Let the setuid search run to its 15-minute bound, ask pacman once, and call a walk with errors incomplete

The search kept a two-minute limit of its own inside its 15-minute bound, so
a long walk always ended incomplete; pacman was asked once per path; and find
exiting with an error but some output was read as a complete walk. The bound
and the not-judged reasons move to the public rootsearch package so the
controller reads the same values (the review of 2026-10-09).

internal/accounts/root_test.go

@@ -38,6 +38,8 @@ type agentMachine struct {
 	// proc is /proc's files, aSafeProc unless a test changes them; findArgs sees find's arguments.
 	proc     map[string]string
 	findArgs func([]string)
+	// pacmanCalls counts the package manager's calls: one for every path found.
+	pacmanCalls int
 }
 
 func (m *agentMachine) readFile(path string) ([]byte, error) {
@@ -107,11 +109,21 @@ func (m *agentMachine) run(_ context.Context, name string, args ...string) (stri
 			m.findArgs(args)
 		}
 		return m.setuid, m.findErr
-	case name == "pacman" && len(args) == 2 && args[0] == "-Qqo":
-		if m.packaged[args[1]] {
-			return "somepackage\n", nil
+	case name == "pacman" && len(args) >= 2 && args[0] == "-Qo":
+		m.pacmanCalls++
+		var out, errs []string
+		for _, p := range args[1:] {
+			if m.packaged[p] {
+				out = append(out, p+" is owned by somepackage 1.0-1")
+			} else {
+				errs = append(errs, "error: No package owns "+p)
+			}
 		}
-		return "", errors.New("pacman exited 1: error: No package owns " + args[1])
+		said := strings.Join(out, "\n")
+		if len(errs) > 0 {
+			return said, errors.New("pacman exited 1: " + strings.Join(errs, "\n"))
+		}
+		return said, nil
 	}
 	return "", errors.New("not a command the judge may run: " + line)
 }
@@ -144,7 +156,7 @@ func lookAgent(t *testing.T, m *agentMachine) Verdict {
 	}
 	for _, a := range m.asked {
 		if !strings.HasPrefix(a, "id ") && a != "sudo -l -U agent" && !strings.HasPrefix(a, "find / ") &&
-			!strings.HasPrefix(a, "pacman -Qqo ") {
+			!strings.HasPrefix(a, "pacman -Qo ") {
 			t.Errorf("the judge asked something that is not a read: %q", a)
 		}
 	}

internal/accounts/ways.go

@@ -10,6 +10,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"github.com/novox/mesh-host/rootsearch"
 	"io/fs"
 	"os"
 	"os/exec"
@@ -398,9 +399,11 @@ type SetuidCache struct {
 	backoff   time.Duration
 }
 
-// SearchBound is how long one search may run in the background; MaxBackoff the longest wait after failures.
+// SearchBound is how long one search may run in the background — the whole search, the walk and the package
+// manager's answers together (rootsearch.Bound, which the controller reads too); MaxBackoff the longest wait
+// after failures.
 const (
-	SearchBound = 15 * time.Minute
+	SearchBound = rootsearch.Bound
 	MaxBackoff  = 6 * time.Hour
 )
 
@@ -424,8 +427,8 @@ func (e *SetuidNotJudged) Error() string {
 
 // The reasons of a root verdict the setuid search could not answer.
 const (
-	ReasonPending    = "not judged yet (search running)"
-	ReasonIncomplete = "not judged (search incomplete)"
+	ReasonPending    = rootsearch.ReasonPending
+	ReasonIncomplete = rootsearch.ReasonIncomplete
 )
 
 // Look answers the last result and when its search finished, starting a search in the background when one is
@@ -475,11 +478,10 @@ func (c *SetuidCache) Look(now time.Time, search func(ctx context.Context) ([]st
 func (c *SetuidCache) Wait() { c.wg.Wait() }
 
