DEP 17: Improve support for directory aliasing in dpkg
From Helmut Grohne@21:1/5 to All on Mon Apr 3 14:10:01 2023
Hi,
I am hereby proposing a new DEP and thus allocating the number 17 for
it. The title is "Improve support for directory aliasing in dpkg". As
per DEP 0, I am announcing this on debian-project@l.d.o. The actual
discussion will start at the same time on debian-devel@l.d.o and debian-dpkg@l.d.o. Please do not reply to debian-project with technical matters.
I'm including the introduction for reference here:
At its core, dpkg assumes that every filename uniquely refers to a
file on disk. The situation where two distinct filenames refer to
the same file on disk is referred to as aliasing. Violating this
assumption leads to undefined behaviour such as file loss. The
assumption is commonly violated when a leading directory component
contains a symbolic link. A situation where this is known to cause
file loss happens when a file is moved from one binary package to
another binary package while at the same time changing the filename
in a way that retains its final location. In this situation, dpkg
may first unpack the new replacing location and then remove the
replaced package thus unknowingly remove the aliased file. Other
components such as dpkg-divert or update-alternatives are likely
affected in similar ways.
The purpose of this DEP is selecting and implementing a change to
dpkg to improve the way it handles such situations that affect
typical Debian installations.