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Date: Sat, 17 Feb 2007 05:07:41 -0800
From: Brian Dessent <brian AT dessent DOT net>
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To: cygwin AT cygwin DOT com
Subject: Re: Problems with setup.exe snapshots?
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Angelo Graziosi wrote:

> 
> It looks as a difficulty to copy post-texmf.sh in /etc/postinstall (adding
> .done).
> 
> The problems disappear if one uses setup.exe-2.510 (the official version).

First, a note: tetex-base and tetex-tiny are meant to be mutually
exclusive: you should install one or the other but not both.  The -tiny
provides a usable subset of the full -base functionality.  (At least
that's the way I understand it.)

The reason for this problem is arguably due to a packaging error.  All
three of tetex-tiny,extra,base own the file
/etc/postinstall/post-texmf.sh.  This is a no-no, as no two packages
should own the same file, otherwise when one is removed it will no
longer remain for the other.

The way this comes to happen with the postinstall is that setup first
runs the postinstall for tetex-base, which succeeds, and is renamed to
post-texmf.sh.done.  Then it tries to run the postinstall for
tetex-extra.  But the .sh file does not exist so we get:

2007/02/17 04:46:04 running: C:\cygwin\bin\bash.exe -c
/etc/postinstall/post-texmf.sh
/usr/bin/bash: /etc/postinstall/post-texmf.sh: No such file or directory
2007/02/17 04:46:04 abnormal exit: exit code=127

Which corresponds to this code:

  if (retval)
    log(LOG_PLAIN) << "abnormal exit: exit code=" << retval << endLog;;

  /* if file exists then delete it otherwise just ignore no file error
*/
  io_stream::remove ("cygfile://" + scriptName + ".done");

  io_stream::move ("cygfile://" + scriptName,
                   "cygfile://" + scriptName + ".done");

And as you can now see, the second invocation of the postinstall deletes
the .done file that was renamed by the first invocation, and the file is
now gone.

The reason it did not happen with 2.510 was because that version was
buggy.  There are two passes that setup.exe uses to determine the list
of postinstall scripts that need to be run.  The first is that while
unpacking package tarballs it keeps a running list of all files
extracted under /etc/postinstall.  It runs these first, renaming each to
.done.

In the second pass, it scans all files that remain under
/etc/postinstall that do not have the .done extension and runs them. 
This allows for one postinstall script to dynamically create a
postinstall script at runtime that did not exist in the package's
tarball, for example.

In setup.exe 2.510 there was a bug in the first pass that caused no
files to ever match /etc/postinstall, so all packages ended up being
processed by the second pass.  This is, incidently, why 2.510 says "No
Package" during the postinstall phase, whereas in the snapshot versions
it actually says the current pacakage name during the postinstall
routine.  This is because the "first pass" method allows it to associate
a package name with each script, whereas the "second pass" method does
not allow to infer which package a script belongs to, so all it can say
is "No Package".

Sooo.  These tetex packages need to be fixed so that there is no
filename overlap.  It would probably also be good to change setup so
that it doesn't try to run the same postinstall script more than once. 
I can think of several ways to do this, I'm not sure which is best.

Brian

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