crypto/sha256: add WriteString and WriteByte method

This can reduce allocations when hashing a string or byte
rather than []byte.

For #38776

Change-Id: I1c6dd1bc018220784a05939e92b47558c0562110
Reviewed-on: https://go-review.googlesource.com/c/go/+/481478
Reviewed-by: Joel Sing <joel@sing.id.au>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/src/crypto/internal/boring/sha.go b/src/crypto/internal/boring/sha.go
index cf82f3f64f..b7843674a5 100644
--- a/src/crypto/internal/boring/sha.go
+++ b/src/crypto/internal/boring/sha.go
@@ -263,6 +263,20 @@ func (h *sha256Hash) Write(p []byte) (int, error) {
 	return len(p), nil
 }
 
+func (h *sha256Hash) WriteString(s string) (int, error) {
+	if len(s) > 0 && C._goboringcrypto_SHA256_Update(h.noescapeCtx(), unsafe.Pointer(unsafe.StringData(s)), C.size_t(len(s))) == 0 {
+		panic("boringcrypto: SHA256_Update failed")
+	}
+	return len(s), nil
+}
+
+func (h *sha256Hash) WriteByte(c byte) error {
+	if C._goboringcrypto_SHA256_Update(h.noescapeCtx(), unsafe.Pointer(&c), 1) == 0 {
+		panic("boringcrypto: SHA256_Update failed")
+	}
+	return nil
+}
+
 func (h0 *sha256Hash) sum(dst []byte) []byte {
 	h := *h0 // make copy so future Write+Sum is valid
 	if C._goboringcrypto_SHA256_Final((*C.uint8_t)(noescape(unsafe.Pointer(&h.out[0]))), h.noescapeCtx()) == 0 {