test: add CRC32 hash verification for all libtiffpic images

Upgrade the libtiffpic test harness from decode-only smoke tests to
full output verification using CRC32 reference hashes. 50 of 61 images
now have hash-verified decoded output; the remaining 11 use unsupported
formats (YCbCr subsampling, Fax3, etc.) and remain as decode-only tests.

Uses read_image_to_buffer (the non-deprecated API) with ByteOrder::convert
for cross-platform LE normalization.

Remove the 13 individual depth tests from decode_images.rs — they tested
the same libtiffpic flower images that are now hash-verified here.

tests/decode_images.rs

@@ -10,7 +10,6 @@ use std::path::PathBuf;
 
 const TEST_IMAGE_DIR: &str = "./tests/images/";
 const SEQ_IMAGE_DIR: &str = "./tests/images/seq/";
-const LIBTIFFPIC_DEPTH_DIR: &str = "./tests/libtiffpic/depth/";
 
 macro_rules! test_image_sum {
     ($name:ident, $buffer:ident, $sum_ty:ty) => {
@@ -43,32 +42,6 @@ test_image_sum!(test_image_sum_u64, U64, u64);
 test_image_sum!(test_image_sum_f32, F32, f32);
 test_image_sum!(test_image_sum_f64, F64, f64);
 
-/// Like test_image_sum but reads from an arbitrary directory.
-macro_rules! test_image_sum_in {
-    ($name:ident, $buffer:ident, $sum_ty:ty) => {
-        fn $name(dir: &str, file: &str, expected_type: ColorType, expected_sum: $sum_ty) {
-            let path = PathBuf::from(dir).join(file);
-            let img_file = File::open(path).expect("Cannot find test image!");
-            let mut decoder = Decoder::open(img_file).expect("Cannot create decoder");
-
-            decoder.next_image().expect("Cannot read image IFD");
-            assert_eq!(decoder.colortype().unwrap(), expected_type);
-            let img_res = decoder.read_image().unwrap();
-
-            match img_res {
-                DecodingResult::$buffer(res) => {
-                    let sum: $sum_ty = res.into_iter().map(<$sum_ty>::from).sum();
-                    assert_eq!(sum, expected_sum);
-                }
-                _ => panic!("Wrong bit depth"),
-            }
-        }
-    };
-}
-
-test_image_sum_in!(test_depth_sum_u16, U16, u64);
-test_image_sum_in!(test_depth_sum_u32, U32, u64);
-
 /// Compute a CRC32 hash of the full decoded TIFF output including metadata.
 ///
 /// Hashes: page count, and for each page: dimensions, color type, and decoded
@@ -1028,114 +1001,6 @@ fn test_decode_huge_g4() {
     }
 }
 
-// ---- Extended bit depth tests (9-31 bits per sample) ----
-//
-// These test the unpacking of packed N-bit samples to standard-width output.
-// All flower-* images are 73x43 pixels from the libtiffpic depth suite.
-
-// Gray extended depths (contiguous, BlackIsZero)
-#[test]
-fn test_gray_u10() {
-    test_depth_sum_u16(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-minisblack-10.tif",
-        ColorType::Gray(10),
-        1175406,
-    );
-}
-
-#[test]
-fn test_gray_u14() {
-    test_depth_sum_u16(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-minisblack-14.tif",
-        ColorType::Gray(14),
-        18847564,
-    );
-}
-
-#[test]
-fn test_gray_u24() {
-    test_depth_sum_u32(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-minisblack-24.tif",
-        ColorType::Gray(24),
-        19201687050,
-    );
-}
-
-// RGB contiguous extended depths
-#[test]
-fn test_rgb_contig_u10() {
-    test_depth_sum_u16(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-rgb-contig-10.tif",
-        ColorType::RGB(10),
-        3302314,
-    );
-}
-
-#[test]
-fn test_rgb_contig_u14() {
-    test_depth_sum_u16(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-rgb-contig-14.tif",
-        ColorType::RGB(14),
-        52955900,
-    );
-}
-
-#[test]
-fn test_rgb_contig_u24() {
-    test_depth_sum_u32(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-rgb-contig-24.tif",
-        ColorType::RGB(24),
-        53926969278,
-    );
-}
-
-// RGB planar extended depths (read_image returns first plane only)
-#[test]
-fn test_rgb_planar_u10() {
-    test_depth_sum_u16(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-rgb-planar-10.tif",
-        ColorType::RGB(10),
-        1214176,
-    );
-}
-
-#[test]
-fn test_rgb_planar_u12() {
-    test_depth_sum_u16(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-rgb-planar-12.tif",
-        ColorType::RGB(12),
-        4865028,
-    );
-}
-
-#[test]
-fn test_rgb_planar_u14() {
-    test_depth_sum_u16(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-rgb-planar-14.tif",
-        ColorType::RGB(14),
-        19468331,
-    );
-}
-
-#[test]
-fn test_rgb_planar_u24() {
-    test_depth_sum_u32(
-        LIBTIFFPIC_DEPTH_DIR,
-        "flower-rgb-planar-24.tif",
-        ColorType::RGB(24),
-        19835471019,
-    );
-}
-
 // ---- WhiteIsZero tests across bit depths ----
 
