Commit e1a0bc1c for libheif
commit e1a0bc1c1ae74f8075eaca30a1cdb2b9bee698d3
Author: Dirk Farin <dirk.farin@gmail.com>
Date: Fri Jun 26 10:03:31 2026 +0200
Return error instead of asserting in get_track() without sequence (#1844)
HeifContext::get_track() asserted has_sequence() up front. Calling the
public heif_context_get_track() on a context that has no sequence tracks
(e.g. a still image, or a crafted sequence file accepted with zero tracks)
therefore aborted the process via the assert, instead of letting the public
wrapper return the documented nullptr. In NDEBUG builds the assert was
compiled out and the track_id==0 path dereferenced begin() on an empty map.
Replace the assert with a normal error return so the public wrapper hands
the caller nullptr as documented.
diff --git a/libheif/context.cc b/libheif/context.cc
index 6c8f2931..aafbcbd9 100644
--- a/libheif/context.cc
+++ b/libheif/context.cc
@@ -2115,7 +2115,14 @@ std::vector<uint32_t> HeifContext::get_track_IDs() const
Result<std::shared_ptr<Track>> HeifContext::get_track(uint32_t track_id)
{
- assert(has_sequence());
+ // The caller is expected to have confirmed (via has_sequence()) that there are
+ // sequence tracks before requesting one. Guard against an empty track map anyway,
+ // since this is reachable through the public API (e.g. on a still image file).
+ if (!has_sequence()) {
+ return Error{heif_error_Usage_error,
+ heif_suberror_Unspecified,
+ "File contains no sequence tracks"};
+ }
if (track_id != 0) {
auto iter = m_tracks.find(track_id);
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index cba24f24..8a572d84 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -63,6 +63,7 @@ add_libheif_test(entity_groups)
add_libheif_test(extended_type)
add_libheif_test(grid_tile_missing)
add_libheif_test(region)
+add_libheif_test(sequence_no_track)
add_libheif_test(tai)
add_libheif_test(text)
add_libheif_test(cxx_wrapper)
diff --git a/tests/sequence_no_track.cc b/tests/sequence_no_track.cc
new file mode 100644
index 00000000..cde11f77
--- /dev/null
+++ b/tests/sequence_no_track.cc
@@ -0,0 +1,108 @@
+/*
+ libheif regression test for requesting a track from a context without sequence tracks.
+
+ MIT License
+
+ Copyright (c) 2026 Dirk Farin <dirk.farin@gmail.com>
+
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice shall be included in all
+ copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ SOFTWARE.
+*/
+
+#include "catch_amalgamated.hpp"
+#include "libheif/heif.h"
+#include "libheif/heif_sequences.h"
+#include "test_utils.h"
+
+#include <cstdint>
+#include <vector>
+
+namespace {
+
+// Sequence API queries that must work on a context that holds no sequence
+// tracks (a still image, or no image at all). heif_context_get_track() is
+// documented to return nullptr on failure; it must not abort/crash. This
+// formerly tripped assert(has_sequence()) in HeifContext::get_track().
+// See https://github.com/strukturag/libheif/issues/1844.
+void check_no_sequence_apis(heif_context* ctx)
+{
+ REQUIRE(heif_context_has_sequence(ctx) == 0);
+ REQUIRE(heif_context_number_of_sequence_tracks(ctx) == 0);
+
+ // Listing track IDs must work (and write nothing) when there are no tracks.
+ heif_context_get_track_ids(ctx, nullptr);
+
+ heif_track* track = heif_context_get_track(ctx, 0);
+ REQUIRE(track == nullptr);
+}
+
+heif_error mem_writer(heif_context*, const void* data, size_t size, void* userdata)
+{
+ auto* out = static_cast<std::vector<uint8_t>*>(userdata);
+ const auto* p = static_cast<const uint8_t*>(data);
+ out->insert(out->end(), p, p + size);
+ return heif_error{heif_error_Ok, heif_suberror_Unspecified, nullptr};
+}
+
+}
+
+TEST_CASE("get_track on context without sequence returns nullptr")
+{
+ heif_context* ctx = heif_context_alloc();
+ REQUIRE(ctx != nullptr);
+
+ // Fresh context, nothing loaded: no sequence tracks present.
+ check_no_sequence_apis(ctx);
+
+ heif_context_free(ctx);
+}
+
+TEST_CASE("get_track on a still-image file returns nullptr")
+{
+ // Encode a tiny still image to an in-memory HEIF file, then read it back.
+ // A still image is a perfectly valid file that contains no sequence tracks.
+ heif_image* img = nullptr;
+ REQUIRE(heif_image_create(16, 16, heif_colorspace_YCbCr, heif_chroma_420, &img).code == heif_error_Ok);
+ fill_new_plane(img, heif_channel_Y, 16, 16);
+ fill_new_plane(img, heif_channel_Cb, 8, 8);
+ fill_new_plane(img, heif_channel_Cr, 8, 8);
+
+ heif_encoder* enc = get_encoder_or_skip_test(heif_compression_HEVC);
+
+ heif_context* enc_ctx = heif_context_alloc();
+ REQUIRE(heif_context_encode_image(enc_ctx, img, enc, nullptr, nullptr).code == heif_error_Ok);
+
+ std::vector<uint8_t> file;
+ heif_writer writer{};
+ writer.writer_api_version = 1;
+ writer.write = mem_writer;
+ REQUIRE(heif_context_write(enc_ctx, &writer, &file).code == heif_error_Ok);
+
+ heif_encoder_release(enc);
+ heif_context_free(enc_ctx);
+ heif_image_release(img);
+
+ // Read the still image back and query the sequence API on it.
+ heif_context* ctx = heif_context_alloc();
+ REQUIRE(ctx != nullptr);
+ REQUIRE(heif_context_read_from_memory(ctx, file.data(), file.size(), nullptr).code == heif_error_Ok);
+
+ check_no_sequence_apis(ctx);
+
+ heif_context_free(ctx);
+}