SCI32: Fix kString signatures to allow null references where appropriate

The original interpreter allowed most string references to be
null references, in which case it would substitute an empty
string.

2 files changed, 36 insertions, 32 deletions

diff --git a/engines/sci/engine/kernel_tables.h b/engines/sci/engine/kernel_tables.h
index f4f96ad253..0f7b9cac6f 100644
--- a/engines/sci/engine/kernel_tables.h
+++ b/engines/sci/engine/kernel_tables.h
@@ -533,34 +533,34 @@ static const SciKernelMapSubEntry kString_subops[] = {
 	// 3)
 	{ SIG_THRU_SCI21MID,   0, MAP_CALL(StringNew),                 "i(i)",                 NULL },
 	{ SIG_THRU_SCI21MID,   1, MAP_CALL(ArrayGetSize),              "r",                    NULL },
-	{ SIG_THRU_SCI21MID,   2, MAP_CALL(StringGetChar),             "ri",                   NULL },
+	{ SIG_THRU_SCI21MID,   2, MAP_CALL(StringGetChar),             "[0r]i",                NULL },
 	{ SIG_THRU_SCI21MID,   3, MAP_CALL(ArraySetElements),          "ri(i*)",               kArraySetElements_workarounds },
 	{ SIG_THRU_SCI21MID,   4, MAP_CALL(StringFree),                "[0r]",                 NULL },
 	{ SIG_THRU_SCI21MID,   5, MAP_CALL(ArrayFill),                 "rii",                  kArrayFill_workarounds },
 	{ SIG_THRU_SCI21MID,   6, MAP_CALL(ArrayCopy),                 "ririi",                NULL },
-	{ SIG_SCI32,           7, MAP_CALL(StringCompare),             "rr(i)",                NULL },
+	{ SIG_SCI32,           7, MAP_CALL(StringCompare),             "[0r][0r](i)",          NULL },
 
 	{ SIG_THRU_SCI21MID,   8, MAP_CALL(ArrayDuplicate),            "r",                    NULL },
 	{ SIG_THRU_SCI21MID,   9, MAP_CALL(StringGetData),             "[0or]",                NULL },
-	{ SIG_THRU_SCI21MID,  10, MAP_CALL(StringLength),              "r",                    NULL },
-	{ SIG_THRU_SCI21MID,  11, MAP_CALL(StringFormat),              "[ro](.*)",             NULL },
-	{ SIG_THRU_SCI21MID,  12, MAP_CALL(StringFormatAt),            "r[ro](.*)",            NULL },
-	{ SIG_THRU_SCI21MID,  13, MAP_CALL(StringToInteger),           "r",                    NULL },
-	{ SIG_THRU_SCI21MID,  14, MAP_CALL(StringTrim),                "ri(i)",                NULL },
-	{ SIG_THRU_SCI21MID,  15, MAP_CALL(StringToUpperCase),         "r",                    NULL },
-	{ SIG_THRU_SCI21MID,  16, MAP_CALL(StringToLowerCase),         "r",                    NULL },
-	{ SIG_THRU_SCI21MID,  17, MAP_CALL(StringReplaceSubstring),    "rrrr",                 NULL },
-	{ SIG_THRU_SCI21MID,  18, MAP_CALL(StringReplaceSubstringEx),  "rrrr",                 NULL },
-
-	{ SIG_SINCE_SCI21LATE, 8, MAP_CALL(StringLength),              "r",                    NULL },
+	{ SIG_THRU_SCI21MID,  10, MAP_CALL(StringLength),              "[0r]",                 NULL },
+	{ SIG_THRU_SCI21MID,  11, MAP_CALL(StringFormat),              "[0ro](.*)",            NULL },
+	{ SIG_THRU_SCI21MID,  12, MAP_CALL(StringFormatAt),            "r[0ro](.*)",           NULL },
+	{ SIG_THRU_SCI21MID,  13, MAP_CALL(StringToInteger),           "[0r]",                 NULL },
+	{ SIG_THRU_SCI21MID,  14, MAP_CALL(StringTrim),                "[0r]i(i)",             NULL },
+	{ SIG_THRU_SCI21MID,  15, MAP_CALL(StringToUpperCase),         "[0r]",                 NULL },
+	{ SIG_THRU_SCI21MID,  16, MAP_CALL(StringToLowerCase),         "[0r]",                 NULL },
+	{ SIG_THRU_SCI21MID,  17, MAP_CALL(StringReplaceSubstring),    "[0r][0r][0r][0r]",     NULL },
+	{ SIG_THRU_SCI21MID,  18, MAP_CALL(StringReplaceSubstringEx),  "[0r][0r][0r][0r]",     NULL },
+
+	{ SIG_SINCE_SCI21LATE, 8, MAP_CALL(StringLength),              "[0r]",                 NULL },
 	{ SIG_SINCE_SCI21LATE, 9, MAP_CALL(StringFormat),              "[0ro](.*)",            NULL },
-	{ SIG_SINCE_SCI21LATE,10, MAP_CALL(StringFormatAt),            "r[0ro](.*)",           NULL },
-	{ SIG_SINCE_SCI21LATE,11, MAP_CALL(StringToInteger),           "r",                    NULL },
-	{ SIG_SINCE_SCI21LATE,12, MAP_CALL(StringTrim),                "ri(i)",                NULL },
-	{ SIG_SINCE_SCI21LATE,13, MAP_CALL(StringToUpperCase),         "r",                    NULL },
-	{ SIG_SINCE_SCI21LATE,14, MAP_CALL(StringToLowerCase),         "r",                    NULL },
-	{ SIG_SINCE_SCI21LATE,15, MAP_CALL(StringReplaceSubstring),    "rrrr",                 NULL },
-	{ SIG_SINCE_SCI21LATE,16, MAP_CALL(StringReplaceSubstringEx),  "rrrr",                 NULL },
+	{ SIG_SINCE_SCI21LATE,10, MAP_CALL(StringFormatAt),            "[0r][0ro](.*)",        NULL },
+	{ SIG_SINCE_SCI21LATE,11, MAP_CALL(StringToInteger),           "[0r]",                 NULL },
+	{ SIG_SINCE_SCI21LATE,12, MAP_CALL(StringTrim),                "[0r]i(i)",             NULL },
+	{ SIG_SINCE_SCI21LATE,13, MAP_CALL(StringToUpperCase),         "[0r]",                 NULL },
+	{ SIG_SINCE_SCI21LATE,14, MAP_CALL(StringToLowerCase),         "[0r]",                 NULL },
+	{ SIG_SINCE_SCI21LATE,15, MAP_CALL(StringReplaceSubstring),    "[0r][0r][0r][0r]",     NULL },
+	{ SIG_SINCE_SCI21LATE,16, MAP_CALL(StringReplaceSubstringEx),  "[0r][0r][0r][0r]",     NULL },
 	SCI_SUBOPENTRY_TERMINATOR
 };
 