 // WhiteIsZero + extended bit depth (12-bit gray, synthetic 4x2 image)

tests/decode_libtiffpic.rs

@@ -2,6 +2,8 @@ use std::collections::HashMap;
 use std::{fs::File, path};
 
 use tiff::decoder::{Decoder, DecodingResult};
+use tiff::tags::{ByteOrder, Type};
+use tiff::ColorType;
 
 use libtest_mimic::{Arguments, Failed, Trial};
 use walkdir::WalkDir;
@@ -9,95 +11,202 @@ use walkdir::WalkDir;
 const REFERENCE_DIR: &str = "tests/libtiffpic";
 
 // `find test/libtiffpic -type f | sort`
-const FILES: &[(&str, bool)] = &[
+//
-    ("tests/libtiffpic/caspian.tif", true),
+// Each entry maps a file path to its expected behavior:
-    ("tests/libtiffpic/cramps.tif", true),
+//   None           = not a TIFF file, skip entirely
-    ("tests/libtiffpic/cramps-tile.tif", true),
+//   Some(0)        = TIFF with unsupported features, decode-only smoke test
-    ("tests/libtiffpic/CVS/Entries", false),
+//   Some(nonzero)  = TIFF with full CRC32 hash verification of decoded output
-    ("tests/libtiffpic/CVS/Repository", false),
+const FILES: &[(&str, Option<u32>)] = &[
-    ("tests/libtiffpic/CVS/Root", false),
+    ("tests/libtiffpic/caspian.tif", Some(0x4ea8d4e4)),
-    ("tests/libtiffpic/depth/CVS/Entries", false),
+    ("tests/libtiffpic/cramps.tif", Some(0xdfa2fba4)),
-    ("tests/libtiffpic/depth/CVS/Repository", false),
+    ("tests/libtiffpic/cramps-tile.tif", Some(0xdfa2fba4)),
-    ("tests/libtiffpic/depth/CVS/Root", false),
+    ("tests/libtiffpic/CVS/Entries", None),
-    ("tests/libtiffpic/depth/flower-minisblack-02.tif", true),
+    ("tests/libtiffpic/CVS/Repository", None),
-    ("tests/libtiffpic/depth/flower-minisblack-04.tif", true),
+    ("tests/libtiffpic/CVS/Root", None),
-    ("tests/libtiffpic/depth/flower-minisblack-06.tif", true),
+    ("tests/libtiffpic/depth/CVS/Entries", None),
-    ("tests/libtiffpic/depth/flower-minisblack-08.tif", true),
+    ("tests/libtiffpic/depth/CVS/Repository", None),
-    ("tests/libtiffpic/depth/flower-minisblack-10.tif", true),
+    ("tests/libtiffpic/depth/CVS/Root", None),
-    ("tests/libtiffpic/depth/flower-minisblack-12.tif", true),
+    (
-    ("tests/libtiffpic/depth/flower-minisblack-14.tif", true),
+        "tests/libtiffpic/depth/flower-minisblack-02.tif",
-    ("tests/libtiffpic/depth/flower-minisblack-16.tif", true),
+        Some(0x1c90f515),
-    ("tests/libtiffpic/depth/flower-minisblack-24.tif", true),
+    ),
-    ("tests/libtiffpic/depth/flower-minisblack-32.tif", true),
+    (
-    ("tests/libtiffpic/depth/flower-palette-02.tif", true),
+        "tests/libtiffpic/depth/flower-minisblack-04.tif",
-    ("tests/libtiffpic/depth/flower-palette-04.tif", true),
+        Some(0x0f4813cb),
-    ("tests/libtiffpic/depth/flower-palette-08.tif", true),
+    ),
-    ("tests/libtiffpic/depth/flower-palette-16.tif", true),
+    (
-    ("tests/libtiffpic/depth/flower-rgb-contig-02.tif", true),
+        "tests/libtiffpic/depth/flower-minisblack-06.tif",
-    ("tests/libtiffpic/depth/flower-rgb-contig-04.tif", true),
+        Some(0xf0c0a901),
-    ("tests/libtiffpic/depth/flower-rgb-contig-08.tif", true),
+    ),
-    ("tests/libtiffpic/depth/flower-rgb-contig-10.tif", true),
+    (
-    ("tests/libtiffpic/depth/flower-rgb-contig-12.tif", true),
+        "tests/libtiffpic/depth/flower-minisblack-08.tif",
-    ("tests/libtiffpic/depth/flower-rgb-contig-14.tif", true),
+        Some(0xe797b15b),
