github.com/prometheus/procfs v0.22.0: FS.Mountinfo

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.FS.Mountinfo in pkg:golang/github.com/prometheus/procfs@v0.22.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/procfs@v0.22.0
Demonstrate these symbols/APIs:
  - github.com/prometheus/procfs.FS.Mountinfo
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:sha256:307a54074c83315b32a541a55a6b729989bfeeb941207ab0ea0a29ef485091ef","contract":["procfs.NewDefaultFS() returns (FS, error) where error is nil","fs.GetMounts() returns ([]*MountInfo, error) where error is nil","fs.GetMounts() returns a non-empty slice of mountinfo entries on a running system","each MountInfo in mounts has a positive MountID and non-empty MountPoint and FSType","fs.GetProcMounts(pid) returns ([]*MountInfo, error) where error is nil for current process"],"goal":"verify github.com/prometheus/procfs.FS.Mountinfo in pkg:golang/github.com/prometheus/procfs@v0.22.0","kind":"HOW","packages":["pkg:golang/github.com/prometheus/procfs@v0.22.0"],"schemaVersion":1,"symbols":["github.com/prometheus/procfs.FS.Mountinfo"]},"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@v0.22.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/procfs@v0.22.0","symbols":["github.com/prometheus/procfs.FS.Mountinfo"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.25.0

require github.com/prometheus/procfs v0.22.0

require golang.org/x/sys v0.47.0 // indirect

github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/prometheus/procfs v0.22.0 h1:6q9+/JL9IKAPbCmBrv9n5O5Ty3NKnciV5X7YGw0oics=
github.com/prometheus/procfs v0.22.0/go.mod h1:CvmFr/GVhIjIvWJZW3tgkODBQMRIf0EyWMQLHCHab58=
golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=

package main

import (
	"fmt"
	"os"

	"github.com/prometheus/procfs"
)

// GetSystemMounts retrieves all mount points from /proc/self/mountinfo.
func GetSystemMounts() ([]*procfs.MountInfo, error) {
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		return nil, fmt.Errorf("procfs.NewDefaultFS failed: %w", err)
	}
	return fs.GetMounts()
}

// GetProcessMounts retrieves mount points for a specific process ID.
func GetProcessMounts(pid int) ([]*procfs.MountInfo, error) {
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		return nil, fmt.Errorf("procfs.NewDefaultFS failed: %w", err)
	}
	return fs.GetProcMounts(pid)
}

func main() {
	mounts, err := GetSystemMounts()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error getting system mounts: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Discovered %d system mount points\n", len(mounts))
	for i, m := range mounts {
		if i >= 3 {
			break
		}
		fmt.Printf("MountID: %d, MountPoint: %s, FSType: %s\n", m.MountID, m.MountPoint, m.FSType)
	}

	procMounts, err := GetProcessMounts(os.Getpid())
	if err != nil {
		fmt.Fprintf(os.Stderr, "error getting process mounts: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("Discovered %d process mount points for pid %d\n", len(procMounts), os.Getpid())
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/prometheus/procfs.FS.Mountinfo in pkg:golang/github.com/prometheus/procfs@v0.22.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/procfs@v0.22.0"
  ],
  "symbols": [
    "github.com/prometheus/procfs.FS.Mountinfo"
  ]
}

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, "FAIL: procfs.NewDefaultFS failed: %v\n", err)
		os.Exit(1)
	}

	// 2. fs.GetMounts() returns ([]*MountInfo, error) where error is nil
	mounts, err := fs.GetMounts()
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: fs.GetMounts failed: %v\n", err)
		os.Exit(1)
	}

	// 3. fs.GetMounts() returns a non-empty slice of mountinfo entries on a running system
	if len(mounts) == 0 {
		fmt.Fprintf(os.Stderr, "FAIL: expected non-empty mounts list\n")
		os.Exit(1)
	}

	// 4. each MountInfo in mounts has a positive MountID and non-empty MountPoint and FSType
	for _, m := range mounts {
		if m.MountID <= 0 {
			fmt.Fprintf(os.Stderr, "FAIL: expected positive MountID, got %d\n", m.MountID)
			os.Exit(1)
		}
		if m.MountPoint == "" {
			fmt.Fprintf(os.Stderr, "FAIL: expected non-empty MountPoint\n")
			os.Exit(1)
		}
		if m.FSType == "" {
			fmt.Fprintf(os.Stderr, "FAIL: expected non-empty FSType\n")
			os.Exit(1)
		}
	}

	// 5. fs.GetProcMounts(pid) returns ([]*MountInfo, error) where error is nil for current process
	procMounts, err := fs.GetProcMounts(os.Getpid())
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: fs.GetProcMounts failed: %v\n", err)
		os.Exit(1)
	}
	if len(procMounts) == 0 {
		fmt.Fprintf(os.Stderr, "FAIL: expected non-empty procMounts list for current pid\n")
		os.Exit(1)
	}

	fmt.Println("PASS: all contract assertions passed")
}