Add bounded concurrent scanner

Single-writer controller with a select loop that offers jobs and accepts results simultaneously, so bounded channels cannot deadlock. statx/fstatat relative to the directory fd on Linux/macOS, portable fallback elsewhere. Hard links counted once, symlink loops detected, virtual filesystems skipped, errors classified and surfaced.
2026-10-02 08:02:32 +01:00
parent 61fd9bf711
commit 8233ddcfba
9 changed files with 1260 additions and 0 deletions
@@ -0,0 +1,82 @@
+//go:build darwin || freebsd
+
+package platform
+
+import (
+	"errors"
+	"io"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// ReadDir streams the entries of a directory in chunks, stat-ing each entry
+// relative to the directory fd.
+func ReadDir(path string, chunk int, fn ChunkFunc) error {
+	fd, err := unix.Open(path, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_CLOEXEC, 0)
+	if err != nil {
+		return &os.PathError{Op: "open", Path: path, Err: err}
+	}
+	f := os.NewFile(uintptr(fd), path)
+	defer f.Close()
+	for {
+		des, err := f.ReadDir(chunk)
+		if len(des) > 0 {
+			out := make([]Meta, len(des))
+			for i, de := range des {
+				var st unix.Stat_t
+				if serr := unix.Fstatat(fd, de.Name(), &st, unix.AT_SYMLINK_NOFOLLOW); serr != nil {
+					out[i] = Meta{Name: de.Name(), Err: &os.PathError{Op: "stat", Path: de.Name(), Err: serr}}
+					continue
+				}
+				out[i] = fromStat(&st)
+				out[i].Name = de.Name()
+			}
+			if ferr := fn(out); ferr != nil {
+				return ferr
+			}
+		}
+		if err != nil {
+			if errors.Is(err, io.EOF) {
+				return nil
+			}
+			return err
+		}
+	}
+}
+
+func fromStat(st *unix.Stat_t) Meta {
+	return Meta{
+		Mode:       modeFromUnix(uint32(st.Mode)),
+		Size:       st.Size,
+		Alloc:      st.Blocks * 512,
+		AllocKnown: true,
+		MTime:      st.Mtim.Nano(),
+		BTime:      st.Btim.Nano(),
+		UID:        st.Uid,
+		GID:        st.Gid,
+		Nlink:      uint32(st.Nlink),
+		Dev:        uint64(st.Dev),
+		Ino:        uint64(st.Ino),
+		HasIno:     true,
+	}
+}
+
+func statPath(path string, follow bool) (Meta, error) {
+	var st unix.Stat_t
+	var err error
+	if follow {
+		err = unix.Stat(path, &st)
+	} else {
+		err = unix.Lstat(path, &st)
+	}
+	if err != nil {
+		return Meta{}, &os.PathError{Op: "stat", Path: path, Err: err}
+	}
+	m := fromStat(&st)
+	m.Name = baseName(path)
+	return m, nil
+}
+
+// IsVirtualFS is Linux-specific; elsewhere nothing is skipped.
+func IsVirtualFS(string) bool { return false }