feat(linux): close three parity gaps against the Windows implementation

[devhardiyanto]

What

Closes the three real behaviour gaps between linux/phpvm.sh and the Windows implementation: unverified PHP downloads, ext list semantics, and a shallower doctor. Linux/macOS only — Windows is untouched apart from the version bump.

Why

An audit of both implementations found the command surface all but identical. cacert (Windows) and deps (Linux) are the only command-level differences and both are by design. Three differences were not by design, and one of them is a genuine integrity hole.

Splitting phpvm.sh into modules the way windows/src/ is split is queued next — deliberately after this, because a split closes no gap and is safer on top of the behaviour work plus its tests.

How

1. SHA-256 verification of the PHP tarball

The tarball came from php.net and went straight into the build with no check at all, then got cached — so a corrupt or substituted archive would be trusted on every later install too, because a cached tarball is never re-downloaded. Composer (SHA-384) and wp-cli (SHA-512) were already verified in this same file; only PHP itself was not.

The digest now comes from php.net's per-version release JSON and is checked after both the download and the cache path. Mismatch aborts and deletes the file. A missing digest, or a host with no sha256sum/shasum/openssl, degrades to a warning instead of blocking an otherwise valid install — the same fallback Windows takes. PHPVM_SKIP_HASH opts out.

Digest lookup can't reuse the hash_file() trick Composer/wp-cli use: this runs before any PHP exists.

2. ext list gains ON/OFF, ext loaded becomes distinct

Both verbs ran php -m, so one was dead weight and there was no way to see an extension that is available but not enabled. ext list now reports ON/OFF across the union of loaded extensions and the .so files in extension_dir; ext loaded is php -m alone.

ON has to come from php -m rather than a directory listing — extensions compiled into the binary (pdo, mbstring, …) own no .so, and reading the directory alone would drop them.

3. Deeper doctor

• PATH: only the first php was inspected, so a distro or Homebrew PHP sitting behind phpvm went unreported — the exact situation the check exists for. It now walks PATH and names the second one. (Split via tr, because for d in $PATH does not split on colons in zsh.)
• extension_dir: checking the directory merely exists passes an ini left pointing at another installed version — precisely what fix-ini repairs. Now compared against PHP_EXTENSION_DIR, mirroring Windows' Test-ExtDirMatch.
• Which php it reads: it went through PATH, which the check above may have just reported resolves somewhere else. Now goes through the active version's own binary.
• OpenSSL: the host version is reported upfront, so the OpenSSL 3 vs PHP < 8.1 limitation surfaces before a download rather than after one. Reported as a note, not a warning, when it cannot be determined.

Changes

• linux/phpvm.sh — _phpvm_php_sha256, _phpvm_sha256_file, _phpvm_verify_tarball; verification wired into phpvm_install after both download and cache paths; phpvm_ext_list rewritten, phpvm_ext_loaded added, ext dispatch de-duplicated; phpvm_doctor checks 2, 3 and a new 6; help text in both phpvm_help and phpvm_ext_help
• tests/linux/verify.bats — new, 12 tests
• tests/linux/commands.bats — +18 tests; fake php stub gained FAKE_PHP_INI_EXT_DIR so ini and compiled-in dirs can be driven apart
• tests/linux/zsh-smoke.zsh — 20 → 40 checks
• README.md — download verification, ext list semantics, doctor description, PHPVM_SKIP_HASH no longer described as Windows-only
• Version 1.13.2 → 1.14.0 (5 files + generated windows/phpvm.ps1)

Testing Done

• bats 82 → 112, all green
• zsh smoke (zsh 5.9) 20 → 40 checks, all green
• ShellCheck clean on linux/install.sh + linux/phpvm.sh
• bash -n and zsh -n clean
• Windows untouched: drift check OK (15 modules), Pester 168/168 still green
• Digest parser checked against the live php.net API for 8.3.0, 8.4.1, 7.3.33 and 5.6.40 — picks the .tar.gz digest, never its .bz2/.xz siblings

Two zsh-specific risks are covered by name in the smoke suite, since bats only runs under bash: the PATH scan (colon splitting) and the ext list ON/OFF counters (a while read fed by a here-string, which would have come back as zeroes had it been a pipeline).