util/uuid: replace with util/token, remove libuuid

Use 128-bit hexadecimal string tokens generated with /dev/urandom
instead of UUIDs for xdg-foreign handles, removing the libuuid
dependency. Update readme and CI. Closes #2830.

build: remove xdg-foreign feature

With no external dependencies required, there's no reason not to always
build it. Remove WLR_HAS_XDG_FOREIGN as well.

14 files changed, 44 insertions, 81 deletions

diff --git a/.builds/alpine.yml b/.builds/alpine.yml
index 3caed345..5427f275 100644
--- a/.builds/alpine.yml
+++ b/.builds/alpine.yml
@@ -7,7 +7,6 @@ packages:
   - mesa-dev
   - meson
   - pixman-dev
-  - util-linux-dev
   - wayland-dev
   - wayland-protocols
   - xcb-util-image-dev
diff --git a/.builds/freebsd.yml b/.builds/freebsd.yml
index 7806b72c..4262feed 100644
--- a/.builds/freebsd.yml
+++ b/.builds/freebsd.yml
@@ -10,7 +10,6 @@ packages:
   - graphics/png
   - graphics/wayland
   - graphics/wayland-protocols
-  - misc/e2fsprogs-libuuid
   - multimedia/ffmpeg
   - x11/libX11
   - x11/libinput
diff --git a/README.md b/README.md
index 83d818c6..f8f9583b 100644
--- a/README.md
+++ b/README.md
@@ -51,7 +51,6 @@ Install dependencies:
 * udev
 * pixman
 * libseat (optional, for (e)logind and seatd support)
-* libuuid (optional, for xdg-foreign support)
 
 If you choose to enable X11 support:
 
diff --git a/include/meson.build b/include/meson.build
index c72eada5..747e5984 100644
--- a/include/meson.build
+++ b/include/meson.build
@@ -9,13 +9,6 @@ if not features.get('xwayland')
 else
 	subdir('xwayland')
 endif
-if not features.get('xdg-foreign')
-	exclude_files += [
-		'types/wlr_xdg_foreign_v1.h',
-		'types/wlr_xdg_foreign_v2.h',
-		'types/wlr_xdg_foreign_registry.h',
-	]
-endif
 
 install_subdir('wlr',
 	install_dir: get_option('includedir'),
diff --git a/include/util/token.h b/include/util/token.h
new file mode 100644
index 00000000..bdfdaf45
--- /dev/null
+++ b/include/util/token.h
@@ -0,0 +1,9 @@
+#ifndef UTIL_TOKEN_H
+#define UTIL_TOKEN_H
+
+#include <stdbool.h>
+
+#define TOKEN_STRLEN 33
+bool generate_token(char out[static TOKEN_STRLEN]);
+
+#endif
diff --git a/include/util/uuid.h b/include/util/uuid.h
deleted file mode 100644
index 2fecb407..00000000
--- a/include/util/uuid.h
+++ /dev/null
@@ -1,8 +0,0 @@
-#ifndef UTIL_UUID_H
-#define UTIL_UUID_H
-
-#include <stdbool.h>
-
-bool generate_uuid(char out[static 37]);
-
-#endif
diff --git a/include/wlr/config.h.in b/include/wlr/config.h.in
index 15aacbfe..bcea55a1 100644
--- a/include/wlr/config.h.in
+++ b/include/wlr/config.h.in
@@ -7,6 +7,4 @@
 
 #mesondefine WLR_HAS_XWAYLAND
 
-#mesondefine WLR_HAS_XDG_FOREIGN
-
 #endif
diff --git a/meson.build b/meson.build
index afa9c86a..84e1a521 100644
--- a/meson.build
+++ b/meson.build
@@ -84,7 +84,6 @@ features = {
 	'libseat': false,
 	'x11-backend': false,
 	'xwayland': false,
-	'xdg-foreign': false,
 }
 internal_features = {
 	'xcb-errors': false,
@@ -104,16 +103,6 @@ pixman = dependency('pixman-1')
 math = cc.find_library('m')
 rt = cc.find_library('rt')
 
-if not get_option('xdg-foreign').disabled()
-	uuid = dependency('uuid', required: false)
-	uuid_create = cc.has_function('uuid_create')
-	if uuid.found() or uuid_create
-		features += { 'xdg-foreign': true }
-	elif get_option('xdg-foreign').enabled()
-		error('Missing dependency uuid and uuid_create function not available ' +
-				'cannot build with xdg-foreign support')
-	endif
-endif
 
