vfs.h

/*
 * (c) 2010 Adam Lackorzynski <adam@os.inf.tu-dresden.de>,
 *          Alexander Warg <warg@os.inf.tu-dresden.de>
 *     economic rights: Technische Universität Dresden (Germany)
 *
 * License: see LICENSE.spdx (in this directory or the directories above)
 */
#pragma once
 
#include <l4/sys/compiler.h>
 
#include <unistd.h>
#include <stdarg.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <utime.h>
#include <errno.h>
 
#ifndef AT_FDCWD
# define AT_FDCWD -100
#endif
 
#ifdef __cplusplus
 
#include <l4/sys/capability>
#include <l4/re/cap_alloc>
#include <l4/re/dataspace>
#include <l4/cxx/pair>
#include <l4/cxx/ref_ptr>
 
namespace L4Re {
namespace Vfs {
 
class Mount_tree;
class File;

class Generic_file
{
public:
  enum Ready_type : unsigned
  {
    Read = 0,
    Write,
    Exception
  };
 
  virtual ~Generic_file() noexcept = 0;

  virtual int unlock_all_locks() noexcept = 0;

  virtual int fstat(struct stat64 *buf) const noexcept = 0;

  virtual int fchmod(mode_t) noexcept = 0;

  virtual int get_status_flags() const noexcept = 0;

  virtual int set_status_flags(long flags) noexcept = 0;
 
  virtual int utime(const struct utimbuf *) noexcept = 0;
  virtual int utimes(const struct timeval [2]) noexcept = 0;
  virtual ssize_t readlink(char *, size_t) = 0;

  virtual bool check_ready(Ready_type rt) noexcept = 0;
};
 
inline
Generic_file::~Generic_file() noexcept
{}

class Directory
{
public:
  virtual ~Directory() noexcept = 0;

  virtual int faccessat(const char *path, int mode, int flags) noexcept = 0;

  virtual int mkdir(const char *path, mode_t mode) noexcept = 0;

  virtual int unlink(const char *path) noexcept = 0;

  virtual int rename(const char *src_path, const char *dst_path) noexcept = 0;

  virtual int link(const char *src_path, const char *dst_path) noexcept = 0;

  virtual int symlink(const char *src_path, const char *dst_path) noexcept = 0;

  virtual int rmdir(const char *path) noexcept = 0;
  virtual int openat(const char *path, int flags, mode_t mode,
                     cxx::Ref_ptr<File> *f) noexcept = 0;
 
  virtual ssize_t getdents(char *buf, size_t sizebytes) noexcept = 0;
 
  virtual int fchmodat(const char *pathname,
                       mode_t mode, int flags) noexcept = 0;
 
  virtual int utimensat(const char *pathname,
                        const struct timespec times[2], int flags) noexcept = 0;

  virtual int get_entry(const char *, int, mode_t, cxx::Ref_ptr<File> *) noexcept = 0;
};
 
inline
Directory::~Directory() noexcept
{}

class Regular_file
{
public:
  virtual ~Regular_file() noexcept = 0;

  virtual L4::Cap<L4Re::Dataspace> data_space() noexcept = 0;

  virtual ssize_t readv(const struct iovec*, int iovcnt) noexcept = 0;

  virtual ssize_t writev(const struct iovec*, int iovcnt) noexcept = 0;
 
  virtual ssize_t preadv(const struct iovec *iov, int iovcnt, off64_t offset) noexcept = 0;
  virtual ssize_t pwritev(const struct iovec *iov, int iovcnt, off64_t offset) noexcept = 0;

  virtual off64_t lseek(off64_t, int) noexcept = 0;
 

  virtual int ftruncate(off64_t pos) noexcept = 0;

  virtual int fsync() const noexcept = 0;

  virtual int fdatasync() const noexcept = 0;

  virtual int get_lock(struct flock64 *lock) noexcept = 0;

  virtual int set_lock(struct flock64 *lock, bool wait) noexcept = 0;
};
 
inline
Regular_file::~Regular_file() noexcept
{}
 
class Socket
{
public:
  virtual ~Socket() noexcept = 0;
  virtual int bind(sockaddr const *, socklen_t) noexcept = 0;
  virtual int connect(sockaddr const *, socklen_t) noexcept = 0;
  virtual ssize_t send(void const *, size_t, int) noexcept = 0;
  virtual ssize_t recv(void *, size_t, int) noexcept = 0;
  virtual ssize_t sendto(void const *, size_t, int, sockaddr const *, socklen_t) noexcept = 0;
  virtual ssize_t recvfrom(void *, size_t, int, sockaddr *, socklen_t *) noexcept = 0;
  virtual ssize_t sendmsg(msghdr const *, int) noexcept = 0;
  virtual ssize_t recvmsg(msghdr *, int) noexcept = 0;
  virtual int getsockopt(int level, int opt, void *, socklen_t *) noexcept = 0;
  virtual int setsockopt(int level, int opt, void const *, socklen_t) noexcept = 0;
  virtual int listen(int) noexcept = 0;
  virtual int accept(sockaddr *addr, socklen_t *) noexcept = 0;
  virtual int shutdown(int) noexcept = 0;
 
