Phase 3: banger kernel import bridges make-*-kernel.sh output

`banger kernel import <name> --from <dir>` copies a staged kernel
bundle into the local catalog. <dir> is the output of
`make void-kernel` or `make alpine-kernel` (build/manual/void-kernel/
or build/manual/alpine-kernel/).

kernelcat.DiscoverPaths locates artifacts under <dir>:
 1. Prefers metadata.json (written by make-void-kernel.sh).
 2. Falls back to globbing: boot/vmlinux-* or vmlinuz-* (Alpine
    fallback), boot/initramfs-*, lib/modules/<latest>.

The daemon's KernelImport copies kernel + optional initrd via
system.CopyFilePreferClone and modules via system.CopyDirContents
(no-sudo mode — catalog lives under ~/.local/state), computes SHA256
over the kernel, and writes the manifest via kernelcat.WriteLocal.

While wiring this up, fixed a latent bug in system.CopyDirContents:
filepath.Join(sourceDir, ".") silently drops the trailing dot, so
`cp -a source source/contents target/` was copying the whole source
directory (including its basename) instead of just its contents.
Replaced the join with a manual "/." suffix. imagemgr.StageBootArtifacts
(the only existing caller) silently benefits.

scripts/register-void-image.sh and scripts/register-alpine-image.sh
are rewritten to use `banger kernel import … && banger image register
--kernel-ref …` instead of the find-and-pass-paths dance. Preserves
the same user-facing commands and env vars.

Tests cover: metadata.json preference, glob fallback, Alpine vmlinuz
fallback, kernel-missing error, round-trip copy into the catalog, and
the --from required flag.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Thales Maciel 2026-04-16 14:53:49 -03:00
parent 48e3a938cf
commit 7192ba24ae
No known key found for this signature in database
GPG key ID: 33112E6833C34679
11 changed files with 542 additions and 80 deletions

