Stdlib: posix_initgroups() — initgroups(3) supplementary groups missing (ext/posix/posix.c)

[PurHur]

Category

stdlib · php-src-strict

Problem

Zend ext/posix exposes posix_initgroups(string $username, int $group_id): bool. This compiler lacks it (function_exists → false). Last remaining common posix gap after getpgrp (with #6504/#6489 landed).

Repro	Zend 8.2+	VM (2026-07-16)
function_exists('posix_initgroups')	true	false

php-src reference

• php/php-src ext/posix/posix.c — PHP_FUNCTION(posix_initgroups) → initgroups()
• php/php-src ext/posix/posix.stub.php

PHP implementation target

• Thin libc ABI initgroups in PosixLibcThinAbi (write syscall — unavoidable; document in PR)
• ext/posix/posix_initgroups.php + VM wrapper; string username via VmString::coerceStringBuiltinArg
• Prefer not growing runtime/*.c

Repro

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php -r "var_export(function_exists(\"posix_initgroups\")); echo PHP_EOL;"
'

Done when

• Function registered; arg TypeErrors match Zend (enum → TypeError)
• Successful call as root matches Zend bool; failure sets posix_get_last_error
• Compliance smoke .phpt
• php-src-strict

Links

• Follows Stdlib: posix_getlogin()/posix_ttyname()/posix_isatty() — terminal session API missing (ext/posix, phase 2 #3339) #6504 / Stdlib: posix_getpwuid()/posix_getgrgid()/posix_getpwnam()/posix_getgrnam() — passwd/group lookup (ext/posix, phase 2 #3339) #6489 · epic Stdlib: ext/posix — posix_getpid/getppid/kill/waitpid (ext/posix parity) #3339

[PurHur]

claim: PHP Compiler STD Lib Advanced — batch (issues #19490, #19470, #19476) — queued after #19470

[PurHur]

Merged via #19511.

Verification: function_exists yes; enum TypeErrors; root posix_initgroups returns bool. Inventory 5082/5082.

Batch complete: #19490, #19470, #19476 merged. #19462 left open (AOT fopen handle-0 blocker; PR #19499 closed).