golang.org/x/sys v0.19.0: 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@v0.19.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/sys@v0.19.0
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:b3e0c41f99bb4b80fc6f14592223e34e2da16dc0a798692cda7d466ed93ee505","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 2 and at least 4096 bytes on Linux.","unix.Getpagesize returns a value that matches the standard library os.Getpagesize and syscall.Getpagesize.","unix.Getpagesize output can be used to calculate page-aligned buffer allocations."],"goal":"verify golang.org/x/sys/unix.Getpagesize in pkg:golang/golang.org/x/sys@v0.19.0","kind":"HOW","packages":["pkg:golang/golang.org/x/sys@v0.19.0"],"schemaVersion":1,"symbols":["golang.org/x/sys/unix.Getpagesize"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","runtime":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/golang.org/x/sys@v0.19.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/sys@v0.19.0","symbols":["golang.org/x/sys/unix.Getpagesize"],"verifierAdapter":"golang@1"}

package getpagesize_test

import (
	"os"
	"syscall"
	"testing"

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

func TestGetpagesizePositiveAndPowerOfTwo(t *testing.T) {
	pageSize := unix.Getpagesize()

	if pageSize <= 0 {
		t.Fatalf("expected positive page size, got %d", pageSize)
	}

	if (pageSize & (pageSize - 1)) != 0 {
		t.Fatalf("expected page size to be a power of two, got %d", pageSize)
	}

	if pageSize < 4096 {
		t.Fatalf("expected page size to be at least 4096 bytes on Linux, got %d", pageSize)
	}
}

func TestGetpagesizeParityWithStdlib(t *testing.T) {
	unixSize := unix.Getpagesize()
	osSize := os.Getpagesize()
	syscallSize := syscall.Getpagesize()

	if unixSize != osSize {
		t.Fatalf("unix.Getpagesize() (%d) does not match os.Getpagesize() (%d)", unixSize, osSize)
	}

	if unixSize != syscallSize {
		t.Fatalf("unix.Getpagesize() (%d) does not match syscall.Getpagesize() (%d)", unixSize, syscallSize)
	}
}

func TestGetpagesizeBufferAlignment(t *testing.T) {
	pageSize := unix.Getpagesize()

	// Verify page size can be used for aligned buffer allocations
	numPages := 4
	totalBytes := numPages * pageSize

	buf := make([]byte, totalBytes)
	if len(buf) != totalBytes {
		t.Fatalf("expected buffer length %d, got %d", totalBytes, len(buf))
	}

	if len(buf)%pageSize != 0 {
		t.Fatalf("buffer length %d is not a multiple of page size %d", len(buf), pageSize)
	}
}

module example.com/getpagesize

go 1.23

require golang.org/x/sys v0.19.0

golang.org/x/sys v0.19.0 h1:q5f1RH2jigJ1MoAWp2KTp3gm5zAGFUTarQZ5U386+4o=
golang.org/x/sys v0.19.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/sys/unix.Getpagesize in pkg:golang/golang.org/x/sys@v0.19.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/sys@v0.19.0"
  ],
  "symbols": [
    "golang.org/x/sys/unix.Getpagesize"
  ]
}