Date: Mon, 18 Oct 1999 15:58:54 +0200 From: Marcel Moolenaar <marcel@scc.nl> To: emulation@FreeBSD.org Subject: Re: duplicate filenames under Linux emulation Message-ID: <380B279E.D4786BEB@scc.nl> References: <380A9278.638D7FC2@freenet.co.uk>, <199910180253.MAA73538@gizmo.internode.com.au>
next in thread | previous in thread | raw e-mail | index | archive | help
Mark Newton wrote:
>
> Alex wrote:
>
> > 444964 -rw-r--r-- 1 ak users 102042 Oct 17 20:23
> > bxutils-c.c
> > 444964 -rw-r--r-- 1 ak users 102042 Oct 17 20:23
> > bxutils-c.c
>
> For what it's worth, I have this bug in the to-do list for the
> SVR4 emulator too. It's caused by the fact that dirent structures
> for BSD and SysVR4 are of different sizes, so svr4_getdents()
> (and svr4_getdents64(), its 64-bit counterpart) fetches a buffer
> full of BSD dirent structures from disk (usually more than the number
> which have actually been requested) with VOP_READDIR(), rewrites them
> into another buffer full of svr4_dirent structures, and returns the
> contents of the second buffer to userspace. Next time getdents() is
> called the emulated version continues from where it left off in the
> first buffer until it has been exhaused, at which point it issues another
> VOP_READDIR() call to refresh it.
The Linuxulator doesn't have that problem. Linux binaries suffer from
the duplicate name because glibc (libc5 too?) explicitly calls lseek on
the fd of the open directory:
Linux-emul(42254): lseek(3, 0, 1)
getdents: nbytes=492, off=0
getdents: 29 cookies: 12 24 40 60 72 88 100 120 136 156 176 192 208 228
244 260
280 300 320 336 356 384 400 420 440 456 476 492 512
0(0) - .
12(12) - ..
24(28) - Archive
40(48) - .netscape
60(68) - SCC
72(84) - linux
88(100) - bin
100(116) - Drumming
120(136) - .emacs
136(156) - .Xauthority
156(180) - .signature
176(204) - Sites
192(220) - .ssh
208(236) - axhome
228(256) - GNUstep
244(276) - Docs
260(292) - .xsession
280(312) - Processors
300(336) - .wmmailrc
320(356) - .acrorc
336(376) - .prognet
356(396) - .xsession-errors
384(424) - Div
400(440) - FreeBSD
420(460) - .cvspass
440(12)
Linux-emul(42254): lseek(3, 356, 0)
Linux-emul(42254): lseek(3, 0, 1)
getdents: nbytes=492, off=356
getdents: 29 cookies: 12 24 40 60 72 88 100 120 136 156 176 192 208 228
244 260
280 300 320 336 356 384 400 420 440 456 476 492 512
356(0) - .xsession-errors
384(28) - Div
400(44) - FreeBSD
420(64) - .cvspass
440(84) - .mailrc
456(104) - .profile
476(124) - .rhosts
492(144) - .ssh2
512(332)
Linux-emul(42254): lseek(3, 0, 1)
getdents: nbytes=492, off=512
getdents: 20 cookies: 532 552 576 592 612 628 648 668 688 708 748 772
804 824 84
8 900 928 960 992 1024
512(0) - .history
532(20) - .Xdefaults
552(44) - .ICEauthority
576(68) - .cshrc
592(88) - .autosave
612(108) - .login
628(128) - Words.aw
648(148) - .mime.types
668(172) - .mailcap
688(192) - Languages
708(212) - RT
748(228) - .xemacs-options
772(256) - .bash_history
804(280) - Repository
824(304) - oracle8i.txt
848(328) - .gimp-1.1
900(348) - odbc_linux.tar.gz
928(376) - Voorstel-1.doc
960(404) - .emacs-places
992(428) - .vacation.msg
1024(40)
Linux-emul(42254): lseek(3, 960, 0)
Linux-emul(42254): lseek(3, 0, 1)
getdents: nbytes=492, off=960
getdents: 20 cookies: 532 552 576 592 612 628 648 668 688 708 748 772
804 824 84
8 900 928 960 992 1024
960(0) - .emacs-places
992(24) - .vacation.msg
1024(444)
<<and so on and so forth>>
\begin{details}
X(Y) - Z
X = file offset
Y = offset in buffer passed to binary
Z = filename
X(Y)
X = file offset at end of syscall
Y = bytes remaining in user buffer
The Linux binary showed .xsession-errors and .emacs-places twice.
\end{details}
> If it does, let me know and I'll fold the result into svr4_getdents()
> as well :-)
I don't know how it is implemented for svr4, but you may also suffer
from lseeks...
--
Marcel Moolenaar mailto:marcel@scc.nl
SCC Internetworking & Databases http://www.scc.nl/
The FreeBSD project mailto:marcel@FreeBSD.org
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-emulation" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?380B279E.D4786BEB>