Re: parse raw image to read block group desc table!
Andreas Dilger <[email protected]> Mon, 28 Sep 2015 13:55:11 -0600
| Newsgroups | gmane.comp.file-systems.ext3.user |
|---|---|
| Message-ID | <[email protected]> |
--===============7158793578157518559== Content-Type: multipart/alternative; boundary=Apple-Mail-AAF3577E-0B99-4384-BA01-31E5E1C9E614 Content-Transfer-Encoding: 7bit --Apple-Mail-AAF3577E-0B99-4384-BA01-31E5E1C9E614 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable On Sep 28, 2015, at 01:07, gagan chhabra <[email protected]> wrote: >=20 > Hi, >=20 > I am writing a piece of code to open a raw image file of a virtual machine= which has ubuntu installed in it. The virtual disk is formatted using MBR p= artitioning method and has 3 primary and 1 extended partition. >=20 > I want to open up that file and read the block group descriptor table and i= node table for each partition. I have written some lines of code and success= fully able to read the partition entries and the superblock of each partitio= n. First question is why you are writing your own code to do this? Much better would be to attach a loop device to the image file to handle the partition table offset, then use libext2fs to open and access the filesystem any way you want. I don't think it is possible to directly access a filesystem within an image= directly, but if that is a requirement and loop devices cannot be used, then this would be WAY easier to fix in libext2fs compared to rewriting the full ext3/4 access yourself.=20 That ensures it will be able to handle the myriad of different ext3/4 options and combinations thereof, both now and in the future.=20 Cheers, Andreas > But now I am stuck and unable to read block group descriptor table and in= ode table. Shall I post my code here? Any suggestion or resource would be of= great help. >=20 > Thanks, > Gagan > Mob: +91 97049 28427 >=20 > _______________________________________________ > Ext3-users mailing list > [email protected] > https://www.redhat.com/mailman/listinfo/ext3-users --Apple-Mail-AAF3577E-0B99-4384-BA01-31E5E1C9E614 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable <html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D= utf-8"></head><body dir=3D"auto"><div>On Sep 28, 2015, at 01:07, gagan chhab= ra <<a href=3D"mailto:[email protected]">[email protected]<= /a>> wrote:</div><div><br></div><blockquote type=3D"cite"><div><div dir=3D= "ltr"><div><div><div>Hi,<br><br></div>I am writing a piece of code to open a= raw image file of a virtual machine which has ubuntu installed in it. The v= irtual disk is formatted using MBR partitioning method and has 3 primary and= 1 extended partition.<br><br></div>I want to open up that file and read the= block group descriptor table and inode table for each partition. I have wri= tten some lines of code and successfully able to read the partition entries a= nd the superblock of each partition.<br></div></div></div></blockquote><div>= <br></div><span style=3D"background-color: rgba(255, 255, 255, 0);">First qu= estion is why you are writing your own code to do this? Much</span><div><spa= n style=3D"background-color: rgba(255, 255, 255, 0);">better would be to att= ach a loop device to the image file to handle</span></div><div><span style=3D= "background-color: rgba(255, 255, 255, 0);">the partition table offset, then= use libext2fs to open and access the</span></div><div><span style=3D"backgr= ound-color: rgba(255, 255, 255, 0);">filesystem any way you want.</span></di= v><div><span style=3D"background-color: rgba(255, 255, 255, 0);"><br></span>= </div><div><span style=3D"background-color: rgba(255, 255, 255, 0);">I don't= think it is possible to directly access </span>a filesystem within an i= mage</div><div>directly, but if that is a requirement and loop devices canno= t be used,</div><div>then this would be WAY easier to fix in libext2fs compa= red to rewriting</div><div>the full ext3/4 access yourself. </div><div>= <div><span style=3D"background-color: rgba(255, 255, 255, 0);"><br></span></= div><div><span style=3D"background-color: rgba(255, 255, 255, 0);">That ensu= res it will be able to handle the myriad of different ext3/4</span></div><di= v><span style=3D"background-color: rgba(255, 255, 255, 0);">options and comb= inations thereof, both now and in the future. <br><br>Cheers, Andreas</= span><div><br><blockquote type=3D"cite"><div><div dir=3D"ltr">But now I am s= tuck and unable to read block group descriptor table and inode table. S= hall I post my code here? Any suggestion or resource would be of great help.= <br><div><div></div><div><br clear=3D"all"></div><div><div><div><div><div cl= ass=3D"gmail_signature"><div dir=3D"ltr"><div><div dir=3D"ltr"><div><div dir= =3D"ltr"><div><div dir=3D"ltr"><div><div dir=3D"ltr"><font color=3D"#888888"= ><div dir=3D"ltr"><span><font color=3D"#888888">Thanks,<br>Gagan<br> Mob: +91 97049 28427<br></font></span></div><div><span><font color=3D"#88888= 8"><br></font></span></div></font></div></div></div></div></div></div></div>= </div></div></div></div> </div></div></div></div></div> </div></blockquote><blockquote type=3D"cite"><div><span>____________________= ___________________________</span><br><span>Ext3-users mailing list</span><b= r><span><a href=3D"mailto:[email protected]">[email protected]</a></= span><br><span><a href=3D"https://www.redhat.com/mailman/listinfo/ext3-users= ">https://www.redhat.com/mailman/listinfo/ext3-users</a></span></div></block= quote></div></div></div></body></html>= --Apple-Mail-AAF3577E-0B99-4384-BA01-31E5E1C9E614-- --===============7158793578157518559== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Ext3-users mailing list [email protected] https://www.redhat.com/mailman/listinfo/ext3-users --===============7158793578157518559==--