golang.org/x/sys v0.40.0: unix.Getpagesize

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify golang.org/x/sys/unix.Getpagesize in pkg:golang/golang.org/x/sys@v0.40.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/sys@v0.40.0
Demonstrate these symbols/APIs:
  - golang.org/x/sys/unix.Getpagesize

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:07db46f4add735f7fa9ffd826062696f5a3635ffa9bc6d947f5f17ab75e22fe7","contract":["unix.Getpagesize returns a strictly positive integer representing the system memory page size in bytes","unix.Getpagesize returns a page size that is a power of two and at least 4096 bytes on Linux","unix.Getpagesize returns a value that matches the standard library os.Getpagesize and syscall.Getpagesize","unix.Getpagesize produces consistent results across repeated invocations","unix.Getpagesize output can be used to allocate page-aligned byte buffers"],"goal":"verify golang.org/x/sys/unix.Getpagesize in pkg:golang/golang.org/x/sys@v0.40.0","kind":"HOW","packages":["pkg:golang/golang.org/x/sys@v0.40.0"],"schemaVersion":1,"symbols":["golang.org/x/sys/unix.Getpagesize"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/golang.org/x/sys@v0.40.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/sys@v0.40.0","symbols":["golang.org/x/sys/unix.Getpagesize"],"verifierAdapter":"golang@1"}

module example.com/getpagesize

go 1.24.0

require golang.org/x/sys v0.40.0

golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=

package main

import (
	"fmt"

	"golang.org/x/sys/unix"
)

func main() {
	pageSize := unix.Getpagesize()
	fmt.Printf("System page size: %d bytes\n", pageSize)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/sys/unix.Getpagesize in pkg:golang/golang.org/x/sys@v0.40.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/sys@v0.40.0"
  ],
  "symbols": [
    "golang.org/x/sys/unix.Getpagesize"
  ]
}

package main

import (
	"fmt"
	"os"
	"syscall"

	"golang.org/x/sys/unix"
)

func main() {
	pageSize := unix.Getpagesize()

	// Assertion 1: unix.Getpagesize returns a strictly positive integer representing the system memory page size in bytes
	if pageSize <= 0 {
		fmt.Fprintf(os.Stderr, "FAIL: expected positive page size, got %d\n", pageSize)
		os.Exit(1)
	}

	// Assertion 2: unix.Getpagesize returns a page size that is a power of two and at least 4096 bytes on Linux
	if (pageSize & (pageSize - 1)) != 0 {
		fmt.Fprintf(os.Stderr, "FAIL: expected page size to be power of two, got %d\n", pageSize)
		os.Exit(1)
	}
	if pageSize < 4096 {
		fmt.Fprintf(os.Stderr, "FAIL: expected page size >= 4096 bytes on Linux, got %d\n", pageSize)
		os.Exit(1)
	}

	// Assertion 3: unix.Getpagesize returns a value that matches the standard library os.Getpagesize and syscall.Getpagesize
	if osPageSize := os.Getpagesize(); pageSize != osPageSize {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Getpagesize (%d) != os.Getpagesize (%d)\n", pageSize, osPageSize)
		os.Exit(1)
	}
	if sysPageSize := syscall.Getpagesize(); pageSize != sysPageSize {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Getpagesize (%d) != syscall.Getpagesize (%d)\n", pageSize, sysPageSize)
		os.Exit(1)
	}

	// Assertion 4: unix.Getpagesize produces consistent results across repeated invocations
	for i := 0; i < 100; i++ {
		if cur := unix.Getpagesize(); cur != pageSize {
			fmt.Fprintf(os.Stderr, "FAIL: unix.Getpagesize produced inconsistent result at iteration %d: %d != %d\n", i, cur, pageSize)
			os.Exit(1)
		}
	}

	// Assertion 5: unix.Getpagesize output can be used to allocate page-aligned byte buffers
	numPages := 4
	totalBytes := numPages * pageSize
	buf := make([]byte, totalBytes)
	if len(buf) != totalBytes || len(buf)%pageSize != 0 {
		fmt.Fprintf(os.Stderr, "FAIL: page-aligned buffer check failed (len=%d, pageSize=%d)\n", len(buf), pageSize)
		os.Exit(1)
	}

	fmt.Println("PASS: golang.org/x/sys/unix.Getpagesize contract verified")
}