golang.org/x/sys v0.41.0: unix.Statfs

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 unix.Statfs in pkg:golang/golang.org/x/sys@v0.41.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/sys@v0.41.0
Demonstrate these symbols/APIs:
  - unix.Statfs

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:sha256:0ec96fc0afdbac100927484713055ba3eecba2220838274e87106807ef0fb977","contract":["unix.Statfs on valid path populates Statfs_t with positive Bsize and non-zero Blocks","unix.Statfs on non-existent path returns unix.ENOENT error","GetDiskStats computes disk metrics from unix.Statfs"],"goal":"verify unix.Statfs in pkg:golang/golang.org/x/sys@v0.41.0","kind":"HOW","packages":["pkg:golang/golang.org/x/sys@v0.41.0"],"schemaVersion":1,"symbols":["unix.Statfs"]},"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@v0.41.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/sys@v0.41.0","symbols":["unix.Statfs"],"verifierAdapter":"golang@1"}

module sample

go 1.24.0

require golang.org/x/sys v0.41.0

golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=

{
  "schemaVersion": 1,
  "goal": "verify unix.Statfs in pkg:golang/golang.org/x/sys@v0.41.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/sys@v0.41.0"
  ],
  "symbols": [
    "unix.Statfs"
  ]
}

package sample

import (
	"errors"

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

// DiskStats holds filesystem capacity and usage information.
type DiskStats struct {
	TotalBytes uint64
	FreeBytes  uint64
	AvailBytes uint64
	BlockSize  int64
	TotalFiles uint64
	FreeFiles  uint64
}

// GetFileSystemInfo queries filesystem statistics for the given path using unix.Statfs.
func GetFileSystemInfo(path string) (*unix.Statfs_t, error) {
	if path == "" {
		return nil, errors.New("path cannot be empty")
	}
	var stat unix.Statfs_t
	if err := unix.Statfs(path, &stat); err != nil {
		return nil, err
	}
	return &stat, nil
}

// GetDiskStats computes disk space metrics from unix.Statfs.
func GetDiskStats(path string) (*DiskStats, error) {
	stat, err := GetFileSystemInfo(path)
	if err != nil {
		return nil, err
	}

	blockSize := stat.Bsize
	if blockSize <= 0 {
		blockSize = 4096
	}

	bsize := uint64(blockSize)
	return &DiskStats{
		TotalBytes: stat.Blocks * bsize,
		FreeBytes:  stat.Bfree * bsize,
		AvailBytes: stat.Bavail * bsize,
		BlockSize:  blockSize,
		TotalFiles: stat.Files,
		FreeFiles:  stat.Ffree,
	}, nil
}

package main

import (
	"errors"
	"fmt"
	"os"

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

func main() {
	if err := runContractTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract tests passed.")
}

func runContractTests() error {
	// 1. Verify unix.Statfs succeeds on valid existing path (".")
	var stat unix.Statfs_t
	if err := unix.Statfs(".", &stat); err != nil {
		return fmt.Errorf("unix.Statfs on '.' failed: %w", err)
	}

	// 2. Verify Statfs_t block size and blocks are positive
	if stat.Bsize <= 0 {
		return fmt.Errorf("expected positive Bsize, got %d", stat.Bsize)
	}
	if stat.Blocks == 0 {
		return fmt.Errorf("expected non-zero Blocks, got %d", stat.Blocks)
	}

	// 3. Verify helper GetDiskStats returns valid metrics
	diskStats, err := sample.GetDiskStats(".")
	if err != nil {
		return fmt.Errorf("GetDiskStats on '.' failed: %w", err)
	}
	if diskStats.TotalBytes == 0 {
		return fmt.Errorf("expected non-zero TotalBytes")
	}
	if diskStats.BlockSize <= 0 {
		return fmt.Errorf("expected positive BlockSize")
	}

	// 4. Verify unix.Statfs on non-existent path returns error (unix.ENOENT)
	var invalidStat unix.Statfs_t
	err = unix.Statfs("non_existent_file_path_xyz_12345", &invalidStat)
	if err == nil {
		return fmt.Errorf("expected error on non-existent path, got nil")
	}
	if !errors.Is(err, unix.ENOENT) {
		return fmt.Errorf("expected unix.ENOENT error, got %v", err)
	}

	// 5. Verify GetFileSystemInfo rejects empty path
	if _, err := sample.GetFileSystemInfo(""); err == nil {
		return fmt.Errorf("expected error on empty path, got nil")
	}

	return nil
}