🐛 fix: bound snap package enumeration over ssh

providers/os/resources/packages/snap_packages.go

@@ -4,10 +4,14 @@
 package packages
 
 import (
+	"bufio"
 	"fmt"
 	"io"
 	"os"
-	"regexp"
+	"path"
+	"sort"
+	"strconv"
+	"strings"
 
 	"github.com/rs/zerolog/log"
 	"github.com/spf13/afero"
@@ -26,6 +30,12 @@ type SnapPkgManager struct {
 	platform *inventory.Platform
 }
 
+type snapListEntry struct {
+	name    string
+	version string
+	rev     string
+}
+
 func (spm *SnapPkgManager) Name() string {
 	return "Snap Package Manager"
 }
@@ -35,50 +45,195 @@ func (spm *SnapPkgManager) Format() string {
 }
 
 func (spm *SnapPkgManager) List() ([]Package, error) {
-	fs := spm.conn.FileSystem()
-	snapDir := "/snap"
-	afs := &afero.Afero{Fs: fs}
-	_, dErr := afs.Stat(snapDir)
-	if dErr != nil {
-		log.Debug().Str("path", snapDir).Msg("cannot find snap dir")
-		return []Package{}, nil
+	if spm.conn.Capabilities().Has(shared.Capability_RunCommand) {
+		packages, err := spm.listFromCLI()
+		if err == nil {
+			return packages, nil
+		}
+
+		log.Debug().Err(err).Msg("mql[snap]> could not enumerate snaps via cli, falling back to filesystem")
 	}
 
-	// e.g. /snap/firefox/6103/meta/snap.yaml
-	// https://snapcraft.io/docs/the-snap-format#p-3326-setup-files
-	snapRegEx := regexp.MustCompile(`/snap/[^/]+/\d+/meta/snap\.yaml`)
-	files := []string{}
-	err := afs.Walk(snapDir, func(path string, info os.FileInfo, err error) error {
-		if info == nil || info.IsDir() {
-			return nil
-		}
-		if !snapRegEx.MatchString(path) {
-			return nil
+	return spm.listFromFS()
+}
+
+func (spm *SnapPkgManager) listFromCLI() ([]Package, error) {
+	cmdResult, err := spm.conn.RunCommand("snap list")
+	if err != nil {
+		return nil, err
+	}
+
+	if cmdResult.ExitStatus != 0 {
+		stderr := "unknown error"
+		if cmdResult.Stderr != nil {
+			stderrBytes, readErr := io.ReadAll(cmdResult.Stderr)
+			if readErr == nil {
+				stderr = strings.TrimSpace(string(stderrBytes))
+				if stderr == "" {
+					stderr = "unknown error"
+				}
+			}
 		}
 
-		files = append(files, path)
-		return nil
-	})
+		return nil, fmt.Errorf("snap list failed: %s", stderr)
+	}
+
+	if cmdResult.Stdout == nil {
+		return []Package{}, nil
+	}
+
+	entries, err := parseSnapListOutput(cmdResult.Stdout)
 	if err != nil {
 		return nil, err
 	}
 
