From bb01b9f2d29524974881e9a88ffb6c229836ddba Mon Sep 17 00:00:00 2001
From: Marcel Braun <marcel.braun@ost.ch>
Date: Sun, 12 Apr 2026 20:45:23 +0200
Subject: Add fs syscall handler

---
 kapi/include/kapi/syscall_handler/filesystem.hpp   | 19 +++++++
 .../kernel/filesystem/file_descriptor_table.hpp    |  3 +-
 kernel/kapi/syscall_handler/filesystem.cpp         | 59 ++++++++++++++++++++++
 kernel/src/filesystem/file_descriptor_table.cpp    |  8 +--
 4 files changed, 84 insertions(+), 5 deletions(-)
 create mode 100644 kapi/include/kapi/syscall_handler/filesystem.hpp
 create mode 100644 kernel/kapi/syscall_handler/filesystem.cpp

diff --git a/kapi/include/kapi/syscall_handler/filesystem.hpp b/kapi/include/kapi/syscall_handler/filesystem.hpp
new file mode 100644
index 0000000..86ae4d2
--- /dev/null
+++ b/kapi/include/kapi/syscall_handler/filesystem.hpp
@@ -0,0 +1,19 @@
+#ifndef TEACHOS_KAPI_SYSCALL_HANDLER_FILESYSTEM_HPP
+#define TEACHOS_KAPI_SYSCALL_HANDLER_FILESYSTEM_HPP
+
+#include <cstddef>
+#include <sys/types.h>
+
+namespace kapi::syscall_handler::filesystem
+{
+  auto mount(char const * source, char const * target) -> int;
+  auto umount(char const * target) -> int;
+
+  auto open(char const * path) -> int;
+  auto close(int fd) -> int;
+
+  auto read(int fd, void * buffer, size_t size) -> ssize_t;
+  auto write(int fd, void const * buffer, size_t size) -> ssize_t;
+}  // namespace kapi::syscall_handler::filesystem
+
+#endif  // TEACHOS_KAPI_SYSCALL_HANDLER_FILESYSTEM_HPP
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/file_descriptor_table.hpp b/kernel/include/kernel/filesystem/file_descriptor_table.hpp
index 5d52c19..5dd91e7 100644
--- a/kernel/include/kernel/filesystem/file_descriptor_table.hpp
+++ b/kernel/include/kernel/filesystem/file_descriptor_table.hpp
@@ -50,8 +50,9 @@ namespace kernel::filesystem
     /**
     @brief Remove a file from the descriptor table.
     @param fd The file descriptor index to remove.
+    @return 0 on success, or -1 on failure.
     */
-    auto remove_file(int fd) -> void;
+    auto remove_file(int fd) -> int;
 
   private:
     file_descriptor_table() = default;
diff --git a/kernel/kapi/syscall_handler/filesystem.cpp b/kernel/kapi/syscall_handler/filesystem.cpp
new file mode 100644
index 0000000..a6e8027
--- /dev/null
+++ b/kernel/kapi/syscall_handler/filesystem.cpp
@@ -0,0 +1,59 @@
+#include "kapi/syscall_handler/filesystem.hpp"
+
+#include "kernel/filesystem/file_descriptor_table.hpp"
+#include "kernel/filesystem/vfs.hpp"
+
+#include <cstddef>
+#include <sys/types.h>
+
+namespace kapi::syscall_handler::filesystem
+{
+  auto mount(char const * source, char const * target) -> int
+  {
+    // TODO BA-FS26
+  }
+
+  auto umount(char const * target) -> int
+  {
+    if (kernel::filesystem::vfs::get().unmount(target) == kernel::filesystem::vfs::operation_result::success)
+    {
+      return 0;
+    }
+    return -1;
+  }
+
+  auto open(char const * path) -> int
+  {
+    if (auto open_file_description = kernel::filesystem::vfs::get().open(path))
+    {
+      return kernel::filesystem::file_descriptor_table::get().add_file(open_file_description);
+    }
+
+    return -1;
+  }
+
+  auto close(int fd) -> int
+  {
+    return kernel::filesystem::file_descriptor_table::get().remove_file(fd);
+  }
+
+  auto read(int fd, void * buffer, size_t size) -> ssize_t
+  {
+    if (auto open_file_description = kernel::filesystem::file_descriptor_table::get().get_file(fd))
+    {
+      return open_file_description->read(buffer, size);
+    }
+
+    return -1;
+  }
+
+  auto write(int fd, void const * buffer, size_t size) -> ssize_t
+  {
+    if (auto open_file_description = kernel::filesystem::file_descriptor_table::get().get_file(fd))
+    {
+      return open_file_description->write(buffer, size);
+    }
+
+    return -1;
+  }
+}  // namespace kapi::syscall_handler::filesystem
\ No newline at end of file
diff --git a/kernel/src/filesystem/file_descriptor_table.cpp b/kernel/src/filesystem/file_descriptor_table.cpp
index 1c062a1..7569cea 100644
--- a/kernel/src/filesystem/file_descriptor_table.cpp
+++ b/kernel/src/filesystem/file_descriptor_table.cpp
@@ -41,7 +41,6 @@ namespace kernel::filesystem
   {
     if (!file_description)
     {
-      // TODO BA-FS26 panic or errorcode?
       return -1;
     }
 
@@ -72,20 +71,21 @@ namespace kernel::filesystem
     return m_open_files.at(index);
   }
 
-  auto file_descriptor_table::remove_file(int fd) -> void
+  auto file_descriptor_table::remove_file(int fd) -> int
   {
     if (fd < 0)
     {
-      return;
+      return -1;
     }
 
     auto const index = static_cast<size_t>(fd);
     if (index >= m_open_files.size())
     {
-      return;
+      return -1;
     }
 
     m_open_files.at(index) = nullptr;
+    return 0;
   }
 }  // namespace kernel::filesystem
 
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