Keep a non-root user's database in the XDG state directory (closes #171)

Without SFDUPES_DATABASE, a user other than root now uses
sfdupes/db.sqlite in the XDG state directory (~/.local/state by
default) instead of failing on /var/lib/sfdupes. scan creates the
missing directories there with mode 0700, as the XDG Base Directory
specification asks. An XDG_STATE_HOME that is not an absolute path is
a fatal error for every subcommand. Root keeps
/var/lib/sfdupes/db.sqlite. The help of sfdupes and of scan, and
README, say where the database is. Adds github.com/adrg/xdg, the
decided XDG library.

Model: opus-5-5

README.md

@@ -136,8 +136,8 @@ point of each disk at or below `/srv` with its own `mountpoint -q`, joined with
     - one line naming the database;
     - progress lines, as described under "Progress";
     - a warning for each path it skips;
-    - a line for each system, temporary or cache directory the walk leaves out
-      (see "Rules for the walk");
+    - a line for each system or temporary directory the walk leaves out (see
+      "Rules for the walk");
     - a line for each path left out because its filesystem is one the kernel,
       the core of the operating system, makes up or keeps in memory, such as
       `tmpfs`;
@@ -309,9 +309,8 @@ The reference below is also the program's specification.
   of directories on other filesystems, as the same flag does for `du` and
   `rsync`. By default the walk also enters directories on other filesystems.
 - `--no-default-excludes` (`scan`, `dwim`) lets the walk enter the default
-  excludes. Those are the system, temporary and cache directories the walk
-  otherwise leaves out, such as `/var/tmp` and `/var/cache` on Linux (see "Rules
-  for the walk").
+  excludes. Those are the system and temporary directories the walk otherwise
+  leaves out, such as `/var/tmp` on Linux (see "Rules for the walk").
 - `--exclude PATH` (`scan`, `dwim`) keeps the walk out of `PATH` and everything
   below it. `PATH` may be a directory or a file. The flag may be given more than
   once. The walk knows `PATH` by its device ID and inode number, as it knows the
@@ -563,7 +562,7 @@ walk practical on large or busy storage pools.
     `scan` prints a line on stderr naming the path and its filesystem type:
 
     ```
-    scan: left out /dev/shm (tmpfs, not a persistent filesystem)
+    scan: skipped /dev/shm (tmpfs, not a persistent filesystem)
     ```
 
     The path is not counted as skipped. The records below it are kept, as
@@ -573,7 +572,7 @@ walk practical on large or busy storage pools.
   For each one it reaches, `scan` prints a line on stderr naming it:
 
     ```
-    scan: left out /srv/cache (--exclude)
+    scan: skipped /srv/cache (--exclude)
     ```
 
     The path is not counted as skipped. The scan keeps the records at and below
@@ -581,17 +580,12 @@ walk practical on large or busy storage pools.
     `--no-default-excludes` does not change this rule.
 
 - Below an operand, the walk does not enter a default exclude. On Linux, the
-  default excludes hold the kernel's view of the running system, temporary
-  files, and caches. A cache here is data that programs and package managers
-  download or build again on their own. The default excludes depend on the
-  system, and `sfdupes scan --help` lists those of the system it runs on. In the
-  lists, `*` stands for any one directory name, so `/home/*/.cache` matches
-  `/home/alice/.cache`. On Linux they are:
+  default excludes hold temporary files and the kernel's view of the running
+  system. They depend on the system, and `sfdupes scan --help` lists those of
+  the system it runs on. On Linux they are:
 
     ```
-    /proc, /sys, /dev, /run, /tmp, /var/tmp, /var/cache
-    /root/.cache, /root/.npm, /root/.cargo/registry, /root/go/pkg/mod
-    /home/*/.cache, /home/*/.npm, /home/*/.cargo/registry, /home/*/go/pkg/mod
+    /proc, /sys, /dev, /run, /tmp, /var/tmp
     ```
 
