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

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.Unlink 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.Unlink

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:sha256:1a2d9c81e425839e01e24dd5098f3c37717a381a2bfe00f6a06f630e836150ec","contract":["unix.Unlink removes an existing regular file from the filesystem","unix.Unlink returns unix.ENOENT when attempting to remove a non-existent path","unix.Unlink removes a symbolic link without removing the target file","unix.Unlink returns an error satisfying unix.EISDIR or unix.EPERM when called on a directory"],"goal":"verify golang.org/x/sys/unix.Unlink 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.Unlink"]},"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.Unlink"],"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("", "unlink_sample_*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temporary file: %v\n", err)
		os.Exit(1)
	}
	filePath := tmpFile.Name()
	if err := tmpFile.Close(); err != nil {
		fmt.Fprintf(os.Stderr, "failed to close temporary file: %v\n", err)
		os.Exit(1)
	}

	if err := unix.Unlink(filePath); err != nil {
		fmt.Fprintf(os.Stderr, "unix.Unlink failed: %v\n", err)
		os.Exit(1)
	}

	if _, err := os.Stat(filePath); !os.IsNotExist(err) {
		fmt.Fprintf(os.Stderr, "file still exists after unlink: %s\n", filePath)
		os.Exit(1)
	}

	fmt.Println("unix.Unlink demonstrated successfully")
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/sys/unix.Unlink 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.Unlink"
  ]
}

package main

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"

	"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.Unlink removes an existing regular file from the filesystem
	tmpFile, err := os.CreateTemp("", "contract_unlink_*")
	if err != nil {
		return fmt.Errorf("failed to create temp file: %w", err)
	}
	filePath := tmpFile.Name()
	if err := tmpFile.Close(); err != nil {
		return fmt.Errorf("failed to close temp file: %w", err)
	}

	if err := unix.Unlink(filePath); err != nil {
		return fmt.Errorf("unix.Unlink failed on regular file: %w", err)
	}

	if _, err := os.Stat(filePath); !os.IsNotExist(err) {
		return fmt.Errorf("file still exists after unix.Unlink: %v", err)
	}

	// 2. unix.Unlink returns unix.ENOENT when attempting to remove a non-existent path
	nonExistentPath := filepath.Join(os.TempDir(), fmt.Sprintf("nonexistent_unlink_%d", os.Getpid()))
	_ = os.Remove(nonExistentPath)

	err = unix.Unlink(nonExistentPath)
	if err == nil {
		return fmt.Errorf("expected unix.Unlink to fail on non-existent path, but got nil error")
	}
	if !errors.Is(err, unix.ENOENT) {
		return fmt.Errorf("expected unix.ENOENT, got: %w", err)
	}

	// 3. unix.Unlink removes a symbolic link without removing the target file
	targetFile, err := os.CreateTemp("", "contract_unlink_target_*")
	if err != nil {
		return fmt.Errorf("failed to create target temp file: %w", err)
	}
	targetPath := targetFile.Name()
	if err := targetFile.Close(); err != nil {
		return fmt.Errorf("failed to close target temp file: %w", err)
	}
	defer unix.Unlink(targetPath)

	symlinkPath := filepath.Join(os.TempDir(), fmt.Sprintf("contract_unlink_symlink_%d", os.Getpid()))
	_ = os.Remove(symlinkPath)
	if err := os.Symlink(targetPath, symlinkPath); err != nil {
		return fmt.Errorf("failed to create symlink: %w", err)
	}

	if err := unix.Unlink(symlinkPath); err != nil {
		return fmt.Errorf("unix.Unlink failed on symlink: %w", err)
	}

	if _, err := os.Lstat(symlinkPath); !os.IsNotExist(err) {
		return fmt.Errorf("symlink still exists after unix.Unlink: %v", err)
	}
	if _, err := os.Stat(targetPath); err != nil {
		return fmt.Errorf("target file was unexpectedly removed or inaccessible: %w", err)
	}

	// 4. unix.Unlink returns an error satisfying unix.EISDIR or unix.EPERM when called on a directory
	tmpDir, err := os.MkdirTemp("", "contract_unlink_dir_*")
	if err != nil {
		return fmt.Errorf("failed to create temp dir: %w", err)
	}
	defer os.Remove(tmpDir)

	err = unix.Unlink(tmpDir)
	if err == nil {
		return fmt.Errorf("expected unix.Unlink on directory to fail, but succeeded")
	}
	if !errors.Is(err, unix.EISDIR) && !errors.Is(err, unix.EPERM) {
		return fmt.Errorf("expected unix.EISDIR or unix.EPERM, got: %w", err)
	}

	return nil
}