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

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.S_IFREG 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.S_IFREG

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:ce02812a0340ebf0c1982041c23e9e54c8e2a267f3326f94007aa16fdb18c976","contract":["unix.S_IFREG constant equals octal 0100000 and is preserved when masked with unix.S_IFMT","unix.Stat and unix.Fstat on a created regular file report file mode matching unix.S_IFREG under unix.S_IFMT mask","unix.Stat on a directory and unix.Fstat on a pipe do not match unix.S_IFREG"],"goal":"verify golang.org/x/sys/unix.S_IFREG 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.S_IFREG"]},"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.S_IFREG"],"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=

package main

import (
	"fmt"
	"os"

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

func main() {
	tmpFile, err := os.CreateTemp("", "s_ifreg_demo_*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp file: %v\n", err)
		os.Exit(1)
	}
	defer os.Remove(tmpFile.Name())
	defer tmpFile.Close()

	var stat unix.Stat_t
	if err := unix.Stat(tmpFile.Name(), &stat); err != nil {
		fmt.Fprintf(os.Stderr, "unix.Stat failed: %v\n", err)
		os.Exit(1)
	}

	isRegular := (stat.Mode & unix.S_IFMT) == unix.S_IFREG
	fmt.Printf("File mode: 0%o\n", stat.Mode)
	fmt.Printf("Is regular file (S_IFREG): %t\n", isRegular)
}

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

package main

import (
	"fmt"
	"os"

	"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 contract assertions passed.")
}

func runTests() error {
	// 1. unix.S_IFREG constant equals octal 0100000 and is preserved when masked with unix.S_IFMT
	if unix.S_IFREG != 0100000 {
		return fmt.Errorf("expected unix.S_IFREG to be octal 0100000 (0x8000), got 0%o", unix.S_IFREG)
	}
	if (unix.S_IFREG & unix.S_IFMT) != unix.S_IFREG {
		return fmt.Errorf("expected unix.S_IFREG & unix.S_IFMT to equal unix.S_IFREG")
	}

	// 2. unix.Stat and unix.Fstat on a created regular file report file mode matching unix.S_IFREG under unix.S_IFMT mask
	tmpFile, err := os.CreateTemp("", "s_ifreg_contract_*")
	if err != nil {
		return fmt.Errorf("failed to create temporary file: %w", err)
	}
	defer os.Remove(tmpFile.Name())
	defer tmpFile.Close()

	if _, err := tmpFile.WriteString("CodeSampleX verification payload for S_IFREG"); err != nil {
		return fmt.Errorf("failed to write test data: %w", err)
	}

	var stat unix.Stat_t
	if err := unix.Stat(tmpFile.Name(), &stat); err != nil {
		return fmt.Errorf("unix.Stat failed: %w", err)
	}

	if (stat.Mode & unix.S_IFMT) != unix.S_IFREG {
		return fmt.Errorf("expected (stat.Mode & unix.S_IFMT) to be unix.S_IFREG, got 0%o", stat.Mode&unix.S_IFMT)
	}
	if (stat.Mode & unix.S_IFREG) == 0 {
		return fmt.Errorf("expected stat.Mode & unix.S_IFREG != 0, got mode 0%o", stat.Mode)
	}

	var fstat unix.Stat_t
	if err := unix.Fstat(int(tmpFile.Fd()), &fstat); err != nil {
		return fmt.Errorf("unix.Fstat failed: %w", err)
	}
	if (fstat.Mode & unix.S_IFMT) != unix.S_IFREG {
		return fmt.Errorf("expected (fstat.Mode & unix.S_IFMT) to be unix.S_IFREG, got 0%o", fstat.Mode&unix.S_IFMT)
	}

	// 3. unix.Stat on a directory and unix.Fstat on a pipe do not match unix.S_IFREG
	tmpDir, err := os.MkdirTemp("", "s_ifreg_dir_*")
	if err != nil {
		return fmt.Errorf("failed to create temporary dir: %w", err)
	}
	defer os.RemoveAll(tmpDir)

	var dirStat unix.Stat_t
	if err := unix.Stat(tmpDir, &dirStat); err != nil {
		return fmt.Errorf("unix.Stat on directory failed: %w", err)
	}
	if (dirStat.Mode & unix.S_IFMT) == unix.S_IFREG {
		return fmt.Errorf("directory unexpectedly matched unix.S_IFREG")
	}
	if (dirStat.Mode & unix.S_IFMT) != unix.S_IFDIR {
		return fmt.Errorf("expected directory mode to match unix.S_IFDIR (0%o), got 0%o", unix.S_IFDIR, dirStat.Mode&unix.S_IFMT)
	}

	pipeFds := make([]int, 2)
	if err := unix.Pipe(pipeFds); err != nil {
		return fmt.Errorf("unix.Pipe failed: %w", err)
	}
	defer unix.Close(pipeFds[0])
	defer unix.Close(pipeFds[1])

	var pipeStat unix.Stat_t
	if err := unix.Fstat(pipeFds[0], &pipeStat); err != nil {
		return fmt.Errorf("unix.Fstat on pipe failed: %w", err)
	}
	if (pipeStat.Mode & unix.S_IFMT) == unix.S_IFREG {
		return fmt.Errorf("pipe unexpectedly matched unix.S_IFREG")
	}
	if (pipeStat.Mode & unix.S_IFMT) != unix.S_IFIFO {
		return fmt.Errorf("expected pipe mode to match unix.S_IFIFO (0%o), got 0%o", unix.S_IFIFO, pipeStat.Mode&unix.S_IFMT)
	}

	return nil
}