Doug Wyatt wrote:
Jose Celestino wrote:
...
1. locate the open (deleted) file you want from the opening pid on
/proc/$PID/fd/*
2. cp /proc/$PID/fd/$FD somewhere
I think I read, somewhere, that in doing that I could end up
with garbage bytes at the end of the last block in the copy,
and would need to use the size from the original inode to
trim the copied file. Don't know if that's fact or not.
Also, by re-linking you preserve the mtime w/o hassling with
touch.
Interesting topic--I was wondering about this just the other day.
A quick test shows that Jose's approach does not suffer from either of
these problems. I'm using F9/ext3.
I can't say /how/ it works, but it works perfectly:
$ cp -p ~/Music/lib/Various\ Artists/Unknown/afm_St9RvdtvLeE.ogg .
$ ls -li afm_St9RvdtvLeE.ogg
233608 -rw-rw-r-- 1 joe joe 2246026 2008-07-11 21:15 afm_St9RvdtvLeE.ogg
$ audacious afm_St9RvdtvLeE.ogg &
[1] 16404
$ file /proc/16404/fd/10
/proc/16404/fd/10: symbolic link to `/home/joe/tmp/afm_St9RvdtvLeE.ogg'
$ ls -l /proc/16404/fd/10
lr-x------ 1 joe joe 64 2008-08-15 22:15 /proc/16404/fd/10 ->
/home/joe/tmp/afm_St9RvdtvLeE.ogg
$ rm afm_St9RvdtvLeE.ogg
$ ls -l /proc/16404/fd/10
lr-x------ 1 joe joe 64 2008-08-15 22:15 /proc/16404/fd/10 ->
/home/joe/tmp/afm_St9RvdtvLeE.ogg (deleted)
$ file /proc/16404/fd/10
/proc/16404/fd/10: broken symbolic link to
`/home/joe/tmp/afm_St9RvdtvLeE.ogg (deleted)'
$ cp -p /proc/16404/fd/10 afm_back_cp.ogg
$ ls -li afm_back_cp.ogg
233609 -rw-rw-r-- 1 joe joe 2246026 2008-07-11 21:15 afm_back_cp.ogg
$
[1]+ Done audacious afm_St9RvdtvLeE.ogg
$ cmp afm_back_cp.ogg ~/Music/lib/Various\
Artists/Unknown/afm_St9RvdtvLeE.ogg
$
Note that the copy has the exact same size, mtime and contents as the
original file--there's no need at all to use debugfs for this.
Even though the /proc/$PID/fd/$FD appears as a symlink in the
filesystem, it doesn't behave like a normal symlink. A plain symlink
definitely won't support this sort of copy after the target file is deleted.
<Joe
--
fedora-list mailing list
fedora-list@xxxxxxxxxx
To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