     On macOS they are:
@@ -599,21 +593,13 @@ walk practical on large or busy storage pools.
     ```
     /dev, /private/tmp, /private/var/tmp, /private/var/vm
     /System/Volumes/VM, /System/Volumes/Data
-    /private/var/folders, /Library/Caches
-    /private/var/root/Library/Caches, /private/var/root/.cache
-    /private/var/root/.npm, /private/var/root/.cargo/registry
-    /private/var/root/go/pkg/mod
-    /Users/*/Library/Caches, /Users/*/.cache, /Users/*/.npm
-    /Users/*/.cargo/registry, /Users/*/go/pkg/mod
     ```
 
-    `/private/var/folders` holds each user's temporary files and caches on
-    macOS. Root's home on macOS is `/var/root`, which the walk reaches as
-    `/private/var/root`. A walk of `/` on macOS reaches everything in
-    `/System/Volumes/Data` already, through firmlinks. Firmlinks are the links
-    macOS uses to show the data volume inside the system volume. Walking
-    `/System/Volumes/Data` as well would record each of those files twice. Any
-    other system has no default excludes.
+    A walk of `/` on macOS reaches everything in `/System/Volumes/Data` already,
+    through firmlinks. Firmlinks are the links macOS uses to show the data
+    volume inside the system volume. Walking `/System/Volumes/Data` as well
+    would record each of those files twice. Any other system has no default
+    excludes.
 
     An operand at or inside a default exclude is walked, so
     `sfdupes scan /tmp/x` works when `/tmp/x` is on a persistent filesystem.
@@ -622,7 +608,7 @@ walk practical on large or busy storage pools.
     not enter, `scan` prints a line on stderr naming it:
 
     ```
-    scan: left out /var/tmp (default exclude)
+    scan: skipped /var/tmp (default exclude)
     ```
 
     The directory is not counted as skipped. `scan` prints the filesystem line
@@ -682,18 +668,6 @@ scan: 123400 files seen (1200 added, 34 updated, 56 removed, 122166 unchanged),
 
 `removed` counts deleted records, which are not part of the files seen.
 
-The warning for a skipped path names the path once and gives the reason:
-
-```
-scan: skipped /srv/a/closed (permission denied)
-scan: skipped /srv/a/pipe (a FIFO)
-```
-
-The summary counts each path named in such a warning. A line for a path left out
-on purpose starts with `scan: left out` instead, and is not counted. A search of
-the log for `scan: skipped` therefore finds the paths the summary counts. When a
-file with several hard links cannot be read, each of its paths gets a warning.
-
 #### Stopping a scan
 
 `scan` stops cleanly on `SIGINT`, the signal Ctrl-C sends, or `SIGTERM`, the

internal/sfdupes/cli_test.go

@@ -1013,7 +1013,8 @@ func TestRunScanSucceedsDespiteWarnings(t *testing.T) {
 
 	stderr := scanOK(t, dir)
 
-	warning := "scan: skipped " + unreadable + " (permission denied)\n"
+	warning := "hash " + unreadable + ": open " + unreadable +
+		": permission denied\n"
 	if !strings.Contains(stderr, warning) {
 		t.Errorf("stderr = %q, want %q", stderr, warning)
 	}
@@ -1285,7 +1286,7 @@ func TestRunScanSkipsSymlinkToFIFOOperand(t *testing.T) {
 
 	stderr := scanOK(t, link)
 
-	warning := "scan: skipped " + fifo + " (a FIFO)\n"
+	warning := "walk " + fifo + ": skipping FIFO operand\n"
 	if !strings.Contains(stderr, warning) {
 		t.Errorf("stderr = %q, want %q", stderr, warning)
 	}
@@ -1320,7 +1321,7 @@ func assertOperandSkipped(t *testing.T, dbPath, operand, kind,
 
 	stderr := scanOK(t, operand)
 
-	warning := "scan: skipped " + operand + " (a " + kind + ")\n"
+	warning := "walk " + operand + ": skipping " + kind + " operand\n"
 	if !strings.Contains(stderr, warning) {
 		t.Errorf("stderr = %q, want %q", stderr, warning)
 	}
@@ -1354,7 +1355,7 @@ func TestRunScanSkipsOperandInsideZFS(t *testing.T) {
 	writeFile(t, hourly, "f", pattern(1, 10))
 	f := writeFile(t, dir, "f", pattern(2, 10))
 
