sd-json: when parsing optionally insist top-level variant is object or array

Typically, the top-level JSON object has to be an object, in any json
document we parse, hence let's add a simple way to enforce that.

Make use of this in various places.

(Note, various other JSON parsers insist on this logic right from the
beginning, but I actually thinking making this insisting optional like
this patch does it is the cleaner approach)

src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-fido2.c

@@ -162,7 +162,7 @@ _public_ int cryptsetup_token_validate(
 
         assert(json);
 
-        r = sd_json_parse(json, 0, &v, NULL, NULL);
+        r = sd_json_parse(json, SD_JSON_PARSE_MUST_BE_OBJECT, &v, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
         if (r < 0)
                 return crypt_log_debug_errno(cd, r, "Could not parse " TOKEN_NAME " json object: %m.");
 

src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-pkcs11.c

@@ -115,7 +115,7 @@ _public_ int cryptsetup_token_validate(
         sd_json_variant *w;
         _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL;
 
-        r = sd_json_parse(json, 0, &v, NULL, NULL);
+        r = sd_json_parse(json, SD_JSON_PARSE_MUST_BE_OBJECT, &v, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
         if (r < 0)
                 return crypt_log_debug_errno(cd, r, "Could not parse " TOKEN_NAME " json object: %m.");
 

src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-tpm2.c

@@ -72,7 +72,7 @@ _public_ int cryptsetup_token_open_pin(
         if (usrptr)
                 params = *(systemd_tpm2_plugin_params *)usrptr;
 
-        r = sd_json_parse(json, 0, &v, NULL, NULL);
+        r = sd_json_parse(json, SD_JSON_PARSE_MUST_BE_OBJECT, &v, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
         if (r < 0)
                 return crypt_log_debug_errno(cd, r, "Failed to parse token JSON data: %m");
 
@@ -186,7 +186,7 @@ _public_ void cryptsetup_token_dump(
 
         assert(json);
 
-        r = sd_json_parse(json, 0, &v, NULL, NULL);
+        r = sd_json_parse(json, SD_JSON_PARSE_MUST_BE_OBJECT, &v, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
         if (r < 0)
                 return (void) crypt_log_debug_errno(cd, r, "Failed to parse " TOKEN_NAME " JSON object: %m");
 
@@ -275,7 +275,7 @@ _public_ int cryptsetup_token_validate(
 
         assert(json);
 
-        r = sd_json_parse(json, 0, &v, NULL, NULL);
+        r = sd_json_parse(json, SD_JSON_PARSE_MUST_BE_OBJECT, &v, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
         if (r < 0)
                 return crypt_log_debug_errno(cd, r, "Could not parse " TOKEN_NAME " json object: %m");
 

src/cryptsetup/cryptsetup-tokens/luks2-fido2.c

@@ -97,7 +97,7 @@ int parse_luks2_fido2_data(
         assert(ret_cid_size);
         assert(ret_required);
 
-        r = sd_json_parse(json, 0, &v, NULL, NULL);
+        r = sd_json_parse(json, SD_JSON_PARSE_MUST_BE_OBJECT, &v, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
         if (r < 0)
                 return crypt_log_error_errno(cd, r, "Failed to parse JSON token data: %m");
 

src/cryptsetup/cryptsetup-tokens/luks2-pkcs11.c

@@ -246,7 +246,7 @@ int parse_luks2_pkcs11_data(
         assert(ret_encrypted_key);
         assert(ret_encrypted_key_size);
 
-        r = sd_json_parse(json, 0, &v, NULL, NULL);
+        r = sd_json_parse(json, SD_JSON_PARSE_MUST_BE_OBJECT, &v, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
         if (r < 0)
                 return r;