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Re: Unexpected behaviour of tsort



Thanks for the report.
This will be fixed in the textutils, eventually.
I don't have time right now.

I'll gladly consider patches.

Torsten Landschoff <torsten@debian.org> writes:
| Hi textutils developers,
|
| I am writing to you because we (Debian) got a release critical bug
| against our textutils package. It seems that tsort does not behave as
| most people would expect.
|
| Note: I am not the maintainer of that package but a member of the
| Quality Assurance team.
|
| As the behaviour of tsort conforms to the documentation this is not
| really a bug. Problem is that the other unices I tried this on report
| the error but nonetheless they try to generate senseful output on
| stdout.
|
| This is from the manpage of tsort on SuSE Linux:
|
|      If the graph contains a cycle (and therefore cannot be properly
|      sorted), one of the arcs in the cycle is ignored and the sort
|      continues.  Cycles are reported on standard error.
|
| SuSE seems to use the BSD version of tsort. On Solaris there is no
| reference to this problem in the manpage but output is generated anyway.
|
| As Debian tries to stay compatible with other Linux versions we are
| thinking of replacing tsort with the BSD version but as we ship
| GNU/Linux we would like a new GNU version which fixes this better.
|
| So please consider changing the behaviour of tsort. If you lack the
| manpower I could help with the patch but I am out of reach starting this
| Friday for a week.
|
| Here is the original bugreport:
|
| > Date: Fri, 27 Aug 1999 12:53:44 +0200
| > From: "J.H.M. Dassen (Ray)" <jdassen@wi.LeidenUniv.nl>
| > To: submit@bugs.debian.org
| > Subject: textutils: tsort behaves unexpectedly
| >
| > Package: textutils
| > Version: 2.0-2
| > Severity: important
| >
| > [Severity motiviation: this breaks behaviour expected by some source builds,
| > e.g. of netkit-telnet-ssl.]
| >
| > Consider the following data:
| >         auth.o auth.o
| >         misc.o misc.o
| >         ssl.o ssl.o
| >         sslapp.o sslapp.o
| >         ssl.o misc.o
| >         ssl.o auth.o
| >         auth.o misc.o
| >         ssl.o auth.o
| >         misc.o auth.o
| >         auth.o ssl.o
| >         sslapp.o ssl.o
| >         auth.o misc.o
| >         ssl.o sslapp.o
| >
| > Running tsort on this results in these errors on stderr
| > [this is correct: a true topological sort does not exists when there are
| > cycles]
| >         tsort: -: input contains a loop:
| >
| >         tsort: auth.o
| >         tsort: misc.o
| > and no output no stdout.
| >
| > In 2.1, tsort was built from bsd sources rather than the GNU textutils. That
| > version also gives warnings on stderr
| >         tsort: cycle in data
| >         tsort: ssl.o
| >         tsort: sslapp.o
| >         tsort: cycle in data
| >         tsort: misc.o
| >         tsort: auth.o
| >         tsort: ssl.o
| >         tsort: cycle in data
| >         tsort: auth.o
| >         tsort: misc.o
| > but does produce output on stdout
| > [namely a fewest-cycles sort of the input]
| >         sslapp.o
| >         ssl.o
| >         misc.o
| >         auth.o
| >
| > This behaviour is expected by a number of source builds, which contain an
| > optimisation in library generation:
| >         ar [some flags] `lorder *.o | tsort`
| >
| > Please make GNU's tsort behave like the BSD one, or coordinate with the
| > bsdmainutils maintainer to switch back to the BSD version.
| >
| > -- System Information
| > Debian Release: potato
| > Kernel Version: Linux jcn206a 2.2.12-int2.2.11.2 #3 Fri Aug 27
| > 10:02:05 CEST 19 99 i586 unknown
| >
| > Versions of the packages textutils depends on:
| > ii  libc6     2.1.2-0pre11   GNU C Library: Shared libraries and timezone
|
| Torsten Landschoff for the Debian QA Group


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