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

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.Mkdir 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.Mkdir

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:sha256:697e7e57a5ad4a8f8fb4e0994890f95376032929023a1665ce5f83587ed617ed","contract":["unix.Mkdir creates a directory with specified permission mode","unix.Mkdir returns unix.EEXIST when the directory already exists at the target path","unix.Mkdir returns unix.ENOENT when a parent directory component does not exist","unix.Mkdir returns unix.ENOTDIR when a parent component in the path is not a directory"],"goal":"verify golang.org/x/sys/unix.Mkdir 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.Mkdir"]},"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.Mkdir"],"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"
	"path/filepath"

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

func main() {
	tmpDir, err := os.MkdirTemp("", "sample_mkdir_*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp directory: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tmpDir)

	targetDir := filepath.Join(tmpDir, "demo_dir")
	if err := unix.Mkdir(targetDir, 0755); err != nil {
		fmt.Fprintf(os.Stderr, "unix.Mkdir failed: %v\n", err)
		os.Exit(1)
	}

	fi, err := os.Stat(targetDir)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to stat directory: %v\n", err)
		os.Exit(1)
	}
	if !fi.IsDir() {
		fmt.Fprintf(os.Stderr, "created path is not a directory\n")
		os.Exit(1)
	}

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

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

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 {
	tmpParent, err := os.MkdirTemp("", "contract_mkdir_*")
	if err != nil {
		return fmt.Errorf("failed to create temp dir: %w", err)
	}
	defer os.RemoveAll(tmpParent)

	// 1. unix.Mkdir creates a directory with specified permission mode
	targetDir := filepath.Join(tmpParent, "created_dir")
	mode := uint32(0750)
	oldUmask := unix.Umask(0)
	err = unix.Mkdir(targetDir, mode)
	unix.Umask(oldUmask)
	if err != nil {
		return fmt.Errorf("unix.Mkdir failed: %w", err)
	}

	fi, err := os.Stat(targetDir)
	if err != nil {
		return fmt.Errorf("os.Stat failed: %w", err)
	}
	if !fi.IsDir() {
		return fmt.Errorf("expected created path to be directory")
	}
	if fi.Mode().Perm() != 0750 {
		return fmt.Errorf("expected perm 0750, got %#o", fi.Mode().Perm())
	}

	// 2. unix.Mkdir returns unix.EEXIST when the directory already exists at the target path
	err = unix.Mkdir(targetDir, 0755)
	if err == nil {
		return fmt.Errorf("expected unix.Mkdir to fail on existing directory")
	}
	if !errors.Is(err, unix.EEXIST) {
		return fmt.Errorf("expected unix.EEXIST, got: %w", err)
	}

	// 3. unix.Mkdir returns unix.ENOENT when a parent directory component does not exist
	nonExistentParentPath := filepath.Join(tmpParent, "nonexistent_sub", "target")
	err = unix.Mkdir(nonExistentParentPath, 0755)
	if err == nil {
		return fmt.Errorf("expected unix.Mkdir to fail when parent dir missing")
	}
	if !errors.Is(err, unix.ENOENT) {
		return fmt.Errorf("expected unix.ENOENT, got: %w", err)
	}

	// 4. unix.Mkdir returns unix.ENOTDIR when a parent component in the path is not a directory
	fileAsParent := filepath.Join(tmpParent, "file_as_parent")
	if err := os.WriteFile(fileAsParent, []byte("file-content"), 0644); err != nil {
		return fmt.Errorf("failed to write dummy file: %w", err)
	}
	invalidPath := filepath.Join(fileAsParent, "child_dir")
	err = unix.Mkdir(invalidPath, 0755)
	if err == nil {
		return fmt.Errorf("expected unix.Mkdir to fail when parent component is a file")
	}
	if !errors.Is(err, unix.ENOTDIR) {
		return fmt.Errorf("expected unix.ENOTDIR, got: %w", err)
	}

	return nil
}