shithub: libmujs

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Use offsetof instead of hardcoded short string length.

--- a/jsrun.c

+++ b/jsrun.c

@@ -103,9 +103,9 @@

 void js_pushstring(js_State *J, const char *v)

 {

-	int n = strlen(v);

+	unsigned int n = strlen(v);

 	CHECKSTACK(1);

-	if (n < 16) {

+	if (n <= offsetof(js_Value, type)) {

 		char *s = STACK[TOP].u.shrstr;

 		while (n--) *s++ = *v++;

 		*s = 0;

@@ -120,7 +120,7 @@

 void js_pushlstring(js_State *J, const char *v, unsigned int n)

 {

 	CHECKSTACK(1);

-	if (n < 16) {

+	if (n <= offsetof(js_Value, type)) {

 		char *s = STACK[TOP].u.shrstr;

 		while (n--) *s++ = *v++;

 		*s = 0;

--- a/jsvalue.h

+++ b/jsvalue.h

@@ -40,6 +40,13 @@

 	JS_CUSERDATA,

 };

+/*

+	Short strings abuse the js_Value struct. By putting the type tag in the

+	last byte, and using 0 as the tag for short strings, we can use the

+	entire js_Value as string storage by letting the type tag serve double

+	purpose as the string zero terminator.

+*/

+

 struct js_Value

 {

 	union {

@@ -50,8 +57,8 @@

 		js_String *memstr;

 		js_Object *object;

 	} u;

-	char pad[7];

-	char type;

+	char pad[7]; /* extra storage for shrstr */

+	char type; /* type tag and zero terminator for shrstr */

 };

 struct js_String