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

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.S_IFDIR 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.S_IFDIR

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:sha256:5cc1166f4975264edfadde69ed539c7865e1ddbf29b975523733cfc76c60668f","contract":["unix.S_IFDIR constant equals octal 0040000 and is preserved when masked with unix.S_IFMT","unix.Stat and unix.Fstat on a created directory report file mode matching unix.S_IFDIR under unix.S_IFMT mask","unix.Stat on a regular file and unix.Fstat on a pipe do not match unix.S_IFDIR"],"goal":"verify golang.org/x/sys/unix.S_IFDIR 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.S_IFDIR"]},"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.S_IFDIR"],"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() {
	tmpDir, err := os.MkdirTemp("", "s_ifdir_demo_*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp dir: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tmpDir)

	var stat unix.Stat_t
	if err := unix.Stat(tmpDir, &stat); err != nil {
		fmt.Fprintf(os.Stderr, "unix.Stat failed: %v\n", err)
		os.Exit(1)
	}

	isDir := (stat.Mode & unix.S_IFMT) == unix.S_IFDIR
	fmt.Printf("Directory mode: 0%o\n", stat.Mode)
	fmt.Printf("Is directory (S_IFDIR): %t\n", isDir)
}

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

package main

import (
	"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 {
	// 1. unix.S_IFDIR constant equals octal 0040000 and is preserved when masked with unix.S_IFMT
	if unix.S_IFDIR != 0040000 {
		return fmt.Errorf("expected unix.S_IFDIR to be octal 0040000 (0x4000), got 0%o", unix.S_IFDIR)
	}
	if (unix.S_IFDIR & unix.S_IFMT) != unix.S_IFDIR {
		return fmt.Errorf("expected unix.S_IFDIR & unix.S_IFMT to equal unix.S_IFDIR")
	}

	// 2. unix.Stat and unix.Fstat on a created directory report file mode matching unix.S_IFDIR under unix.S_IFMT mask
	tmpDir, err := os.MkdirTemp("", "s_ifdir_contract_*")
	if err != nil {
		return fmt.Errorf("failed to create temporary dir: %w", err)
	}
	defer os.RemoveAll(tmpDir)

	var stat unix.Stat_t
	if err := unix.Stat(tmpDir, &stat); err != nil {
		return fmt.Errorf("unix.Stat failed: %w", err)
	}

	if (stat.Mode & unix.S_IFMT) != unix.S_IFDIR {
		return fmt.Errorf("expected (stat.Mode & unix.S_IFMT) to be unix.S_IFDIR, got 0%o", stat.Mode&unix.S_IFMT)
	}
	if (stat.Mode & unix.S_IFDIR) == 0 {
		return fmt.Errorf("expected stat.Mode & unix.S_IFDIR != 0, got mode 0%o", stat.Mode)
	}

	dirFd, err := unix.Open(tmpDir, unix.O_RDONLY|unix.O_DIRECTORY, 0)
	if err != nil {
		return fmt.Errorf("unix.Open failed on dir: %w", err)
	}
	defer unix.Close(dirFd)

	var fstat unix.Stat_t
	if err := unix.Fstat(dirFd, &fstat); err != nil {
		return fmt.Errorf("unix.Fstat failed: %w", err)
	}
	if (fstat.Mode & unix.S_IFMT) != unix.S_IFDIR {
		return fmt.Errorf("expected (fstat.Mode & unix.S_IFMT) to be unix.S_IFDIR, got 0%o", fstat.Mode&unix.S_IFMT)
	}

	// 3. unix.Stat on a regular file and unix.Fstat on a pipe do not match unix.S_IFDIR
	tmpFile, err := os.CreateTemp("", "s_ifdir_reg_*")
	if err != nil {
		return fmt.Errorf("failed to create temporary file: %w", err)
	}
	defer os.Remove(tmpFile.Name())
	defer tmpFile.Close()

	var fileStat unix.Stat_t
	if err := unix.Stat(tmpFile.Name(), &fileStat); err != nil {
		return fmt.Errorf("unix.Stat on regular file failed: %w", err)
	}
	if (fileStat.Mode & unix.S_IFMT) == unix.S_IFDIR {
		return fmt.Errorf("regular file unexpectedly matched unix.S_IFDIR")
	}
	if (fileStat.Mode & unix.S_IFMT) != unix.S_IFREG {
		return fmt.Errorf("expected regular file mode to match unix.S_IFREG (0%o), got 0%o", unix.S_IFREG, fileStat.Mode&unix.S_IFMT)
	}

	pipeFds := make([]int, 2)
	if err := unix.Pipe(pipeFds); err != nil {
		return fmt.Errorf("unix.Pipe failed: %w", err)
	}
	defer unix.Close(pipeFds[0])
	defer unix.Close(pipeFds[1])

	var pipeStat unix.Stat_t
	if err := unix.Fstat(pipeFds[0], &pipeStat); err != nil {
		return fmt.Errorf("unix.Fstat on pipe failed: %w", err)
	}
	if (pipeStat.Mode & unix.S_IFMT) == unix.S_IFDIR {
		return fmt.Errorf("pipe unexpectedly matched unix.S_IFDIR")
	}
	if (pipeStat.Mode & unix.S_IFMT) != unix.S_IFIFO {
		return fmt.Errorf("expected pipe mode to match unix.S_IFIFO (0%o), got 0%o", unix.S_IFIFO, pipeStat.Mode&unix.S_IFMT)
	}

	return nil
}