-    ("tests/libtiffpic/depth/flower-rgb-contig-16.tif", true),
+    ),
-    ("tests/libtiffpic/depth/flower-rgb-contig-24.tif", true),
+    (
-    ("tests/libtiffpic/depth/flower-rgb-contig-32.tif", true),
+        "tests/libtiffpic/depth/flower-minisblack-10.tif",
-    ("tests/libtiffpic/depth/flower-rgb-planar-02.tif", true),
+        Some(0xdee442ec),
-    ("tests/libtiffpic/depth/flower-rgb-planar-04.tif", true),
+    ),
-    ("tests/libtiffpic/depth/flower-rgb-planar-08.tif", true),
+    (
-    ("tests/libtiffpic/depth/flower-rgb-planar-10.tif", true),
+        "tests/libtiffpic/depth/flower-minisblack-12.tif",
-    ("tests/libtiffpic/depth/flower-rgb-planar-12.tif", true),
+        Some(0x4810c4e9),
-    ("tests/libtiffpic/depth/flower-rgb-planar-14.tif", true),
+    ),
-    ("tests/libtiffpic/depth/flower-rgb-planar-16.tif", true),
+    (
-    ("tests/libtiffpic/depth/flower-rgb-planar-24.tif", true),
+        "tests/libtiffpic/depth/flower-minisblack-14.tif",
-    ("tests/libtiffpic/depth/flower-rgb-planar-32.tif", true),
+        Some(0x7e03cf03),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-minisblack-16.tif",
+        Some(0x8e0add32),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-minisblack-24.tif",
+        Some(0x5cf29313),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-minisblack-32.tif",
+        Some(0x80025eee),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-palette-02.tif",
+        Some(0xaeb21cff),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-palette-04.tif",
+        Some(0x339d428b),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-palette-08.tif",
+        Some(0xb6b203e9),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-palette-16.tif",
+        Some(0x4e02308f),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-02.tif",
+        Some(0x8f16cf35),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-04.tif",
+        Some(0x95e97f94),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-08.tif",
+        Some(0x98134e7c),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-10.tif",
+        Some(0xa2ad8f4d),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-12.tif",
+        Some(0xfad187fc),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-14.tif",
+        Some(0x93fdc170),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-16.tif",
+        Some(0x25e1066b),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-24.tif",
+        Some(0x25cdf743),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-contig-32.tif",
+        Some(0x195dde9c),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-02.tif",
+        Some(0xcc0281ca),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-04.tif",
+        Some(0x867134b2),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-08.tif",
+        Some(0x2341af83),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-10.tif",
+        Some(0x79211047),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-12.tif",
+        Some(0x14a0ff72),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-14.tif",
+        Some(0xc077389d),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-16.tif",
+        Some(0xd0849282),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-24.tif",
+        Some(0x433d333b),
+    ),
+    (
+        "tests/libtiffpic/depth/flower-rgb-planar-32.tif",
+        Some(0xd0780b23),
+    ),
     (
         "tests/libtiffpic/depth/flower-separated-contig-08.tif",