-	warning := "scan: skipped " + hourly + " (inside a .zfs directory)\n"
+	warning := "walk " + hourly + ": skipping operand inside a .zfs directory\n"
 
 	for _, tc := range []struct {
 		operands []string
@@ -1406,7 +1407,7 @@ func TestRunScanSkipsOperandThroughSymlinkIntoZFS(t *testing.T) {
 	stderr := scanOK(t, filepath.Join(snaps, "daily"))
 
 	daily := filepath.Join(dir, "pool", ".zfs", "snapshot", "daily")
-	warning := "scan: skipped " + daily + " (inside a .zfs directory)\n"
+	warning := "walk " + daily + ": skipping operand inside a .zfs directory\n"
 	summary := "scan: 0 files seen (0 added, 0 updated, 0 removed, " +
 		"0 unchanged), 1 skipped\n"
 

internal/sfdupes/dwim_test.go

@@ -121,9 +121,9 @@ func TestRunDwimExcludeLeavesTreeOut(t *testing.T) {
 		t.Errorf("group = %q, want it to start %q", lines[1], want)
 	}
 
-	leftOut := "scan: left out " + excluded + " (--exclude)\n"
-	if got := stderr(); !strings.Contains(got, leftOut) {
-		t.Errorf("stderr = %q, want it to contain %q", got, leftOut)
+	skipped := "scan: skipped " + excluded + " (--exclude)\n"
+	if got := stderr(); !strings.Contains(got, skipped) {
+		t.Errorf("stderr = %q, want it to contain %q", got, skipped)
 	}
 }
 

internal/sfdupes/exclude.go

@@ -72,31 +72,14 @@ type walkRules struct {
 func defaultExcludes(goos string) []string {
 	switch goos {
 	case goosLinux:
-		// The kernel's view of the running system, temporary files, and
-		// caches that programs and package managers fill again on their
-		// own: the system's, root's and those in each home in /home.
-		return []string{
-			"/proc", "/sys", "/dev", "/run", "/tmp", "/var/tmp", "/var/cache",
-			"/root/.cache", "/root/.npm", "/root/.cargo/registry",
-			"/root/go/pkg/mod",
-			"/home/*/.cache", "/home/*/.npm", "/home/*/.cargo/registry",
-			"/home/*/go/pkg/mod",
-		}
+		return []string{"/proc", "/sys", "/dev", "/run", "/tmp", "/var/tmp"}
 	case goosDarwin:
 		// A walk of / reaches everything in /System/Volumes/Data through
 		// the firmlinks, so walking it as well would record each of
-		// those files twice. /private/var/folders holds each user's
-		// temporary files and caches. The walk reaches root's home,
-		// /var/root, as /private/var/root.
+		// those files twice.
 		return []string{
 			"/dev", "/private/tmp", "/private/var/tmp", "/private/var/vm",
 			"/System/Volumes/VM", "/System/Volumes/Data",
-			"/private/var/folders", "/Library/Caches",
-			"/private/var/root/Library/Caches", "/private/var/root/.cache",
-			"/private/var/root/.npm", "/private/var/root/.cargo/registry",
-			"/private/var/root/go/pkg/mod",
-			"/Users/*/Library/Caches", "/Users/*/.cache", "/Users/*/.npm",
-			"/Users/*/.cargo/registry", "/Users/*/go/pkg/mod",
 		}
 	case goosWindows:
 		// Relative to the root of the drive an operand lies on. The
@@ -203,7 +186,7 @@ func (rules walkRules) excludePathLine(path string, fi fs.FileInfo) string {
 		return ""
 	}
 
-	return fmt.Sprintf("scan: left out %s (--exclude)", path)
+	return fmt.Sprintf("scan: skipped %s (--exclude)", path)
 }
 
 // nonPersistentFilesystemTypes returns the filesystem types that are
@@ -233,7 +216,7 @@ func (rules walkRules) nonPersistentLine(path string, fi fs.FileInfo) string {
 		return ""
 	}
 
