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.

3 files changed, 30 insertions, 40 deletions

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