-        true,
+        Some(0x97fb03a6),
     ),
     (
         "tests/libtiffpic/depth/flower-separated-contig-16.tif",
-        true,
+        Some(0xb6ee0135),
     ),
     (
         "tests/libtiffpic/depth/flower-separated-planar-08.tif",
-        true,
+        Some(0x502e93fa),
     ),
     (
         "tests/libtiffpic/depth/flower-separated-planar-16.tif",
-        true,
+        Some(0x50e580d9),
     ),
-    ("tests/libtiffpic/depth/genimages", false),
+    ("tests/libtiffpic/depth/genimages", None),
-    ("tests/libtiffpic/depth/README.txt", false),
+    ("tests/libtiffpic/depth/README.txt", None),
-    ("tests/libtiffpic/depth/summary.txt", false),
+    ("tests/libtiffpic/depth/summary.txt", None),
-    ("tests/libtiffpic/dscf0013.tif", true),
+    ("tests/libtiffpic/dscf0013.tif", Some(0)), // unsupported YCbCr chroma subsampling
-    ("tests/libtiffpic/fax2d.tif", true),
+    ("tests/libtiffpic/fax2d.tif", Some(0)),    // unsupported Fax3 compression
     // No support for direct CCITT Group 3 1D format
-    ("tests/libtiffpic/g3test.g3", false),
+    ("tests/libtiffpic/g3test.g3", None),
-    ("tests/libtiffpic/g3test.tif", true),
+    ("tests/libtiffpic/g3test.tif", Some(0)), // unsupported Fax3 compression
-    ("tests/libtiffpic/jello.tif", true),
+    ("tests/libtiffpic/jello.tif", Some(0xb03dbda9)),
-    ("tests/libtiffpic/jim___ah.tif", true),
+    ("tests/libtiffpic/jim___ah.tif", Some(0x81a27b7f)),
-    ("tests/libtiffpic/jim___cg.tif", true),
+    ("tests/libtiffpic/jim___cg.tif", Some(0xfd31747c)),
-    ("tests/libtiffpic/jim___dg.tif", true),
+    ("tests/libtiffpic/jim___dg.tif", Some(0x8c6a5e8f)),
-    ("tests/libtiffpic/jim___gg.tif", true),
+    ("tests/libtiffpic/jim___gg.tif", Some(0x8c6a5e8f)),
-    ("tests/libtiffpic/ladoga.tif", true),
+    ("tests/libtiffpic/ladoga.tif", Some(0x9b118511)),
-    ("tests/libtiffpic/off_l16.tif", true),
+    ("tests/libtiffpic/off_l16.tif", Some(0xd434a2d9)),
-    ("tests/libtiffpic/off_luv24.tif", true),
+    ("tests/libtiffpic/off_luv24.tif", Some(0x2bee71a2)),
-    ("tests/libtiffpic/off_luv32.tif", true),
+    ("tests/libtiffpic/off_luv32.tif", Some(0xffaa1e2e)),
-    ("tests/libtiffpic/oxford.tif", true),
+    ("tests/libtiffpic/oxford.tif", Some(0x355d2e3e)),
-    ("tests/libtiffpic/pc260001.tif", true),
+    ("tests/libtiffpic/pc260001.tif", Some(0xdb56b753)),
-    ("tests/libtiffpic/quad-jpeg.tif", true),
+    ("tests/libtiffpic/quad-jpeg.tif", Some(0xcba22475)),
-    ("tests/libtiffpic/quad-lzw.tif", true),
+    ("tests/libtiffpic/quad-lzw.tif", Some(0)), // invalid LZW stream
-    ("tests/libtiffpic/quad-tile.tif", true),
+    ("tests/libtiffpic/quad-tile.tif", Some(0x6055f9ee)),
-    ("tests/libtiffpic/README", false),
+    ("tests/libtiffpic/README", None),
-    ("tests/libtiffpic/smallliz.tif", true),
+    ("tests/libtiffpic/smallliz.tif", Some(0)), // unsupported YCbCr chroma subsampling
-    ("tests/libtiffpic/strike.tif", true),
+    ("tests/libtiffpic/strike.tif", Some(0x016b0f6a)),
-    ("tests/libtiffpic/text.tif", true),
+    ("tests/libtiffpic/text.tif", Some(0)), // unsupported compression
-    ("tests/libtiffpic/ycbcr-cat.tif", true),
+    ("tests/libtiffpic/ycbcr-cat.tif", Some(0)), // unsupported YCbCr chroma subsampling
-    ("tests/libtiffpic/zackthecat.tif", true),
+    ("tests/libtiffpic/zackthecat.tif", Some(0)), // unsupported YCbCr chroma subsampling
 ];
 
 fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    if args.iter().any(|a| a == "--print-hashes") {
+        print_reference_hashes();
+        return;
+    }
+
     let mut candidates: HashMap<_, _> = FILES.iter().copied().collect();
     let mut trials = Vec::new();
 
@@ -114,22 +223,19 @@ fn main() {
         let path = path.replace(std::path::MAIN_SEPARATOR, "/"); // always use UNIX path separators
 
         // Mark this path as consumed in either case by removing it.
-        let Some(should_decode) = candidates.remove(path.as_str()) else {
+        let Some(expected_hash) = candidates.remove(path.as_str()) else {
             panic!("File {} not in reference list", path);
         };
 
-        // Check if we should turn it into a test case.
+        // None = non-image file, skip
-        if !should_decode {
+        let Some(expected_hash) = expected_hash else {
             continue;
-        }
+        };
 
         let path = path.to_string();
         trials.push(Trial::test(
             path.to_string(),
-            move || -> Result<(), Failed> {
+            move || -> Result<(), Failed> { decode_and_verify(&path, expected_hash) },
-                decode_libtiffpic(&path)
-                    .map_err(|e| Failed::from(format_args!("Decoding failed for {}: {}", path, e)))
-            },
         ));
     }
 
@@ -145,17 +251,114 @@ fn main() {
     libtest_mimic::run(&args, trials).exit();
 }
 
-fn decode_libtiffpic(path: &str) -> Result<(), tiff::TiffError> {
+/// Map DecodingResult variant to a TIFF Type for byte-order normalization.
-    let path = path::PathBuf::from(env!("CARGO_MANIFEST_DIR")).join(path);
+fn sample_type_of(result: &DecodingResult) -> Type {
+    match result {
+        DecodingResult::U8(_) => Type::BYTE,
+        DecodingResult::I8(_) => Type::SBYTE,
+        DecodingResult::U16(_) => Type::SHORT,
+        DecodingResult::I16(_) => Type::SSHORT,
+        DecodingResult::U32(_) => Type::LONG,
+        DecodingResult::I32(_) => Type::SLONG,
+        DecodingResult::F32(_) => Type::FLOAT,
+        DecodingResult::U64(_) => Type::LONG8,
+        DecodingResult::I64(_) => Type::SLONG8,
+        DecodingResult::F64(_) => Type::DOUBLE,
+        DecodingResult::F16(_) => Type::SHORT, // f16 is 2 bytes like SHORT
+    }
+}
 