diff --git a/engines/sci/engine/kstring.cpp b/engines/sci/engine/kstring.cpp
index 3c6a0424f8..5bab422425 100644
--- a/engines/sci/engine/kstring.cpp
+++ b/engines/sci/engine/kstring.cpp
@@ -803,26 +803,30 @@ Common::String format(const Common::String &source, int argc, const reg_t *argv)
 }
 
 reg_t kStringFormat(EngineState *s, int argc, reg_t *argv) {
-	reg_t stringHandle;
-	SciArray &target = *s->_segMan->allocateArray(kArrayTypeString, 0, &stringHandle);
-	reg_t source = argv[0];
-	// Str objects may be passed in place of direct references to string data
-	if (s->_segMan->isObject(argv[0])) {
-		source = readSelector(s->_segMan, argv[0], SELECTOR(data));
-	}
-	target.fromString(format(s->_segMan->getString(source), argc - 1, argv + 1));
-	return stringHandle;
+	Common::Array<reg_t> args;
+	args.resize(argc + 1);
+	args[0] = NULL_REG;
+	Common::copy(argv, argv + argc, &args[1]);
+	return kStringFormatAt(s, args.size(), &args[0]);
 }
 
 reg_t kStringFormatAt(EngineState *s, int argc, reg_t *argv) {
-	SciArray &target = *s->_segMan->lookupArray(argv[0]);
+	reg_t stringHandle;
+	SciArray *target;
+	if (argv[0].isNull()) {
+		target = s->_segMan->allocateArray(kArrayTypeString, 0, &stringHandle);
+	} else {
+		target = s->_segMan->lookupArray(argv[0]);
+		stringHandle = argv[0];
+	}
+
 	reg_t source = argv[1];
 	// Str objects may be passed in place of direct references to string data
 	if (s->_segMan->isObject(argv[1])) {
 		source = readSelector(s->_segMan, argv[1], SELECTOR(data));
 	}
-	target.fromString(format(s->_segMan->getString(source), argc - 2, argv + 2));
-	return argv[0];
+	target->fromString(format(s->_segMan->getString(source), argc - 2, argv + 2));
+	return stringHandle;
 }
 
 reg_t kStringToInteger(EngineState *s, int argc, reg_t *argv) {