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package kernelcat
import (
"encoding/json"
"errors"
"fmt"
"os"
"path/filepath"
"sort"
)
// DiscoveredArtifacts is what DiscoverPaths returns: absolute paths to a
// kernel, an optional initrd, and an optional modules directory located
// under the staged output of make-*-kernel.sh (or an equivalent layout).
type DiscoveredArtifacts struct {
KernelPath string
InitrdPath string
ModulesDir string
}
// metadataFile is the JSON dropped by scripts/make-void-kernel.sh alongside
// its staged output. We read it when present to avoid guessing at filenames.
type metadataFile struct {
KernelPath string `json:"kernel_path"`
InitrdPath string `json:"initrd_path"`
ModulesDir string `json:"modules_dir"`
}
// DiscoverPaths locates kernel / initrd / modules artifacts under fromDir.
// It prefers a metadata.json emitted by make-*-kernel.sh; otherwise it
// falls back to globbing boot/vmlinux-*, boot/vmlinuz-* (for Alpine),
// boot/initramfs-*, and the newest subdir under lib/modules/.
func DiscoverPaths(fromDir string) (DiscoveredArtifacts, error) {
info, err := os.Stat(fromDir)
if err != nil {
return DiscoveredArtifacts{}, err
}
if !info.IsDir() {
return DiscoveredArtifacts{}, fmt.Errorf("%s is not a directory", fromDir)
}
if paths, ok, err := discoverFromMetadata(fromDir); err != nil {
return DiscoveredArtifacts{}, err
} else if ok {
return paths, nil
}
bootDir := filepath.Join(fromDir, "boot")
kernel, err := latestMatch(bootDir, []string{"vmlinux-*", "vmlinuz-*"})
if err != nil {
return DiscoveredArtifacts{}, fmt.Errorf("locate kernel under %s: %w", bootDir, err)
}
initrd, err := latestMatch(bootDir, []string{"initramfs-*"})
if err != nil && !errors.Is(err, os.ErrNotExist) {
return DiscoveredArtifacts{}, fmt.Errorf("locate initrd under %s: %w", bootDir, err)
}
modules, err := latestSubdir(filepath.Join(fromDir, "lib", "modules"))
if err != nil && !errors.Is(err, os.ErrNotExist) {
return DiscoveredArtifacts{}, fmt.Errorf("locate modules under %s: %w", fromDir, err)
}
return DiscoveredArtifacts{
KernelPath: kernel,
InitrdPath: initrd,
ModulesDir: modules,
}, nil
}
func discoverFromMetadata(fromDir string) (DiscoveredArtifacts, bool, error) {
data, err := os.ReadFile(filepath.Join(fromDir, "metadata.json"))
if err != nil {
if errors.Is(err, os.ErrNotExist) {
return DiscoveredArtifacts{}, false, nil
}
return DiscoveredArtifacts{}, false, err
}
var meta metadataFile
if err := json.Unmarshal(data, &meta); err != nil {
return DiscoveredArtifacts{}, false, fmt.Errorf("parse metadata.json in %s: %w", fromDir, err)
}
kernel := absoluteOrAnchored(fromDir, meta.KernelPath)
if kernel == "" {
return DiscoveredArtifacts{}, false, nil
}
if _, err := os.Stat(kernel); err != nil {
return DiscoveredArtifacts{}, false, fmt.Errorf("metadata.json references missing kernel %s: %w", kernel, err)
}
out := DiscoveredArtifacts{KernelPath: kernel}
if meta.InitrdPath != "" {
candidate := absoluteOrAnchored(fromDir, meta.InitrdPath)
if _, err := os.Stat(candidate); err == nil {
out.InitrdPath = candidate
}
}
if meta.ModulesDir != "" {
candidate := absoluteOrAnchored(fromDir, meta.ModulesDir)
if info, err := os.Stat(candidate); err == nil && info.IsDir() {
out.ModulesDir = candidate
}
}
return out, true, nil
}
// absoluteOrAnchored returns path as-is if absolute; otherwise joins it to
// anchor. Empty input returns "".
func absoluteOrAnchored(anchor, path string) string {
path = filepath.Clean(path)
if path == "" || path == "." {
return ""
}
if filepath.IsAbs(path) {
return path
}
return filepath.Join(anchor, path)
}
// latestMatch returns the lexicographically latest file in dir matching any
// of patterns (filename globs, not full paths). Returns os.ErrNotExist if no
// match.
func latestMatch(dir string, patterns []string) (string, error) {
if _, err := os.Stat(dir); err != nil {
return "", err
}
entries, err := os.ReadDir(dir)
if err != nil {
return "", err
}
var matches []string
for _, entry := range entries {
if entry.IsDir() {
continue
}
for _, pattern := range patterns {
ok, _ := filepath.Match(pattern, entry.Name())
if ok {
matches = append(matches, entry.Name())
break
}
}
}
if len(matches) == 0 {
return "", os.ErrNotExist
}
sort.Strings(matches)
return filepath.Join(dir, matches[len(matches)-1]), nil
}
// latestSubdir returns the lexicographically latest subdirectory of root.
// Returns os.ErrNotExist if root is missing or has no subdirs.
func latestSubdir(root string) (string, error) {
if _, err := os.Stat(root); err != nil {
return "", err
}
entries, err := os.ReadDir(root)
if err != nil {
return "", err
}
var dirs []string
for _, entry := range entries {
if entry.IsDir() {
dirs = append(dirs, entry.Name())
}
}
if len(dirs) == 0 {
return "", os.ErrNotExist
}
sort.Strings(dirs)
return filepath.Join(root, dirs[len(dirs)-1]), nil
}

