Add UUIDv4 generation

1 files changed, 46 insertions, 0 deletions

diff --git a/notemap.c b/notemap.c
new file mode 100644
index 0000000..7d06205
--- /dev/null
+++ b/notemap.c
@@ -0,0 +1,46 @@
+/* Copyright (C) 2020  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sysexits.h>
+
+typedef unsigned char byte;
+
+static const char *uuidGen(void) {
+	byte uuid[16];
+	arc4random_buf(uuid, sizeof(uuid));
+	uuid[6] &= 0x0F;
+	uuid[6] |= 0x40;
+	uuid[8] &= 0x3F;
+	uuid[8] |= 0x80;
+
+	static char str[sizeof("00000000-0000-0000-0000-000000000000")];
+	snprintf(
+		str, sizeof(str),
+		"%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+		uuid[0], uuid[1], uuid[2], uuid[3],
+		uuid[4], uuid[5], uuid[6], uuid[7],
+		uuid[8], uuid[9], uuid[10], uuid[11],
+		uuid[12], uuid[13], uuid[14], uuid[15]
+	);
+	return str;
+}
+
+int main(void) {
+	printf("%s\n", uuidGen());
+}