[Buildroot] [PATCH 12/15] package/pkg-generic.mk: Generate final rsync exclude file list

Hi,

On Tue, 22 Jun 2021 23:15:10 +0200
"Yann E. MORIN" [off-list ref] wrote:

Ideally, we would in fact redirect the package installation to an emoty
directory, so that we can actually find what it installs.

However, as has been discussed in the past, this is fraught with
unworkable issues. For example, some paths may be hard-coded at
configure time and/or build time, and thus the package would still
install in the original stagin we presented it with (for target/, this
is not an isue, because target/ is never looked at during configure or
build, only at install time). Or a package may try to modify an existing
file (bad, but still). Or a file just assumes that tdirectory structure
exists (bad, but eh...)

Modifying existing files is no more allowed -> Overwrites detection.

So, yes, the rsync exclusion list is a good workaround.

I see you have provided detailed comit logs, that is great. Still, for
such core stuff, I think they still miss the bigger picture, like I
explained above for example, and which should have been part of the
commit log to explain why we resort to an exclusion list rather than the
more obvious and simple empty-DESTDIR.

I can add at the end of commit log :

--- 8< ---

Using an empty directory for per-package installation directory would be the
simplest way to find what a package installs.
However, as it has been discussed in the past, this is fraught with unworkable
issues. For example, some paths may be hard-coded at configure time and/or build
time, and thus the package would still install in the original stagin we presented
it with (for target/, this is not an isue, because target/ is never looked at
during configure or build, only@install time). Or a package installation
process just assumes that the directory structure exists (bad, but eh...).

--- 8< ---

Is that ok for you ?

quoted

+define pkg_final_rsync_after
+	cd $(1); \
+	LC_ALL=C find . \( -type f -o -type l \) -printf '%T@:%i:%#m:%y:%s,%p\n' \
+		| LC_ALL=C sort > $($(PKG)_DIR)/.files-final-rsync$(2).after
+	LC_ALL=C comm -2 \
+		$($(PKG)_DIR)/.files-final-rsync$(2).before \
+		$($(PKG)_DIR)/.files-final-rsync$(2).after \
+		| sed -r -e 's/^[^,]+,./- /' \
+		> $($(PKG)_DIR)/.files-final-rsync$(2).exclude_rsync
+	rm -f $($(PKG)_DIR)/.files-final-rsync$(2).after  

You forgot to remove .files-final-rsync$(2).before

I cannot remove it in this patch.

.files-final-rsync$(2).before is generated by .stamp_configured rule calling
pkg_final_rsync_before call and if we run 'make && make foo-rebuild' the file
generated by first make invocation will be no more present for second make
invocation.

We can remove .files-final-rsync$(2).before only after patch
"package/pkg-generic.mk: Fix per-package <pkg>-{reconfigure,rebuild,reinstall}"
Indeed, in this patch, pkg_final_rsync_after is called after the per-package
host and target dir are recreated from scratch.

I will remove .files-final-rsync$(2).before in a dedicated patch after
"package/pkg-generic.mk: Fix per-package <pkg>-{reconfigure,rebuild,reinstall}"

Is that ok for you ?

Herv?

-- 
Herv? Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com