-	return fmt.Sprintf("scan: left out %s (%s, not a persistent filesystem)",
+	return fmt.Sprintf("scan: skipped %s (%s, not a persistent filesystem)",
 		path, fsType)
 }
 

internal/sfdupes/exclude_test.go

@@ -24,22 +24,10 @@ func TestDefaultExcludes(t *testing.T) {
 	// on any other system. The Windows list exists in the code only: the
 	// binary does not build for Windows, so the README leaves it out.
 	cases := map[string][]string{
-		goosLinux: {
-			"/proc", "/sys", "/dev", "/run", "/tmp", "/var/tmp", "/var/cache",
-			"/root/.cache", "/root/.npm", "/root/.cargo/registry",
-			"/root/go/pkg/mod",
-			"/home/*/.cache", "/home/*/.npm", "/home/*/.cargo/registry",
-			"/home/*/go/pkg/mod",
-		},
+		goosLinux: {"/proc", "/sys", "/dev", "/run", "/tmp", "/var/tmp"},
 		goosDarwin: {
 			"/dev", "/private/tmp", "/private/var/tmp", "/private/var/vm",
 			"/System/Volumes/VM", "/System/Volumes/Data",
-			"/private/var/folders", "/Library/Caches",
-			"/private/var/root/Library/Caches", "/private/var/root/.cache",
-			"/private/var/root/.npm", "/private/var/root/.cargo/registry",
-			"/private/var/root/go/pkg/mod",
-			"/Users/*/Library/Caches", "/Users/*/.cache", "/Users/*/.npm",
-			"/Users/*/.cargo/registry", "/Users/*/go/pkg/mod",
 		},
 		goosWindows: {
 			"pagefile.sys", "swapfile.sys", "hiberfil.sys",
@@ -75,29 +63,6 @@ func TestIsDefaultExclude(t *testing.T) {
 			t.Errorf("isDefaultExclude(%q) = %v, want %v", path, got, want)
 		}
 	}
-
-	// The Linux list matches the cache directories in /root and in each
-	// home in /home, but nothing below them and no .cache directory
-	// elsewhere.
-	linux := map[string]bool{
-		"/home/u/.cache":           true,
-		"/home/u/go/pkg/mod":       true,
-		"/root/.cache":             true,
-		"/var/cache":               true,
-		"/home/u/.cache/pip":       false,
-		"/home/u/src/.cache":       false,
-		"/srv/home/u/.cache":       false,
-		"/home/u/.cargo/bin":       false,
-		"/home/u/go/pkg/mod/cache": false,
-	}
-
-	for path, want := range linux {
-		got := isDefaultExclude(path, defaultExcludes(goosLinux))
-		if got != want {
-			t.Errorf("isDefaultExclude(%q, Linux list) = %v, want %v", path,
-				got, want)
-		}
-	}
 }
 
 func TestReadMountInfo(t *testing.T) {
@@ -242,7 +207,7 @@ func TestScanDoesNotEnterDefaultExclude(t *testing.T) {
 		t.Errorf("%s recorded: the walk entered %s", unseen, excluded)
 	}
 
-	line := "\nscan: left out " + excluded + " (default exclude)\n"
+	line := "\nscan: skipped " + excluded + " (default exclude)\n"
 	if !strings.Contains(stderr(), line) {
 		t.Errorf("stderr = %q, want %q", stderr(), line)
 	}
@@ -311,7 +276,7 @@ func TestScanNamesNoDefaultExcludeThatIsAnOperand(t *testing.T) {
 
 	recordByPath(t, dbRecords(t, db), f)
 
-	if strings.Contains(stderr(), "scan: left out") {
+	if strings.Contains(stderr(), "scan: skipped") {
 		t.Errorf("stderr = %q, want no line for %s", stderr(), excluded)
 	}
 }
@@ -325,15 +290,15 @@ func TestRunScanTempDirOperand(t *testing.T) {
 	t.Setenv(databaseEnv, path)
 
 	dir := realTempDir(t)
-	if !insideDefaultExclude(dir, defaultExcludes(runtime.GOOS)) {
+	if !underAnyRoot(dir, defaultExcludes(runtime.GOOS)) {
 		t.Skip(dir + " is not inside a default exclude")
 	}
 
 	f := writeFile(t, dir, "sub/f", pattern(1, 10))
 
 	stderr := scanOK(t, dir)
-	if strings.Contains(stderr, "scan: left out") {
-		t.Errorf("stderr = %q, want no line saying a path was left out",
+	if strings.Contains(stderr, "scan: skipped") {
+		t.Errorf("stderr = %q, want no line saying a path was skipped",
 			stderr)
 	}
 
