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119 lines
3.8 KiB
Python
119 lines
3.8 KiB
Python
"""
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Linux swap file.
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Documentation: Linux kernel source code, files:
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- mm/swapfile.c
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- include/linux/swap.h
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Author: Victor Stinner
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Creation date: 25 december 2006 (christmas ;-))
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"""
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from hachoir.parser import Parser
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from hachoir.field import (ParserError, GenericVector,
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UInt32, String,
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Bytes, NullBytes, RawBytes)
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from hachoir.core.endian import LITTLE_ENDIAN
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from hachoir.core.tools import humanFilesize
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from hachoir.core.bits import str2hex
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PAGE_SIZE = 4096
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# Definition of MAX_SWAP_BADPAGES in Linux kernel:
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# (__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int)
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MAX_SWAP_BADPAGES = ((PAGE_SIZE - 10) - 1536) // 4
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class Page(RawBytes):
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static_size = PAGE_SIZE * 8
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def __init__(self, parent, name):
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RawBytes.__init__(self, parent, name, PAGE_SIZE)
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class UUID(Bytes):
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static_size = 16 * 8
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def __init__(self, parent, name, *args, **kwargs):
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Bytes.__init__(self, parent, name, 16, *args, **kwargs)
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def createDisplay(self):
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text = str2hex(self.value, format=r"%02x")
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return "%s-%s-%s-%s-%s" % (
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text[:8], text[8:12], text[12:16], text[16:20], text[20:])
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class LinuxSwapFile(Parser):
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PARSER_TAGS = {
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"id": "linux_swap",
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"file_ext": ("",),
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"category": "file_system",
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"min_size": PAGE_SIZE * 8,
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"description": "Linux swap file",
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"magic": (
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(b"SWAP-SPACE", (PAGE_SIZE - 10) * 8),
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(b"SWAPSPACE2", (PAGE_SIZE - 10) * 8),
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(b"S1SUSPEND\0", (PAGE_SIZE - 10) * 8),
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),
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}
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endian = LITTLE_ENDIAN
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def validate(self):
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magic = self.stream.readBytes((PAGE_SIZE - 10) * 8, 10)
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if magic not in (b"SWAP-SPACE", b"SWAPSPACE2", b"S1SUSPEND\0"):
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return "Unknown magic string"
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if MAX_SWAP_BADPAGES < self["nb_badpage"].value:
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return "Invalid number of bad page (%u)" % self["nb_badpage"].value
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return True
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def getPageCount(self):
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"""
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Number of pages which can really be used for swapping:
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number of page minus bad pages minus one page (used for the header)
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"""
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# -1 because first page is used for the header
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return self["last_page"].value - self["nb_badpage"].value - 1
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def createDescription(self):
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if self["magic"].value == "S1SUSPEND\0":
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text = "Suspend swap file version 1"
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elif self["magic"].value == "SWAPSPACE2":
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text = "Linux swap file version 2"
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else:
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text = "Linux swap file version 1"
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nb_page = self.getPageCount()
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return "%s, page size: %s, %s pages" % (
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text, humanFilesize(PAGE_SIZE), nb_page)
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def createFields(self):
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# First kilobyte: boot sectors
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yield RawBytes(self, "boot", 1024, "Space for disklabel etc.")
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# Header
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yield UInt32(self, "version")
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yield UInt32(self, "last_page")
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yield UInt32(self, "nb_badpage")
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yield UUID(self, "sws_uuid")
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yield UUID(self, "sws_volume")
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yield NullBytes(self, "reserved", 117 * 4)
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# Read bad pages (if any)
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count = self["nb_badpage"].value
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if count:
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if MAX_SWAP_BADPAGES < count:
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raise ParserError("Invalid number of bad page (%u)" % count)
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yield GenericVector(self, "badpages", count, UInt32, "badpage")
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# Read magic
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padding = self.seekByte(PAGE_SIZE - 10, "padding", null=True)
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if padding:
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yield padding
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yield String(self, "magic", 10, charset="ASCII")
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# Read all pages
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yield GenericVector(self, "pages", self["last_page"].value, Page, "page")
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# Padding at the end
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padding = self.seekBit(self.size, "end_padding", null=True)
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if padding:
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yield padding
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