basic + fundamental: Clean up includes

Split out of #37344.

src/basic/sha256.c

@@ -1,12 +1,11 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <errno.h>
 #include <unistd.h>
 
 #include "alloc-util.h"
 #include "hexdecoct.h"
-#include "macro.h"
 #include "sha256.h"
+#include "string-util.h"
 
 int sha256_fd(int fd, uint64_t max_size, uint8_t ret[static SHA256_DIGEST_SIZE]) {
         struct sha256_ctx ctx;
@@ -50,3 +49,7 @@ int parse_sha256(const char *s, uint8_t ret[static SHA256_DIGEST_SIZE]) {
         memcpy(ret, data, size);
         return 0;
 }
+
+bool sha256_is_valid(const char *s) {
+        return s && in_charset(s, HEXDIGITS) && (strlen(s) == SHA256_DIGEST_SIZE * 2);
+}