vxcontrol/pentagi · error

tar entry '%s' has invalid size %d

Error message

tar entry '%s' has invalid size %d

What it means

For regular-file entries, ExtractTar validates hdr.Size before accounting. A negative size is impossible for well-formed archives produced by archive/tar, so this error indicates a malformed or hostile header. It is a defensive integrity check, not an environmental failure.

Source

Thrown at backend/pkg/flowfiles/files.go:403

			return fmt.Errorf("failed to read tar entry: %w", err)
		}
		if hdr.Typeflag == tar.TypeSymlink || hdr.Typeflag == tar.TypeLink {
			continue
		}

		entryPath := filepath.Join(destDir, filepath.Clean(filepath.FromSlash(hdr.Name)))
		if !IsWithinDir(entryPath, destDir) {
			continue
		}

		switch hdr.Typeflag {
		case tar.TypeDir:
			if err := os.MkdirAll(entryPath, 0755); err != nil {
				return fmt.Errorf("failed to create directory '%s': %w", entryPath, err)
			}
		case tar.TypeReg, tar.TypeRegA:
			if hdr.Size < 0 {
				return fmt.Errorf("tar entry '%s' has invalid size %d", hdr.Name, hdr.Size)
			}
			filesCount++
			if filesCount > MaxPullFiles {
				return fmt.Errorf("tar archive exceeds maximum file count of %d", MaxPullFiles)
			}
			totalSize += hdr.Size
			if totalSize > MaxPullTotalSize {
				return fmt.Errorf("tar archive exceeds maximum total size of %d bytes", MaxPullTotalSize)
			}

			if err := os.MkdirAll(filepath.Dir(entryPath), 0755); err != nil {
				return fmt.Errorf("failed to create parent directory for '%s': %w", entryPath, err)
			}

			f, err := os.OpenFile(entryPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644)
			if err != nil {
				return fmt.Errorf("failed to create file '%s': %w", entryPath, err)
			}

View on GitHub (pinned to ea665308ba)

Solutions

1. Verify the archive producer: only archive/tar or GNU tar output can produce valid sizes; regenerate the archive.
2. Confirm the stream is not being misread (e.g. wrong offset — a seekable reader positioned mid-archive yields garbage headers).
3. If the archive comes from an untrusted party, treat this rejection as working as intended — the extractor refused a malformed archive.

// Producers: only emit archives via archive/tar or GNU tar; reject any
// archive that fails a prior verification pass:
//   sha256sum bundle.tar  # compare against expected digest before ExtractTar

err := flowfiles.ExtractTar(rc, destDir)
if err != nil {
    if strings.Contains(err.Error(), "has invalid size") {
        return fmt.Errorf("refusing malformed archive (negative entry size): %w", err)
    }
    return err
}

When it happens

Trigger: A tar header inside the stream read by PullFlowFiles declares a negative Size for a TypeReg/TypeRegA entry — only reachable with hand-crafted, corrupted, or non-conforming tar bytes.

Common situations: Practically only seen when feeding binary garbage that still parsed as a header, fuzzing, or a broken custom tar writer producing invalid headers.

Related errors

• failed to read tar entry: %w
• tar archive exceeds maximum file count of %d
• tar archive exceeds maximum total size of %d bytes
• path must be relative (no leading /)
• Internal

AI-assisted analysis of vxcontrol/pentagi@ea665308ba (2026-09-01). Data as JSON: /api/errors/3eed76270c3c9f03. Report an issue: GitHub.