From 4e2624b63236fa309c9ecf53a694b6ac9babf4e6 Mon Sep 17 00:00:00 2001
From: Lukas Oesch <lukasoesch20@gmail.com>
Date: Sun, 26 Apr 2026 10:11:24 +0200
Subject: rename open_file_description to open_file_descriptor

---
 .../src/filesystem/open_file_descriptor.tests.cpp  | 114 +++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 kernel/src/filesystem/open_file_descriptor.tests.cpp

(limited to 'kernel/src/filesystem/open_file_descriptor.tests.cpp')

diff --git a/kernel/src/filesystem/open_file_descriptor.tests.cpp b/kernel/src/filesystem/open_file_descriptor.tests.cpp
new file mode 100644
index 0000000..095e203
--- /dev/null
+++ b/kernel/src/filesystem/open_file_descriptor.tests.cpp
@@ -0,0 +1,114 @@
+#include <kernel/filesystem/open_file_descriptor.hpp>
+#include <kernel/filesystem/vfs.hpp>
+#include <kernel/test_support/filesystem/inode.hpp>
+#include <kernel/test_support/filesystem/storage_boot_module_vfs_fixture.hpp>
+
+#include <kstd/memory>
+#include <kstd/print>
+#include <kstd/vector>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <cstddef>
+#include <filesystem>
+#include <string_view>
+
+SCENARIO("Open file descriptor construction", "[filesystem][open_file_descriptor]")
+{
+  GIVEN("an inode and an open file descriptor for that inode")
+  {
+    auto inode = kstd::make_shared<kernel::tests::filesystem::inode>();
+    auto file_descriptor = kernel::filesystem::open_file_descriptor{inode};
+
+    THEN("the initial offset is zero")
+    {
+      REQUIRE(file_descriptor.offset() == 0);
+    }
+  }
+}
+
+SCENARIO("Open file descriptor read/write offset management", "[filesystem][open_file_descriptor]")
+{
+  GIVEN("an inode that tracks read/write calls and an open file descriptor for that inode")
+  {
+    auto inode = kstd::make_shared<kernel::tests::filesystem::inode>();
+    auto file_descriptor = kernel::filesystem::open_file_descriptor{inode};
+
+    THEN("the offset is updated correctly after reads")
+    {
+      REQUIRE(file_descriptor.read(nullptr, 100) == 100);
+      REQUIRE(file_descriptor.offset() == 100);
+      REQUIRE(file_descriptor.read(nullptr, 50) == 50);
+      REQUIRE(file_descriptor.offset() == 150);
+    }
+
+    THEN("the offset is updated correctly after writes")
+    {
+      REQUIRE(file_descriptor.write(nullptr, 200) == 200);
+      REQUIRE(file_descriptor.offset() == 200);
+      REQUIRE(file_descriptor.write(nullptr, 25) == 25);
+      REQUIRE(file_descriptor.offset() == 225);
+    }
+
+    THEN("reads and writes both update the same offset")
+    {
+      REQUIRE(file_descriptor.read(nullptr, 10) == 10);
+      REQUIRE(file_descriptor.offset() == 10);
+      REQUIRE(file_descriptor.write(nullptr, 20) == 20);
+      REQUIRE(file_descriptor.offset() == 30);
+      REQUIRE(file_descriptor.read(nullptr, 5) == 5);
+      REQUIRE(file_descriptor.offset() == 35);
+      REQUIRE(file_descriptor.write(nullptr, 15) == 15);
+      REQUIRE(file_descriptor.offset() == 50);
+    }
+  }
+}
+
+SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "Open file descriptor read with real image",
+                "[filesystem][open_file_descriptor][img]")
+{
+  auto const image_path = std::filesystem::path{KERNEL_TEST_ASSETS_DIR} / "ext2_1KB_fs.img";
+
+  GIVEN("an open file descriptor for a file in a real image")
+  {
+    REQUIRE(std::filesystem::exists(image_path));
+    REQUIRE_NOTHROW(setup_modules_from_img_and_init_vfs({"test_img_module"}, {image_path}));
+
+    auto & vfs = kernel::filesystem::vfs::get();
+    auto dentry = vfs.open("/information/info_1.txt");
+    REQUIRE(dentry != nullptr);
+    auto ofd = kstd::make_shared<kernel::filesystem::open_file_descriptor>(dentry->get_inode());
+
+    THEN("the file can be read and the offset is updated")
+    {
+      kstd::vector<std::byte> buffer(32);
+      auto bytes_read = ofd->read(buffer.data(), buffer.size());
+      REQUIRE(bytes_read == 32);
+      REQUIRE(ofd->offset() == 32);
+
+      std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), static_cast<size_t>(bytes_read)};
+      auto const content_end = buffer_as_str.find('\0');
+      REQUIRE(buffer_as_str.substr(0, content_end) == "info_1\n");
+
+      for (auto i = content_end; i < buffer_as_str.size(); ++i)
+      {
+        REQUIRE(buffer_as_str[i] == '\0');
+      }
+    }
+
+    THEN("the file can be read multiple times")
+    {
+      kstd::vector<std::byte> buffer(4);
+      auto bytes_read_1 = ofd->read(buffer.data(), buffer.size() / 2);
+      REQUIRE(bytes_read_1 == buffer.size() / 2);
+      REQUIRE(ofd->offset() == buffer.size() / 2);
+
+      auto bytes_read_2 = ofd->read(buffer.data() + buffer.size() / 2, buffer.size() / 2);
+      REQUIRE(bytes_read_2 == buffer.size() / 2);
+      REQUIRE(ofd->offset() == buffer.size());
+
+      std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), bytes_read_1 + bytes_read_2};
+      REQUIRE(buffer_as_str == "info");
+    }
+  }
+}
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