Date: Wed, 6 Sep 2000 19:20:03 -0700 (PDT) From: Gerhard Sittig <Gerhard.Sittig@gmx.net> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/21017: mtree's "no such file" message at job's end Message-ID: <200009070220.TAA18476@freefall.freebsd.org>
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The following reply was made to PR bin/21017; it has been noted by GNATS.
From: Gerhard Sittig <Gerhard.Sittig@gmx.net>
To: FreeBSD-gnats-submit@freebsd.org
Cc: Sheldon Hearn <sheldonh@uunet.co.za>
Subject: Re: bin/21017: mtree's "no such file" message at job's end
Date: Wed, 6 Sep 2000 22:26:08 +0200
On Tue, Sep 05, 2000 at 18:28 +0200, Gerhard Sittig wrote:
>
> [ ... ] I hope to have the stderr tail of truss available,
> then. Maybe I can tell you soon which syscall results in the
> ENOENT(?) error.
truss(1)ing mtree is what happened now. The result of
KEYS=nlink,type,mode,flags,uid,gid,size,time,cksum,md5digest,sha1digest,ripemd160digest
truss /usr/sbin/mtree -K $KEYS -p /usr -x -X $DBDIR/_usr.ex < $DBDIR/_usr.db 2>&1 >/dev/null | tail -500
looks like this
----- truss mtree | tail snippets -------------------------------
...
open("./compat/linux/usr/lib/libz.so.1",0,027757774510) = 3 (0x3)
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
...
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
read(0x3,0xbfbff548,0x400) = 421 (0x1a5)
read(0x3,0xbfbff548,0x400) = 0 (0x0)
close(3) = 0 (0x0)
open("./compat/linux/usr/lib/libz.so.1",0,027757774510) = 3 (0x3)
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
...
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
read(0x3,0xbfbff548,0x400) = 421 (0x1a5)
read(0x3,0xbfbff548,0x400) = 0 (0x0)
close(3) = 0 (0x0)
open("./compat/linux/usr/lib/libz.so.1.1.3",0,00) = 3 (0x3)
read(0x3,0xbfbfb948,0x4000) = 16384 (0x4000)
read(0x3,0xbfbfb948,0x4000) = 16384 (0x4000)
read(0x3,0xbfbfb948,0x4000) = 16384 (0x4000)
read(0x3,0xbfbfb948,0x4000) = 13733 (0x35a5)
read(0x3,0xbfbfb948,0x4000) = 0 (0x0)
close(3) = 0 (0x0)
open("./compat/linux/usr/lib/libz.so.1.1.3",0,027757774510) = 3 (0x3)
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
...
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
read(0x3,0xbfbff548,0x400) = 421 (0x1a5)
read(0x3,0xbfbff548,0x400) = 0 (0x0)
close(3) = 0 (0x0)
open("./compat/linux/usr/lib/libz.so.1.1.3",0,027757774510) = 3 (0x3)
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
...
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
read(0x3,0xbfbff548,0x400) = 421 (0x1a5)
read(0x3,0xbfbff548,0x400) = 0 (0x0)
close(3) = 0 (0x0)
...
open("./compat/linux/usr/lib/python1.5/site-packages/rpmmodule.so",0,027757774510) = 3 (0x3)
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
...
read(0x3,0xbfbff548,0x400) = 1024 (0x400)
read(0x3,0xbfbff548,0x400) = 168 (0xa8)
read(0x3,0xbfbff548,0x400) = 0 (0x0)
close(3) = 0 (0x0)
readlink("X11",0x804ef00,1023) ERR#2 'No such file or directory'
mtree: write(2,0xbfbff1b4,7) = 7 (0x7)
line 1361949: X11write(2,0xbfbff1e4,17) = 17 (0x11)
: write(2,0xbfbff1a4,2) = 2 (0x2)
No such file or directory
write(2,0xbfbff1a4,26) = 26 (0x1a)
sigprocmask(0x1,0x280605a0,0xbfbff84c) = 0 (0x0)
sigprocmask(0x3,0x280605b0,0x0) = 0 (0x0)
write(1,0xd2da000,958) = 958 (0x3be)
exit(0x1) process exit, rval = 256
----- truss mtree | tail snippets -------------------------------
Whoops! Why is libz.so.1.1.3 being read in chunks of 16KB when
every other file is read in single KB buffers? This "finding"
was done by chance ... There's no (obvious) reference to read in
usr.sbin/mtree/*.[ch], so I would expect it to be called from
{MD5,SHA1_,RIPEMD160_}File(3).
The symlink /usr/compat/linux/usr/lib/X11 seems to cause the
error. The db description looks like this:
----- _usr.db snippet for the symlink ---------------------------
...
# ./compat/linux/usr/lib
/set type=file uid=0 gid=0 mode=0755 nlink=1
lib type=dir nlink=8 size=1536 time=964377066.0
X11 type=link size=16 time=964377066.0 link=../X11R6/lib/X11
libbfd-2.9.1.0.24.so \
...
----- _usr.db snippet for the symlink ---------------------------
The symlink is there but "broken". This should never hurt mtree,
neither when creating nor when comparing the database.
----- ls -l output ----------------------------------------------
lrwxr-xr-x 1 root wheel 16 Jul 23 20:31 /usr/compat/linux/usr/lib/X11@ -> ../X11R6/lib/X11
ls: /usr/compat/linux/usr/X11R6/lib/X11: No such file or directory
----- ls -l output ----------------------------------------------
So I ctag(1)ed /usr/src/usr.sbin/mtree, read manpages for
readlink(2), symlink(7) and fts(3) and tried building and
checking a database for the /usr/compat/linux path only -- this
time everything worked! Well that's a surprise. (Now I can see
why you wish for a better way to cause the symptom ...)
The only thing I could see is that the above mentioned "X11" file
is the only broken symlink on the /usr filesystem (that's what I
get from "find /usr -xdev -type l -print0 | xargs -0 file | grep
broken", although symlinks aren't necessarily a problem -- perl
has a lot of these). And why does this broken symlink break
readlink(2) sometimes and sometimes it does not?
The only readlink(2) reference I can see in mtree is in the
rlink() function in compare.c -- but of course I miss all the
implicit invocations libc or fts(3) could bring with them. But
the code makes me quite sure: errors in readlink cause err(3) to
be called with the formerly mentioned "line %d: %s" message with
lineno and fname. Does it matter that lineno is always _behind_
the last db line? I'll dig into this place a little further ...
I'm really confused as to where to continue searching, but I'm
willing to help with whatever I can do ...
To summarize: It's not about the broken symlink in itself. But
readlink(2) fails at a broken symlink when something else
happened before -- but I don't know what this is. :< Could
bin/4961 (nonzero errno although there's no error) apply in this
case?
virtually yours 82D1 9B9C 01DC 4FB4 D7B4 61BE 3F49 4F77 72DE DA76
Gerhard Sittig true | mail -s "get gpg key" Gerhard.Sittig@gmx.net
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