<br>Section S(...); // fill requirements (параметры)<br>hSection=Allocate(S);                //  выделить память<br>Share(hKey_FileServer,hSection); //  разрешить совместное использование секции<br>RunMessage(hKey_FileServer,"hStream=open_file(hSection,""/usr/bin/perl"", O_READ);");<br>    // открыть файл (сообщение приведено в текстовом виде для наглядности)<br>

struct Section<br>{<br>    pointer start;<br>    pointer end;<br>    int segment_selector;<br>    enum Type {CODE, DATA, STACK, OTHER};<br>    Type type;<br>    bool read_only;<br>    bool is_static; // невыгружаемая<br>};

// kernelmode structures:<br><br>struct vma_s<br>{<br>    void        *start_addr;    // start address in userspace<br>    void        *end_addr;      // last address in userspace<br>    avl_node_s  *node;          // AVL tree node to speed up search<br>    void        *param;         // subsystem-specific parameter<br>    vma_vtbl_s  *vtbl;          // subsystem-specific functions<br>    uint        flags;          // subsystem-specific flags<br>};<br><br>struct vma_vtbl_s<br>{<br>    void (*page_fault)(vma_s *vma, void *fault_addr, uint fault_flags);  // #PF handler<br>    void (*close)(vma_s *vma);   // finalize VMA when process or handle destroyed<br>    // ...<br>};<br><br>struct avl_node_s  // Adelson-Velskii-Landis (locally balanced) tree<br>{<br>      avl_node_s  *left;   // left kid of node<br>      avl_node_s  *right;  // right kid of node<br>      uint        depth;   // depth (height) of node's subtree<br>};

// get stream:<br>hStream = open_file("/usr/bin/perl", O_READ);    // open file for reading<br>// - or -<br>hStream = shared_alloc(0x80000, "/ipc/x-wnd/oem_font");   // allocate 0x80000 bytes<br>// - or -<br>hStream = shared_open("/ipc/x-wnd/oem_font");   // open shared memory<br>// - or -<br>hStream = local_alloc(0x80000);   // allocate 0x80000 bytes of local memory<br>// - or -<br>hStream = open_vesa_vbuf();   // open VESA video buffer<br>// VMA can stick together parts of VESA1.x fragmented buffer<br><br>// map hStream at memory range [dwStart, dwEnd], from position dwOffset<br>hVma = map_stream(hStream, dwOffset, dwStart, dwEnd, VMA_READ | VMA_WRITE_COPY);

// kernel directs map_stream() syscall to kernelmode function usr_map_stream()<br>// all hanles are translated to its respective kernel struct's pointers<br><br>struct vma_s *usr_map_stream (struct stream_s *stream, size_t offset, void *start, void *end, uint flags)<br>{<br>    struct vma_s *vma;<br><br>      vma = kmalloc(sizeof(vma_s));<br>      vma->vma.start_addr = start;<br>      vma->vma.end_addr = end;<br>      avl_insert_node(¤t_process->vma_tree, vma);<br>      vma->vma.vtbl = stream_mapping_vtbl;<br>      vma->vma.param = stream;<br>      vma->flags = flags;<br><br>      return vma;<br>}

// member function from struct vma_vtbl_s<br><br>void stream_mapping_page_fault (struct vma_s *vma, void *fault_addr, uint fault_flags)<br>{<br>    // if page is not present, get it:<br>    // ((struct stream_s *)vma->param)->vtbl->map_page(vma->param, pos, fault_addr)<br>    // to make page to be available<br><br>    // if page is write-protected, generate exception<br>}

// system-wide exception handler<br><br>void page_fault_exception (void *fault_addr, uint fault_flags)<br>{<br>    struct vma_s *vma;<br><br>    if (vma = avl_find_node(current_process->vma_tree, fault_addr))<br>        vma->vtbl->page_fault(vma, fault_addr, fault_flags);<br>    else<br>        raise_user_exception(UNHANDLED_PAGE_FAULT);<br>}