github.com/prometheus/procfs v0.6.0: NewDefaultFS

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/prometheus/procfs.NewDefaultFS in pkg:golang/github.com/prometheus/procfs@v0.6.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/procfs@v0.6.0
Demonstrate these symbols/APIs:
  - github.com/prometheus/procfs.NewDefaultFS

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:sha256:94a34eae28475998924f4c472b369dda0cd6c8872d1e4f26dd105e59edc5bf21","contract":["procfs.NewDefaultFS() returns (FS, error) where error is nil","fs.Meminfo() returns (Meminfo, error) where error is nil and MemTotal is non-nil","fs.Self() returns (Proc, error) where error is nil and PID is positive","proc.Stat() returns (ProcStat, error) where error is nil, PID matches, and Comm is non-empty","fs.Stat() returns (Stat, error) where error is nil and BootTime is non-zero","fs.CPUInfo() returns ([]CPUInfo, error) where error is nil and len is positive"],"goal":"verify github.com/prometheus/procfs.NewDefaultFS in pkg:golang/github.com/prometheus/procfs@v0.6.0","kind":"HOW","packages":["pkg:golang/github.com/prometheus/procfs@v0.6.0"],"schemaVersion":1,"symbols":["github.com/prometheus/procfs.NewDefaultFS"]},"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/prometheus/procfs@v0.6.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/procfs@v0.6.0","symbols":["github.com/prometheus/procfs.NewDefaultFS"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require github.com/prometheus/procfs v0.6.0

require golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c // indirect

github.com/google/go-cmp v0.5.4 h1:L8R9j+yAqZuZjsqh/z+F1NCffTKKLShY6zXTItVIZ8M=
github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
github.com/prometheus/procfs v0.6.0 h1:mxy4L2jP6qMonqmq+aTtOx1ifVWUgG/TAmntgbh3xv4=
github.com/prometheus/procfs v0.6.0/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
golang.org/x/sync v0.0.0-20201207232520-09787c993a3a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c h1:VwygUrnw9jn88c4u8GD3rZQbqrP/tgas88tPUbBxQrk=
golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

package main

import (
	"fmt"
	"os"

	"github.com/prometheus/procfs"
)

func ReadSystemMemory() (uint64, error) {
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		return 0, err
	}
	meminfo, err := fs.Meminfo()
	if err != nil {
		return 0, err
	}
	if meminfo.MemTotal == nil {
		return 0, fmt.Errorf("memtotal not found")
	}
	return *meminfo.MemTotal, nil
}

func ReadSystemStat() (uint64, error) {
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		return 0, err
	}
	stat, err := fs.Stat()
	if err != nil {
		return 0, err
	}
	return stat.BootTime, nil
}

func ReadCPUInfo() (int, error) {
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		return 0, err
	}
	cpuInfo, err := fs.CPUInfo()
	if err != nil {
		return 0, err
	}
	return len(cpuInfo), nil
}

func ReadCurrentProcess() (int, string, error) {
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		return 0, "", err
	}
	proc, err := fs.Self()
	if err != nil {
		return 0, "", err
	}
	stat, err := proc.Stat()
	if err != nil {
		return 0, "", err
	}
	return proc.PID, stat.Comm, nil
}

func main() {
	_, err := procfs.NewDefaultFS()
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to open default procfs: %v\n", err)
		os.Exit(1)
	}

	memTotal, err := ReadSystemMemory()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error reading meminfo: %v\n", err)
		os.Exit(1)
	}

	bootTime, err := ReadSystemStat()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error reading stat: %v\n", err)
		os.Exit(1)
	}

	cpuCount, err := ReadCPUInfo()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error reading cpuinfo: %v\n", err)
		os.Exit(1)
	}

	pid, comm, err := ReadCurrentProcess()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error reading proc stat: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Default procfs initialized: PID=%d, Comm=%s, MemTotal=%d kB, BootTime=%d, CPUs=%d\n",
		pid, comm, memTotal, bootTime, cpuCount)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/prometheus/procfs.NewDefaultFS in pkg:golang/github.com/prometheus/procfs@v0.6.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/procfs@v0.6.0"
  ],
  "symbols": [
    "github.com/prometheus/procfs.NewDefaultFS"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/prometheus/procfs"
)

func main() {
	// 1. procfs.NewDefaultFS() returns (FS, error) where error is nil
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		fmt.Fprintf(os.Stderr, "procfs.NewDefaultFS() failed: %v\n", err)
		os.Exit(1)
	}

	// 2. fs.Meminfo() returns (Meminfo, error) where error is nil and MemTotal is non-nil
	mem, err := fs.Meminfo()
	if err != nil {
		fmt.Fprintf(os.Stderr, "fs.Meminfo() failed: %v\n", err)
		os.Exit(1)
	}
	if mem.MemTotal == nil {
		fmt.Fprintf(os.Stderr, "mem.MemTotal is nil\n")
		os.Exit(1)
	}

	// 3. fs.Self() returns (Proc, error) where error is nil and PID is positive
	proc, err := fs.Self()
	if err != nil {
		fmt.Fprintf(os.Stderr, "fs.Self() failed: %v\n", err)
		os.Exit(1)
	}
	if proc.PID <= 0 {
		fmt.Fprintf(os.Stderr, "expected positive proc.PID, got %d\n", proc.PID)
		os.Exit(1)
	}

	// 4. proc.Stat() returns (ProcStat, error) where error is nil, PID matches, and Comm is non-empty
	procStat, err := proc.Stat()
	if err != nil {
		fmt.Fprintf(os.Stderr, "proc.Stat() failed: %v\n", err)
		os.Exit(1)
	}
	if procStat.PID != proc.PID {
		fmt.Fprintf(os.Stderr, "expected PID %d, got %d\n", proc.PID, procStat.PID)
		os.Exit(1)
	}
	if procStat.Comm == "" {
		fmt.Fprintf(os.Stderr, "expected non-empty Comm\n")
		os.Exit(1)
	}

	// 5. fs.Stat() returns (Stat, error) where error is nil and BootTime is non-zero
	stat, err := fs.Stat()
	if err != nil {
		fmt.Fprintf(os.Stderr, "fs.Stat() failed: %v\n", err)
		os.Exit(1)
	}
	if stat.BootTime == 0 {
		fmt.Fprintf(os.Stderr, "expected non-zero BootTime\n")
		os.Exit(1)
	}

	// 6. fs.CPUInfo() returns ([]CPUInfo, error) where error is nil and len is positive
	cpuInfo, err := fs.CPUInfo()
	if err != nil {
		fmt.Fprintf(os.Stderr, "fs.CPUInfo() failed: %v\n", err)
		os.Exit(1)
	}
	if len(cpuInfo) == 0 {
		fmt.Fprintf(os.Stderr, "expected at least one CPUInfo entry\n")
		os.Exit(1)
	}

	fmt.Println("All contract assertions passed.")
}