From 6db1b23eb1f02f248e64065b5a6559128f9bdef1 Mon Sep 17 00:00:00 2001
From: Sun Yimin <emmansun@users.noreply.github.com>
Date: Thu, 18 Aug 2022 15:00:11 +0800
Subject: [PATCH] subtle: fix generic bug

---
 internal/subtle/xor.go         | 20 --------------------
 internal/subtle/xor_amd64.go   | 17 +++++++++++++++++
 internal/subtle/xor_arm64.go   | 18 ++++++++++++++++++
 internal/subtle/xor_generic.go | 15 ++++++++++++++-
 4 files changed, 49 insertions(+), 21 deletions(-)
 delete mode 100644 internal/subtle/xor.go

diff --git a/internal/subtle/xor.go b/internal/subtle/xor.go
deleted file mode 100644
index 5120862..0000000
--- a/internal/subtle/xor.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package subtle
-
-// XORBytes sets dst[i] = x[i] ^ y[i] for all i < n = min(len(x), len(y)),
-// returning n, the number of bytes written to dst.
-// If dst does not have length at least n,
-// XORBytes panics without writing anything to dst.
-func XORBytes(dst, x, y []byte) int {
-	n := len(x)
-	if len(y) < n {
-		n = len(y)
-	}
-	if n == 0 {
-		return 0
-	}
-	if n > len(dst) {
-		panic("subtle.XORBytes: dst too short")
-	}
-	xorBytes(&dst[0], &x[0], &y[0], n) // arch-specific
-	return n
-}
diff --git a/internal/subtle/xor_amd64.go b/internal/subtle/xor_amd64.go
index c65a77f..b1854d8 100644
--- a/internal/subtle/xor_amd64.go
+++ b/internal/subtle/xor_amd64.go
@@ -7,5 +7,22 @@
 
 package subtle
 
+// XORBytes xors the bytes in a and b. The destination should have enough
+// space, otherwise XORBytes will panic. Returns the number of bytes xor'd.
+func XORBytes(dst, a, b []byte) int {
+	n := len(a)
+	if len(b) < n {
+		n = len(b)
+	}
+	if n == 0 {
+		return 0
+	}
+	if n > len(dst) {
+		panic("subtle.XORBytes: dst too short")
+	}
+	xorBytes(&dst[0], &a[0], &b[0], n) // amd64 must have SSE2
+	return n
+}
+
 //go:noescape
 func xorBytes(dst, a, b *byte, n int)
diff --git a/internal/subtle/xor_arm64.go b/internal/subtle/xor_arm64.go
index 68989ca..fcce86c 100644
--- a/internal/subtle/xor_arm64.go
+++ b/internal/subtle/xor_arm64.go
@@ -7,5 +7,23 @@
 
 package subtle
 
+// XORBytes xors the bytes in a and b. The destination should have enough
+// space, otherwise XORBytes will panic. Returns the number of bytes xor'd.
+func XORBytes(dst, a, b []byte) int {
+	n := len(a)
+	if len(b) < n {
+		n = len(b)
+	}
+	if n == 0 {
+		return 0
+	}
+	if n > len(dst) {
+		panic("subtle.XORBytes: dst too short")
+	}
+
+	xorBytes(&dst[0], &a[0], &b[0], n)
+	return n
+}
+
 //go:noescape
 func xorBytes(dst, a, b *byte, n int)
diff --git a/internal/subtle/xor_generic.go b/internal/subtle/xor_generic.go
index 3c7bae5..6af8a82 100644
--- a/internal/subtle/xor_generic.go
+++ b/internal/subtle/xor_generic.go
@@ -19,7 +19,20 @@ const supportsUnaligned = runtime.GOARCH == "386" ||
 	runtime.GOARCH == "ppc64le" ||
 	runtime.GOARCH == "s390x"
 
-func xorBytes(dst, a, b []byte, n int) int {
+// XORBytes xors the bytes in a and b. The destination should have enough
+// space, otherwise XORBytes will panic. Returns the number of bytes xor'd.
+func XORBytes(dst, a, b []byte) int {
+	n := len(a)
+	if len(b) < n {
+		n = len(b)
+	}
+	if n == 0 {
+		return 0
+	}
+	if n > len(dst) {
+		panic("subtle.XORBytes: dst too short")
+	}
+
 	switch {
 	case supportsUnaligned:
 		fastXORBytes(dst, a, b, n)