crypto: add .free() and .reset() methods to reduce memory leaks with -autofree (#16992)

* Fix unsafe pointer

I was compile vab with '-prod' and it was needed  to fix and it is of course warning

* Add files via upload

* reduce memory  leak s sha512

* add method .free() and .reset() for some

vlib/crypto/md5/md5.v

@@ -33,9 +33,23 @@ mut:
 	len u64
 }
 
-fn (mut d Digest) reset() {
+// free the resources taken by the Digest `d`
+[unsafe]
+pub fn (mut d Digest) free() {
+	$if prealloc {
+		return
+	}
+	unsafe { d.x.free() }
+}
+
+fn (mut d Digest) init() {
 	d.s = []u32{len: (4)}
 	d.x = []u8{len: md5.block_size}
+	d.reset()
+}
+
+// reset the state of the Digest `d`
+pub fn (mut d Digest) reset() {
 	d.s[0] = u32(md5.init0)
 	d.s[1] = u32(md5.init1)
 	d.s[2] = u32(md5.init2)
@@ -47,7 +61,7 @@ fn (mut d Digest) reset() {
 // new returns a new Digest (implementing hash.Hash) computing the MD5 checksum.
 pub fn new() &Digest {
 	mut d := &Digest{}
-	d.reset()
+	d.init()
 	return d
 }
 

vlib/crypto/md5/md5_test.v

@@ -6,3 +6,23 @@ import crypto.md5
 fn test_crypto_md5() {
 	assert md5.sum('this is a md5 checksum.'.bytes()).hex() == '6fb421ff99036547655984da12973431'
 }
+
+fn test_crypto_md5_writer() {
+	mut digest := md5.new()
+	digest.write('this is a'.bytes()) or { assert false }
+	digest.write(' md5 checksum.'.bytes()) or { assert false }
+	sum := digest.sum([])
+	assert sum.hex() == '6fb421ff99036547655984da12973431'
+}
+
+fn test_crypto_md5_writer_reset() {
+	mut digest := md5.new()
+	digest.write('this is a'.bytes()) or { assert false }
+	digest.write(' md5 checksum.'.bytes()) or { assert false }
+	_ = digest.sum([])
+	digest.reset()
+	digest.write('this is a'.bytes()) or { assert false }
+	digest.write(' md5 checksum.'.bytes()) or { assert false }
+	sum := digest.sum([])
+	assert sum.hex() == '6fb421ff99036547655984da12973431'
+}