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killertux / solder

Library to help you build php extensions using Rust
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Segmentation fault (core dumped) #3

Open Norbytus opened 4 years ago

Norbytus commented 4 years ago

If take example and hello_world function like this:

<?php
hello_world('R');
?>

It will crash with segmentation fault (core dumped) looks like problem in add_zend_value_zval

wizzwizz4 commented 4 years ago

I have a sneaking suspicion that this is caused by the conflict between different allocators. When writing Rust code to interface with PHP, you've got four allocation systems to juggle, but Solder currently assumes that everything will happily free everything else's memory.

To solve this, you need to pass everything back to the place from whence it came; never drop any Rust stuff inside PHP, or PHP stuff inside Rust. A later version of solder might expose the three allocators to the wider world, but for now this will have to do.

wizzwizz4 commented 4 years ago

Specifically, the issue is (as far as I can tell) in the section beginning:

impl From<&str> for Zval {

It shouldn't pass the pointer into the ZendString; it should allocate new memory using the PHP allocator and copy the bytes into it. (Also – that should really be a &mut if you're not planning to set the GC_IMMUTABLE flag!) Alternatively, the GC_COLLECTABLE, GC_PROTECTED and / or GC_PERSISTENT(_LOCAL) (intended for malloc, which is not the Rust allocator! Be careful, because I don't know what assumptions PHP makes about that) might be possible to combine to solve the problem.