Merge branch 'ext2-sparse-files' into 'develop-BA-FS26'

Ext2 sparse files

See merge request teachos/kernel!35

1 files changed, 93 insertions, 8 deletions

diff --git a/kernel/src/filesystem/ext2/inode.tests.cpp b/kernel/src/filesystem/ext2/inode.tests.cpp
index 783d930..45bea51 100644
--- a/kernel/src/filesystem/ext2/inode.tests.cpp
+++ b/kernel/src/filesystem/ext2/inode.tests.cpp
@@ -15,6 +15,7 @@
 
 #include <catch2/catch_test_macros.hpp>
 
+#include <algorithm>
 #include <cstddef>
 #include <filesystem>
 #include <string_view>
@@ -126,10 +127,10 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_fixture, "Ext2 in
   }
 }
 
-SCENARIO("Ext2 inode read stops when block mapping resolves to zero", "[filesystem][ext2][inode]")
+SCENARIO("Ext2 inode handles zeros in block mappings as file holes", "[filesystem][ext2][inode]")
 {
   auto const block_size = 1024uz;
-  GIVEN("an ext2 inode without mapped data blocks")
+  GIVEN("an ext2 inode with only direct mapped data blocks")
   {
     auto device = kstd::make_shared<kernel::tests::devices::block_device>(0, 0, "mock", block_size, 64 * block_size);
     REQUIRE(device != nullptr);
@@ -141,16 +142,100 @@ SCENARIO("Ext2 inode read stops when block mapping resolves to zero", "[filesyst
     REQUIRE(fs.mount(dev_inode) == kernel::filesystem::filesystem::operation_result::success);
 
