shithub: libmujs

Info  •  Files  •  Log  •  Branches

Use manual loop instead of memcpy/strcpy when creating short strings.

Due to our slightly icky struct layout, some versions of gcc barf and
generate crashing code when using strcpy and memcpy. I suspect gcc tries
to do some weird optimizations that fail because we intentionally
overwrite the 'pad' data in the js_Value struct for short strings.

--- a/jsrun.c

+++ b/jsrun.c

@@ -106,9 +106,10 @@

 	int n = strlen(v);

 	CHECKSTACK(1);

 	if (n < 16) {

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

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

+		*s = 0;

 		STACK[TOP].type = JS_TSHRSTR;

-		memcpy(STACK[TOP].u.shrstr, v, n);

-		STACK[TOP].u.shrstr[n] = 0;

 	} else {

 		STACK[TOP].type = JS_TMEMSTR;

 		STACK[TOP].u.memstr = jsV_newmemstring(J, v, n);

@@ -120,9 +121,10 @@

 {

 	CHECKSTACK(1);

 	if (n < 16) {

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

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

+		*s = 0;

 		STACK[TOP].type = JS_TSHRSTR;

-		memcpy(STACK[TOP].u.shrstr, v, n);

-		STACK[TOP].u.shrstr[n] = 0;

 	} else {

 		STACK[TOP].type = JS_TMEMSTR;

 		STACK[TOP].u.memstr = jsV_newmemstring(J, v, n);