# -*- coding: utf-8 -*- # # Copyright (C) 2014 GNS3 Technologies Inc. # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program 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 General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see . import os import hashlib from ..config import Config from . import force_unix_path from io import DEFAULT_BUFFER_SIZE import logging log = logging.getLogger(__name__) def list_images(emulator_type): """ Scan directories for available image for a given emulator type :param emulator_type: emulator type (dynamips, qemu, iou) """ files = set() images = [] server_config = Config.instance().get_section_config("Server") general_images_directory = os.path.expanduser(server_config.get("images_path", "~/GNS3/images")) # Subfolder of the general_images_directory specific to this emulator type default_directory = default_images_directory(emulator_type) for directory in images_directories(emulator_type): # We limit recursion to path outside the default images directory # the reason is in the default directory manage file organization and # it should be flat to keep things simple recurse = True if os.path.commonprefix([directory, general_images_directory]) == general_images_directory: recurse = False directory = os.path.normpath(directory) for root, _, filenames in _os_walk(directory, recurse=recurse): for filename in filenames: if filename in files: log.debug("File {} has already been found, skipping...".format(filename)) continue if filename.endswith(".md5sum") or filename.startswith("."): continue files.add(filename) filesize = os.stat(os.path.join(root, filename)).st_size if filesize < 7: log.debug("File {} is too small to be an image, skipping...".format(filename)) continue try: with open(os.path.join(root, filename), "rb") as f: # read the first 7 bytes of the file. elf_header_start = f.read(7) if emulator_type == "dynamips" and elf_header_start != b'\x7fELF\x01\x02\x01': # IOS images must start with the ELF magic number, be 32-bit, big endian and have an ELF version of 1 log.warning("IOS image {} does not start with a valid ELF magic number, skipping...".format(filename)) continue elif emulator_type == "iou" and elf_header_start != b'\x7fELF\x02\x01\x01' and elf_header_start != b'\x7fELF\x01\x01\x01': # IOU images must start with the ELF magic number, be 32-bit or 64-bit, little endian and have an ELF version of 1 log.warning("IOU image {} does not start with a valid ELF magic number, skipping...".format(filename)) continue elif emulator_type == "qemu" and elf_header_start[:4] == b'\x7fELF': # QEMU images should not start with an ELF magic number log.warning("QEMU image {} starts with an ELF magic number, skipping...".format(filename)) continue # It the image is located in the standard directory the path is relative if os.path.commonprefix([root, default_directory]) != default_directory: path = os.path.join(root, filename) else: path = os.path.relpath(os.path.join(root, filename), default_directory) images.append( { "filename": filename, "path": force_unix_path(path), "md5sum": md5sum(os.path.join(root, filename)), "filesize": filesize } ) except OSError as e: log.warning("Can't add image {}: {}".format(path, str(e))) return images def _os_walk(directory, recurse=True, **kwargs): """ Work like os.walk but if recurse is False just list current directory """ if recurse: for root, dirs, files in os.walk(directory, **kwargs): yield root, dirs, files else: files = [] for filename in os.listdir(directory): if os.path.isfile(os.path.join(directory, filename)): files.append(filename) yield directory, [], files def default_images_directory(emulator_type): """ :returns: Return the default directory for a node type """ server_config = Config.instance().get_section_config("Server") img_dir = os.path.expanduser(server_config.get("images_path", "~/GNS3/images")) if emulator_type == "qemu": return os.path.join(img_dir, "QEMU") elif emulator_type == "iou": return os.path.join(img_dir, "IOU") elif emulator_type == "dynamips": return os.path.join(img_dir, "IOS") else: raise NotImplementedError("%s node type is not supported", emulator_type) def images_directories(emulator_type): """ Return all directories where we will look for images by priority :param emulator_type: Type of emulator """ server_config = Config.instance().get_section_config("Server") paths = [] img_dir = os.path.expanduser(server_config.get("images_path", "~/GNS3/images")) type_img_directory = default_images_directory(emulator_type) try: os.makedirs(type_img_directory, exist_ok=True) paths.append(type_img_directory) except (OSError, PermissionError): pass for directory in server_config.get("additional_images_path", "").split(";"): paths.append(directory) # Compatibility with old topologies we look in parent directory paths.append(img_dir) # Return only the existing paths return [force_unix_path(p) for p in paths if os.path.exists(p)] def md5sum(path, stopped_event=None): """ Return the md5sum of an image and cache it on disk :param path: Path to the image :param stopped_event: In case you execute this function on thread and would like to have possibility to cancel operation pass the `threading.Event` :returns: Digest of the image """ if path is None or len(path) == 0 or not os.path.exists(path): return None try: with open(path + '.md5sum') as f: md5 = f.read().strip() if len(md5) == 32: return md5 # Unicode error is when user rename an image to .md5sum .... except (OSError, UnicodeDecodeError): pass try: m = hashlib.md5() log.debug("Calculating MD5 sum of `{}`".format(path)) with open(path, 'rb') as f: while True: if stopped_event is not None and stopped_event.is_set(): log.error("MD5 sum calculation of `{}` has stopped due to cancellation".format(path)) return buf = f.read(DEFAULT_BUFFER_SIZE) if not buf: break m.update(buf) digest = m.hexdigest() except OSError as e: log.error("Can't create digest of %s: %s", path, str(e)) return None try: with open('{}.md5sum'.format(path), 'w+') as f: f.write(digest) except OSError as e: log.error("Can't write digest of %s: %s", path, str(e)) return digest def remove_checksum(path): """ Remove the checksum of an image from cache if exists """ path = '{}.md5sum'.format(path) if os.path.exists(path): os.remove(path)