Stdlib: hrtime() — sub-microsecond nanoseconds always zero (/proc/uptime µs path) (ext/standard/hrtime.c) #12225

Summary

hrtime() array form tv_nsec and hrtime(true) integer nanoseconds should retain sub-microsecond precision from clock_gettime(CLOCK_MONOTONIC) (php-src). This VM reads monotonic time via /proc/uptime in VmHrtimeNative (µs precision documented in-file), so the low three decimal digits of nanoseconds are always 000.

clock_gettime() shares the same VmHrtimeNative reader (#11624) — fix both when upgrading the clock source.

php-src reference: ext/standard/hrtime.c — clock_gettime(CLOCK_MONOTONIC).

PHP implementation target: ext/standard/VmHrtimeNative.php — prefer clock_gettime FFI / VmClockGettime path with ns fidelity; shrink µs-only /proc/uptime to bootstrap fallback only.

Repro (php-src-strict)

./script/docker-exec.sh -- bash -lc '
  php test/repro/maintainer_gap_hrtime_nsec_precision.php
  php bin/vm.php test/repro/maintainer_gap_hrtime_nsec_precision.php
'

Zend: hrtime()[1] % 1000 and hrtime(true) % 1000 are usually non-zero (e.g. 147, 757)
VM: both always 0

Done when

• hrtime() array and hrtime(true) preserve ns precision matching php-src on Linux.
• clock_gettime(CLOCK_MONOTONIC)['tv_nsec'] shares the same high-fidelity source.
• Existing test/unit/VmHrtimeTest.php sub-ms assertion stays green.
• Compliance .phpt; php-src-strict.