v0.1.0 (#17)

internal/layout/layout.go

@@ -1,11 +1,15 @@
 package layout
 
 import (
+	"fmt"
+	"os"
 	"path/filepath"
+	"sort"
+	"strings"
 
 	"github.com/jackc/pgx/v5/pgtype"
 
-	"git.omukk.dev/wrenn/wrenn/internal/id"
+	"git.omukk.dev/wrenn/wrenn/pkg/id"
 )
 
 // IsMinimal reports whether the given team and template IDs represent the
@@ -47,6 +51,75 @@ func KernelPath(wrennDir string) string {
 	return filepath.Join(wrennDir, "kernels", "vmlinux")
 }
 
+// KernelPathVersioned returns the path to a specific kernel version.
+func KernelPathVersioned(wrennDir, version string) string {
+	return filepath.Join(wrennDir, "kernels", "vmlinux-"+version)
+}
+
+// LatestKernel scans the kernels directory for files matching vmlinux-{semver}
+// and returns the path and version of the latest one (by semver sort).
+func LatestKernel(wrennDir string) (path, version string, err error) {
+	dir := filepath.Join(wrennDir, "kernels")
+	return latestVersionedFile(dir, "vmlinux-")
+}
+
+// latestVersionedFile scans dir for files with the given prefix, extracts the
+// version suffix, sorts by semver, and returns the path and version of the latest.
+func latestVersionedFile(dir, prefix string) (path, version string, err error) {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return "", "", fmt.Errorf("read directory %s: %w", dir, err)
+	}
+
+	var versions []string
+	for _, e := range entries {
+		if e.IsDir() {
+			continue
+		}
+		name := e.Name()
+		if v, ok := strings.CutPrefix(name, prefix); ok && v != "" {
+			versions = append(versions, v)
+		}
+	}
+
+	if len(versions) == 0 {
+		return "", "", fmt.Errorf("no %s* files found in %s", prefix, dir)
+	}
+
+	sort.Slice(versions, func(i, j int) bool {
+		return compareSemver(versions[i], versions[j]) < 0
+	})
+
+	latest := versions[len(versions)-1]
+	return filepath.Join(dir, prefix+latest), latest, nil
+}
+
+// compareSemver compares two dotted-numeric version strings.
+// Returns -1 if a < b, 0 if equal, 1 if a > b.
+func compareSemver(a, b string) int {
+	aParts := strings.Split(a, ".")
+	bParts := strings.Split(b, ".")
+
+	maxLen := max(len(aParts), len(bParts))
+
+	for i := 0; i < maxLen; i++ {
+		var av, bv int
+		if i < len(aParts) {
+			_, _ = fmt.Sscanf(aParts[i], "%d", &av)
+		}
+		if i < len(bParts) {
+			_, _ = fmt.Sscanf(bParts[i], "%d", &bv)
+		}
+		if av < bv {
+			return -1
+		}
+		if av > bv {
+			return 1
+		}
+	}
+	return 0
+}
+
 // ImagesRoot returns the root images directory.
 func ImagesRoot(wrennDir string) string {
 	return filepath.Join(wrennDir, "images")

internal/layout/layout_test.go

@@ -6,7 +6,7 @@ import (
 
 	"github.com/jackc/pgx/v5/pgtype"
 
-	"git.omukk.dev/wrenn/wrenn/internal/id"
+	"git.omukk.dev/wrenn/wrenn/pkg/id"
 )
 
 func TestIsMinimal(t *testing.T) {