From fc7e8b57fc79baf0a93b5ab4c14efe839e6f8f43 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Mon, 17 Aug 2026 21:01:55 +0200
Subject: kernel/ram_disk: predicate read size on buffer

---
 kernel/kernel/drivers/storage/ram_disk.cpp | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/kernel/kernel/drivers/storage/ram_disk.cpp b/kernel/kernel/drivers/storage/ram_disk.cpp
index b1b0d2b3..778feeeb 100644
--- a/kernel/kernel/drivers/storage/ram_disk.cpp
+++ b/kernel/kernel/drivers/storage/ram_disk.cpp
@@ -6,6 +6,7 @@
 #include <kapi/boot_modules.hpp>
 #include <kapi/devices.hpp>
 #include <kapi/filesystem.hpp>
+#include <kapi/memory.hpp>
 
 #include <kstd/cstring.hpp>
 #include <kstd/format.hpp>
@@ -29,8 +30,6 @@ namespace kernel::drivers::storage
 
   namespace
   {
-    constexpr auto default_block_size = 512_B;
-
     struct descriptor final : kapi::devices::driver_descriptor
     {
     public:
@@ -57,27 +56,23 @@ namespace kernel::drivers::storage
       [[nodiscard]] auto read_block(std::size_t block_index, std::span<std::byte> buffer)
           -> kstd::result<kstd::units::bytes> override
       {
-        auto info = devices::block_device_utils::calculate_transfer(*this, block_index);
+        auto const info = devices::block_device_utils::calculate_transfer(*this, block_index);
+        auto const transfer_size = std::min(info.to_transfer, kstd::units::bytes{buffer.size()});
 
-        if (info.to_transfer > 0_B)
+        if (transfer_size > 0_B)
         {
           auto source = static_cast<std::byte const *>(m_module.start_address) + info.offset;
-          kstd::libc::memcpy(buffer.data(), source, info.to_transfer.value);
+          kstd::libc::memcpy(buffer.first(transfer_size.value).data(), source, transfer_size.value);
         }
 
-        if (info.remainder > 0_B)
-        {
-          kstd::libc::memset(buffer.data() + info.to_transfer, 0, info.remainder.value);
-        }
-
-        return info.to_transfer;
+        return transfer_size;
       }
 
       auto write_block(std::size_t block_index, std::span<std::byte const> buffer)
           -> kstd::result<kstd::units::bytes> override
       {
         auto const info = devices::block_device_utils::calculate_transfer(*this, block_index);
-        auto transfer_size = std::min(info.to_transfer, kstd::units::bytes{buffer.size()});
+        auto const transfer_size = std::min(info.to_transfer, kstd::units::bytes{buffer.size()});
 
         if (transfer_size > 0_B)
         {
@@ -90,7 +85,7 @@ namespace kernel::drivers::storage
 
       [[nodiscard]] auto block_size() const -> kstd::units::bytes override
       {
-        return default_block_size;
+        return kapi::memory::page_size;
       }
 
       [[nodiscard]] auto capacity() const -> kstd::units::bytes override
-- 
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