i think it works

code/kernel/io_file.c

@@ -0,0 +1,113 @@
+// io_file.c - VFS dispatch layer
+#include "ke_list.h"
+#include "io_file.h"
+#include "mm_virt.h"
+#include "ob_object.h"
+#include <string.h>
+
+#define MAX_DRIVES  8
+
+typedef struct {
+    IO_FILESYSTEM   *Fs;
+    IO_VOLUME_PARAMS Vol;
+} VOLUME_ENTRY;
+
+static VOLUME_ENTRY gVolumes[MAX_DRIVES];
+
+// ---------------------------------------------------------------------------
+// Registration
+// ---------------------------------------------------------------------------
+KSTATUS IoRegisterFilesystem(uint8_t volumeIndex,
+                              IO_FILESYSTEM *fs,
+                              const IO_VOLUME_PARAMS *vol) {
+    if (volumeIndex >= MAX_DRIVES || !fs || !vol)
+        return STATUS_INVALID_PARAMETER;
+    if (gVolumes[volumeIndex].Fs)
+        return STATUS_ALREADY_EXISTS;
+    gVolumes[volumeIndex].Fs  = fs;
+    gVolumes[volumeIndex].Vol = *vol;
+    return STATUS_SUCCESS;
+}
+
+// ---------------------------------------------------------------------------
+// Path parsing - "0:\apps\shell.exe" or just "apps\shell.exe" (drive 0)
+// ---------------------------------------------------------------------------
+static uint8_t ParseDrive(const char* path, const char **pathOut) {
+    // Accept "N:\..." prefix, otherwise default to drive 0.
+    if (path[0] >= '0' && path[0] <= '7' &&
+        path[1] == ':' && (path[2] == '\\' || path[2] == '/')) {
+        *pathOut = path + 3;
+        return (uint8_t)(path[0] - '0');
+    }
+    *pathOut = path;
+    return 0;
+}
+
+// ---------------------------------------------------------------------------
+// Destructor
+// ---------------------------------------------------------------------------
+static void FileDestroy(OBJECT* obj) {
+    FILE_OBJECT* f = CONTAINING_RECORD(obj, FILE_OBJECT, Header);
+    if (f->Fs && f->FileCtx) f->Fs->Close(f->Fs, f->FileCtx);
+}
+
+// ---------------------------------------------------------------------------
+// IoOpenFile
+// ---------------------------------------------------------------------------
+KSTATUS IoOpenFile(const char* path, FILE_OBJECT **out) {
+    if (!path || !out) return STATUS_INVALID_PARAMETER;
+
+    const char* relPath;
+    uint8_t drive = ParseDrive(path, &relPath);
+
+    IO_FILESYSTEM* fs = gVolumes[drive].Fs;
+    if (!fs) return STATUS_NOT_FOUND;
+
+    void* fileCtx;
+    KSTATUS s = fs->Open(fs, relPath, &fileCtx);
+    if (!KSUCCESS(s)) return s;
+
+    FILE_OBJECT* f = (FILE_OBJECT *)ObAllocateObject(ObjectTypeFile /* reuse slot */,
+                                                      sizeof(FILE_OBJECT));
+    if (!f) { fs->Close(fs, fileCtx); return STATUS_NO_MEMORY; }
+    f->Header.Destroy = FileDestroy;
+    f->Fs      = fs;
+    f->FileCtx = fileCtx;
+    f->Size    = fs->GetSize(fs, fileCtx);
+    f->Offset  = 0;
+
+    *out = f;
+    return STATUS_SUCCESS;
+}
+
+// ---------------------------------------------------------------------------
+// IoReadFile - sequential read at current offset
+// ---------------------------------------------------------------------------
+KSTATUS IoReadFile(FILE_OBJECT* file, void* buf, size_t size, size_t* bytesRead) {
+    if (!file || !buf) return STATUS_INVALID_PARAMETER;
+    if (file->Offset >= file->Size) { *bytesRead = 0; return STATUS_SUCCESS; }
+
+    // Clamp to remaining bytes.
+    size_t remaining = (size_t)(file->Size - file->Offset);
+    if (size > remaining) size = remaining;
+
+    KSTATUS s = file->Fs->Read(file->Fs, file->FileCtx,
+                                file->Offset, buf, size, bytesRead);
+    if (KSUCCESS(s)) file->Offset += *bytesRead;
+    return s;
+}
+
+// ---------------------------------------------------------------------------
+KSTATUS IoSeekFile(FILE_OBJECT* file, uint64_t offset) {
+    if (!file) return STATUS_INVALID_PARAMETER;
+    file->Offset = offset;
+    return STATUS_SUCCESS;
+}
+
+uint64_t IoGetFileSize(FILE_OBJECT* file) {
+    return file ? file->Size : 0;
+}
+
+void IoCloseFile(FILE_OBJECT* file) {
+    if (file) ObDereferenceObject(&file->Header);
+}