golang.org/x/sys v0.0.0-20220406155245-289d7a0edf71: unix.O_WRONLY

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.O_WRONLY in pkg:golang/golang.org/x/sys@v0.0.0-20220406155245-289d7a0edf71
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/sys@v0.0.0-20220406155245-289d7a0edf71
Demonstrate these symbols/APIs:
  - golang.org/x/sys/unix.O_WRONLY
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:d5f25fc6b9e5d8f475f964e6746cae4b45bc7eda465f9e229881acbf21515f31","contract":["unix.O_WRONLY constant equals 1 representing POSIX write-only file access mode","unix.Open with unix.O_WRONLY creates or opens file for writing","unix.Write writes data to file descriptor opened with unix.O_WRONLY","unix.Read on file descriptor opened with unix.O_WRONLY returns EBADF error","unix.Close cleanly releases the file descriptor opened with unix.O_WRONLY","unix.Open with unix.O_WRONLY combined with O_CREAT and O_TRUNC truncates existing file contents"],"goal":"verify golang.org/x/sys/unix.O_WRONLY in pkg:golang/golang.org/x/sys@v0.0.0-20220406155245-289d7a0edf71","kind":"HOW","packages":["pkg:golang/golang.org/x/sys@v0.0.0-20220406155245-289d7a0edf71"],"schemaVersion":1,"symbols":["golang.org/x/sys/unix.O_WRONLY"]},"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@v0.0.0-20220406155245-289d7a0edf71"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/sys@v0.0.0-20220406155245-289d7a0edf71","symbols":["golang.org/x/sys/unix.O_WRONLY"],"verifierAdapter":"golang@1"}

module sample

go 1.23.0

require golang.org/x/sys v0.0.0-20220406155245-289d7a0edf71

golang.org/x/sys v0.0.0-20220406155245-289d7a0edf71 h1:PRD0hj6tTuUnCFD08vkvjkYFbQg/9lV8KIxe1y4/cvU=
golang.org/x/sys v0.0.0-20220406155245-289d7a0edf71/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

package main

import (
	"fmt"
	"os"

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

func main() {
	tmpFile := "sample_output.txt"
	defer os.Remove(tmpFile)

	// Open file with unix.O_WRONLY | unix.O_CREAT | unix.O_TRUNC
	flags := unix.O_WRONLY | unix.O_CREAT | unix.O_TRUNC
	mode := uint32(0644)
	fd, err := unix.Open(tmpFile, flags, mode)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Failed to open file: %v\n", err)
		os.Exit(1)
	}
	defer unix.Close(fd)

	message := []byte("Demonstrating golang.org/x/sys/unix.O_WRONLY file writing\n")
	n, err := unix.Write(fd, message)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Failed to write: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Successfully wrote %d bytes using unix.O_WRONLY (flag value: %d)\n", n, unix.O_WRONLY)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/sys/unix.O_WRONLY in pkg:golang/golang.org/x/sys@v0.0.0-20220406155245-289d7a0edf71",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/sys@v0.0.0-20220406155245-289d7a0edf71"
  ],
  "symbols": [
    "golang.org/x/sys/unix.O_WRONLY"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

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

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

func main() {
	if err := runContract(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract verification failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All golang.org/x/sys/unix.O_WRONLY contract assertions passed successfully.")
}

func runContract() error {
	tempDir, err := os.MkdirTemp("", "csx-test-unix-*")
	if err != nil {
		return fmt.Errorf("failed to create temp dir: %w", err)
	}
	defer os.RemoveAll(tempDir)

	// Assertion 1: unix.O_WRONLY constant equals 1 (POSIX write-only flag)
	if unix.O_WRONLY != 1 {
		return fmt.Errorf("expected unix.O_WRONLY to equal 1, got %d", unix.O_WRONLY)
	}

	// Assertion 2: unix.Open with unix.O_WRONLY creates or opens file for writing
	testFile := filepath.Join(tempDir, "test_wronly.txt")
	fd, err := unix.Open(testFile, unix.O_WRONLY|unix.O_CREAT|unix.O_TRUNC, 0644)
	if err != nil {
		return fmt.Errorf("expected unix.Open with O_WRONLY to succeed: %w", err)
	}

	// Assertion 3: unix.Write writes data to file descriptor opened with unix.O_WRONLY
	payload := []byte("hello unix.O_WRONLY")
	n, err := unix.Write(fd, payload)
	if err != nil {
		unix.Close(fd)
		return fmt.Errorf("expected unix.Write to succeed: %w", err)
	}
	if n != len(payload) {
		unix.Close(fd)
		return fmt.Errorf("expected unix.Write to write %d bytes, got %d", len(payload), n)
	}

	// Assertion 4: unix.Read on file descriptor opened with unix.O_WRONLY returns EBADF error
	readBuf := make([]byte, 32)
	_, readErr := unix.Read(fd, readBuf)
	if readErr == nil {
		unix.Close(fd)
		return fmt.Errorf("expected unix.Read on O_WRONLY fd to return error, but got nil")
	}
	if !errors.Is(readErr, unix.EBADF) {
		unix.Close(fd)
		return fmt.Errorf("expected read error to be EBADF, got: %v", readErr)
	}

	// Assertion 5: unix.Close cleanly releases the file descriptor opened with unix.O_WRONLY
	if err := unix.Close(fd); err != nil {
		return fmt.Errorf("expected unix.Close to succeed: %w", err)
	}

	// Verify file content on disk after close
	readBack, err := os.ReadFile(testFile)
	if err != nil {
		return fmt.Errorf("failed to read back written file: %w", err)
	}
	if !bytes.Equal(readBack, payload) {
		return fmt.Errorf("written file content mismatch: got %q, want %q", string(readBack), string(payload))
	}

	// Assertion 6: unix.Open with unix.O_WRONLY combined with O_CREAT and O_TRUNC truncates existing file contents
	fdTrunc, err := unix.Open(testFile, unix.O_WRONLY|unix.O_CREAT|unix.O_TRUNC, 0644)
	if err != nil {
		return fmt.Errorf("failed to re-open file with O_TRUNC: %w", err)
	}
	newPayload := []byte("short")
	if _, err := unix.Write(fdTrunc, newPayload); err != nil {
		unix.Close(fdTrunc)
		return fmt.Errorf("failed to write truncated content: %w", err)
	}
	if err := unix.Close(fdTrunc); err != nil {
		return fmt.Errorf("failed to close fdTrunc: %w", err)
	}

	truncatedReadBack, err := os.ReadFile(testFile)
	if err != nil {
		return fmt.Errorf("failed to read back truncated file: %w", err)
	}
	if !bytes.Equal(truncatedReadBack, newPayload) {
		return fmt.Errorf("truncated file content mismatch: got %q, want %q", string(truncatedReadBack), string(newPayload))
	}

	return nil
}