Why does the following XS code leak?
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
typedef struct {
char *buf;
} Foo;
Foo *FooAlloc(pTHX) {
Foo *foo;
New(0, foo, 1, Foo);
New(0, foo->buf, 1024, char);
return foo;
}
void FooFree(pTHX_ Foo *foo) {
Safefree(foo->buf);
//Safefree(foo);
}
MODULE = Foo PACKAGE = Foo
void
foo()
PPCODE:
{
SV *sv;
Foo *foo;
sv = NEWSV(0, 0);
foo = FooAlloc(aTHX);
sv_usepvn(sv, (char *)foo, sizeof *foo);
SvPOK_only(sv);
SvREADONLY_on(sv);
FooFree(aTHX_ foo);
SvREFCNT_dec(sv);
}
The Safefree(foo) is commented out in FooFree() because I believe that
sv_usepvn() has reallo()'ed foo and will free() it for me when sv's
refcount becomes 0. I tried uncommenting the Safefree(foo) to see if it
made any difference, but it still leaks.
The leak is easily seen just by building a Foo module out of the above
and running
perl -Mblib -MFoo -e "<STDIN>; for (1 ..10000) { Foo::foo() } <STDIN>;"
If I comment-out the sv_usepvn() call, and accordingly restore the
Safefree(foo) once more, then the XSUB doesn't leak.
- Steve
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