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package kernelcat
import (
"errors"
"os"
"path/filepath"
"testing"
)
func writeFile(t *testing.T, path string, data string) {
t.Helper()
if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
t.Fatal(err)
}
if err := os.WriteFile(path, []byte(data), 0o644); err != nil {
t.Fatal(err)
}
}
func TestDiscoverPathsPrefersMetadataJSON(t *testing.T) {
t.Parallel()
dir := t.TempDir()
writeFile(t, filepath.Join(dir, "boot", "vmlinux-custom"), "ignored")
writeFile(t, filepath.Join(dir, "boot", "initramfs-custom"), "ignored")
writeFile(t, filepath.Join(dir, "boot", "vmlinux-pick-me"), "kernel")
writeFile(t, filepath.Join(dir, "boot", "initramfs-pick-me"), "initrd")
if err := os.MkdirAll(filepath.Join(dir, "lib", "modules", "6.12.79_1"), 0o755); err != nil {
t.Fatal(err)
}
metadata := `{
"kernel_path": "boot/vmlinux-pick-me",
"initrd_path": "boot/initramfs-pick-me",
"modules_dir": "lib/modules/6.12.79_1"
}`
writeFile(t, filepath.Join(dir, "metadata.json"), metadata)
got, err := DiscoverPaths(dir)
if err != nil {
t.Fatalf("DiscoverPaths: %v", err)
}
if got.KernelPath != filepath.Join(dir, "boot", "vmlinux-pick-me") {
t.Errorf("KernelPath = %q", got.KernelPath)
}
if got.InitrdPath != filepath.Join(dir, "boot", "initramfs-pick-me") {
t.Errorf("InitrdPath = %q", got.InitrdPath)
}
if got.ModulesDir != filepath.Join(dir, "lib", "modules", "6.12.79_1") {
t.Errorf("ModulesDir = %q", got.ModulesDir)
}
}
func TestDiscoverPathsFallsBackToGlobbing(t *testing.T) {
t.Parallel()
dir := t.TempDir()
writeFile(t, filepath.Join(dir, "boot", "vmlinux-6.12.0"), "k")
writeFile(t, filepath.Join(dir, "boot", "vmlinux-6.12.1"), "newer")
writeFile(t, filepath.Join(dir, "boot", "initramfs-6.12.1"), "i")
if err := os.MkdirAll(filepath.Join(dir, "lib", "modules", "6.12.0"), 0o755); err != nil {
t.Fatal(err)
}
if err := os.MkdirAll(filepath.Join(dir, "lib", "modules", "6.12.1"), 0o755); err != nil {
t.Fatal(err)
}
got, err := DiscoverPaths(dir)
if err != nil {
t.Fatalf("DiscoverPaths: %v", err)
}
if got.KernelPath != filepath.Join(dir, "boot", "vmlinux-6.12.1") {
t.Errorf("KernelPath = %q, want latest", got.KernelPath)
}
if got.InitrdPath != filepath.Join(dir, "boot", "initramfs-6.12.1") {
t.Errorf("InitrdPath = %q", got.InitrdPath)
}
if got.ModulesDir != filepath.Join(dir, "lib", "modules", "6.12.1") {
t.Errorf("ModulesDir = %q, want latest subdir", got.ModulesDir)
}
}
func TestDiscoverPathsAlpineVmlinuzFallback(t *testing.T) {
t.Parallel()
dir := t.TempDir()
// Alpine older layouts may only ship vmlinuz-virt.
writeFile(t, filepath.Join(dir, "boot", "vmlinuz-virt"), "k")
writeFile(t, filepath.Join(dir, "boot", "initramfs-virt"), "i")
got, err := DiscoverPaths(dir)
if err != nil {
t.Fatalf("DiscoverPaths: %v", err)
}
if got.KernelPath != filepath.Join(dir, "boot", "vmlinuz-virt") {
t.Errorf("KernelPath = %q, want vmlinuz-virt fallback", got.KernelPath)
}
}
func TestDiscoverPathsMissingKernelIsError(t *testing.T) {
t.Parallel()
dir := t.TempDir()
// boot/ exists but contains no kernel
if err := os.MkdirAll(filepath.Join(dir, "boot"), 0o755); err != nil {
t.Fatal(err)
}
_, err := DiscoverPaths(dir)
if err == nil {
t.Fatal("expected error when no kernel present")
}
if !errors.Is(err, os.ErrNotExist) && !containsErr(err, "locate kernel") {
t.Fatalf("error shape: %v", err)
}
}
func TestDiscoverPathsNotADirectory(t *testing.T) {
t.Parallel()
path := filepath.Join(t.TempDir(), "file")
writeFile(t, path, "")
_, err := DiscoverPaths(path)
if err == nil {
t.Fatal("expected error when fromDir is a file")
}
}
func containsErr(err error, substr string) bool {
return err != nil && (err.Error() == substr || len(err.Error()) >= len(substr) && errContains(err.Error(), substr))
}
func errContains(s, substr string) bool {
for i := 0; i+len(substr) <= len(s); i++ {
if s[i:i+len(substr)] == substr {
return true
}
}
return false
}