github.com/prometheus/procfs v0.6.0: FS.Meminfo

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.Meminfo 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.FS.Meminfo

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:bb2c77612b07ebfeb325bc1929be2fe18eeaeeeeb61dbfad2f9cabd58393e578","contract":["procfs.NewFS initializes an FS instance for a valid directory","FS.Meminfo fails if meminfo file does not exist in mount directory","FS.Meminfo returns error on malformed meminfo content","FS.Meminfo parses memory stats including MemTotal, MemFree, and MemAvailable","FS.Meminfo parses buffer and cache stats including Buffers and Cached","FS.Meminfo parses swap stats including SwapTotal and SwapFree"],"goal":"verify github.com/prometheus/procfs.FS.Meminfo 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.FS.Meminfo"]},"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.FS.Meminfo"],"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 main() {
	fs, err := procfs.NewFS(procfs.DefaultMountPoint)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to open procfs: %v\n", err)
		os.Exit(1)
	}

	meminfo, err := fs.Meminfo()
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to read meminfo: %v\n", err)
		os.Exit(1)
	}

	if meminfo.MemTotal != nil && meminfo.MemFree != nil {
		fmt.Printf("Memory: Total=%d kB, Free=%d kB\n", *meminfo.MemTotal, *meminfo.MemFree)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/prometheus/procfs.FS.Meminfo 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.FS.Meminfo"
  ]
}

package main

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

	"github.com/prometheus/procfs"
)

func main() {
	// 1. procfs.NewFS initializes an FS instance for a valid directory
	mockDir, err := os.MkdirTemp("", "mock-procfs-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create mock directory: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(mockDir)

	fs, err := procfs.NewFS(mockDir)
	if err != nil {
		fmt.Fprintf(os.Stderr, "expected NewFS to succeed for valid directory: %v\n", err)
		os.Exit(1)
	}

	// 2. FS.Meminfo fails if meminfo file does not exist in mount directory
	_, err = fs.Meminfo()
	if err == nil {
		fmt.Fprintf(os.Stderr, "expected Meminfo to fail when meminfo file is missing, but got nil error\n")
		os.Exit(1)
	}

	// 3. FS.Meminfo returns error on malformed meminfo content
	malformedFile := filepath.Join(mockDir, "meminfo")
	if err := os.WriteFile(malformedFile, []byte("invalid_line_without_fields\n"), 0644); err != nil {
		fmt.Fprintf(os.Stderr, "failed to write malformed meminfo: %v\n", err)
		os.Exit(1)
	}
	_, err = fs.Meminfo()
	if err == nil {
		fmt.Fprintf(os.Stderr, "expected Meminfo to fail on malformed content, but got nil error\n")
		os.Exit(1)
	}

	// 4. FS.Meminfo parses memory stats including MemTotal, MemFree, and MemAvailable
	validContent := `MemTotal:       16384000 kB
MemFree:         8192000 kB
MemAvailable:   12288000 kB
Buffers:          512000 kB
Cached:          2048000 kB
SwapTotal:       4096000 kB
SwapFree:        3072000 kB
Dirty:              1024 kB
Writeback:             0 kB
AnonPages:       1024000 kB
`
	if err := os.WriteFile(malformedFile, []byte(validContent), 0644); err != nil {
		fmt.Fprintf(os.Stderr, "failed to write valid meminfo: %v\n", err)
		os.Exit(1)
	}

	meminfo, err := fs.Meminfo()
	if err != nil {
		fmt.Fprintf(os.Stderr, "expected Meminfo to succeed: %v\n", err)
		os.Exit(1)
	}

	if meminfo.MemTotal == nil || *meminfo.MemTotal != 16384000 {
		fmt.Fprintf(os.Stderr, "expected MemTotal 16384000, got %v\n", meminfo.MemTotal)
		os.Exit(1)
	}
	if meminfo.MemFree == nil || *meminfo.MemFree != 8192000 {
		fmt.Fprintf(os.Stderr, "expected MemFree 8192000, got %v\n", meminfo.MemFree)
		os.Exit(1)
	}
	if meminfo.MemAvailable == nil || *meminfo.MemAvailable != 12288000 {
		fmt.Fprintf(os.Stderr, "expected MemAvailable 12288000, got %v\n", meminfo.MemAvailable)
		os.Exit(1)
	}

	// 5. FS.Meminfo parses buffer and cache stats including Buffers and Cached
	if meminfo.Buffers == nil || *meminfo.Buffers != 512000 {
		fmt.Fprintf(os.Stderr, "expected Buffers 512000, got %v\n", meminfo.Buffers)
		os.Exit(1)
	}
	if meminfo.Cached == nil || *meminfo.Cached != 2048000 {
		fmt.Fprintf(os.Stderr, "expected Cached 2048000, got %v\n", meminfo.Cached)
		os.Exit(1)
	}

	// 6. FS.Meminfo parses swap stats including SwapTotal and SwapFree
	if meminfo.SwapTotal == nil || *meminfo.SwapTotal != 4096000 {
		fmt.Fprintf(os.Stderr, "expected SwapTotal 4096000, got %v\n", meminfo.SwapTotal)
		os.Exit(1)
	}
	if meminfo.SwapFree == nil || *meminfo.SwapFree != 3072000 {
		fmt.Fprintf(os.Stderr, "expected SwapFree 3072000, got %v\n", meminfo.SwapFree)
		os.Exit(1)
	}

	fmt.Println("All procfs.FS.Meminfo contract assertions passed.")
}