Merge pull request #2896 from thetarnav/js-rand

Add system_random and random_bytes for js target

3 files changed, 36 insertions, 2 deletions

diff --git a/core/crypto/rand_generic.odin b/core/crypto/rand_generic.odin
index 52abfe4d7..fde91f85a 100644
--- a/core/crypto/rand_generic.odin
+++ b/core/crypto/rand_generic.odin
@@ -1,7 +1,7 @@
 package crypto
 
-when ODIN_OS != .Linux && ODIN_OS != .OpenBSD && ODIN_OS != .Windows {
-	_rand_bytes :: proc (dst: []byte) {
+when ODIN_OS != .Linux && ODIN_OS != .OpenBSD && ODIN_OS != .Windows && ODIN_OS != .JS {
+	_rand_bytes :: proc(dst: []byte) {
 		unimplemented("crypto: rand_bytes not supported on this OS")
 	}
 }
diff --git a/core/crypto/rand_js.odin b/core/crypto/rand_js.odin
new file mode 100644
index 000000000..353b1e6b9
--- /dev/null
+++ b/core/crypto/rand_js.odin
@@ -0,0 +1,20 @@
+package crypto
+
+foreign import "odin_env"
+foreign odin_env {
+	@(link_name = "rand_bytes")
+	env_rand_bytes :: proc "contextless" (buf: []byte) ---
+}
+
+_MAX_PER_CALL_BYTES :: 65536 // 64kiB
+
+_rand_bytes :: proc(dst: []byte) {
+	dst := dst
+
+	for len(dst) > 0 {
+		to_read := min(len(dst), _MAX_PER_CALL_BYTES)
+		env_rand_bytes(dst[:to_read])
+
+		dst = dst[to_read:]
+	}
+}
diff --git a/core/math/rand/system_js.odin b/core/math/rand/system_js.odin
new file mode 100644
index 000000000..b9b71c4a6
--- /dev/null
+++ b/core/math/rand/system_js.odin
@@ -0,0 +1,14 @@
+package rand
+
+foreign import "odin_env"
+foreign odin_env {
+	@(link_name = "rand_bytes")
+	env_rand_bytes :: proc "contextless" (buf: []byte) ---
+}
+
+@(require_results)
+_system_random :: proc() -> u64 {
+	buf: [8]u8
+	env_rand_bytes(buf[:])
+	return transmute(u64)buf
+}