  virtual int getsockname(sockaddr *, socklen_t *) noexcept = 0;
  virtual int getpeername(sockaddr *, socklen_t *) noexcept = 0;
};
 
inline
Socket::~Socket() noexcept
{}

class Special_file
{
public:
  virtual ~Special_file() noexcept = 0;

  virtual int ioctl(unsigned long cmd, va_list args) noexcept = 0;
};
 
inline
Special_file::~Special_file() noexcept
{}

class File :
  public Generic_file,
  public Regular_file,
  public Directory,
  public Special_file,
  public Socket
{
  friend class Mount_tree;
 
private:
  void operator = (File const &);
 
protected:
  File() noexcept : _ref_cnt(0) {}
  File(File const &)
  : Generic_file(),Regular_file(), Directory(), Special_file(), _ref_cnt(0)
  {}
 
public:
 
  const char *get_mount(const char *path, cxx::Ref_ptr<File> *dir,
                        cxx::Ref_ptr<Mount_tree> *mt = 0) noexcept;
 
  int openat(const char *path, int flags, mode_t mode,
             cxx::Ref_ptr<File> *f) noexcept override;
 
  void add_ref() noexcept { ++_ref_cnt; }
  int remove_ref() noexcept { return --_ref_cnt; }
 
  virtual ~File() noexcept = 0;
 
  cxx::Ref_ptr<Mount_tree> mount_tree() const noexcept
  { return _mount_tree; }
 
  char const *path() const noexcept { return _path; }
 
private:
  int _ref_cnt;
  cxx::Ref_ptr<Mount_tree> _mount_tree;
  char _path[80] = "";
};
 
inline
File::~File() noexcept
{}
 
class Path
{
private:
  char const *_p;
  unsigned _l;
 
public:
  Path() noexcept : _p(0), _l(0) {}
 
  explicit Path(char const *p) noexcept : _p(p)
  { for (_l = 0; *p; ++p, ++_l) ; }
 
  Path(char const *p, unsigned l) noexcept : _p(p), _l(l)
  {}
 
  static bool __is_sep(char s) noexcept;
 
  Path cmp_path(char const *prefix) const noexcept;
 
  struct Invalid_ptr;
  operator Invalid_ptr const * () const
  { return reinterpret_cast<Invalid_ptr const *>(_p); }
 
  unsigned length() const { return _l; }
  char const *path() const { return _p; }
 
  bool empty() const { return _l == 0; }
 
  bool is_sep(unsigned offset) const { return __is_sep(_p[offset]); }
 
  bool strip_sep()
  {
    bool s = false;
    for (; __is_sep(*_p) && _l; ++_p, --_l)
      s = true;
    return s;
  }
 
  Path first() const
  {
    unsigned i;
    for (i = 0; i < _l && !is_sep(i); ++i)
      ;
 
    return Path(_p, i);
  }
 
  Path strip_first()
  {
    Path r = first();
    _p += r.length();
    _l -= r.length();
    strip_sep();
    return r;
  }
 
};
 

class Mount_tree
{
public:
 
  explicit Mount_tree(char *n) noexcept;
 
  Path lookup(Path const &path, cxx::Ref_ptr<Mount_tree> *mt,
              cxx::Ref_ptr<Mount_tree> *mp = 0) noexcept;
 
  Path find(Path const &p, cxx::Ref_ptr<Mount_tree> *t) noexcept;
 
  cxx::Ref_ptr<File> mount() const
  { return _mount; }
 
  void mount(cxx::Ref_ptr<File> const &m)
  {
    m->_mount_tree = cxx::ref_ptr(this);
    _mount = m;
  }
 
  static int create_tree(cxx::Ref_ptr<Mount_tree> const &root,
                         char const *path,
                         cxx::Ref_ptr<File> const &dir) noexcept;
 
  void add_child_node(cxx::Ref_ptr<Mount_tree> const &cld);
 
  virtual ~Mount_tree() noexcept  = 0;
 
  void add_ref() noexcept { ++_ref_cnt; }
  int remove_ref() noexcept { return --_ref_cnt; }
 
private:
  friend class Real_mount_tree;
 
  int _ref_cnt;
  char *_name;
  cxx::Ref_ptr<Mount_tree> _cld;
  cxx::Ref_ptr<Mount_tree> _sib;
  cxx::Ref_ptr<File> _mount;
};
 
inline
Mount_tree::~Mount_tree() noexcept
{}
 
inline bool
Path::__is_sep(char s) noexcept
{ return s == '/'; }
 
inline Path
Path::cmp_path(char const *n) const noexcept
{
  char const *p = _p;
  for (; *p && !__is_sep(*p) && *n; ++p, ++n)
    if (*p != *n)
      return Path();
 
  if (*n || (*p && !__is_sep(*p)))
    return Path();
 