 wlr_files = []
 wlr_deps = [
diff --git a/meson_options.txt b/meson_options.txt
index 770f604d..033019cc 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -4,4 +4,3 @@ option('xwayland', type: 'feature', value: 'auto', yield: true, description: 'En
 option('x11-backend', type: 'feature', value: 'auto', description: 'Enable X11 backend')
 option('examples', type: 'boolean', value: true, description: 'Build example applications')
 option('icon_directory', description: 'Location used to look for cursors (default: ${datadir}/icons)', type: 'string', value: '')
-option('xdg-foreign', type: 'feature', value: 'auto', description: 'Enable xdg-foreign protocol')
diff --git a/types/meson.build b/types/meson.build
index d7b1bc5d..47431429 100644
--- a/types/meson.build
+++ b/types/meson.build
@@ -63,13 +63,9 @@ wlr_files += files(
 	'wlr_virtual_pointer_v1.c',
 	'wlr_xcursor_manager.c',
 	'wlr_xdg_decoration_v1.c',
+	'wlr_xdg_foreign_v1.c',
+	'wlr_xdg_foreign_v2.c',
+	'wlr_xdg_foreign_registry.c',
 	'wlr_xdg_output_v1.c',
 )
 
-if features.get('xdg-foreign')
-	wlr_files += files(
-		'wlr_xdg_foreign_v1.c',
-		'wlr_xdg_foreign_v2.c',
-		'wlr_xdg_foreign_registry.c',
-	)
-endif
diff --git a/types/wlr_xdg_foreign_registry.c b/types/wlr_xdg_foreign_registry.c
index 7af137b5..0b75e593 100644
--- a/types/wlr_xdg_foreign_registry.c
+++ b/types/wlr_xdg_foreign_registry.c
@@ -1,6 +1,6 @@
 #include <wlr/types/wlr_xdg_foreign_registry.h>
 #include "util/signal.h"
-#include "util/uuid.h"
+#include "util/token.h"
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
@@ -9,7 +9,7 @@ bool wlr_xdg_foreign_exported_init(
 		struct wlr_xdg_foreign_exported *exported,
 		struct wlr_xdg_foreign_registry *registry) {
 	do {
-		if (!generate_uuid(exported->handle)) {
+		if (!generate_token(exported->handle)) {
 			return false;
 		}
 	} while (wlr_xdg_foreign_registry_find_by_handle(registry, exported->handle) != NULL);
diff --git a/util/meson.build b/util/meson.build
index 9d3f1587..5e31cbbe 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -6,11 +6,6 @@ wlr_files += files(
 	'shm.c',
 	'signal.c',
 	'time.c',
+	'token.c',
 )
 
-
-if features.get('xdg-foreign')
-	add_project_arguments('-DHAS_LIBUUID=@0@'.format(uuid.found().to_int()), language: 'c')
-	wlr_deps += uuid
-	wlr_files += files('uuid.c')
-endif
diff --git a/util/token.c b/util/token.c
new file mode 100644
index 00000000..cf6034a3
--- /dev/null
+++ b/util/token.c
@@ -0,0 +1,29 @@
+#include "util/token.h"
+#include "wlr/util/log.h"
+
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+bool generate_token(char out[static TOKEN_STRLEN]) {
+	static FILE *urandom = NULL;
+	uint64_t data[2];
+
+	if (!urandom) {
+		if (!(urandom = fopen("/dev/urandom", "r"))) {
+			wlr_log_errno(WLR_ERROR, "Failed to open random device");
+			return false;
+		}
+	}
+	if (fread(data, sizeof(data), 1, urandom) != 1) {
+		wlr_log_errno(WLR_ERROR, "Failed to read from random device");
+		return false;
+	}
+	if (snprintf(out, TOKEN_STRLEN, "%016" PRIx64 "%016" PRIx64, data[0], data[1]) != TOKEN_STRLEN - 1) {
+		wlr_log_errno(WLR_ERROR, "Failed to format hex string token");
+		return false;
+	}
+	return true;
+}
+
diff --git a/util/uuid.c b/util/uuid.c
deleted file mode 100644
index 82e310b9..00000000
--- a/util/uuid.c
+++ /dev/null
@@ -1,34 +0,0 @@
-#include <uuid.h>
-#include "util/uuid.h"
-
-#if HAS_LIBUUID
-bool generate_uuid(char out[static 37]) {
-	uuid_t uuid;
-	uuid_generate_random(uuid);
-	uuid_unparse(uuid, out);
-	return true;
-}
-#else
-#include <assert.h>
-#include <string.h>
-#include <stdlib.h>
-
-bool generate_uuid(char out[static 37]) {
-	uuid_t uuid;
-	uint32_t status;
-	uuid_create(&uuid, &status);
-	if (status != uuid_s_ok) {
-		return false;
-	}
-	char *str;
-	uuid_to_string(&uuid, &str, &status);
-	if (status != uuid_s_ok) {
-		return false;
-	}
-
-	assert(strlen(str) + 1 == 37);
-	memcpy(out, str, 37);
-	free(str);
-	return true;
-}
-#endif