:param workdir_dir: where to store .md5sum files
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:param stopped_event: In case you execute this function on thread and would like to have possibility
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to cancel operation pass the `threading.Event`
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:returns: Digest of the image
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"""
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if path is None or len(path) == 0 or not os.path.exists(path):
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return None
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if working_dir:
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md5sum_file = os.path.join(working_dir, os.path.basename(path) + ".md5sum")
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else:
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md5sum_file = path + ".md5sum"
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try:
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with open(md5sum_file) as f:
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md5 = f.read().strip()
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if len(md5) == 32:
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return md5
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# Unicode error is when user rename an image to .md5sum ....
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except (OSError, UnicodeDecodeError):
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pass
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try:
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m = hashlib.md5()
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with open(path, "rb") as f:
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while True:
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if stopped_event is not None and stopped_event.is_set():
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log.error(f"MD5 sum calculation of `{path}` has stopped due to cancellation")
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return
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buf = f.read(128)
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if not buf:
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break
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m.update(buf)
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digest = m.hexdigest()
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except OSError as e:
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log.error("Can't create digest of %s: %s", path, str(e))
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return None
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try:
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with open(md5sum_file, "w+") as f:
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f.write(digest)
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except OSError as e:
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log.error("Can't write digest of %s: %s", path, str(e))
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return digest
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def remove_checksum(path):
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"""
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Remove the checksum of an image from cache if exists
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"""
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path = f"{path}.md5sum"
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if os.path.exists(path):
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os.remove(path)
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class InvalidImageError(Exception):
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def __init__(self, message: str):
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super().__init__()
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self._message = message
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def __str__(self):
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return self._message
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def check_valid_image_header(data: bytes) -> str:
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if data[:7] == b'\x7fELF\x01\x02\x01':
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# for IOS images: file must start with the ELF magic number, be 32-bit, big endian and have an ELF version of 1
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return "ios"
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elif data[:7] == b'\x7fELF\x01\x01\x01' or data[:7] == b'\x7fELF\x02\x01\x01':
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# for IOU images file must start with the ELF magic number, be 32-bit or 64-bit, little endian and
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# have an ELF version of 1 (normal IOS images are big endian!)
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return "iou"
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elif data[:4] != b'QFI\xfb' or data[:4] != b'KDMV':
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return "qemu"
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else:
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raise InvalidImageError("Could not detect image type, please make sure it is a valid image")
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async def write_image(
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image_filename: str,
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image_path: str,
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stream: AsyncGenerator[bytes, None],
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images_repo: ImagesRepository,
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check_image_header=True
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) -> models.Image:
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image_dir, image_name = os.path.split(image_filename)
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log.info(f"Writing image file to '{image_path}'")
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# Store the file under its final name only when the upload is completed
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tmp_path = image_path + ".tmp"
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os.makedirs(os.path.dirname(image_path), exist_ok=True)
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checksum = hashlib.md5()
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header_magic_len = 7
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image_type = None
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try:
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async with aiofiles.open(tmp_path, "wb") as f:
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async for chunk in stream:
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if check_image_header and len(chunk) >= header_magic_len:
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check_image_header = False
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image_type = check_valid_image_header(chunk)
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await f.write(chunk)
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checksum.update(chunk)
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image_size = os.path.getsize(tmp_path)
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if not image_size or image_size < header_magic_len:
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raise InvalidImageError("The image content is empty or too small to be valid")
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checksum = checksum.hexdigest()
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duplicate_image = await images_repo.get_image_by_checksum(checksum)
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if duplicate_image and os.path.dirname(duplicate_image.path) == os.path.dirname(image_path):
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raise InvalidImageError(f"Image {duplicate_image.filename} with "
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f"same checksum already exists in the same directory")
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except InvalidImageError:
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os.remove(tmp_path)
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raise
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os.chmod(tmp_path, stat.S_IWRITE | stat.S_IREAD | stat.S_IEXEC)
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if not image_dir:
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directory = default_images_directory(image_type)
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os.makedirs(directory, exist_ok=True)
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image_path = os.path.abspath(os.path.join(directory, image_filename))
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shutil.move(tmp_path, image_path)
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return await images_repo.add_image(image_name, image_type, image_size, image_path, checksum, checksum_algorithm="md5")
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