github.com/vishvananda/netns v0.0.0-20211101163701-50045581ed74: Get

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 github.com/vishvananda/netns.Get in pkg:golang/github.com/vishvananda/netns@v0.0.0-20211101163701-50045581ed74
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/vishvananda/netns@v0.0.0-20211101163701-50045581ed74
Demonstrate these symbols/APIs:
  - github.com/vishvananda/netns.Get

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:sha256:04dcddc6231dc9f455918e444d6918a665e0b97e6256350284c64a472a6d1f96","contract":["netns.Get retrieves an open NsHandle representing the current thread network namespace","netns.Get returns an NsHandle with a valid non-empty UniqueId formatted as NS(dev, ino)","multiple calls to netns.Get on the same thread return handles that report Equal to each other","NsHandle returned by netns.Get can be closed, making IsOpen return false"],"goal":"verify github.com/vishvananda/netns.Get in pkg:golang/github.com/vishvananda/netns@v0.0.0-20211101163701-50045581ed74","kind":"HOW","packages":["pkg:golang/github.com/vishvananda/netns@v0.0.0-20211101163701-50045581ed74"],"schemaVersion":1,"symbols":["github.com/vishvananda/netns.Get"]},"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/github.com/vishvananda/netns@v0.0.0-20211101163701-50045581ed74"],"schemaVersion":1,"subject":"pkg:golang/github.com/vishvananda/netns@v0.0.0-20211101163701-50045581ed74","symbols":["github.com/vishvananda/netns.Get"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require github.com/vishvananda/netns v0.0.0-20211101163701-50045581ed74

require golang.org/x/sys v0.0.0-20200217220822-9197077df867 // indirect

github.com/vishvananda/netns v0.0.0-20211101163701-50045581ed74 h1:gga7acRE695APm9hlsSMoOoE65U4/TcqNj90mc69Rlg=
github.com/vishvananda/netns v0.0.0-20211101163701-50045581ed74/go.mod h1:DD4vA1DwXk04H54A1oHXtwZmA0grkVMdPxx/VGLCah0=
golang.org/x/sys v0.0.0-20200217220822-9197077df867 h1:JoRuNIf+rpHl+VhScRQQvzbHed86tKkqwPMV34T8myw=
golang.org/x/sys v0.0.0-20200217220822-9197077df867/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

package main

import (
	"fmt"
	"os"
	"runtime"

	"github.com/vishvananda/netns"
)

// GetCurrentThreadNamespace retrieves the network namespace of the calling OS thread.
func GetCurrentThreadNamespace() (netns.NsHandle, error) {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	handle, err := netns.Get()
	if err != nil {
		return netns.None(), fmt.Errorf("failed to get thread netns: %w", err)
	}
	return handle, nil
}

func main() {
	handle, err := GetCurrentThreadNamespace()
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
		os.Exit(1)
	}
	defer handle.Close()

	fmt.Printf("Current NetNS Handle: %d\n", int(handle))
	fmt.Printf("Current NetNS Unique ID: %s\n", handle.UniqueId())
	fmt.Printf("Is Open: %t\n", handle.IsOpen())
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/vishvananda/netns.Get in pkg:golang/github.com/vishvananda/netns@v0.0.0-20211101163701-50045581ed74",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/vishvananda/netns@v0.0.0-20211101163701-50045581ed74"
  ],
  "symbols": [
    "github.com/vishvananda/netns.Get"
  ]
}

package main

import (
	"fmt"
	"os"
	"runtime"
	"strings"

	"github.com/vishvananda/netns"
)

func main() {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	// Assertion 1: netns.Get retrieves an open NsHandle representing the current thread network namespace
	curNs, err := netns.Get()
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: netns.Get() returned error: %v\n", err)
		os.Exit(1)
	}
	if !curNs.IsOpen() {
		fmt.Fprintf(os.Stderr, "FAIL: netns.Get() handle is not open\n")
		os.Exit(1)
	}
	if int(curNs) <= 0 {
		fmt.Fprintf(os.Stderr, "FAIL: expected valid positive file descriptor, got %d\n", int(curNs))
		os.Exit(1)
	}

	// Assertion 2: netns.Get returns an NsHandle with a valid non-empty UniqueId formatted as NS(dev, ino)
	uid := curNs.UniqueId()
	if uid == "" || !strings.HasPrefix(uid, "NS(") || !strings.HasSuffix(uid, ")") {
		fmt.Fprintf(os.Stderr, "FAIL: expected UniqueId formatted as NS(dev, ino), got %q\n", uid)
		os.Exit(1)
	}

	// Assertion 3: multiple calls to netns.Get on the same thread return handles that report Equal to each other
	secondNs, err := netns.Get()
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: second netns.Get() returned error: %v\n", err)
		os.Exit(1)
	}
	if !curNs.Equal(secondNs) {
		fmt.Fprintf(os.Stderr, "FAIL: expected identical namespace for subsequent netns.Get() call\n")
		os.Exit(1)
	}

	// Assertion 4: NsHandle returned by netns.Get can be closed, making IsOpen return false
	if err := secondNs.Close(); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: secondNs.Close() failed: %v\n", err)
		os.Exit(1)
	}
	if secondNs.IsOpen() {
		fmt.Fprintf(os.Stderr, "FAIL: expected closed handle IsOpen() to return false\n")
		os.Exit(1)
	}

	_ = curNs.Close()
	fmt.Println("PASS: netns.Get contract passed")
}