 // setuidSearch is every setuid- or setgid-root regular file on the root filesystem that no installed package
-// owns, found with find and asked of the package manager. Bounded: a search that does not finish is an
-// unanswered question, never "none".
+// owns, found with find and asked of the package manager. Bounded by its caller (SearchBound, the whole search):
+// a search that does not finish is an unanswered question, never "none". A walk find could not complete — it
+// exited with an error — is incomplete too, unless every error was a file that vanished while it walked.
 func (e Exec) setuidSearch(ctx context.Context, mounts []string) ([]string, error) {
-	ctx, cancel := context.WithTimeout(ctx, 2*time.Minute)
-	defer cancel()
 	// Each mount point a starting point of its own, -xdev keeping each to its own filesystem: every local
 	// filesystem mounted without nosuid is searched once (the re-review of 2026-10-08), and a program setgid to
 	// root's group counts whoever owns it.
@@ -489,10 +491,10 @@ func (e Exec) setuidSearch(ctx context.Context, mounts []string) ([]string, erro
 		"-2000", ")", ")", "-print")
 	out, err := e.Run(ctx, "find", args...)
 	if ctx.Err() != nil {
-		return nil, fmt.Errorf("the search for setuid programs did not finish within two minutes")
+		return nil, fmt.Errorf("the search for setuid programs did not finish within %s", SearchBound)
 	}
-	if err != nil && strings.TrimSpace(out) == "" {
-		return nil, fmt.Errorf("the search for setuid programs did not finish: %w", err)
+	if err != nil && (strings.TrimSpace(out) == "" || !onlyVanished(err)) {
+		return nil, fmt.Errorf("the search for setuid programs did not complete its walk: %w", err)
 	}
 	var paths []string
 	for _, l := range strings.Split(out, "\n") {
@@ -501,36 +503,88 @@ func (e Exec) setuidSearch(ctx context.Context, mounts []string) ([]string, erro
 		}
 	}
 	sort.Strings(paths)
-	var unowned []string
-	for _, p := range paths {
-		owned, err := e.packaged(ctx, p)
-		if err != nil {
-			return nil, err
-		}
-		if !owned {
-			unowned = append(unowned, p)
-		}
-	}
-	return unowned, nil
+	return e.unpackaged(ctx, paths)
 }
 
-// packaged says whether an installed package owns a path: pacman's or apk's answer, never a guess.
-func (e Exec) packaged(ctx context.Context, path string) (bool, error) {
-	out, err := e.Run(ctx, "pacman", "-Qqo", path)
-	if err == nil {
-		return strings.TrimSpace(out) != "", nil
+// onlyVanished says every error find reported was a file that went while it walked — the one error that leaves
+// the walk complete for what still exists. find's own words come after its exit, one per line.
+func onlyVanished(err error) bool {
+	said := false
+	for _, l := range errorLines(err, "find") {
+		said = true
+		if !strings.Contains(l, "No such file or directory") {
+			return false
+		}
 	}
-	if strings.Contains(out+err.Error(), "No package owns") || strings.Contains(err.Error(), "exited 1") {
-		return false, nil
+	return said
+}
+
+// errorLines are the lines a command said on its error stream, as the runner words a failure: "<name> exited N:
+// <its words>", the prefix taken off the first line. Empty lines are dropped.
+func errorLines(err error, name string) []string {
+	words := err.Error()
+	if strings.HasPrefix(words, name+" exited") {
+		if i := strings.Index(words, ": "); i >= 0 {
+			words = words[i+2:]
+		}
 	}
-	if !errors.Is(err, exec.ErrNotFound) && !errors.Is(err, fs.ErrNotExist) {
-		return false, fmt.Errorf("pacman could not say who owns %s: %w", path, err)
+	var out []string
+	for _, l := range strings.Split(words, "\n") {
+		if l = strings.TrimSpace(l); l != "" {
+			out = append(out, l)
+		}
 	}
-	out, err = e.Run(ctx, "apk", "info", "-W", path)
-	if err != nil {
-		return false, fmt.Errorf("no package manager could say who owns %s: %w", path, err)
+	return out
+}
+
+// unpackaged is every path no installed package owns: pacman asked about all of them in one call, else apk
+// about each. Never a guess: a path neither said owned nor said unowned is an unanswered question.
+func (e Exec) unpackaged(ctx context.Context, paths []string) ([]string, error) {
+	if len(paths) == 0 {
+		return nil, nil
 	}
-	return strings.Contains(out, " is owned by "), nil
+	out, err := e.Run(ctx, "pacman", append([]string{"-Qo"}, paths...)...)
+	if err == nil || !errors.Is(err, exec.ErrNotFound) && !errors.Is(err, fs.ErrNotExist) {
+		owned := map[string]bool{}
+		for _, l := range strings.Split(out, "\n") {
+			if p, _, ok := strings.Cut(strings.TrimSpace(l), " is owned by "); ok {
+				owned[p] = true
+			}
+		}
+		unowned := map[string]bool{}
+		if err != nil {
+			// pacman exits 1 when a path is owned by nothing, and says which on its error stream.
+			for _, l := range errorLines(err, "pacman") {
+				if _, p, ok := strings.Cut(l, "No package owns "); ok {
+					unowned[strings.TrimSpace(p)] = true
+				} else {
+					return nil, fmt.Errorf("pacman could not say who owns the setuid programs found: %s", l)
+				}
+			}
+		}
+		var out []string
+		for _, p := range paths {
+			switch {
+			case owned[p]:
+			case unowned[p]:
+				out = append(out, p)
+			default:
+				return nil, fmt.Errorf("pacman said nothing of who owns %s", p)
+			}
+		}
+		return out, nil
+	}
+	var none []string
+	for _, p := range paths {
+		said, err := e.Run(ctx, "apk", "info", "-W", p)
+		if err != nil {
+			return nil, fmt.Errorf("no package manager could say who owns %s: %w", p, err)
+		}
+		if !strings.Contains(said, " is owned by ") {
+			none = append(none, p)
+		}
+	}
+	return none, nil
 }
 
