Win10 ISO挂载一次之后，sha1sum就变了，为什么？？

kashu · **发表于 :** 2016-04-24 19:18

已经有人发了帖子（https://forum.ubuntu.org.cn/viewtopic.php?p=3162525#p3162525），说有灵异现象，其实，我好像也碰到了……
所以想确认一下

这是我在“我告诉你”上下载的Win 10镜像文件

引用:

文件名 cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso
SHA1 883A8DD83863DC68A56090FB69D82F8043273D10
文件大小 3.99GB
发布时间 2016-03-30
ed2k://|file|cn_windows_10_multiple_edi ... 3EFC3C79|/

先校验，sha1sum确实一致

引用:

kashu:~$ sha1sum /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso
883a8dd83863dc68a56090fb69d82f8043273d10 /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso

kashu:~$ file /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso
/home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso: # ISO 9660 CD-ROM filesystem data 'CCSA_X64FRE_ZH-CN_DV5' (bootable)

kashu:~$ sudo mount -t iso9660 /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso /mnt
mount: block device /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso is write-protected, mounting read-only

kashu:~$ ls /mnt
readme.txt

kashu:~$ sudo umount /mnt
kashu:~$ sha1sum /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso
883a8dd83863dc68a56090fb69d82f8043273d10 /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso

kashu:~$ sudo mount -t loop /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso /mnt
mount: unknown filesystem type 'loop'

kashu:~$ sha1sum /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso
883a8dd83863dc68a56090fb69d82f8043273d10 /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso

kashu:~$ sudo mount -t udf /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso /mnt
mount: block device /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso is write-protected, mounting read-only

kashu:~$ ls /mnt
autorun.inf boot bootmgr bootmgr.efi efi setup.exe sources support

kashu:~$ sudo umount /mnt

kashu:~$ sha1sum /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso
424f51a35d0e901c3f5690217e8c1c332a354328 /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso

上面是我一系列连续的操作，最后，sha1sum就变了……
实际上只做了一个操作：sudo mount -t udf /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso /mnt
为什么会这样？

操作系统：Xubuntu 14.04.4 LTS 64-bit
kashu:~$ mount --version
mount from util-linux 2.20.1 (with libblkid and selinux support)

kashu · **发表于 :** 2016-04-24 19:30

然后，我再挂载一次，又变了……

引用:

kashu:~$ sudo mount -t udf /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso /mnt
mount: block device /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso is write-protected, mounting read-only

kashu:~$ ll /mnt
total 1.6M
-r-xr-xr-x 1 nobody nogroup 128 Mar 20 07:29 autorun.inf*
dr-xr-xr-x 5 nobody nogroup 564 Mar 20 07:29 boot/
-r-xr-xr-x 1 nobody nogroup 395K Mar 20 07:29 bootmgr*
-r-xr-xr-x 1 nobody nogroup 1.2M Mar 20 07:29 bootmgr.efi*
dr-xr-xr-x 4 nobody nogroup 148 Mar 20 07:29 efi/
-r-xr-xr-x 1 nobody nogroup 68K Mar 20 07:29 setup.exe*
dr-xr-xr-x 11 nobody nogroup 15K Mar 20 07:29 sources/
dr-xr-xr-x 3 nobody nogroup 96 Mar 20 07:29 support/

kashu:~$ sudo umount /mnt

kashu:~$ sha1sum /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso
8826e9211ec11a54c219121f435eb5655a43c194 /home/kashu/cn_windows_10_multiple_editions_insider_preview_14295_x64_dvd_8475180.iso

vickycq · **发表于 :** 2016-04-24 20:28

man mount 写道:

-r, --read-only
Mount the filesystem read-only. A synonym is -o ro.

Note that, depending on the filesystem type, state and kernel behavior, the system may still write to the device. For example, ext3 and ext4 will replay the journal if the filesystem is dirty. To prevent this kind of write access, you may want to mount an ext3 or ext4 filesystem with the ro,noload mount options or set the block device itself to read-only mode, see the blockdev(8) command.

参考
http://unix.stackexchange.com/questions/149459/mount-o-loop-changes-mounted-iso-image-file
http://unix.stackexchange.com/questions/64872/md5sum-change-after-mount
https://bugs.launchpad.net/ubuntu/+source/kernel-package/+bug/1277146
http://www.spinics.net/lists/linux-fsdevel/msg89010.html

kashu · **发表于 :** 2016-04-24 20:34

谢谢！学习了，mount用了这么久，我第一次知道仅仅做个 mount 操作，文件完整性居然也是会变化的。

看来，-o ro 有时千万不能省略

Win10 ISO挂载一次之后，sha1sum就变了，为什么？？

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