port string_hashsum from libgcrypt to openssl^gcrypt

This allows resolved and importd to be built without libgcrypt.

Note that we now say either 'cryptographic library' or 'cryptolib'.

Co-authored-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>

src/basic/build.c

@@ -48,7 +48,7 @@ const char* const systemd_features =
         " -SECCOMP"
 #endif
 
-        /* crypto libraries */
+        /* cryptographic libraries */
 
 #if HAVE_GCRYPT
         " +GCRYPT"

src/basic/gcrypt-util.c

@@ -18,6 +18,7 @@ void initialize_libgcrypt(bool secmem) {
         gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
 }
 
+#  if !PREFER_OPENSSL
 int string_hashsum(const char *s, size_t len, int md_algorithm, char **out) {
         _cleanup_(gcry_md_closep) gcry_md_hd_t md = NULL;
         gcry_error_t err;
@@ -47,4 +48,5 @@ int string_hashsum(const char *s, size_t len, int md_algorithm, char **out) {
         *out = enc;
         return 0;
 }
+#  endif
 #endif

src/basic/gcrypt-util.h

@@ -12,23 +12,28 @@
 #include "macro.h"
 
 void initialize_libgcrypt(bool secmem);
-int string_hashsum(const char *s, size_t len, int md_algorithm, char **out);
 
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(gcry_md_hd_t, gcry_md_close, NULL);
 #endif
 
+#if !PREFER_OPENSSL
+#  if HAVE_GCRYPT
+int string_hashsum(const char *s, size_t len, int md_algorithm, char **out);
+#  endif
+
 static inline int string_hashsum_sha224(const char *s, size_t len, char **out) {
-#if HAVE_GCRYPT
+#  if HAVE_GCRYPT
         return string_hashsum(s, len, GCRY_MD_SHA224, out);
-#else
+#  else
         return -EOPNOTSUPP;
-#endif
+#  endif
 }
 
 static inline int string_hashsum_sha256(const char *s, size_t len, char **out) {
-#if HAVE_GCRYPT
+#  if HAVE_GCRYPT
         return string_hashsum(s, len, GCRY_MD_SHA256, out);
-#else
+#  else
         return -EOPNOTSUPP;
-#endif
+#  endif
 }
+#endif