 // moreWays is every way beyond uid, groups and sudo; an unanswered question is an error, never none.

internal/accounts/ways_test.go

@@ -5,6 +5,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"github.com/novox/mesh-host/rootsearch"
 	"os/exec"
 	"strings"
 	"testing"
@@ -318,3 +319,72 @@ polkit.addRule(function(a, s) { /* isInGroup("wheel") */ return polkit.Result.YE
 		t.Error("each .pkla section on its own")
 	}
 }
+
+// The search's bound is the one the controller reads (rootsearch.Bound): a search may run its whole fifteen
+// minutes, with no shorter limit inside it that would end every long walk incomplete (the review of 2026-10-09).
+func TestTheSearchRunsToItsBoundWithNoShorterLimitInside(t *testing.T) {
+	if rootsearch.Bound != 15*time.Minute {
+		t.Fatalf("the shared bound is %s", rootsearch.Bound)
+	}
+	m := clean()
+	var left time.Duration
+	run := func(ctx context.Context, name string, args ...string) (string, error) {
+		if name == "find" {
+			if d, ok := ctx.Deadline(); ok {
+				left = time.Until(d)
+			}
+		}
+		return m.run(ctx, name, args...)
+	}
+	ctx, cancel := context.WithTimeout(t.Context(), SearchBound)
+	defer cancel()
+	if _, err := (Exec{Run: run}).setuidSearch(ctx, []string{"/"}); err != nil {
+		t.Fatal(err)
+	}
+	if left < SearchBound-time.Minute {
+		t.Fatalf("find was given %s, less than the search's bound of %s", left, SearchBound)
+	}
+}
+
+// The package manager is asked about every path found in one call, and answers each: owned, or owned by nothing.
+func TestThePackageManagerIsAskedOnceForEveryPathFound(t *testing.T) {
+	m := clean()
+	m.setuid = "/usr/bin/sudo\n/usr/bin/passwd\n/usr/local/bin/x\n/opt/y\n"
+	m.packaged = map[string]bool{"/usr/bin/sudo": true, "/usr/bin/passwd": true}
+	found, err := (Exec{Run: m.run}).setuidSearch(t.Context(), []string{"/"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if m.pacmanCalls != 1 {
+		t.Errorf("pacman was asked %d times for four paths", m.pacmanCalls)
+	}
+	if strings.Join(found, ",") != "/opt/y,/usr/local/bin/x" {
+		t.Errorf("unowned: %v", found)
+	}
+	// An error pacman says that is not "owned by nothing" is no answer.
+	odd := func(ctx context.Context, name string, args ...string) (string, error) {
+		if name == "pacman" {
+			return "", errors.New("pacman exited 1: error: could not open database")
+		}
+		return m.run(ctx, name, args...)
+	}
+	if _, err := (Exec{Run: odd}).setuidSearch(t.Context(), []string{"/"}); err == nil {
+		t.Error("a package manager that could not answer was read as an answer")
+	}
+}
+
+// find that exits with an error has not walked everything: the search is incomplete, unless every error was a
+// file that vanished while it walked.
+func TestAWalkFindDidNotCompleteIsIncomplete(t *testing.T) {
+	m := clean()
+	m.setuid = "/usr/local/bin/x\n"
+	m.findErr = errors.New("find exited 1: find: '/mnt/data/private': Permission denied")
+	if _, err := (Exec{Run: m.run}).setuidSearch(t.Context(), []string{"/"}); err == nil {
+		t.Fatal("a walk that could not enter a directory was read as complete")
+	}
+	m.findErr = errors.New("find exited 1: find: '/tmp/a': No such file or directory\nfind: '/tmp/b': No such file or directory")
+	found, err := (Exec{Run: m.run}).setuidSearch(t.Context(), []string{"/"})
+	if err != nil || len(found) != 1 {
+		t.Fatalf("files that vanished while find walked: %v %v", found, err)
+	}
+}