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Date: Tue, 17 Apr 2012 15:06:32 +0800
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To: Yader Hernandez <yader.hernandez@gmail.com>
Cc: PHP Developers Mailing List <internals@lists.php.net>
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Subject: Re: [PHP-DEV] EXC_BAD_ACCESS, Could not access memory zval array type
From: laruence@php.net (Laruence)

Hi:

 you can core dump the backtrace,  then exam the related hash table to
find out what's going wrong there.

 and some maybe un-relevant issues:
   1. plz put all var declarations at the begining of a block (C89)
   2. do not use "this" keyword as variable name (it's C++ keyword)

thanks

On Tue, Apr 17, 2012 at 2:12 PM, Yader Hernandez
<yader.hernandez@gmail.com> wrote:
> Hello,
>
> I'm trying to create an ArrayList as an extension. I'm currently
> implementing ArrayList::contains(mixed $element) but I'm running into a
> blocking issue.
>
> It's currently causing a segfault when you call contains. I've tried to
> track down what I'm doing wrong, but I've had no luck with it.
>
> When running gdb this is what I get:
>
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> Reason: 13 at address: 0x00000000000000000x00000001005812ca in
> _zend_is_inconsistent
>
> /* {{{ proto public boolean ArrayList::contain(mixed $element[, boolean
> strict])
> =C2=A0Returns true if this list contains the specified element. */
> ZEND_METHOD(arraymap_class, contains) {
> =C2=A0zval *element;
> =C2=A0zend_bool strict =3D 0; =C2=A0 /* strict comparison or not */
>
> =C2=A0if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z|b", &elemen=
t,
> &strict) =3D=3D FAILURE) {
> =C2=A0 =C2=A0RETURN_FALSE;
> =C2=A0}
>
> =C2=A0zval *this =3D getThis();
> =C2=A0arraylist_object *intern;
>
> =C2=A0intern =3D (arraylist_object *) zend_object_store_get_object(this
> TSRMLS_CC);
>
> =C2=A0/* Don't use "ht" as a variable, it's already being used. All ZEND_=
METHOD
> have "ht" defined. */
> =C2=A0HashTable *hash_table =3D Z_ARRVAL_P(intern->elements);
> =C2=A0HashPosition pos;
> =C2=A0zval **current;
> =C2=A0zval res; /* comparison result */
>
> =C2=A0int (*is_equal_func)(zval *, zval *, zval * TSRMLS_DC) =3D
> is_equal_function;
>
> =C2=A0if (strict) {
> =C2=A0 =C2=A0is_equal_func =3D is_identical_function;
> =C2=A0}
>
> =C2=A0zend_hash_internal_pointer_reset_ex(hash_table, &pos);
>
> =C2=A0while (zend_hash_get_current_data_ex(hash_table, (void **)&current,=
 &pos)
> =3D=3D SUCCESS) {
> =C2=A0 =C2=A0is_equal_func(&res, element, *current TSRMLS_CC);
>
> =C2=A0 =C2=A0if (Z_LVAL(res)) {
> =C2=A0 =C2=A0 =C2=A0RETURN_TRUE;
> =C2=A0 =C2=A0}
>
> =C2=A0 =C2=A0zend_hash_move_forward_ex(hash_table, &pos);
> =C2=A0}
>
> =C2=A0RETURN_FALSE;
> }
>
> I can't seem to spot any errors with this implementation. The next thing =
I
> thought that could be wrong is how I'm creating elements pointer, but tha=
t
> seems correct too:
>
> static zend_object_value create_arraylist_object(zend_class_entry *ce
> TSRMLS_DC) /* {{{ */
> {
> =C2=A0zend_object_value retval;
> =C2=A0arraylist_object *intern;
>
> =C2=A0intern =3D emalloc(sizeof(arraylist_object));
>
> =C2=A0intern->size =3D 0;
>
> =C2=A0zend_object_std_init(&intern->std, ce TSRMLS_CC);
>
> =C2=A0ALLOC_INIT_ZVAL(intern->elements);
> =C2=A0array_init(intern->elements);
>
> =C2=A0intern->std.ce =3D ce;
>
> =C2=A0object_properties_init(&intern->std, ce);
>
> =C2=A0retval.handle =3D zend_objects_store_put(intern, NULL,
> destroy_arraylist_object, NULL TSRMLS_CC);
> =C2=A0retval.handlers =3D &arraylist_object_handlers;
>
> =C2=A0return retval;
> }
> /* }}} */
>
> I'm not getting any compilation errors or any type of warnings. Everythin=
g
> seems to be glueing itself correctly.
>
> I'm hoping someone can see what I'm doing wrong so that I can move forwar=
d
> with this.
>
> thanks!



--=20
Laruence =C2=A0Xinchen Hui
http://www.laruence.com/