golang.org/x/sys v0.22.0: unix.Close

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.Close in pkg:golang/golang.org/x/sys@v0.22.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/sys@v0.22.0
Demonstrate these symbols/APIs:
  - golang.org/x/sys/unix.Close

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:sha256:870c638e7d34694b913d355b9b2990901f7046368d312a2157990080f0b37fee","contract":["unix.Close closes a valid open file descriptor successfully","unix.Close returns unix.EBADF for an invalid file descriptor","unix.Close returns unix.EBADF when called on an already closed file descriptor"],"goal":"verify golang.org/x/sys/unix.Close in pkg:golang/golang.org/x/sys@v0.22.0","kind":"HOW","packages":["pkg:golang/golang.org/x/sys@v0.22.0"],"schemaVersion":1,"symbols":["golang.org/x/sys/unix.Close"]},"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@v0.22.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/sys@v0.22.0","symbols":["golang.org/x/sys/unix.Close"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/sys v0.22.0

golang.org/x/sys v0.22.0 h1:RI27ohtqKCnwULzJLqkv897zojh5/DwS/ENaMzUOaWI=
golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

package main

import (
	"fmt"
	"os"

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

func main() {
	tmpFile, err := os.CreateTemp("", "close_sample_*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp file: %v\n", err)
		os.Exit(1)
	}
	defer os.Remove(tmpFile.Name())

	fd := int(tmpFile.Fd())
	if err := unix.Close(fd); err != nil {
		fmt.Fprintf(os.Stderr, "unix.Close failed: %v\n", err)
		os.Exit(1)
	}

	fmt.Println("unix.Close succeeded")
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/sys/unix.Close in pkg:golang/golang.org/x/sys@v0.22.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/sys@v0.22.0"
  ],
  "symbols": [
    "golang.org/x/sys/unix.Close"
  ]
}

package main

import (
	"errors"
	"fmt"
	"os"

	"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 {
	tmpFile, err := os.CreateTemp("", "contract_close_*")
	if err != nil {
		return fmt.Errorf("failed to create temp file: %w", err)
	}
	defer os.Remove(tmpFile.Name())

	fd := int(tmpFile.Fd())

	// 1. unix.Close closes a valid open file descriptor successfully
	if err := unix.Close(fd); err != nil {
		return fmt.Errorf("unix.Close failed on valid fd: %w", err)
	}

	// 2. unix.Close returns unix.EBADF for an invalid file descriptor
	err = unix.Close(-1)
	if err == nil {
		return fmt.Errorf("expected unix.Close(-1) to fail, but succeeded")
	}
	if !errors.Is(err, unix.EBADF) {
		return fmt.Errorf("expected unix.EBADF for fd=-1, got: %w", err)
	}

	// 3. unix.Close returns unix.EBADF when called on an already closed file descriptor
	err = unix.Close(fd)
	if err == nil {
		return fmt.Errorf("expected unix.Close on closed fd to fail, but succeeded")
	}
	if !errors.Is(err, unix.EBADF) {
		return fmt.Errorf("expected unix.EBADF for closed fd, got: %w", err)
	}

	return nil
}