Reject overlong host type and field names

Co-authored-by: Andrew Kesterson <andrew@starfort.tech>

include/akbasic/host.h

@@ -105,6 +105,8 @@ typedef struct
  * Registering before the script is loaded is the normal case. A host type and a
  * `TYPE` the script declares share one namespace, so a script cannot declare a
  * type the host already registered -- and would be refused if it tried.
+ * Host type and field names are limited to 31 characters, matching
+ * script-declared types and fields.
  *
  * @param obj Object to initialize, inspect, or modify.
  * @param type The host's description of its own struct.
@@ -112,6 +114,7 @@ typedef struct
  * @throws AKERR_NULLPOINTER When either argument is NULL.
  * @throws AKBASIC_ERR_VALUE When a field name carries no type suffix, a nested
  *         type is not registered, or the name is already taken.
+ * @throws AKERR_OUTOFBOUNDS When a type or field name exceeds 31 characters.
  * @throws AKBASIC_ERR_BOUNDS When the type table or a field list is full.
  */
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_host_register_type(struct akbasic_Runtime *obj, const akbasic_HostType *type);

src/host.c

@@ -235,16 +235,9 @@ akerr_ErrorContext *akbasic_host_register_type(akbasic_Runtime *obj, const akbas
 
     dest = &obj->structtypes.types[obj->structtypes.count];
     PASS(errctx, aksl_memset(dest, 0, sizeof(*dest)));
-    /*
-     * Raw snprintf, and a latent defect rather than a settled decision: a host
-     * type name over 31 characters truncates silently here, and two that share a
-     * 31-character prefix then collide in akbasic_structtype_find. scan_names()
-     * in structtype.c already refuses the same case for a script-declared type
-     * with an explicit limit message, so the two paths disagree. Converting this
-     * to aksl_strcpy is the fix and it is a behaviour change on a public
-     * registration call, so it wants its own issue rather than this port.
-     */
-    snprintf(dest->name, sizeof(dest->name), "%s", type->name);
+    /* Host and script registration share the 32-byte-including-NUL limit for
+       both type names and field names. */
+    PASS(errctx, aksl_strcpy(dest->name, sizeof(dest->name), type->name));
     dest->used = true;
     dest->ishost = true;
     dest->hostsize = type->size;
@@ -270,8 +263,7 @@ akerr_ErrorContext *akbasic_host_register_type(akbasic_Runtime *obj, const akbas
 			 "%s.%s must end in '%c' for the C type it describes",
 			 type->name, src->name, suffix_for(src->kind));
 
-	/* Same silent truncation as the type name above, and the same fix. */
-	snprintf(field->name, sizeof(field->name), "%s", src->name);
+	PASS(errctx, aksl_strcpy(field->name, sizeof(field->name), src->name));
 	field->hostkind = src->kind;
 	field->hostoffset = src->offset;
 	field->hostwidth = src->width;

tests/hoststruct.c

@@ -208,6 +208,72 @@ static void test_suffix_must_match_the_c_type(void)
     harness_stop();
 }
 
+/** @brief Host names use the same bounded storage as script-declared names. */
+static void test_registration_name_limits(void)
+{
+    static const akbasic_HostField SHORT_FIELD[] = {
+	AKBASIC_HOST_FIELD( test_Enemy, hp, "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234#",
+			   AKBASIC_HOSTFIELD_INT32 )
+    };
+    static const akbasic_HostField LONG_FIELD_A[] = {
+	AKBASIC_HOST_FIELD( test_Enemy, hp, "ABCDEFGHIJKLMNOPQRSTUVWXYZ123456A#",
+			   AKBASIC_HOSTFIELD_INT32 )
+    };
+    static const akbasic_HostField LONG_FIELD_B[] = {
+	AKBASIC_HOST_FIELD( test_Enemy, hp, "ABCDEFGHIJKLMNOPQRSTUVWXYZ123456B#",
+			   AKBASIC_HOSTFIELD_INT32 )
+    };
+    static const akbasic_HostType SHORT_TYPE = {
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZ12345", sizeof(test_Enemy), SHORT_FIELD, 1
+    };
+    static const akbasic_HostType LONG_TYPE_A = {
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZ123456A", sizeof(test_Enemy), SHORT_FIELD, 1
+    };
+    static const akbasic_HostType LONG_TYPE_B = {
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZ123456B", sizeof(test_Enemy), SHORT_FIELD, 1
+    };
+    static const akbasic_HostType LONG_FIELD_TYPE_A = {
+	"LONGFIELDA", sizeof(test_Enemy), LONG_FIELD_A, 1
+    };
+    static const akbasic_HostType LONG_FIELD_TYPE_B = {
+	"LONGFIELDB", sizeof(test_Enemy), LONG_FIELD_B, 1
+    };
+    akerr_ErrorContext *raised = NULL;
+
+	TEST_REQUIRE_OK(harness_start(NULL));
+	TEST_REQUIRE_OK(akbasic_host_register_type(&HARNESS_RUNTIME, &SHORT_TYPE));
+	harness_stop();
+
+	TEST_REQUIRE_OK(harness_start(NULL));
+	raised = akbasic_host_register_type(&HARNESS_RUNTIME, &LONG_TYPE_A);
+	TEST_REQUIRE(raised != NULL, "an overlong type name must be refused");
+	TEST_REQUIRE_INT(raised->status, AKERR_OUTOFBOUNDS);
+	test_discard_error(raised);
+	raised = akbasic_host_register_type(&HARNESS_RUNTIME, &LONG_TYPE_B);
+	TEST_REQUIRE(raised != NULL, "a second long type name must fail cleanly");
+	TEST_REQUIRE_INT(raised->status, AKERR_OUTOFBOUNDS);
+	test_discard_error(raised);
+	harness_stop();
+
+	TEST_REQUIRE_OK(harness_start(NULL));
+	TEST_REQUIRE_OK(akbasic_host_register_type(&HARNESS_RUNTIME,
+						  &(akbasic_HostType){
+						      "SHORTFIELDS", sizeof(test_Enemy), SHORT_FIELD, 1
+						  }));
+	harness_stop();
+
+	TEST_REQUIRE_OK(harness_start(NULL));
+	raised = akbasic_host_register_type(&HARNESS_RUNTIME, &LONG_FIELD_TYPE_A);
+	TEST_REQUIRE(raised != NULL, "an overlong field name must be refused");
+	TEST_REQUIRE_INT(raised->status, AKERR_OUTOFBOUNDS);
+	test_discard_error(raised);
+	raised = akbasic_host_register_type(&HARNESS_RUNTIME, &LONG_FIELD_TYPE_B);
+	TEST_REQUIRE(raised != NULL, "a second long field name must fail cleanly");
+	TEST_REQUIRE_INT(raised->status, AKERR_OUTOFBOUNDS);
+	test_discard_error(raised);
+	harness_stop();
+}
+
 /**
  * @brief After unbinding, the name is refused rather than read.
  *
@@ -258,6 +324,7 @@ int main(void)
     test_conversion_refuses_rather_than_truncates();
     test_copy_versus_point();
     test_suffix_must_match_the_c_type();
+    test_registration_name_limits();
     test_unbind_refuses_later_reads();
     test_registration_survives_a_rerun();