From 2f0cf575ec2323f94fa2704c4e72ca48e1f963e3 Mon Sep 17 00:00:00 2001
From: Anton Midyukov <antohami@altlinux.org>
Date: Mon, 27 Mar 2023 15:59:14 +0700
Subject: [PATCH] alternatives: initial feature

This feature allows you to set alternatives [1].
For example, like this:

   @$(call add,ALTERNATIVES,/usr/bin/xvt:/usr/bin/xterm)

Also, in the config itself, targets for setting alternatives may already
be predefined. For example, use/alternatives/xvt/% allows you to specify
arbitrary alternatives for xvt:
use/alternatives/xvt/xterm, use/alternatives/xvt/mate-terminal, etc.
However, an alternative must be available.

1. https://www.altlinux.org/Alternatives
---
 doc/mkimage-profiles.asciidoc                       |  2 ++
 features.in/alternatives/README                     | 13 +++++++++++++
 features.in/alternatives/config.mk                  |  6 ++++++
 .../rootfs/image-scripts.d/99-alternatives          | 10 ++++++++++
 4 files changed, 31 insertions(+)
 create mode 100644 features.in/alternatives/README
 create mode 100644 features.in/alternatives/config.mk
 create mode 100755 features.in/alternatives/rootfs/image-scripts.d/99-alternatives

diff --git a/doc/mkimage-profiles.asciidoc b/doc/mkimage-profiles.asciidoc
index 43b622a1..12f65d85 100644
--- a/doc/mkimage-profiles.asciidoc
+++ b/doc/mkimage-profiles.asciidoc
@@ -54,6 +54,8 @@ include::../features.in/README[]
 
 include::../features.in/00example/README[]
 
+include::../features.in/alternatives/README[]
+
 include::../features.in/apt-conf/README[]
 
 include::../features.in/armh-mcom02/README[]
diff --git a/features.in/alternatives/README b/features.in/alternatives/README
new file mode 100644
index 00000000..c0ce72b9
--- /dev/null
+++ b/features.in/alternatives/README
@@ -0,0 +1,13 @@
+=== features.in/alternatives ===
+
+Данная фича позволяет задавать альтернативы [1].
+Например, так:
+
+  @$(call add,ALTERNATIVES,/usr/bin/xvt:/usr/bin/xterm)
+
+Также в самом конфиге могут быть уже преопределены цели для установки альтернатив.
+Например, use/alternatives/xvt/% позволяет задавать произвольные альтернативы для xvt:
+use/alternatives/xvt/xterm, use/alternatives/xvt/mate-terminal и т.д.
+При этом альтернатива должна быть доступна.
+
+1. https://www.altlinux.org/Alternatives
diff --git a/features.in/alternatives/config.mk b/features.in/alternatives/config.mk
new file mode 100644
index 00000000..e65456b7
--- /dev/null
+++ b/features.in/alternatives/config.mk
@@ -0,0 +1,6 @@
+use/alternatives:
+	@$(call add_feature)
+	@$(call xport,ALTERNATIVES)
+
+use/alternatives/xvt/%: use/alternatives
+	@$(call add,ALTERNATIVES,/usr/bin/xvt:/usr/bin/$*)
diff --git a/features.in/alternatives/rootfs/image-scripts.d/99-alternatives b/features.in/alternatives/rootfs/image-scripts.d/99-alternatives
new file mode 100755
index 00000000..c8747aaf
--- /dev/null
+++ b/features.in/alternatives/rootfs/image-scripts.d/99-alternatives
@@ -0,0 +1,10 @@
+#!/bin/sh -efu
+
+[ -n "$GLOBAL_ALTERNATIVES" ] || exit 0
+for alternative in $GLOBAL_ALTERNATIVES; do
+	candidate="${alternative#*:}"
+	alternative="${alternative%:*}"
+	alternatives-manual "$alternative" "$candidate"
+done
+
+alternatives-update