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

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.Mkfifo 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.Mkfifo

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:sha256:005a18a5550aba44ac7491ce2f0e4e084b56928c238e61ea13dce86da3585afe","contract":["unix.Mkfifo creates a FIFO special file with os.ModeNamedPipe at the specified path","unix.Mkfifo returns EEXIST when the target path already exists","unix.Mkfifo created FIFO transmits data between concurrent reader and writer goroutines"],"goal":"verify golang.org/x/sys/unix.Mkfifo 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.Mkfifo"]},"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.Mkfifo"],"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"
	"io"
	"os"
	"path/filepath"

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

func main() {
	fifoPath := filepath.Join(os.TempDir(), fmt.Sprintf("mkfifo_sample_%d.pipe", os.Getpid()))
	defer os.Remove(fifoPath)

	if err := unix.Mkfifo(fifoPath, 0600); err != nil {
		fmt.Fprintf(os.Stderr, "unix.Mkfifo failed: %v\n", err)
		os.Exit(1)
	}

	msg := "Hello from unix.Mkfifo"
	errCh := make(chan error, 1)

	go func() {
		f, err := os.OpenFile(fifoPath, os.O_WRONLY, 0)
		if err != nil {
			errCh <- fmt.Errorf("writer open failed: %w", err)
			return
		}
		defer f.Close()

		if _, err := f.WriteString(msg); err != nil {
			errCh <- fmt.Errorf("writer write failed: %w", err)
			return
		}
		errCh <- nil
	}()

	f, err := os.OpenFile(fifoPath, os.O_RDONLY, 0)
	if err != nil {
		fmt.Fprintf(os.Stderr, "reader open failed: %v\n", err)
		os.Exit(1)
	}
	defer f.Close()

	buf, err := io.ReadAll(f)
	if err != nil {
		fmt.Fprintf(os.Stderr, "reader read failed: %v\n", err)
		os.Exit(1)
	}

	if err := <-errCh; err != nil {
		fmt.Fprintf(os.Stderr, "writer goroutine error: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Received: %s\n", string(buf))
}

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

package main

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"time"

	"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 {
	// Assertion 1: unix.Mkfifo creates a FIFO special file with os.ModeNamedPipe at the specified path
	tempDir, err := os.MkdirTemp("", "csx_fifo_test_*")
	if err != nil {
		return fmt.Errorf("failed to create temporary directory: %w", err)
	}
	defer os.RemoveAll(tempDir)

	fifoPath := filepath.Join(tempDir, "test_fifo.pipe")
	if err := unix.Mkfifo(fifoPath, 0620); err != nil {
		return fmt.Errorf("unix.Mkfifo failed: %w", err)
	}

	fi, err := os.Stat(fifoPath)
	if err != nil {
		return fmt.Errorf("os.Stat on created FIFO failed: %w", err)
	}
	if fi.Mode()&os.ModeNamedPipe == 0 {
		return fmt.Errorf("expected file mode to have ModeNamedPipe set, got: %v", fi.Mode())
	}

	// Assertion 2: unix.Mkfifo returns EEXIST when the target path already exists
	err = unix.Mkfifo(fifoPath, 0620)
	if err == nil {
		return fmt.Errorf("expected EEXIST error when creating existing FIFO, got nil")
	}
	if !errors.Is(err, unix.EEXIST) {
		return fmt.Errorf("expected unix.EEXIST error, got: %v", err)
	}

	// Assertion 3: unix.Mkfifo created FIFO transmits data between concurrent reader and writer goroutines
	payload := []byte("CodeSampleX FIFO verification payload test 12345")
	errCh := make(chan error, 2)
	readCh := make(chan []byte, 1)

	go func() {
		w, err := os.OpenFile(fifoPath, os.O_WRONLY, 0)
		if err != nil {
			errCh <- fmt.Errorf("writer OpenFile failed: %w", err)
			return
		}
		defer w.Close()

		if _, err := w.Write(payload); err != nil {
			errCh <- fmt.Errorf("writer Write failed: %w", err)
			return
		}
		errCh <- nil
	}()

	go func() {
		r, err := os.OpenFile(fifoPath, os.O_RDONLY, 0)
		if err != nil {
			errCh <- fmt.Errorf("reader OpenFile failed: %w", err)
			return
		}
		defer r.Close()

		buf := make([]byte, len(payload))
		if _, err := io.ReadFull(r, buf); err != nil {
			errCh <- fmt.Errorf("reader ReadFull failed: %w", err)
			return
		}
		readCh <- buf
		errCh <- nil
	}()

	timeout := time.After(5 * time.Second)
	for i := 0; i < 2; i++ {
		select {
		case err := <-errCh:
			if err != nil {
				return err
			}
		case <-timeout:
			return fmt.Errorf("timed out waiting for FIFO read/write operations")
		}
	}

	received := <-readCh
	if !bytes.Equal(received, payload) {
		return fmt.Errorf("payload mismatch: expected %q, got %q", string(payload), string(received))
	}

	return nil
}