Seg fault when using active_symbol_table called from userspace function.

15 years ago by Mark Skilbeck — view source

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Can you explain to me why the following causes a segfault:

[code]
PHP_FUNCTION(sample_var_a_exists)
{
if (!zend_hash_exists(EG(active_symbol_table), "a", sizeof("a"))) {
RETURN_BOOL(0);
}
RETURN_BOOL(1);
}
[/code]

Note: the segfault only occurs when the sample_var_a_exists function is
called from within a userspace function:

[code]
$a = '';
var_dump(sample_var_a_exists()); // bool(true)

function x() {
var_dump(sample_var_a_exists()); // segmentation fault
}

x();
[/code]

Thanks.

15 years ago by Scott MacVicar — view source

unread

Can you explain to me why the following causes a segfault:

[code]
PHP_FUNCTION(sample_var_a_exists)
{
if (!zend_hash_exists(EG(active_symbol_table), "a", sizeof("a"))) {
RETURN_BOOL(0);
}
RETURN_BOOL(1);
}
[/code]

Note: the segfault only occurs when the sample_var_a_exists function
is called from within a userspace function:

[code]
$a = '';
var_dump(sample_var_a_exists()); // bool(true)

function x() {
var_dump(sample_var_a_exists()); // segmentation fault
}

x()

There is no symbol table as there are no variables. You should check
if it's NULL before using zend_hash_exists.

Scott

15 years ago by Mark Skilbeck — view source

unread

Scott MacVicar wrote:

[snip]

There is no symbol table as there are no variables. You should check if
it's NULL before using zend_hash_exists.

Scott

Ah - of course.

Thanks for that, Scott.

15 years ago by Mark Skilbeck — view source

unread

Scott MacVicar wrote:

[snip]

There is no symbol table as there are no variables. You should check if
it's NULL before using zend_hash_exists.

Scott

Hi, Scott. I'm having trouble - I added the check to see if the symbol
table i available, yet it returns false even if I have added variables
within the function:

[code]
PHP_FUNCTION(sample_var_a_exists)
{
if (!EG(active_symbol_table) ||
!zend_hash_exists(EG(active_symbol_table), "a", sizeof("a"))) {
RETURN_BOOL(0);
}
RETURN_BOOL(1);
}
[/code]

[code]
$a = '';
var_dump(sample_var_a_exists());

function x() {
$a = ''; // Add a symbol to the hash table.
var_dump(sample_var_a_exists()); // Shows bool(false)
}

x();
[/code]

15 years ago by Scott MacVicar — view source

unread

Scott MacVicar wrote:

On 1 Nov 2009, at 21:09, Mark Skilbeck markskilbeck@gmail.com
wrote:

[snip]
There is no symbol table as there are no variables. You should
check if it's NULL before using zend_hash_exists.
Scott

Hi, Scott. I'm having trouble - I added the check to see if the
symbol table i available, yet it returns false even if I have added
variables within the function:

[code]
PHP_FUNCTION(sample_var_a_exists)
{
if (!EG(active_symbol_table) ||
!zend_hash_exists(EG(active_symbol_table), "a", sizeof("a"))) {
RETURN_BOOL(0);
}
RETURN_BOOL(1);
}
[/code]

[code]
$a = '';
var_dump(sample_var_a_exists());

function x() {
$a = ''; // Add a symbol to the hash table.
var_dump(sample_var_a_exists()); // Shows bool(false)
}

x();
[/code]

--

You probably want the following to build the symbol table.

if (!EG(active_symbol_table)) {
	zend_rebuild_symbol_table(TSRMLS_C);
}

Scott

15 years ago by Mark Skilbeck — view source

unread

Scott MacVicar wrote:

Scott MacVicar wrote:

[snip]
There is no symbol table as there are no variables. You should check
if it's NULL before using zend_hash_exists.
Scott

Hi, Scott. I'm having trouble - I added the check to see if the symbol
table i available, yet it returns false even if I have added variables
within the function:

[code]
PHP_FUNCTION(sample_var_a_exists)
{
if (!EG(active_symbol_table) ||
!zend_hash_exists(EG(active_symbol_table), "a",
sizeof("a"))) {
RETURN_BOOL(0);
}
RETURN_BOOL(1);
}
[/code]

[code]
$a = '';
var_dump(sample_var_a_exists());

function x() {
$a = ''; // Add a symbol to the hash table.
var_dump(sample_var_a_exists()); // Shows bool(false)
}

x();
[/code]

--

You probably want the following to build the symbol table.
if (!EG(active_symbol_table)) {
    zend_rebuild_symbol_table(TSRMLS_C);
}
Scott

Yes, that works. Do you know why we have to rebuild it? I'd assume that
the symbol table was built automatically?

15 years ago by Mark Skilbeck — view source

unread

Mark Skilbeck wrote:

Scott MacVicar wrote:
Scott MacVicar wrote:

[snip]
There is no symbol table as there are no variables. You should check
if it's NULL before using zend_hash_exists.
Scott

Hi, Scott. I'm having trouble - I added the check to see if the
symbol table i available, yet it returns false even if I have added
variables within the function:

[code]
PHP_FUNCTION(sample_var_a_exists)
{
if (!EG(active_symbol_table) ||
!zend_hash_exists(EG(active_symbol_table), "a",
sizeof("a"))) {
RETURN_BOOL(0);
}
RETURN_BOOL(1);
}
[/code]

[code]
$a = '';
var_dump(sample_var_a_exists());

function x() {
$a = ''; // Add a symbol to the hash table.
var_dump(sample_var_a_exists()); // Shows bool(false)
}

x();
[/code]

--

You probably want the following to build the symbol table.
if (!EG(active_symbol_table)) {
    zend_rebuild_symbol_table(TSRMLS_C);
}
Scott
Yes, that works. Do you know why we have to rebuild it? I'd assume that
the symbol table was built automatically?

Anyone?

15 years ago by Felipe Pena — view source

unread

2009/11/2 Mark Skilbeck markskilbeck@gmail.com

Anyone?

See:
http://markmail.org/message/33ee6aitsyqxgu6x#query:+page:1+mid:33ee6aitsyqxgu6x+state:results

--
Regards,
Felipe Pena