meson: de-duplicate binaries using hard links

Use custom targets to create hard links for testing.
meson will install these as duplicate files, so use a custom install script.

meson.build

@@ -6,7 +6,7 @@ project('OpenRC', 'c',
     'prefix=/usr',
     'warning_level=3',
     ],
-  meson_version : '>=0.53.2')
+  meson_version : '>=0.57.0')
 
 cc = meson.get_compiler('c')
 fs = import('fs')
@@ -201,6 +201,8 @@ init_d_conf_data.set('SYSCONFDIR', get_option('sysconfdir'))
 dl_dep = cc.find_library('dl', required: false)
 util_dep = cc.find_library('util', required: false)
 
+install_hardlinks = files('tools' / 'meson_install_hardlinks.sh')
+
 subdir('bash-completion')
 subdir('conf.d')
 subdir('etc')

src/einfo/meson.build

@@ -1,6 +1,5 @@
 einfo_execs = [
   'einfon',
-  'einfo',
   'ewarnn',
   'ewarn',
   'eerrorn',
@@ -22,11 +21,21 @@ einfo_execs = [
   'veoutdent',
   ]
 
+einfo = executable('einfo',
+  ['einfo.c', version_h],
+  include_directories: [incdir, einfo_incdir, rc_incdir],
+  link_with: [libeinfo, librc],
+  install: true,
+  install_dir: rc_bindir)
+
 foreach exec: einfo_execs
-  executable(exec,
-    ['einfo.c', version_h],
-    include_directories: [incdir, einfo_incdir, rc_incdir],
-    link_with: [libeinfo, librc],
-    install: true,
-    install_dir: rc_bindir)
+  custom_target(exec,
+    build_by_default: true,
+    command: ['ln', '-fn', einfo, '@OUTPUT@'],
+    output: exec)
 endforeach
+
+meson.add_install_script(install_hardlinks,
+  rc_bindir,
+  'einfo',
+  einfo_execs)

src/mark_service/meson.build

@@ -1,5 +1,4 @@
 mark_service_execs =	[
-  'mark_service_starting',
   'mark_service_started',
   'mark_service_stopping',
   'mark_service_stopped',
@@ -10,11 +9,21 @@ mark_service_execs =	[
   'mark_service_crashed',
   ]
 
+mark_service = executable('mark_service_starting',
+  ['mark_service.c', misc_c, version_h],
+  include_directories: [incdir, einfo_incdir, rc_incdir],
+  link_with: [libeinfo,librc],
+  install: true,
+  install_dir: rc_sbindir)
+
 foreach exec : mark_service_execs
-  executable(exec,
-    ['mark_service.c', misc_c, version_h],
-    include_directories: [incdir, einfo_incdir, rc_incdir],
-    link_with: [libeinfo,librc],
-    install: true,
-    install_dir: rc_sbindir)
+  custom_target(exec,
+    build_by_default: true,
+    command: ['ln', '-fn', mark_service, '@OUTPUT@'],
+    output: exec)
 endforeach
+
+meson.add_install_script(install_hardlinks,
+  rc_sbindir,
+  'mark_service_starting',
+  mark_service_execs)

src/service/meson.build

@@ -1,5 +1,4 @@
 service_execs = [
-  'service_starting',
   'service_started',
   'service_stopping',
   'service_stopped',
@@ -10,11 +9,21 @@ service_execs = [
   'service_crashed',
   ]
 
+service = executable('service_starting',
+  ['service.c', misc_c, version_h],
+  include_directories: [incdir, einfo_incdir, rc_incdir],
+  link_with: [libeinfo, librc],
+  install: true,
+  install_dir: rc_bindir)
+
 foreach exec : service_execs
-  executable(exec,
-    ['service.c', misc_c, version_h],
-    include_directories: [incdir, einfo_incdir, rc_incdir],
-    link_with: [libeinfo, librc],
-    install: true,
-    install_dir: rc_bindir)
+  custom_target(exec,
+    build_by_default: true,
+    command: ['ln', '-fn', service, '@OUTPUT@'],
+    output: exec)
 endforeach
+
+meson.add_install_script(install_hardlinks,
+  rc_bindir,
+  'service_starting',
+  service_execs)

src/value/meson.build

@@ -1,15 +1,24 @@
 value_execs = [
-  'service_get_value',
   'service_set_value',
   'get_options',
   'save_options',
   ]
 
+value = executable('service_get_value',
+  ['value.c', misc_c, version_h],
+  include_directories: [incdir, einfo_incdir, rc_incdir],
+  link_with: [libeinfo, librc],
+  install: true,
+  install_dir: rc_bindir)
+
 foreach exec : value_execs
-  executable(exec,
-    ['value.c', misc_c, version_h],
-    include_directories: [incdir, einfo_incdir, rc_incdir],
-    link_with: [libeinfo, librc],
-    install: true,
-    install_dir: rc_bindir)
+  custom_target(exec,
+    build_by_default: true,
+    command: ['ln', '-fn', value, '@OUTPUT@'],
+    output: exec)
 endforeach
+
+meson.add_install_script(install_hardlinks,
+  rc_bindir,
+  'service_get_value',
+  value_execs)

tools/meson_install_hardlinks.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+set -eu
+dir=$1
+target=$2
+shift 2
+for linkname; do
+	ln -fn "${DESTDIR}${dir}/${target}" "${DESTDIR}${dir}/${linkname}"
+done