From 198ebc6c86380351662b8b01537f449538ff1e6b Mon Sep 17 00:00:00 2001
From: Thomas Lamprecht <t.lamprecht@proxmox.com>
Date: Thu, 14 Jan 2021 17:30:09 +0100
Subject: [PATCH] d/rules: patch out wrongly linked libraries from ELFs

this is a HACK!

It seems that due to lots of binaries getting compiled from a single
crate the compiler is confused when linking in dependencies to each
binaries ELF.

It picks up the combined set (union) of all dependencies and sets
those to every ELF. This results in the client, for example, linking
to libapt-pkg or libsystemd even if none of that symbols are used..

This could be possibly fixed by restructuring the source tree into
sub crates/workspaces or what not, not really tested and *lots* of
work.

So as stop gap measure use `ldd -u` to find out unused linkage and
remove them using `patchelf`.

While this works well, and seems to not interfere with any debug
symbol usage or other usage in general it still is a hack and should
be dropped once the restructuring of the source tree has shown to
bring similar effects.

This allows for much easier re-use of the generated client .deb
package on other Debian derivaties (e.g., Ubuntu) which got blocked
until now due to wrong libt-apt verison or the like.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
 debian/control                                |  1 +
 debian/debcargo.toml                          |  1 +
 debian/rules                                  |  7 +++++++
 .../scripts/elf-strip-unused-dependencies.sh  | 20 +++++++++++++++++++
 4 files changed, 29 insertions(+)
 create mode 100755 debian/scripts/elf-strip-unused-dependencies.sh

diff --git a/debian/control b/debian/control
index d78e575d..8a4d1dd1 100644
--- a/debian/control
+++ b/debian/control
@@ -85,6 +85,7 @@ Build-Depends: debhelper (>= 11),
  fonts-open-sans <!nodoc>,
  graphviz <!nodoc>,
  latexmk <!nodoc>,
+ patchelf,
  pve-eslint (>= 7.12.1-1),
  python3-docutils,
  python3-pygments,
diff --git a/debian/debcargo.toml b/debian/debcargo.toml
index afb9ffa0..612b5e33 100644
--- a/debian/debcargo.toml
+++ b/debian/debcargo.toml
@@ -18,6 +18,7 @@ build_depends = [
   "fonts-open-sans <!nodoc>",
   "graphviz <!nodoc>",
   "latexmk <!nodoc>",
+  "patchelf",
   "pve-eslint (>= 7.12.1-1)",
   "python3-docutils",
   "python3-pygments",
diff --git a/debian/rules b/debian/rules
index 9012f82f..22671c0a 100755
--- a/debian/rules
+++ b/debian/rules
@@ -50,5 +50,12 @@ override_dh_fixperms:
 override_dh_dwz:
 	dh_dwz --no-dwz-multifile
 
+override_dh_strip:
+	dh_strip
+	for exe in $$(find debian/proxmox-backup-client/usr \
+	  debian/proxmox-backup-server/usr -executable -type f); do \
+	  debian/scripts/elf-strip-unused-dependencies.sh "$$exe" || true; \
+	done
+
 override_dh_compress:
 	dh_compress -X.pdf
diff --git a/debian/scripts/elf-strip-unused-dependencies.sh b/debian/scripts/elf-strip-unused-dependencies.sh
new file mode 100755
index 00000000..9f89c09c
--- /dev/null
+++ b/debian/scripts/elf-strip-unused-dependencies.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+
+binary=$1
+
+exec 3< <(ldd -u "$binary" | grep -oP '[^/:]+$')
+
+patchargs=""
+dropped=""
+while read -r dep; do
+    dropped="$dep $dropped"
+    patchargs="--remove-needed $dep $patchargs"
+done <&3
+exec 3<&-
+
+if [[ $dropped == "" ]]; then
+    exit 0
+fi
+
+echo -e "patchelf '$binary' - removing unused dependencies:\n $dropped"
+patchelf $patchargs $binary