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

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.Read 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.Read

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:c402b8ec7a915cc3a51139b79a4539da0c5d8a28780330029497dfcf005bffbd","contract":["unix.Read reads bytes from a valid file descriptor into a buffer","unix.Read returns zero bytes and no error on end of file","unix.Read returns EBADF when passed an invalid file descriptor"],"goal":"verify golang.org/x/sys/unix.Read 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.Read"]},"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.Read"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.20

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"
)

// ReadFromFD reads up to len(buf) bytes from the given file descriptor using unix.Read.
func ReadFromFD(fd int, buf []byte) (int, error) {
	n, err := unix.Read(fd, buf)
	if err != nil {
		return 0, fmt.Errorf("unix.Read failed: %w", err)
	}
	return n, nil
}

func main() {
	var fds [2]int
	if err := unix.Pipe(fds[:]); err != nil {
		fmt.Fprintf(os.Stderr, "failed to create pipe: %v\n", err)
		os.Exit(1)
	}
	defer unix.Close(fds[0])
	defer unix.Close(fds[1])

	msg := []byte("hello from unix.Read")
	if _, err := unix.Write(fds[1], msg); err != nil {
		fmt.Fprintf(os.Stderr, "failed to write to pipe: %v\n", err)
		os.Exit(1)
	}

	buf := make([]byte, 64)
	n, err := ReadFromFD(fds[0], buf)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to read: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Read %d bytes: %s\n", n, string(buf[:n]))
}

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

package main

import (
	"errors"
	"fmt"
	"os"

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

func main() {
	// Assertion 1: unix.Read reads bytes from a valid file descriptor into a buffer
	var p [2]int
	if err := unix.Pipe(p[:]); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Pipe failed: %v\n", err)
		os.Exit(1)
	}
	defer unix.Close(p[0])
	defer unix.Close(p[1])

	testData := []byte("contract test payload")
	if _, err := unix.Write(p[1], testData); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Write failed: %v\n", err)
		os.Exit(1)
	}

	buf := make([]byte, 64)
	n, err := unix.Read(p[0], buf)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Read failed: %v\n", err)
		os.Exit(1)
	}
	if n != len(testData) {
		fmt.Fprintf(os.Stderr, "FAIL: expected %d bytes, got %d\n", len(testData), n)
		os.Exit(1)
	}
	if string(buf[:n]) != string(testData) {
		fmt.Fprintf(os.Stderr, "FAIL: expected content %q, got %q\n", string(testData), string(buf[:n]))
		os.Exit(1)
	}

	// Assertion 2: unix.Read returns zero bytes and no error on end of file
	var p2 [2]int
	if err := unix.Pipe(p2[:]); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Pipe for EOF failed: %v\n", err)
		os.Exit(1)
	}
	defer unix.Close(p2[0])
	if err := unix.Close(p2[1]); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: closing write end failed: %v\n", err)
		os.Exit(1)
	}

	eofBuf := make([]byte, 32)
	nEof, errEof := unix.Read(p2[0], eofBuf)
	if errEof != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Read on EOF expected nil error, got %v\n", errEof)
		os.Exit(1)
	}
	if nEof != 0 {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Read on EOF expected 0 bytes, got %d\n", nEof)
		os.Exit(1)
	}

	// Assertion 3: unix.Read returns EBADF when passed an invalid file descriptor
	invalidBuf := make([]byte, 16)
	_, errInvalid := unix.Read(-1, invalidBuf)
	if errInvalid == nil {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Read(-1) expected error, got nil\n")
		os.Exit(1)
	}
	if !errors.Is(errInvalid, unix.EBADF) {
		fmt.Fprintf(os.Stderr, "FAIL: unix.Read(-1) expected EBADF, got %v\n", errInvalid)
		os.Exit(1)
	}

	fmt.Println("PASS: golang.org/x/sys/unix Read contract passed")
}