API Breakage: php_base64_encode No Longer Exported in php8ts.dll

[mitkonikov]

Description

In PHP 8.4.5 (and possibly earlier versions), php_base64_encode is no longer exported from php8ts.dll. While the function still exists, it has been made static, meaning extensions that rely on it as an exported symbol (in my example, the MongoDB extension) failed to run.

Here's a reference in the code:

php-src/ext/standard/base64.h

Lines 67 to 70 in b5446e4

	PHPAPI extern zend_string *php_base64_encode_ex(const unsigned char *, size_t, zend_long flags);
	PHPAPI extern zend_string *php_base64_decode_ex(const unsigned char *, size_t, bool);
	static inline zend_string *php_base64_encode(const unsigned char *str, size_t len) {

Would it be possible to restore the export of php_base64_encode, or should affected extensions downstream switch to php_base64_encode_ex instead? As far as I can see, this breakage happened between 8.3.0 and 8.4.0 (minor versions), I would guess it's best to fix it in the PHP repository.

PHP Version

PHP 8.4.5

Operating System

Windows 11

[remicollet]

I don't see any problem
In all cases extension built with 8.3 (and using this symbol) won't work with 8.4
Rebuild will find and use the static inline function.

[mitkonikov]

Yes, but dynamically loading it via Composer throws an error, as it can't find the symbol.

[remicollet]

Don't know how Windows works, but I don't see why it will require this symbol

Using the extension build with 8.3

$ objdump -T  mongodb.so | grep base64
0000000000000000      D  *UND*	0000000000000000  Base        php_base64_decode_ex
0000000000000000      D  *UND*	0000000000000000  Base        php_base64_encode

Using the extension build with 8.4

$ objdump -T mongodb.so | grep base64
0000000000000000      D  *UND*	0000000000000000  Base        php_base64_decode_ex
0000000000000000      D  *UND*	0000000000000000  Base        php_base64_encode_ex

[iluuu1994]

This changed happened in 8.4, but PHP doesn't follow semantic versioning. Neither do we provide ABI compatibility between "minor" versions. You will need to compile your extension against each supported PHP version. When correctly compiled against 8.4, the static function will be inlined and not referenced from the resulting binary, as @remicollet has mentioned.

[remicollet]

Additional notice: if all symbols were present, the extension would still failed to load with something like

Warning: PHP 
Startup: xxx: Unable to initialize module
Module compiled with module API=20230831
PHP    compiled with module API=20240924
These options need to match

[mitkonikov]

I didn't know that PHP doesn't follow semantic versioning, nor that it doesn't provide backwards-compatible ABI. It might be a good thing to mention this in your README. Otherwise, yes, when compiled against the 8.4.0, the function is correctly inlined on Windows as well. So, thank you for the feedback. I will close this issue now.