From 32e34486215b46a1a244962998c893640b18a792 Mon Sep 17 00:00:00 2001
From: manuel <manuel.bott@eps.ch>
Date: Thu, 29 Oct 2026 10:03:17 +0000
Subject: kernel/filesystem: Add inode:read

---
 kernel/kapi/filesystem.tests.cpp | 92 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

(limited to 'kernel/kapi/filesystem.tests.cpp')

diff --git a/kernel/kapi/filesystem.tests.cpp b/kernel/kapi/filesystem.tests.cpp
index efcb4fd3..f46c6bb8 100644
--- a/kernel/kapi/filesystem.tests.cpp
+++ b/kernel/kapi/filesystem.tests.cpp
@@ -12,7 +12,9 @@
 #include <cstddef>
 #include <filesystem>
 #include <ranges>
+#include <string>
 #include <string_view>
+#include <utility>
 #include <vector>
 
 using namespace kstd::units_literals;
@@ -339,4 +341,94 @@ SCENARIO_METHOD(kernel::tests::vfs::storage_boot_module_vfs_fixture,
   }
 }
 
+SCENARIO_METHOD(kernel::tests::vfs::storage_boot_module_vfs_fixture, "Kapi filesystem with a mounted fat32 image",
+                "[kapi][filesystem][fat32]")
+{
+  auto const ext2_image_path = std::filesystem::path{KERNEL_TEST_ASSETS_DIR} / "ext2_1KB_fs.img";
+  auto const fat32_image_path = std::filesystem::path{KERNEL_TEST_ASSETS_DIR} / "fat32.img";
+
+  GIVEN("an ext2 root filesystem with a fat32 image mounted on /information")
+  {
+    REQUIRE(std::filesystem::exists(ext2_image_path));
+    REQUIRE(std::filesystem::exists(fat32_image_path));
+    REQUIRE_NOTHROW(setup_modules_from_img_and_init_vfs({"test_img_module_1", "test_img_module_2"},
+                                                        {ext2_image_path, fat32_image_path}));
+    REQUIRE(kapi::filesystem::mount("/dev/ram1", "/information"));
+
+    auto const read_text = [](std::size_t fd, std::size_t chunk_size) {
+      auto text = std::string{};
+      auto buffer = std::vector<std::byte>(chunk_size);
+      while (true)
+      {
+        auto const bytes_read = kapi::filesystem::read(fd, buffer);
+        REQUIRE(bytes_read);
+        if (*bytes_read == 0_B)
+        {
+          return text;
+        }
+        text.append(std::bit_cast<char *>(buffer.data()), bytes_read->value);
+      }
+    };
+
+    THEN("a file can be opened by its lowercase name, read and closed again")
+    {
+      auto const fd = kapi::filesystem::open("/information/hello.txt");
+      REQUIRE(fd);
+      REQUIRE(read_text(*fd, 64) == "Hello World!");
+      REQUIRE(kapi::filesystem::close(*fd));
+    }
+
+    THEN("a file can be read in small chunks through its file descriptor")
+    {
+      auto const fd = kapi::filesystem::open("/information/hello.txt");
+      REQUIRE(fd);
+      REQUIRE(read_text(*fd, 5) == "Hello World!");
+      REQUIRE(kapi::filesystem::close(*fd));
+    }
+
+    THEN("reading continues at a seeked position")
+    {
+      auto const fd = kapi::filesystem::open("/information/hello.txt");
+      REQUIRE(fd);
+      REQUIRE(kapi::filesystem::seek(*fd, 6_B_off, kapi::filesystem::seek_origin::beginning) == 6_B);
+      REQUIRE(read_text(*fd, 16) == "World!");
+      REQUIRE(kapi::filesystem::close(*fd));
+    }
+
+    THEN("the status of a file reports its type and size")
+    {
+      auto const status = kapi::filesystem::status("/information/hello.txt");
+      REQUIRE(status);
+      REQUIRE(status->mode == std::to_underlying(kapi::filesystem::file_type::regular));
+      REQUIRE(status->size == 12_B);
+    }
+
+    THEN("the mounted root directory can be listed")
+    {
+      auto const directory = kapi::filesystem::open("/information");
+      REQUIRE(directory);
+
+      auto buffer = std::vector<kapi::filesystem::directory_entry>{10};
+      REQUIRE(kapi::filesystem::read_directory(*directory, buffer) == 1);
+      REQUIRE(buffer[0].name == "HELLO.TXT");
+      REQUIRE(kapi::filesystem::read_directory(*directory, buffer) == 0);
+    }
+
+    THEN("writing to a file fails because the filesystem is read only")
+    {
+      auto const fd = kapi::filesystem::open("/information/hello.txt");
+      REQUIRE(fd);
+
+      auto const buffer = std::vector<std::byte>{std::byte{'X'}};
+      REQUIRE(kapi::filesystem::write(*fd, buffer).error() == kstd::errc::read_only_file_system);
+      REQUIRE(kapi::filesystem::close(*fd));
+    }
+
+    THEN("opening a missing file fails")
+    {
+      REQUIRE(kapi::filesystem::open("/information/missing.txt").error() == kstd::errc::no_such_file_or_directory);
+    }
+  }
+}
+
 // NOLINTEND (readability-magic-numbers)
\ No newline at end of file
-- 
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