@@ -377,7 +342,7 @@ func TestRunScanNoDefaultExcludes(t *testing.T) {
 	path := testDBPath(t)
 	t.Setenv(databaseEnv, path)
 
-	line := "scan: left out /var/tmp (default exclude)\n"
+	line := "scan: skipped /var/tmp (default exclude)\n"
 
 	if stderr := scanOK(t, "/var"); !strings.Contains(stderr, line) {
 		t.Errorf("scan /var: stderr = %q, want %q", stderr, line)
@@ -418,7 +383,7 @@ func TestRunScanExcludeNested(t *testing.T) {
 
 	stderr := scanOK(t, excludeFlag, excluded, dir)
 
-	line := "scan: left out " + excluded + " (--exclude)\n"
+	line := "scan: skipped " + excluded + " (--exclude)\n"
 	if !strings.Contains(stderr, line) {
 		t.Errorf("stderr = %q, want %q", stderr, line)
 	}
@@ -480,8 +445,8 @@ func TestRunScanExcludeReachedByAnotherPath(t *testing.T) {
 	stderr := scanOK(t, excludeFlag, filepath.Join(link, "cache"),
 		excludeFlag, dotDot, dir)
 
-	for _, leftOut := range []string{filepath.Dir(inDir), file, hardLink} {
-		line := "scan: left out " + leftOut + " (--exclude)\n"
+	for _, skipped := range []string{filepath.Dir(inDir), file, hardLink} {
+		line := "scan: skipped " + skipped + " (--exclude)\n"
 		if !strings.Contains(stderr, line) {
 			t.Errorf("stderr = %q, want %q", stderr, line)
 		}
@@ -615,7 +580,7 @@ func TestRunScanSkipsNonPersistentOperand(t *testing.T) {
 
 	t.Setenv(databaseEnv, testDBPath(t))
 
-	line := "scan: left out " + shm + " (" + fsType +
+	line := "scan: skipped " + shm + " (" + fsType +
 		", not a persistent filesystem)\n"
 	summary := "scan: 0 files seen"
 
@@ -669,7 +634,7 @@ func TestScanKeepsRecordsOnNonPersistent(t *testing.T) {
 		t.Errorf("%s recorded", unseen)
 	}
 
-	line := "scan: left out " + shm + " (" + fsType +
+	line := "scan: skipped " + shm + " (" + fsType +
 		", not a persistent filesystem)\n"
 	if !strings.Contains(stderr(), line) {
 		t.Errorf("stderr = %q, want %q", stderr(), line)
@@ -702,7 +667,7 @@ func TestWalkLeavesOutNonPersistent(t *testing.T) {
 
 		leftOut = append(leftOut, ev.leftOut)
 
-		want := "scan: left out " + ev.leftOut + " (" + fsType +
+		want := "scan: skipped " + ev.leftOut + " (" + fsType +
 			", not a persistent filesystem)"
 		if ev.warn != want {
 			t.Errorf("line = %q, want %q", ev.warn, want)
@@ -746,20 +711,6 @@ func shmTempDir(t *testing.T) (string, string, walkRules) {
 	return dir, fsType, walkRules{nonPersistent: nonPersistent}
 }
 
-// insideDefaultExclude reports whether path, which is absolute and
-// clean, or a directory above it is one of excludes.
-func insideDefaultExclude(path string, excludes []string) bool {
-	for dir := path; ; dir = filepath.Dir(dir) {
-		if isDefaultExclude(dir, excludes) {
-			return true
-		}
-
-		if dir == "/" {
-			return false
-		}
-	}
-}
-
 // assertRecorded checks that the database at dbPath holds a record for
 // path when want is set, and none when it is not.
 func assertRecorded(t *testing.T, dbPath, path string, want bool) {

