Ensure a dynamically linked xxhash lib is >= 0.8 for XX3.

checksum.c

@@ -62,6 +62,8 @@ struct name_num_obj valid_checksums = {
 int xfersum_type = 0; /* used for the file transfer checksums */
 int checksum_type = 0; /* used for the pre-transfer (--checksum) checksums */
 
+static int initialized_choices = 0;
+
 int parse_csum_name(const char *name, int len)
 {
 	struct name_num_item *nni;
@@ -79,6 +81,9 @@ int parse_csum_name(const char *name, int len)
 		return CSUM_MD4_ARCHAIC;
 	}
 
+	if (!initialized_choices)
+		init_checksum_choices();
+
 	nni = get_nni_by_name(&valid_checksums, name, len);
 
 	if (!nni) {
@@ -623,3 +628,31 @@ int sum_end(char *sum)
 
 	return csum_len_for_type(cursum_type, 0);
 }
+
+void init_checksum_choices()
+{
+#ifdef SUPPORT_XXH3
+	char buf[32816];
+	int j;
+	for (j = 0; j < (int)sizeof buf; j++) {
+		buf[j] = ' ' + (j % 96);
+	}
+	sum_init(CSUM_XXH3_64, 0);
+	sum_update(buf, 32816);
+	sum_update(buf, 31152);
+	sum_update(buf, 32474);
+	sum_update(buf, 9322);
+	if (XXH3_64bits_digest(xxh3_state) != 0xadbcf16d4678d1de) {
+		int t, f;
+		struct name_num_item *nni = valid_checksums.list;
+		for (t = f = 0; nni[f].name; f++) {
+			if (nni[f].num == CSUM_XXH3_64 || nni[f].num == CSUM_XXH3_128)
+				continue;
+			if (t != f)
+				nni[t++] = nni[f];
+		}
+		nni[t].name = NULL;
+	}
+#endif
+	initialized_choices = 1;
+}

compat.c

@@ -523,6 +523,8 @@ static void negotiate_the_strings(int f_in, int f_out)
 {
 	/* We send all the negotiation strings before we start to read them to help avoid a slow startup. */
 
+	init_checksum_choices();
+
 	if (!checksum_choice)
 		send_negotiate_str(f_out, &valid_checksums, NSTR_CHECKSUM);
 

usage.c

@@ -195,6 +195,8 @@ void print_rsync_version(enum logcode f)
 
 	print_info_flags(f);
 
+	init_checksum_choices();
+
 	rprintf(f, "Checksum list:\n");
 	get_default_nno_list(&valid_checksums, tmpbuf, sizeof tmpbuf, '(');
 	rprintf(f, "    %s\n", tmpbuf);