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

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.Stat 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.Stat

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:sha256:87d837603c9aa3e2718d6e5a6f64fe287357e9649f2587a24f5bf8548527b2b4","contract":["unix.Stat populates Stat_t with size, mode, and inode for an existing regular file","unix.Stat returns ENOENT when called on a non-existent file path","unix.Stat follows a symbolic link and returns metadata of the target file","unix.Stat retrieves directory metadata with S_IFDIR flag set in Mode","unix.Stat returns ENOTDIR when a component of the path prefix is not a directory"],"goal":"verify golang.org/x/sys/unix.Stat 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.Stat"]},"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.Stat"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

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=

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

package sample

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

// StatFile retrieves file metadata for the given path using unix.Stat.
func StatFile(path string) (*unix.Stat_t, error) {
	var st unix.Stat_t
	if err := unix.Stat(path, &st); err != nil {
		return nil, err
	}
	return &st, nil
}

// IsRegularFile reports whether the stat represents a regular file.
func IsRegularFile(st *unix.Stat_t) bool {
	return (st.Mode & unix.S_IFMT) == unix.S_IFREG
}

// IsDirectory reports whether the stat represents a directory.
func IsDirectory(st *unix.Stat_t) bool {
	return (st.Mode & unix.S_IFMT) == unix.S_IFDIR
}

package main

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

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

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

func runTests() error {
	tmpDir, err := os.MkdirTemp(".", "csx_stat_test_*")
	if err != nil {
		return fmt.Errorf("failed to create temp dir: %w", err)
	}
	defer os.RemoveAll(tmpDir)

	filePath := filepath.Join(tmpDir, "sample_file.txt")
	testData := []byte("hello unix stat")
	if err := os.WriteFile(filePath, testData, 0644); err != nil {
		return fmt.Errorf("failed to write test file: %w", err)
	}

	// 1. unix.Stat populates Stat_t with size, mode, and inode for an existing regular file
	st, err := sample.StatFile(filePath)
	if err != nil {
		return fmt.Errorf("sample.StatFile failed: %w", err)
	}
	if st.Size != int64(len(testData)) {
		return fmt.Errorf("expected size %d, got %d", len(testData), st.Size)
	}
	if !sample.IsRegularFile(st) {
		return fmt.Errorf("expected regular file mode for %s", filePath)
	}
	if st.Ino == 0 {
		return fmt.Errorf("expected non-zero inode")
	}

	// 2. unix.Stat returns ENOENT when called on a non-existent file path
	nonExistentPath := filepath.Join(tmpDir, "does_not_exist.txt")
	_, err = sample.StatFile(nonExistentPath)
	if err == nil {
		return fmt.Errorf("expected error for non-existent path, got nil")
	}
	if !errors.Is(err, unix.ENOENT) {
		return fmt.Errorf("expected ENOENT, got %w", err)
	}

	// 3. unix.Stat follows a symbolic link and returns metadata of the target file
	symlinkPath := filepath.Join(tmpDir, "sample_symlink")
	if err := os.Symlink("sample_file.txt", symlinkPath); err != nil {
		return fmt.Errorf("failed to create symlink: %w", err)
	}
	symStat, err := sample.StatFile(symlinkPath)
	if err != nil {
		return fmt.Errorf("StatFile on symlink failed: %w", err)
	}
	if !sample.IsRegularFile(symStat) {
		return fmt.Errorf("expected target to be regular file when following symlink")
	}
	if symStat.Ino != st.Ino || symStat.Size != st.Size {
		return fmt.Errorf("symlink target stat mismatch: got ino=%d size=%d, expected ino=%d size=%d",
			symStat.Ino, symStat.Size, st.Ino, st.Size)
	}

	// 4. unix.Stat retrieves directory metadata with S_IFDIR flag set in Mode
	dirStat, err := sample.StatFile(tmpDir)
	if err != nil {
		return fmt.Errorf("StatFile on directory failed: %w", err)
	}
	if !sample.IsDirectory(dirStat) {
		return fmt.Errorf("expected directory mode for tmpDir")
	}
	if sample.IsRegularFile(dirStat) {
		return fmt.Errorf("expected IsRegularFile false for directory")
	}

	// 5. unix.Stat returns ENOTDIR when a component of the path prefix is not a directory
	invalidChildPath := filepath.Join(filePath, "child.txt")
	_, err = sample.StatFile(invalidChildPath)
	if err == nil {
		return fmt.Errorf("expected error for path with file as parent, got nil")
	}
	if !errors.Is(err, unix.ENOTDIR) {
		return fmt.Errorf("expected ENOTDIR, got %w", err)
	}

	return nil
}