internal/sfdupes/scan.go

@@ -664,8 +664,8 @@ func isDatabaseFile(f fileRec, rules walkRules) bool {
 // inode run, committing completed records to the database in batches
 // as results arrive, so a long scan persists its progress as it goes
 // (an interrupted scan resumes cheaply: the next run skips everything
-// already recorded). Each path of a run that fails to hash is warned
-// about and counted as skipped; stale records for them, if any, are deleted
+// already recorded). A run that fails to hash is warned about and
+// counted as skipped; stale records for its paths, if any, are deleted
 // by the update phase. A run whose file no longer exists gets no record
 // and no warning, and is not counted as skipped. The total counts actual
 // reads, so the display's time remaining is meaningful.
@@ -706,12 +706,9 @@ func (s *scanState) hashPhase(ctx context.Context, workers int) error {
 		}
 
 		if r.err != nil {
-			// Every path in the run is counted, so every path gets a line.
-			for _, rec := range r.run {
-				s.st.skipped++
+			s.st.skipped += len(r.run)
 
-				prog.warnf("%s", skippedLine(rec.path, r.err))
-			}
+			prog.warnf("hash %s: %v", r.run[0].path, r.err)
 
 			continue
 		}
@@ -918,7 +915,8 @@ func operandWarning(root string, fi fs.FileInfo) string {
 	// The walk never enters a .zfs directory, so it starts from nothing
 	// inside one either.
 	if slices.Contains(strings.Split(filepath.Dir(root), "/"), ".zfs") {
-		return fmt.Sprintf("scan: skipped %s (inside a .zfs directory)", root)
+		return fmt.Sprintf("walk %s: skipping operand inside a .zfs directory",
+			root)
 	}
 
 	var kind string
@@ -944,21 +942,7 @@ func operandWarning(root string, fi fs.FileInfo) string {
 		kind = "non-regular file"
 	}
 
-	return fmt.Sprintf("scan: skipped %s (a %s)", root, kind)
-}
-
-// skippedLine returns the warning for a path the scan skips because of
-// err. The reason is the error without its path, which the line already
-// names.
-func skippedLine(path string, err error) string {
-	reason := err.Error()
-
-	var pathErr *fs.PathError
-	if errors.As(err, &pathErr) {
-		reason = pathErr.Err.Error()
-	}
-
-	return fmt.Sprintf("scan: skipped %s (%s)", path, reason)
+	return fmt.Sprintf("walk %s: skipping %s operand", root, kind)
 }
 
 // seedRoot turns one PATH operand into the walk's starting state: a
@@ -981,7 +965,7 @@ func seedRoot(ctx context.Context, root string, rules walkRules,
 
 	if err != nil {
 		sendEvent(ctx, events, walkEvent{
-			warn: skippedLine(root, err),
+			warn: fmt.Sprintf("walk %s: %v", root, err),
 			fail: true,
 		})
 
@@ -1110,7 +1094,7 @@ func walkOneDir(ctx context.Context, job dirJob, oneFS bool,
 
 	if err != nil {
 		sendEvent(ctx, events, walkEvent{
-			warn: skippedLine(job.path, err),
+			warn: fmt.Sprintf("walk %s: %v", job.path, err),
 			fail: true,
 		})
 
@@ -1169,7 +1153,7 @@ func emitFile(ctx context.Context, p string, e fs.DirEntry,
 
 	if err != nil {
 		sendEvent(ctx, events, walkEvent{
-			warn: skippedLine(p, err),
+			warn: fmt.Sprintf("stat %s: %v", p, err),
 			fail: true,
 		})
 
@@ -1230,7 +1214,7 @@ func subdirJob(ctx context.Context, p string, e fs.DirEntry,
 
 	if err != nil {
 		sendEvent(ctx, events, walkEvent{
-			warn: skippedLine(p, err),
+			warn: fmt.Sprintf("walk %s: %v", p, err),
 			fail: true,
 		})
 
@@ -1251,7 +1235,7 @@ func subdirJob(ctx context.Context, p string, e fs.DirEntry,
 	if isDefaultExclude(p, rules.defaultExcludes) {
 		sendEvent(ctx, events, walkEvent{
 			leftOut: p,
-			warn:    fmt.Sprintf("scan: left out %s (default exclude)", p),
+			warn:    fmt.Sprintf("scan: skipped %s (default exclude)", p),
 		})
 
