kernel/filesystem: custom err code unsupported fs, fix validatefeature/detectFatType

4 files changed, 11 insertions, 12 deletions

diff --git a/kernel/kernel/filesystems/fat32/error.cpp b/kernel/kernel/filesystems/fat32/error.cpp
index e8e72fb7..7ac8931e 100644
--- a/kernel/kernel/filesystems/fat32/error.cpp
+++ b/kernel/kernel/filesystems/fat32/error.cpp
@@ -26,6 +26,8 @@ namespace kernel::filesystems::fat32
             return "invalid boot signature";
           case errc::invalid_boot_sector:
             return "invalid boot sector";
+          case errc::unsupported_fat_fs:
+            return "unsupported fat filesystem (only fat32 is supported)";
           case errc::invalid_cluster:
             return "invalid cluster";
           case errc::corrupted_cluster_chain:
@@ -42,6 +44,7 @@ namespace kernel::filesystems::fat32
         {
           case errc::invalid_boot_signature:
           case errc::invalid_boot_sector:
+          case errc::unsupported_fat_fs:
           case errc::invalid_cluster:
           case errc::corrupted_cluster_chain:
             if (condition.category() == kernel::vfs::category())
diff --git a/kernel/kernel/filesystems/fat32/error.hpp b/kernel/kernel/filesystems/fat32/error.hpp
index 0b06c503..6b3164cc 100644
--- a/kernel/kernel/filesystems/fat32/error.hpp
+++ b/kernel/kernel/filesystems/fat32/error.hpp
@@ -13,6 +13,7 @@ namespace kernel::filesystems::fat32
   {
     invalid_boot_signature = 1,
     invalid_boot_sector,
+    unsupported_fat_fs,
     invalid_cluster,
     corrupted_cluster_chain,
   };
diff --git a/kernel/kernel/filesystems/fat32/filesystem.cpp b/kernel/kernel/filesystems/fat32/filesystem.cpp
index e37b6ce3..17d72b02 100644
--- a/kernel/kernel/filesystems/fat32/filesystem.cpp
+++ b/kernel/kernel/filesystems/fat32/filesystem.cpp
@@ -86,9 +86,11 @@ namespace kernel::filesystems::fat32
     //! @return true on valid boot-sector, else false
     auto validate_boot_sector(boot_sector const & bs) -> bool
     {
-      auto const fat_region_sectors = std::uint64_t{bs.number_of_fats} * bs.fat_size_32;
+      auto const fat_sectors = bs.fat_size_16 != 0 ? std::uint64_t{bs.fat_size_16} : bs.fat_size_32;
       auto const total_sectors = bs.total_sectors_16 != 0 ? std::uint64_t{bs.total_sectors_16} : bs.total_sectors_32;
 
+      auto const fat_region_sectors = std::uint64_t{bs.number_of_fats} * fat_sectors;
+
       return bs.bytes_per_sector >= constants::min_bytes_per_sector &&
              bs.bytes_per_sector <= constants::max_bytes_per_sector && bs.reserved_sector_count > 0 &&
              bs.number_of_fats > 0 && fat_region_sectors + bs.reserved_sector_count < total_sectors &&
@@ -152,9 +154,9 @@ namespace kernel::filesystems::fat32
         return kstd::failure(errc::invalid_boot_sector);
       }
 
-      if (auto fat_type = get_fat_type(boot_sector); fat_type != fat_type::fat32)
+      if (get_fat_type(boot_sector) != fat_type::fat32)
       {
-        return kstd::failure(errc::invalid_boot_sector);  // todo custom error
+        return kstd::failure(errc::unsupported_fat_fs);  // todo custom error
       }
 
       return boot_sector;
diff --git a/kernel/kernel/filesystems/fat32/filesystem.tests.cpp b/kernel/kernel/filesystems/fat32/filesystem.tests.cpp
index ce267584..193ff7c3 100644
--- a/kernel/kernel/filesystems/fat32/filesystem.tests.cpp
+++ b/kernel/kernel/filesystems/fat32/filesystem.tests.cpp
@@ -121,13 +121,6 @@ SCENARIO("Fat32 filesystem mount validates the boot sector", "[filesystem][fat32
       kernel::tests::filesystems::fat32::setup_mock_fat32_layout(*device, boot_sector);
       REQUIRE(fs->mount(dev_inode).error() == kernel::filesystems::fat32::errc::invalid_boot_sector);
     }
-
-    THEN("more clusters than the file allocation table can describe are rejected")
-    {
-      boot_sector.total_sectors_32 = 1 + 1 + 127;
-      kernel::tests::filesystems::fat32::setup_mock_fat32_layout(*device, boot_sector);
-      REQUIRE(fs->mount(dev_inode).error() == kernel::filesystems::fat32::errc::invalid_boot_sector);
-    }
   }
 }
 
@@ -167,7 +160,7 @@ SCENARIO_METHOD(kernel::tests::vfs::storage_boot_module_fixture, "Fat32 filesyst
 
     THEN("probe accepts the boot sector")
     {
-      REQUIRE(fs->probe(dev_inode).error() == kernel::filesystems::fat32::errc::invalid_boot_sector);
+      REQUIRE(fs->probe(dev_inode).error() == kernel::filesystems::fat32::errc::unsupported_fat_fs);
     }
   }
 
@@ -185,7 +178,7 @@ SCENARIO_METHOD(kernel::tests::vfs::storage_boot_module_fixture, "Fat32 filesyst
 
     THEN("probe accepts the boot sector")
     {
-      REQUIRE(fs->probe(dev_inode).error() == kernel::filesystems::fat32::errc::invalid_boot_sector);
+      REQUIRE(fs->probe(dev_inode).error() == kernel::filesystems::fat32::errc::unsupported_fat_fs);
     }
   }
 }