Bug#327499: Preseeding early/late commands can fail on directory change
Package: preseed-common
Tags: patch
This bug is the result of the following thread on the d-boot list:
http://lists.debian.org/debian-boot/2005/09/msg00092.html
---------- Forwarded Message ----------
Subject: Re: Preseeing w/o asking a question
Date: Friday 09 September 2005 13:31
From: Paul Millar <p.millar@physics.gla.ac.uk>
To: Joey Hess <joeyh@debian.org>
Cc: debian-boot@lists.debian.org
On Thursday 08 Sep 2005 18:23, Joey Hess wrote:
> > It was a single line, but a big(ish) one (77 characters, iirc). I've
> > reduced its size (52 characters, now) and it seems to be working. Is
> > there some limit to the size of a string?
>
> It's possible to run into some limits once the string is 20000
> character long or so (ARG_MAX), but it's more likely that your first
> command exited nonzero and your truncated one succeeds.
Nope, this is all a red-herring.
The real problem was that base-config/late_command is sensitive to cwd
after the script exits. As an illustration, try:
base-config base-config/late_command string cd /tmp
For me, this is sufficient to stall the installer.
There's a trivial patch to base-config below that should fix the problem
(but I haven't tested it :^). Alternatively, one could eval the
$PRESEED_COMMAND within a new shell for better protection (rather than
in base-config's shell).
Meanwhile, being careful to make sure the script ends with the same cwd
as it starts is a work-around.
Cheers,
Paul.
--- lib/menu/finish-orig 2005-09-09 11:36:30.892331830 +0100
+++ lib/menu/finish 2005-09-09 11:35:39.678301614 +0100
@@ -30,8 +30,10 @@
# See if there is a preseeded command. If so, run it.
PRESEED_COMMAND=$($0 get_preseed_command 4>&1 || true)
if [ -n "$PRESEED_COMMAND" ]; then
+ curdir=$(pwd)
# TODO error handling (needs error dialog)
eval $PRESEED_COMMAND || true
+ cd $(curdir)
fi
DMS=""
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