php-in-php: VmFsReadNative — pure PHP file_get_contents path without libc open/read FFI (#1492)

[PurHur]

Category

php-in-php · stdlib · bootstrap

Problem

VM file reads (file_get_contents, readfile, zip extract, compiler include I/O) funnel through VmFsReadNative — libc open(2)/read(2) via FFI (ext/standard/VmFsReadNative.php). When PHP_COMPILER_DISABLE_FFI=1 (bootstrap/self-host probes), file_get_contents() returns false for readable paths — blocking inventory, capability checks, and M5 fast path without host Zend.

Pure PHP can read regular files via fopen/fread stream wrappers compiled through this pipeline (or thin read(2) syscall stub only when ABI-unavoidable).

php-src reference

• php/php-src ext/standard/file.c — php_stream_copy_to_mem, file_get_contents
• php/php-src main/streams/streams.c — stream layer (reference semantics)

Repro

PHP_COMPILER_DISABLE_FFI=1 php bin/vm.php -r '
echo file_get_contents(__FILE__) === false ? "FAIL\n" : "ok\n";
'

Observed: FAIL (FFI path returns false from VmFsReadNative::read()).

Expected: file contents string (match Zend on same path).

Scope

Path	Work
ext/standard/VmFsReadNative.php	Add VmFsReadPure fallback (PHP streams / compiled fread path)
ext/standard/VmFsWriteNative.php	Pair write path if needed for symmetry
Callers	file_get_contents.php, VmZipArchive.php, VmString::realpath helpers
Tests	test/unit/ext/standard/VmFsReadPureTest.php + repro under PHP_COMPILER_DISABLE_FFI=1

Shrink C/FFI: delete or gate libc read FFI once PHP path is proven; document lines removed.

Done when

• PHP_COMPILER_DISABLE_FFI=1 php bin/vm.php repro reads __FILE__ successfully
• Normal FFI builds unchanged (php-src-strict)
• Bootstrap inventory / spine smoke no longer depends on libc read FFI for committed paths
• PR notes FFI symbols/lines removed from VmFsReadNative.php

Links

• Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · php-in-php: VmStatNative — pure PHP stat()/lstat() layout, drop libc stat FFI (#1492) #8903 stat FFI sibling · Stdlib: crypt() — POSIX DES/BCRYPT string hashing (ext/standard/password.c parity) #3771 crypt (libcrypt pattern)

[PurHur]

claim: PHP Runtime → PHP — batch (#8920, #8991)\n\nStarting with #8920 (VmFsReadNative pure PHP fallback when FFI disabled), then #8991 (dir/perm mutators).

[PurHur]

claim: PHP Runtime → PHP — batch (issues #8920)

[PurHur]

Merged via #11555.

Verification: VmFsReadPureRuntimeShrinkTest + VmFsReadNativeRuntimeShrinkTest OK (12 tests); PHP_COMPILER_DISABLE_FFI=1 file_get_contents repro green; spine sync + VM driver probe OK.

PHP path: VmFsReadNative → VmFsReadPure (fopen/fread) when FFI disabled; VmEnvEnvironNative no longer uses host file_get_contents.