     auto data = kernel::filesystem::ext2::inode_data{};
-    data.blocks = 2;
-    data.block[0] = 0;
+    data.block[0] = 30;
+    data.block[1] = 0;
+    data.block[2] = 31;
+    data.size = block_size * 3;
+
+    kernel::tests::filesystem::ext2::write_bytes(*device, 30 * block_size, "Hello", 5);
+    kernel::tests::filesystem::ext2::write_bytes(*device, 31 * block_size, "World!", 6);
+
+    auto inode = kernel::filesystem::ext2::inode{&fs, data};
+
+    auto buffer = kstd::vector<std::byte>(data.size, std::byte{0xAB});
+
+    THEN("correct number of bytes are read and holes are returned as zeros")
+    {
+      auto const bytes_read = inode.read(buffer.data(), 0, buffer.size());
+      REQUIRE(bytes_read == data.size);
+
+      auto const text = std::string_view{reinterpret_cast<char const *>(buffer.data()), bytes_read};
+      REQUIRE(text.substr(0, 5) == "Hello");
+      REQUIRE(std::ranges::all_of(text.substr(5, block_size - 5), [](char c) { return c == '\0'; }));
+      REQUIRE(text.substr(2 * block_size, 6) == "World!");
+      REQUIRE(std::ranges::all_of(text.substr(2 * block_size + 6, 3 * block_size), [](char c) { return c == '\0'; }));
+    }
+  }
+
+  GIVEN("an ext2 indode with file holes in singly indirect blocks")
+  {
+    auto device = kstd::make_shared<kernel::tests::devices::block_device>(0, 0, "mock", block_size, 64 * block_size);
+    REQUIRE(device != nullptr);
+    kernel::tests::filesystem::ext2::setup_mock_ext2_layout(*device);
+
+    auto dev_inode = kstd::make_shared<kernel::filesystem::device_inode>(device);
+
+    auto fs = kernel::filesystem::ext2::filesystem{};
+    REQUIRE(fs.mount(dev_inode) == kernel::filesystem::filesystem::operation_result::success);
+
+    auto data = kernel::filesystem::ext2::inode_data{};
+    data.block[0] = 30;
+    data.block[12] = 31;
+    data.size = block_size * 15;
+
+    kernel::tests::filesystem::ext2::write_u32(*device, 31 * block_size, 50);
+    kernel::tests::filesystem::ext2::write_u32(*device, 31 * block_size + 4, 0);
+    kernel::tests::filesystem::ext2::write_u32(*device, 31 * block_size + 8, 51);
+
+    kernel::tests::filesystem::ext2::write_bytes(*device, 30 * block_size, "Hello", 5);
+    kernel::tests::filesystem::ext2::write_bytes(*device, 50 * block_size, "Blub", 4);
+    kernel::tests::filesystem::ext2::write_bytes(*device, 51 * block_size, "World!", 6);
+
+    auto inode = kernel::filesystem::ext2::inode{&fs, data};
+
+    auto buffer = kstd::vector<std::byte>(data.size, std::byte{0xAB});
+
+    THEN("correct number of bytes are read and holes are returned as zeros")
+    {
+      auto const bytes_read = inode.read(buffer.data(), 0, buffer.size());
+      REQUIRE(bytes_read == data.size);
+
+      auto const text = std::string_view{reinterpret_cast<char const *>(buffer.data()), bytes_read};
+      REQUIRE(text.substr(0, 5) == "Hello");
+      REQUIRE(std::ranges::all_of(text.substr(5, 12 * block_size - 5), [](char c) { return c == '\0'; }));
+      REQUIRE(text.substr(12 * block_size, 4) == "Blub");
+      REQUIRE(
+          std::ranges::all_of(text.substr(12 * block_size + 4, 2 * block_size - 4), [](char c) { return c == '\0'; }));
+      REQUIRE(text.substr(14 * block_size, 6) == "World!");
+      REQUIRE(
+          std::ranges::all_of(text.substr(14 * block_size + 6, 1 * block_size - 6), [](char c) { return c == '\0'; }));
+    }
+  }
+
+  GIVEN("an ext2 inode with zero singly indirect block pointer")
+  {
+    auto device = kstd::make_shared<kernel::tests::devices::block_device>(0, 0, "mock", block_size, 64 * block_size);
+    REQUIRE(device != nullptr);
+    kernel::tests::filesystem::ext2::setup_mock_ext2_layout(*device);
+
+    auto dev_inode = kstd::make_shared<kernel::filesystem::device_inode>(device);
+
+    auto fs = kernel::filesystem::ext2::filesystem{};
+    REQUIRE(fs.mount(dev_inode) == kernel::filesystem::filesystem::operation_result::success);
+
+    auto data = kernel::filesystem::ext2::inode_data{};
+    data.block[12] = 0;
+    data.size = block_size * 15;
+
     auto inode = kernel::filesystem::ext2::inode{&fs, data};
 
-    auto buffer = kstd::vector<std::byte>(32, std::byte{0xAB});
+    auto buffer = kstd::vector<std::byte>(block_size * 15, std::byte{0xAB});
 
-    THEN("no bytes are read")
+    THEN("all direct blocks are zero when singly indirect block pointer is zero")
     {
       auto const bytes_read = inode.read(buffer.data(), 0, buffer.size());
-      REQUIRE(bytes_read == 0);
+      REQUIRE(bytes_read == buffer.size());
+      REQUIRE(std::ranges::all_of(buffer, [](std::byte c) { return c == std::byte{0x00}; }));
     }
   }
 }
@@ -170,7 +255,7 @@ SCENARIO("Ext2 inode read across block boundaries", "[filesystem][ext2][inode]")
     REQUIRE(fs.mount(dev_inode) == kernel::filesystem::filesystem::operation_result::success);
 
     auto inode_data = kernel::filesystem::ext2::inode_data{};
-    inode_data.blocks = 2;
+    inode_data.size = block_size * 2;
     inode_data.block[0] = 20;
     kernel::tests::filesystem::ext2::write_bytes(*device, 21 * block_size - 6, "Hello ", 6);
     inode_data.block[1] = 21;