 		return dirJob{}, false

internal/sfdupes/scan_test.go

@@ -752,9 +752,8 @@ func TestWalkPassesOverRemovedPaths(t *testing.T) {
 
 // TestScanWarnsAboutUnreadablePaths checks that a permission error is
 // still warned about and counted as skipped, unlike a removed path. The
-// walk reaches an unreadable directory. It also reaches a file and a
-// subdirectory in a directory that can be read but not searched. Another
-// such file is an operand.
+// walk reaches an unreadable directory, and a file in a directory that
+// can be read but not searched. Another such file is an operand.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestScanWarnsAboutUnreadablePaths(t *testing.T) {
@@ -766,7 +765,6 @@ func TestScanWarnsAboutUnreadablePaths(t *testing.T) {
 	dir := t.TempDir()
 	tree := filepath.Join(dir, "tree")
 	walked := writeFile(t, tree, "unsearchable/f", []byte("x"))
-	subdir := filepath.Join(filepath.Dir(walked), "d")
 	operand := writeFile(t, dir, "unsearchable/f", []byte("y"))
 	unreadable := filepath.Join(tree, "unreadable")
 
@@ -775,11 +773,6 @@ func TestScanWarnsAboutUnreadablePaths(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	err = os.Mkdir(subdir, 0o750)
-	if err != nil {
-		t.Fatal(err)
-	}
-
 	modes := map[string]fs.FileMode{
 		unreadable:            0,
 		filepath.Dir(walked):  0o400,
@@ -800,16 +793,15 @@ func TestScanWarnsAboutUnreadablePaths(t *testing.T) {
 	}
 
 	st := syncTree(t, openTestDB(t), tree, operand)
-	if st != (scanStats{skipped: 4}) {
-		t.Errorf("stats = %+v, want 4 skipped and nothing else", st)
+	if st != (scanStats{skipped: 3}) {
+		t.Errorf("stats = %+v, want 3 skipped and nothing else", st)
 	}
 
 	got := stderr()
 	for _, warning := range []string{
-		"scan: skipped " + unreadable + " (permission denied)\n",
-		"scan: skipped " + walked + " (permission denied)\n",
-		"scan: skipped " + subdir + " (permission denied)\n",
-		"scan: skipped " + operand + " (permission denied)\n",
+		"walk " + unreadable + ": open " + unreadable + ": permission denied\n",
+		"stat " + walked + ": lstat " + walked + ": permission denied\n",
+		"walk " + operand + ": lstat " + operand + ": permission denied\n",
 	} {
 		if !strings.Contains(got, warning) {
 			t.Errorf("stderr = %q, want %q", got, warning)
@@ -1949,19 +1941,14 @@ func TestScanHardlinksReadOnce(t *testing.T) {
 	}
 }
 
-// TestScanHardlinkRunFailsTogether makes a file with two hard links
-// unreadable. Both paths are counted as skipped, and each gets its own
-// warning.
-//
-//nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestScanHardlinkRunFailsTogether(t *testing.T) {
-	stderr := captureStderr(t)
+	t.Parallel()
+
 	dir := t.TempDir()
 	db := openTestDB(t)
 	a := writeFile(t, dir, "a.bin", pattern(1, 300))
-	b := filepath.Join(dir, "b.bin")
 
-	err := os.Link(a, b)
+	err := os.Link(a, filepath.Join(dir, "b.bin"))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1977,15 +1964,6 @@ func TestScanHardlinkRunFailsTogether(t *testing.T) {
 	if st.skipped != 2 || st.added != 0 {
 		t.Fatalf("stats = %+v, want both hardlink paths skipped", st)
 	}
-
-	got := stderr()
-
-	for _, p := range []string{a, b} {
-		warning := "scan: skipped " + p + " (permission denied)\n"
-		if !strings.Contains(got, warning) {
-			t.Errorf("stderr = %q, want %q", got, warning)
-		}
-	}
 }
 
 // TestHashPhaseSkipsFileReplacedByFIFO replaces a walked regular file
@@ -2023,7 +2001,7 @@ func TestHashPhaseSkipsFileReplacedByFIFO(t *testing.T) {
 			s.st.skipped, len(s.batch))
 	}
 
-	warning := "scan: skipped " + p + " (not a regular file)\n"
+	warning := "hash " + p + ": not a regular file\n"
 	if got := stderr(); strings.Count(got, warning) != 1 {
 		t.Errorf("stderr = %q, want %q once", got, warning)
 	}