[andreybolonin]

Preparing SCRIPT_FILENAME currently prepends / even when the request path already starts with it. The resulting extra slash makes path.Clean rebuild an otherwise clean path.

Only prepend / for unrooted paths. Keep path cleaning, the Windows locality check, and trailing-slash handling. Add cases for repeated leading slashes and traversal, plus a benchmark for rooted, relative, and traversal paths.

Earlier standalone measurements of this helper (Go 1.27.3, darwin/arm64, median of five 200ms samples):

Path	Before	After	Time reduction	Go B/op	allocs/op
/index.php	111.8 ns	69.69 ns	37.7%	80 → 32	4 → 1
/products/catalog/index.php	153.9 ns	110.9 ns	27.9%	144 → 48	4 → 1
Long rooted path	499.2 ns	413.3 ns	17.2%	656 → 176	4 → 1

These are helper-level results, not whole-request or RSS measurements. Relative paths had a 2.4% time reduction with unchanged allocations; traversal paths had an 11.0% reduction with Go B/op dropping from 96 to 72. The original benchmark cases were not rerun.

Validation:

• gofmt and git diff --check passed.
• The exact helper and its repository path tests passed with -race in an isolated harness without PHP linkage.
• A differential fuzz run against the original helper passed 657,119 executions.
• The isolated tests cross-compiled for Windows; Windows runtime tests were not run locally.
• Full FrankenPHP tests were not run: the local environment lacks the required PHP ZTS/shared-library and watcher setup.

Adversarial benchmark cases use 4096 leading slashes and 512 rooted a/../ segments. Separate exploratory measurements (Go 1.27.3, Apple M2, darwin/arm64; one 300ms sample per case):

Input	Before	After	Go B/op	allocs/op
4096 leading slashes	3260 ns	2782 ns	9776 → 4912	4 → 3
512 rooted a/../ segments	3533 ns	3391 ns	5424 → 2736	4 → 3

These exploratory measurements do not establish statistical significance or an improvement on every input. Allocation counts and bytes do not increase in these cases.

The branch also restores the os import needed by os.ErrDeadlineExceeded, which was lost when main was merged and caused the CI compilation failure.

[henderkes]

You've not measured the adversary case yet, please do that too. Otherwise approved.

[henderkes]

We have ensureLeadingSlaah I think. Can't it be used here?