Segmentation Fault when trying to call zend_new_array.

4 years ago by Ivan Zanev — view source

unread

Hello,

I'm trying to learn a bit more about HashTable in PHP internally and how
memory is allocated when generating arrays with various sizes. I created a
simple C script that would call

HashTable *ht = zend_new_array(15);

However, when I compile the script with gcc, I get segmentation fault; gdb
tells that the problem is located within _emalloc_56, specifically:

2535 if (UNEXPECTED(AG(mm_heap)->use_custom_heap)) {

That's how I compiled the script:
gcc -I./Zend -I. -I./TSRM -I./main Zend/*.c TSRM/TSRM.c test.c -ldl -lm -g

For the configuration I used:
./configure

Could you please guide me in the right direction? Is there something I
should do before calling zend_new_array?

Sincerely,
Ivan

4 years ago by Levi Morrison via internals — view source

unread

Hello,

I'm trying to learn a bit more about HashTable in PHP internally and how
memory is allocated when generating arrays with various sizes. I created a
simple C script that would call

HashTable *ht = zend_new_array(15);

However, when I compile the script with gcc, I get segmentation fault; gdb
tells that the problem is located within _emalloc_56, specifically:

2535 if (UNEXPECTED(AG(mm_heap)->use_custom_heap)) {

That's how I compiled the script:
gcc -I./Zend -I. -I./TSRM -I./main Zend/*.c TSRM/TSRM.c test.c -ldl -lm -g

For the configuration I used:
./configure

Could you please guide me in the right direction? Is there something I
should do before calling zend_new_array?

Sincerely,
Ivan

Does test.c include a main? If so you probably want to use the embed
SAPI. If not then you probably want to build it as an extension.

4 years ago by Ivan Zanev — view source

unread

Yes, it does.

I recompiled php now with

--configure --enable-embed=static

and wrote a simple script:

#include <stdlib.h>
#include <stdio.h>

#include "sapi/embed/php_embed.h"

int main(int argc, char *argv[]) {
php_embed_init(argc, argv);

    HashTable *ht = zend_new_array(15);

    return 0;

}

Compiled with the following command:

gcc -I./Zend -I. -I./TSRM -I./main Zend/*.c TSRM/TSRM.c test-embed.c -ldl
-lm -lphp7 -g

The segmentation fault problem still occurs, when calling php_embed_init.

Not sure if that's a problem of libphp7.so which I installed via apt or it
is something related to a missing piece in the test-embed.c script I wrote?

On Tue, Aug 25, 2020 at 2:39 PM Levi Morrison levi.morrison@datadoghq.com
wrote:

Hello,

I'm trying to learn a bit more about HashTable in PHP internally and how
memory is allocated when generating arrays with various sizes. I created
a
simple C script that would call

HashTable *ht = zend_new_array(15);

However, when I compile the script with gcc, I get segmentation fault;
gdb
tells that the problem is located within _emalloc_56, specifically:

2535 if (UNEXPECTED(AG(mm_heap)->use_custom_heap)) {

That's how I compiled the script:
gcc -I./Zend -I. -I./TSRM -I./main Zend/*.c TSRM/TSRM.c test.c -ldl -lm
-g

For the configuration I used:
./configure

Could you please guide me in the right direction? Is there something I
should do before calling zend_new_array?

Sincerely,
Ivan

Does test.c include a main? If so you probably want to use the embed
SAPI. If not then you probably want to build it as an extension.

4 years ago by Alex — view source

unread

Dear Ivan,

Some suggestions:

Build your own copy of the PHP embed library using ./configure
--enable-embed=shared or ./configure --enable-embed=static. Link against
that.
If it doesn't work, get some already-working sample code for use of the
PHP embed SAPI and modify it rather than starting from scratch.
If you are still struggling, run your test under gdb so you can get a
stack trace when it segfaults. It's as simple as "gdb --args <CLI invocation here>". Make sure that both the PHP embed SAPI and your own test
code were compiled with debug info enabled.

Alex

Yes, it does.