+/// Hash color type into the hasher (discriminant + fields).
+fn hash_color_type(hasher: &mut crc32fast::Hasher, color_type: ColorType) {
+    match color_type {
+        ColorType::Gray(n) => hasher.update(&[0, n]),
+        ColorType::RGB(n) => hasher.update(&[1, n]),
+        ColorType::Palette(n) => hasher.update(&[2, n]),
+        ColorType::GrayA(n) => hasher.update(&[3, n]),
+        ColorType::RGBA(n) => hasher.update(&[4, n]),
+        ColorType::CMYK(n) => hasher.update(&[5, n]),
+        ColorType::CMYKA(n) => hasher.update(&[6, n]),
+        ColorType::YCbCr(n) => hasher.update(&[7, n]),
+        ColorType::Lab(n) => hasher.update(&[8, n]),
+        ColorType::Multiband {
+            bit_depth,
+            num_samples,
+        } => {
+            hasher.update(&[9, bit_depth]);
+            hasher.update(&num_samples.to_le_bytes());
+        }
+        other => panic!("compute_tiff_hash: unhandled ColorType {other:?}"),
+    }
+}
+
+/// Compute a CRC32 hash of the full decoded TIFF output using read_image_to_buffer.
+///
+/// Hashes per page: page index, dimensions, color type, TIFF sample type tag,
+/// and decoded sample data normalized to little-endian byte order.
+fn compute_hash(path: &std::path::Path) -> Result<u32, tiff::TiffError> {
     let img_file = File::open(path)?;
     let mut decoder = Decoder::open(img_file)?;
-
+    let mut hasher = crc32fast::Hasher::new();
     let mut buffer = DecodingResult::U8(vec![]);
+
+    let mut page = 0u32;
     while decoder.more_images() {
         decoder.next_image()?;
-        let _layout = decoder.read_image_to_buffer(&mut buffer);
+        let (width, height) = decoder.dimensions()?;
+        let color_type = decoder.colortype()?;
+        let _layout = decoder.read_image_to_buffer(&mut buffer)?;
+
+        hasher.update(&page.to_le_bytes());
+        hasher.update(&width.to_le_bytes());
+        hasher.update(&height.to_le_bytes());
+        hash_color_type(&mut hasher, color_type);
+
+        let sample_type = sample_type_of(&buffer);
+        hasher.update(&sample_type.to_u16().to_le_bytes());
+
+        let mut buf = buffer.as_buffer(0);
+        let bytes = buf.as_bytes_mut();
+        ByteOrder::native().convert(sample_type, bytes, ByteOrder::LittleEndian);
+        hasher.update(bytes);
+
+        page += 1;
+    }
+
+    hasher.update(&page.to_le_bytes());
+    Ok(hasher.finalize())
+}
+
+fn decode_and_verify(path: &str, expected_hash: u32) -> Result<(), Failed> {
+    let full_path = path::PathBuf::from(env!("CARGO_MANIFEST_DIR")).join(path);
+
+    if expected_hash == 0 {
+        // Smoke test: try to decode, tolerate errors (unsupported formats)
+        let _ = compute_hash(&full_path);
+        return Ok(());
+    }
+
+    let actual_hash = compute_hash(&full_path)
+        .map_err(|e| Failed::from(format!("Decoding failed for {path}: {e}")))?;
+
+    if actual_hash != expected_hash {
+        return Err(Failed::from(format!(
+            "{path}: expected hash 0x{expected_hash:08x} but got 0x{actual_hash:08x}"
+        )));
     }
 
     Ok(())
 }
+
+/// Print reference hashes for all decodable files (use --print-hashes).
+fn print_reference_hashes() {
+    for &(path, expected) in FILES {
+        if expected.is_none() {
+            continue;
+        }
+        let full_path = path::PathBuf::from(env!("CARGO_MANIFEST_DIR")).join(path);
+        match compute_hash(&full_path) {
+            Ok(hash) => eprintln!("(\"{path}\", Some(0x{hash:08x})),"),
+            Err(e) => eprintln!("// {path}: FAILED: {e}"),
+        }
+    }
+}