golang.org/x/sys v0.0.0-20210510120138-977fb7262007: 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@v0.0.0-20210510120138-977fb7262007
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/sys@v0.0.0-20210510120138-977fb7262007
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:sha256:59f20b6a28be03037c7ea6f0033ad311bc284d1880145fccde20dfaf8101613b","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 os.Getpagesize and syscall.Getpagesize","unix.Getpagesize produces consistent and idempotent results across consecutive invocations"],"goal":"verify golang.org/x/sys/unix.Getpagesize in pkg:golang/golang.org/x/sys@v0.0.0-20210510120138-977fb7262007","kind":"HOW","packages":["pkg:golang/golang.org/x/sys@v0.0.0-20210510120138-977fb7262007"],"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@v0.0.0-20210510120138-977fb7262007"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/sys@v0.0.0-20210510120138-977fb7262007","symbols":["golang.org/x/sys/unix.Getpagesize"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.20

require golang.org/x/sys v0.0.0-20210510120138-977fb7262007

golang.org/x/sys v0.0.0-20210510120138-977fb7262007 h1:gG67DSER+11cZvqIMb8S8bt0vZtiN6xWYARwirrOSfE=
golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

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@v0.0.0-20210510120138-977fb7262007",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/sys@v0.0.0-20210510120138-977fb7262007"
  ],
  "symbols": [
    "golang.org/x/sys/unix.Getpagesize"
  ]
}

package main

import (
	"fmt"
	"os"
	"syscall"

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

func main() {
	if err := runTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract assertions passed.")
}

func runTests() error {
	// 1. unix.Getpagesize returns a strictly positive integer representing the system memory page size in bytes
	pageSize := unix.Getpagesize()
	if pageSize <= 0 {
		return fmt.Errorf("expected positive page size, got %d", pageSize)
	}

	// 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 {
		return fmt.Errorf("expected page size to be a power of two, got %d", pageSize)
	}
	if pageSize < 4096 {
		return fmt.Errorf("expected page size >= 4096 bytes on Linux, got %d", pageSize)
	}

	// 3. unix.Getpagesize returns a value that matches os.Getpagesize and syscall.Getpagesize
	osSize := os.Getpagesize()
	if pageSize != osSize {
		return fmt.Errorf("unix.Getpagesize() (%d) does not match os.Getpagesize() (%d)", pageSize, osSize)
	}
	syscallSize := syscall.Getpagesize()
	if pageSize != syscallSize {
		return fmt.Errorf("unix.Getpagesize() (%d) does not match syscall.Getpagesize() (%d)", pageSize, syscallSize)
	}

	// 4. unix.Getpagesize produces consistent and idempotent results across consecutive invocations
	for i := 0; i < 10; i++ {
		nextSize := unix.Getpagesize()
		if nextSize != pageSize {
			return fmt.Errorf("inconsistent unix.Getpagesize() on iteration %d: expected %d, got %d", i, pageSize, nextSize)
		}
	}

	return nil
}