I recompiled php now with

--configure --enable-embed=static

and wrote a simple script:

#include <stdlib.h>
#include <stdio.h>

#include "sapi/embed/php_embed.h"

int main(int argc, char *argv[]) {
php_embed_init(argc, argv);
    HashTable *ht = zend_new_array(15);

    return 0;
}

Compiled with the following command:

gcc -I./Zend -I. -I./TSRM -I./main Zend/*.c TSRM/TSRM.c test-embed.c -ldl
-lm -lphp7 -g

The segmentation fault problem still occurs, when calling php_embed_init.

Not sure if that's a problem of libphp7.so which I installed via apt or it
is something related to a missing piece in the test-embed.c script I wrote?

On Tue, Aug 25, 2020 at 2:39 PM Levi Morrison <levi.morrison@datadoghq.com

wrote:

On Tue, Aug 25, 2020 at 5:31 AM Ivan Zanev ivanzanev477@gmail.com
wrote:

Hello,

I'm trying to learn a bit more about HashTable in PHP internally and
how
memory is allocated when generating arrays with various sizes. I
created
a
simple C script that would call

HashTable *ht = zend_new_array(15);

However, when I compile the script with gcc, I get segmentation fault;
gdb
tells that the problem is located within _emalloc_56, specifically:

2535 if (UNEXPECTED(AG(mm_heap)->use_custom_heap)) {

That's how I compiled the script:
gcc -I./Zend -I. -I./TSRM -I./main Zend/*.c TSRM/TSRM.c test.c -ldl -lm
-g

For the configuration I used:
./configure

Could you please guide me in the right direction? Is there something I
should do before calling zend_new_array?

Sincerely,
Ivan

Does test.c include a main? If so you probably want to use the embed
SAPI. If not then you probably want to build it as an extension.

4 years ago by Ivan Zanev — view source

unread

Thank you!

Dear Ivan,

Some suggestions:

Build your own copy of the PHP embed library using ./configure
--enable-embed=shared or ./configure --enable-embed=static. Link against
that.

If it doesn't work, get some already-working sample code for use of the
PHP embed SAPI and modify it rather than starting from scratch.

If you are still struggling, run your test under gdb so you can get a
stack trace when it segfaults. It's as simple as "gdb --args <CLI invocation here>". Make sure that both the PHP embed SAPI and your own test
code were compiled with debug info enabled.

Alex
Yes, it does.

I recompiled php now with

--configure --enable-embed=static

and wrote a simple script:

#include <stdlib.h>
#include <stdio.h>

#include "sapi/embed/php_embed.h"

int main(int argc, char *argv[]) {
php_embed_init(argc, argv);
    HashTable *ht = zend_new_array(15);

    return 0;
}

Compiled with the following command:

gcc -I./Zend -I. -I./TSRM -I./main Zend/*.c TSRM/TSRM.c test-embed.c -ldl
-lm -lphp7 -g

The segmentation fault problem still occurs, when calling php_embed_init.

Not sure if that's a problem of libphp7.so which I installed via apt or it
is something related to a missing piece in the test-embed.c script I
wrote?

On Tue, Aug 25, 2020 at 2:39 PM Levi Morrison <
levi.morrison@datadoghq.com>
wrote:

On Tue, Aug 25, 2020 at 5:31 AM Ivan Zanev ivanzanev477@gmail.com
wrote:

Hello,

I'm trying to learn a bit more about HashTable in PHP internally and
how
memory is allocated when generating arrays with various sizes. I
created
a
simple C script that would call

HashTable *ht = zend_new_array(15);

However, when I compile the script with gcc, I get segmentation fault;
gdb
tells that the problem is located within _emalloc_56, specifically:

2535 if (UNEXPECTED(AG(mm_heap)->use_custom_heap)) {

That's how I compiled the script:
gcc -I./Zend -I. -I./TSRM -I./main Zend/*.c TSRM/TSRM.c test.c -ldl
-lm
-g

For the configuration I used:
./configure

Could you please guide me in the right direction? Is there something I
should do before calling zend_new_array?

Sincerely,
Ivan

Does test.c include a main? If so you probably want to use the embed
SAPI. If not then you probably want to build it as an extension.