Investigate .dat file condition in PROXYFS mmap - no changes needed

[Copilot]

Investigated reviewer feedback questioning whether the if (!path.endsWith('.dat')) condition in PROXYFS mmap implementation is necessary.

Findings

The condition is required. Removing it breaks ICU data file loading through PROXYFS:

• Without condition: All 18 Intl extension tests fail with IntlException: Constructor failed
• With condition: All tests pass

Root Cause

For .dat files, the length parameter passed by PHP to mmap is already correct. Using fstat() to override it breaks ICU's mmap implementation. For other files, fstat() provides the correct length that PHP fails to pass.

Code Location

// packages/php-wasm/universal/src/lib/proxy-file-system.ts
const path = FS.getPath(stream.node);
if (!path.endsWith('.dat')) {
    const proxyFS = stream.node.mount.opts.fs;
    if (proxyFS && stream.nfd !== undefined) {
        const stat = proxyFS.fstat(stream.nfd);
        if (stat && stat.size !== undefined) {
            length = stat.size >>> 0;
        }
    }
}

The condition is correct as implemented. No changes made.

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