Utility function to delete content of dir pointed to by open file

tools/utils/rmtree.go

@@ -0,0 +1,80 @@
+package utils
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+var _ = fmt.Print
+
+// RemoveChildren recursively removes all files and subdirectories
+// within the directory pointed to by dirFile. Removes all it can but returns
+// the first error, if any.
+func RemoveChildren(dirFile *os.File) error {
+	fd := int(dirFile.Fd())
+	var firstErr error
+
+	// Rewind directory pointer to ensure we start from the beginning
+	if _, err := dirFile.Seek(0, 0); err != nil {
+		return &os.PathError{Op: "seek", Path: dirFile.Name(), Err: err}
+	}
+
+	for {
+		// Read names in small chunks to handle very large directories
+		names, err := dirFile.Readdirnames(64)
+		if err != nil {
+			if errors.Is(err, io.EOF) {
+				break
+			}
+			if firstErr == nil {
+				firstErr = &os.PathError{Op: "readdirnames", Path: dirFile.Name(), Err: err}
+			}
+			break
+		}
+
+		for _, name := range names {
+			var stat unix.Stat_t
+			// Get file info relative to the parent FD
+			err := unix.Fstatat(fd, name, &stat, unix.AT_SYMLINK_NOFOLLOW)
+			if err != nil {
+				if firstErr == nil {
+					firstErr = &os.PathError{Op: "fstatat", Path: name, Err: err}
+				}
+				continue
+			}
+
+			if (stat.Mode & unix.S_IFMT) == unix.S_IFDIR {
+				// Open subdirectory relative to parent FD
+				childFd, err := unix.Openat(fd, name, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_CLOEXEC, 0)
+				if err != nil {
+					if firstErr == nil {
+						firstErr = &os.PathError{Op: "openat", Path: name, Err: err}
+					}
+					continue
+				}
+
+				childFile := os.NewFile(uintptr(childFd), name)
+				if err := RemoveChildren(childFile); err != nil && firstErr == nil {
+					firstErr = err
+				}
+				childFile.Close()
+
+				// Remove the empty subdirectory
+				if err := unix.Unlinkat(fd, name, unix.AT_REMOVEDIR); err != nil && firstErr == nil {
+					firstErr = &os.PathError{Op: "unlinkat", Path: name, Err: err}
+				}
+			} else {
+				// Remove file/symlink
+				if err := unix.Unlinkat(fd, name, 0); err != nil && firstErr == nil {
+					firstErr = &os.PathError{Op: "unlinkat", Path: name, Err: err}
+				}
+			}
+		}
+	}
+	_, _ = dirFile.Seek(0, 0)
+	return firstErr
+}