golang.org/x/sys v0.23.0: unix.O_RDONLY

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_RDONLY in pkg:golang/golang.org/x/sys@v0.23.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/sys@v0.23.0
Demonstrate these symbols/APIs:
  - golang.org/x/sys/unix.O_RDONLY

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:a44de72ad53499c06a89b04719cd6d9302f1c1b1347e3a5a86be7d66bb1baa88","contract":["unix.O_RDONLY evaluates to 0","unix.Open with unix.O_RDONLY opens existing file for reading content","unix.Write returns EBADF on file descriptor opened with unix.O_RDONLY","unix.Open with unix.O_RDONLY returns ENOENT when target file does not exist"],"goal":"verify golang.org/x/sys/unix.O_RDONLY in pkg:golang/golang.org/x/sys@v0.23.0","kind":"HOW","packages":["pkg:golang/golang.org/x/sys@v0.23.0"],"schemaVersion":1,"symbols":["golang.org/x/sys/unix.O_RDONLY"]},"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@v0.23.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/sys@v0.23.0","symbols":["golang.org/x/sys/unix.O_RDONLY"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.22.0

require golang.org/x/sys v0.23.0

golang.org/x/sys v0.23.0 h1:YfKFowiIMvtgl1UERQoTPPToxltDeZfbj4H7dVUCwmM=
golang.org/x/sys v0.23.0/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-rdonly-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp dir: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tmpDir)

	filePath := filepath.Join(tmpDir, "data.txt")
	if err := os.WriteFile(filePath, []byte("hello"), 0644); err != nil {
		fmt.Fprintf(os.Stderr, "failed to write file: %v\n", err)
		os.Exit(1)
	}

	fd, err := unix.Open(filePath, unix.O_RDONLY, 0)
	if err != nil {
		fmt.Fprintf(os.Stderr, "unix.Open with O_RDONLY failed: %v\n", err)
		os.Exit(1)
	}
	defer unix.Close(fd)

	fmt.Printf("Opened %s with O_RDONLY=%d (fd=%d)\n", filePath, unix.O_RDONLY, fd)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/sys/unix.O_RDONLY in pkg:golang/golang.org/x/sys@v0.23.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/sys@v0.23.0"
  ],
  "symbols": [
    "golang.org/x/sys/unix.O_RDONLY"
  ]
}

package main

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

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

func main() {
	// 1. unix.O_RDONLY evaluates to 0
	if unix.O_RDONLY != 0 {
		fmt.Fprintf(os.Stderr, "FAIL: expected unix.O_RDONLY == 0, got %d\n", unix.O_RDONLY)
		os.Exit(1)
	}

	tmpDir, err := os.MkdirTemp("", "contract-rdonly-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: MkdirTemp failed: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tmpDir)

	filePath := filepath.Join(tmpDir, "testfile.txt")
	expectedContent := []byte("sample verification payload")
	if err := os.WriteFile(filePath, expectedContent, 0644); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: WriteFile failed: %v\n", err)
		os.Exit(1)
	}

	// 2. unix.Open with unix.O_RDONLY opens an existing file for reading
	fd, err := unix.Open(filePath, unix.O_RDONLY, 0)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Open with O_RDONLY failed: %v\n", err)
		os.Exit(1)
	}
	defer unix.Close(fd)

	buf := make([]byte, 128)
	n, err := unix.Read(fd, buf)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Read on O_RDONLY fd failed: %v\n", err)
		os.Exit(1)
	}
	if !bytes.Equal(buf[:n], expectedContent) {
		fmt.Fprintf(os.Stderr, "FAIL: read content %q != expected %q\n", buf[:n], expectedContent)
		os.Exit(1)
	}

	// 3. unix.Write returns EBADF on a file descriptor opened with unix.O_RDONLY
	_, err = unix.Write(fd, []byte("denied"))
	if !errors.Is(err, unix.EBADF) {
		fmt.Fprintf(os.Stderr, "FAIL: expected EBADF on unix.Write with O_RDONLY fd, got %v\n", err)
		os.Exit(1)
	}

	// 4. unix.Open with unix.O_RDONLY without O_CREAT returns ENOENT when file does not exist
	missingPath := filepath.Join(tmpDir, "missing.txt")
	_, err = unix.Open(missingPath, unix.O_RDONLY, 0)
	if !errors.Is(err, unix.ENOENT) {
		fmt.Fprintf(os.Stderr, "FAIL: expected ENOENT when opening non-existent file with O_RDONLY, got %v\n", err)
		os.Exit(1)
	}

	fmt.Println("PASS")
}