-	pkgList := []Package{}
-	for _, file := range files {
-		manifest, err := afs.Open(file)
+	afs := &afero.Afero{Fs: spm.conn.FileSystem()}
+	pkgList := make([]Package, 0, len(entries))
+
+	for _, entry := range entries {
+		manifestPath := path.Join("/snap", entry.name, entry.rev, "meta", "snap.yaml")
+		manifest, err := afs.Open(manifestPath)
 		if err != nil {
-			log.Error().Err(err).Str("file", file).Msg("could not open manifest file")
+			log.Debug().Err(err).Str("path", manifestPath).Msg("mql[snap]> could not open snap manifest from cli revision")
 			continue
 		}
+
 		pkg, err := spm.parseSnapManifest(manifest)
+		manifest.Close()
 		if err != nil {
-			log.Error().Err(err).Str("file", file).Msg("could not parse manifest file")
-			manifest.Close()
+			log.Debug().Err(err).Str("path", manifestPath).Msg("mql[snap]> could not parse snap manifest from cli revision")
 			continue
 		}
+
 		pkgList = append(pkgList, pkg)
-		manifest.Close()
 	}
+
+	return pkgList, nil
+}
+
+func parseSnapListOutput(input io.Reader) ([]snapListEntry, error) {
+	scanner := bufio.NewScanner(input)
+	entries := []snapListEntry{}
+	firstNonEmptyLine := true
+
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" {
+			continue
+		}
+
+		fields := strings.Fields(line)
+		if len(fields) == 0 {
+			continue
+		}
+
+		if firstNonEmptyLine {
+			firstNonEmptyLine = false
+			if len(fields) >= 3 && fields[0] == "Name" && fields[2] == "Rev" {
+				continue
+			}
+		}
+
+		if len(fields) < 3 {
+			continue
+		}
+
+		entries = append(entries, snapListEntry{
+			name:    fields[0],
+			version: fields[1],
+			rev:     fields[2],
+		})
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return entries, nil
+}
+
+func (spm *SnapPkgManager) listFromFS() ([]Package, error) {
+	afs := &afero.Afero{Fs: spm.conn.FileSystem()}
+	const snapDir = "/snap"
+
+	dirEntries, err := afs.ReadDir(snapDir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			log.Debug().Str("path", snapDir).Msg("cannot find snap dir")
+			return []Package{}, nil
+		}
+
+		return nil, err
+	}
+
+	pkgList := []Package{}
+	for _, entry := range dirEntries {
+		name := entry.Name()
+		currentManifestPath := path.Join(snapDir, name, "current", "meta", "snap.yaml")
+		manifest, err := afs.Open(currentManifestPath)
+		if err == nil {
+			pkg, err := spm.parseSnapManifest(manifest)
+			manifest.Close()
+			if err != nil {
+				log.Debug().Err(err).Str("path", currentManifestPath).Msg("mql[snap]> could not parse current snap manifest")
+				continue
+			}
+
+			pkgList = append(pkgList, pkg)
+			continue
+		}
+
+		if !os.IsNotExist(err) {
+			log.Debug().Err(err).Str("path", currentManifestPath).Msg("mql[snap]> could not open current snap manifest")
+			continue
+		}
+
+		revisionDir := path.Join(snapDir, name)
+		revisionEntries, err := afs.ReadDir(revisionDir)
+		if err != nil {
+			if !os.IsNotExist(err) {
+				log.Debug().Err(err).Str("path", revisionDir).Msg("mql[snap]> could not inspect snap revisions")
+			}
+			continue
+		}
+
+		revisions := make([]int, 0, len(revisionEntries))
+		for _, revisionEntry := range revisionEntries {
+			if !revisionEntry.IsDir() {
+				continue
+			}
+
+			revision, err := strconv.Atoi(revisionEntry.Name())
+			if err != nil {
+				continue
+			}
+
+			revisions = append(revisions, revision)
+		}
+
+		sort.Sort(sort.Reverse(sort.IntSlice(revisions)))
+		for _, revision := range revisions {
+			manifestPath := path.Join(snapDir, name, strconv.Itoa(revision), "meta", "snap.yaml")
+			manifest, err := afs.Open(manifestPath)
+			if err != nil {
+				if !os.IsNotExist(err) {
+					log.Debug().Err(err).Str("path", manifestPath).Msg("mql[snap]> could not open snap manifest from revision fallback")
+				}
+				continue
+			}
+
+			pkg, err := spm.parseSnapManifest(manifest)
+			manifest.Close()
+			if err != nil {
+				log.Debug().Err(err).Str("path", manifestPath).Msg("mql[snap]> could not parse snap manifest from revision fallback")
+				continue
+			}
+
+			pkgList = append(pkgList, pkg)
+			break
+		}
+	}
+
 	return pkgList, nil
 }