Add support for installing binaries with DT_RPATH

It's better to use DT_RPATH dynamic section of the elf binary to store
the paths of libraries to load instead of overwriting LD_LIBRARY_PATH
for the whole environment, causing surprises. This solution is much more
transparent and perfectly suitable for running contained installations
of wayland/wlroots/sway.

The code unsetting the LD_LIBRARY_PATH/LD_PRELOAD was also deleted as
it's a placebo security at best - we should trust the execution path
that leads us to running sway, and it's way too late to care about those
variables since we already started executing our compositor, thus we
would be compromised anyway.

10 files changed, 19 insertions, 10 deletions

diff --git a/meson.build b/meson.build
index 080709fa..1e7ce281 100644
--- a/meson.build
+++ b/meson.build
@@ -128,7 +128,16 @@ else
 endif
 add_project_arguments('-DSWAY_VERSION=@0@'.format(version), language: 'c')
 
-add_project_arguments('-D_LD_LIBRARY_PATH="@0@"'.format(get_option('ld-library-path')), language: 'c')
+if get_option('use_rpath')
+	if get_option('custom_rpath') == ''
+		# default to platform specific libdir, one level up from the binary
+		rpathdir = join_paths('$ORIGIN', '..', '$LIB')
+	else
+		rpathdir = get_option('custom_rpath')
+	endif
+else
+	rpathdir = ''
+endif
 
 sway_inc = include_directories('include')
 
diff --git a/meson_options.txt b/meson_options.txt
index 50d646fd..2db852fc 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -1,5 +1,6 @@
 option('sway-version', type : 'string', description: 'The version string reported in `sway --version`.')
-option('ld-library-path', type: 'string', value: '', description: 'The LD_LIBRARY_PATH environment variable.')
+option('use_rpath', type: 'boolean', value: false, description: 'install binaries with rpath set')
+option('custom_rpath', type: 'string', value: '', description: 'override rpath with a custom one')
 option('default-wallpaper', type: 'boolean', value: true, description: 'Install the default wallpaper.')
 option('zsh-completions', type: 'boolean', value: true, description: 'Install zsh shell completions.')
 option('bash-completions', type: 'boolean', value: true, description: 'Install bash shell completions.')
diff --git a/sway/main.c b/sway/main.c
index 50b05b21..dea4a31c 100644
--- a/sway/main.c
+++ b/sway/main.c
@@ -241,14 +241,6 @@ int main(int argc, char **argv) {
 		"      --get-socketpath   Gets the IPC socket path and prints it, then exits.\n"
 		"\n";
 
-	// Security:
-	unsetenv("LD_PRELOAD");
-#ifdef _LD_LIBRARY_PATH
-	setenv("LD_LIBRARY_PATH", _LD_LIBRARY_PATH, 1);
-#else
-	unsetenv("LD_LIBRARY_PATH");
-#endif
-
 	int c;
 	while (1) {
 		int option_index = 0;
diff --git a/sway/meson.build b/sway/meson.build
index b6394ecb..6eb9a9d7 100644
--- a/sway/meson.build
+++ b/sway/meson.build
@@ -187,5 +187,6 @@ executable(
 	include_directories: [sway_inc],
 	dependencies: sway_deps,
 	link_with: [lib_sway_common],
+	install_rpath : rpathdir,
 	install: true
 )
diff --git a/swaybar/meson.build b/swaybar/meson.build
index d65edb11..7a02a33f 100644
--- a/swaybar/meson.build
+++ b/swaybar/meson.build
@@ -24,5 +24,6 @@ executable(
 		wlroots,
 	],
 	link_with: [lib_sway_common, lib_sway_client],
+	install_rpath : rpathdir,
 	install: true
 )
diff --git a/swaybg/meson.build b/swaybg/meson.build
index 8704de6d..095c5488 100644
--- a/swaybg/meson.build
+++ b/swaybg/meson.build
@@ -14,5 +14,6 @@ executable(
 		wlroots,
 	],
 	link_with: [lib_sway_common, lib_sway_client],
+	install_rpath : rpathdir,
 	install: true
 )
diff --git a/swayidle/meson.build b/swayidle/meson.build
index f62545f8..6c3ac119 100644
--- a/swayidle/meson.build
+++ b/swayidle/meson.build
@@ -14,5 +14,6 @@ executable(
 		swayidle_deps,
 	],
 	link_with: [lib_sway_common, lib_sway_client],
+	install_rpath : rpathdir,
 	install: true
 )
diff --git a/swaylock/meson.build b/swaylock/meson.build
index 6c87d173..6605340b 100644
--- a/swaylock/meson.build
+++ b/swaylock/meson.build
@@ -33,6 +33,7 @@ executable('swaylock',
 	include_directories: [sway_inc],
 	dependencies: dependencies,
 	link_with: [lib_sway_common, lib_sway_client],
+	install_rpath : rpathdir,
 	install: true
 )
 
diff --git a/swaymsg/meson.build b/swaymsg/meson.build
index 8638b838..7318349d 100644
--- a/swaymsg/meson.build
+++ b/swaymsg/meson.build
@@ -4,5 +4,6 @@ executable(
     include_directories: [sway_inc],
     dependencies: [jsonc, wlroots],
     link_with: [lib_sway_common],
+    install_rpath : rpathdir,
     install: true
 )
diff --git a/swaynag/meson.build b/swaynag/meson.build
index 2ba3ed95..223a0bc7 100644
--- a/swaynag/meson.build
+++ b/swaynag/meson.build
@@ -19,5 +19,6 @@ executable(
 		wlroots,
 	],
 	link_with: [lib_sway_common, lib_sway_client],
+	install_rpath : rpathdir,
 	install: true
 )