feat(firmware): add bounded USB configuration and device author operations

tests/hostlink/test_image_source_linux.cpp

@@ -0,0 +1,57 @@
+#include "platform/linux/runtime_paths.h"
+#include "track_sharing/image_source_binding.h"
+#include <cassert>
+#include <filesystem>
+#include <fstream>
+#include <string>
+namespace platform::ui::route_storage
+{
+std::filesystem::path root;
+std::filesystem::path route_dir_path() { return root; }
+#include "image_source_linux_actual.inc"
+} // namespace platform::ui::route_storage
+int main()
+{
+    namespace fs = std::filesystem;
+    using namespace platform::ui::route_storage;
+    root = fs::current_path() / "image-source-linux-fixture";
+    fs::create_directories(root);
+    const auto image = root / "test-owned.jpg", binding = root / "test-owned.jpg.source";
+    const auto outside = fs::current_path() / "image-source-linux-owned-outside.source";
+    uint8_t source[32]{1}, file_hash[32]{2}, record[track_sharing::kImageSourceBindingBytes];
+    assert(track_sharing::encodeImageSourceBinding({{source, 32}, {file_hash, 32}, 5}, record, sizeof(record)));
+    const auto write = [](const fs::path& path, const uint8_t* bytes, size_t size)
+    {std::ofstream output(path,std::ios::binary|std::ios::trunc);assert(output.write(reinterpret_cast<const char*>(bytes),size)); };
+    write(image, file_hash, 5);
+    write(binding, record, sizeof(record));
+    assert(route_image_source_matches(image.string(), source));
+    assert(route_image_source_matches("test-owned.jpg", source));
+    source[0] ^= 1;
+    assert(!route_image_source_matches(image.string(), source));
+    source[0] ^= 1;
+    assert(!route_image_source_matches("../image-source-linux-owned-outside.source", source));
+    write(outside, record, sizeof(record));
+    assert(!route_image_source_matches(outside.string(), source));
+    write(image, file_hash, 4);
+    assert(!route_image_source_matches(image.string(), source));
+    write(image, file_hash, 5);
+    record[20] ^= 1;
+    write(binding, record, sizeof(record));
+    assert(!route_image_source_matches(image.string(), source));
+    record[20] ^= 1;
+    write(binding, record, sizeof(record) - 1);
+    assert(!route_image_source_matches(image.string(), source));
+    fs::remove(binding);
+    assert(!route_image_source_matches(image.string(), source));
+    // Symlink coverage is conditional on the host permitting link creation.
+    std::error_code error;
+    fs::create_symlink(outside, binding, error);
+    if (!error)
+    {
+        assert(!route_image_source_matches(image.string(), source));
+        fs::remove(binding);
+    }
+    fs::remove(image);
+    fs::remove(outside);
+    fs::remove(root);
+}