  return Path(p, _l - (p - _p));
}
 
inline
Mount_tree::Mount_tree(char *n) noexcept
: _ref_cnt(0), _name(n)
{}
 
inline Path
Mount_tree::find(Path const &p, cxx::Ref_ptr<Mount_tree> *t) noexcept
{
  if (!_cld)
    return Path();
 
  for (cxx::Ref_ptr<Mount_tree> x = _cld; x; x = x->_sib)
    {
      Path const r = p.cmp_path(x->_name);
      if (r)
  {
    *t = x;
    return r;
  }
    }
 
  return Path();
}
 
inline Path
Mount_tree::lookup(Path const &path, cxx::Ref_ptr<Mount_tree> *mt,
                   cxx::Ref_ptr<Mount_tree> *mp) noexcept
{
  cxx::Ref_ptr<Mount_tree> x(this);
  Path p = path;
 
  if (p.first().cmp_path("."))
    p.strip_first();
 
  Path last_mp = p;
 
  if (mp)
    *mp = x;;
 
  while (1)
    {
      Path r = x->find(p, &x);
 
      if (!r)
  {
    if (mp)
      return last_mp;
 
    if (mt)
      *mt = x;
 
    return p;
  }
 
      r.strip_sep();
 
      if (mp && x->_mount)
  {
    last_mp = r;
    *mp = x;
  }
 
      if (r.empty())
  {
    if (mt)
      *mt = x;
 
    if (mp)
      return last_mp;
    else
      return r;
  }
 
      p = r;
    }
}
 
inline
void
Mount_tree::add_child_node(cxx::Ref_ptr<Mount_tree> const &cld)
{
  cld->_sib = _cld;
  _cld = cld;
}
 
inline
const char *
File::get_mount(const char *path, cxx::Ref_ptr<File> *dir,
                cxx::Ref_ptr<Mount_tree> *mt) noexcept
{
  if (!_mount_tree)
    {
      *dir = cxx::ref_ptr(this);
      return path;
    }
 
  cxx::Ref_ptr<Mount_tree> mp;
  Path p = _mount_tree->lookup(Path(path), mt, &mp);
  if (mp->mount())
    {
      *dir = mp->mount();
      return p.path();
    }
  else
    {
      *dir = cxx::ref_ptr(this);
      return path;
    }
}
 
inline int
File::openat(const char *path, int flags, mode_t mode,
             cxx::Ref_ptr<File> *f) noexcept
{
  cxx::Ref_ptr<File> dir;
  cxx::Ref_ptr<Mount_tree> mt;
  char const *m_path = get_mount(path, &dir, &mt);
 
  int res = dir->get_entry(m_path, flags, mode, f);
 
  if (res < 0)
    return res;
 
  if (!(*f)->_mount_tree && mt)
    (*f)->_mount_tree = mt;
 
  // Debugging {
  size_t i = 0;
  for (; i < sizeof((*f)->_path) - 1 && path[i]; ++i)
    (*f)->_path[i] = path[i];
  (*f)->_path[i] = '\0';
  // } Debugging
 
  return res;
}

class Mman
{
public:
  virtual int mmap2(void *start, size_t len, int prot, int flags, int fd,
                    off_t offset, void **ptr) noexcept = 0;

  virtual int munmap(void *start, size_t len) noexcept = 0;

  virtual int mremap(void *old, size_t old_sz, size_t new_sz, int flags,
                     void **new_addr) noexcept = 0;

  virtual int mprotect(const void *a, size_t sz, int prot) noexcept = 0;

  virtual int msync(void *addr, size_t len, int flags) noexcept = 0;

  virtual int madvise(void *addr, size_t len, int advice) noexcept = 0;
 
  virtual ~Mman() noexcept = 0;
};
 
inline
Mman::~Mman() noexcept {}
 
class File_factory
{
private:
  int _ref_cnt = 0;
  int _proto = 0;
  char const *_proto_name = 0;
 
  template<typename T> friend struct cxx::Default_ref_counter;
  void add_ref() noexcept { ++_ref_cnt; }
  int remove_ref() noexcept { return --_ref_cnt; }
 
public:
  explicit File_factory(int proto) : _proto(proto) {}
  explicit File_factory(char const *proto_name) : _proto_name(proto_name) {}
  File_factory(int proto, char const *proto_name)
  : _proto(proto), _proto_name(proto_name)
  {}
 
  File_factory(File_factory const &) = delete;
  File_factory &operator = (File_factory const &) = delete;
 
  char const *proto_name() const { return _proto_name; }
  int proto() const { return _proto; }
 
  virtual ~File_factory() noexcept = 0;
  virtual cxx::Ref_ptr<File> create(L4::Cap<void> file) = 0;
};
 
inline File_factory::~File_factory() noexcept {}
 
template<typename IFACE, typename IMPL>
class File_factory_t : public File_factory
{
public:
  File_factory_t()
  : File_factory(IFACE::Protocol, L4::kobject_typeid<IFACE>()->name())
  {}
 
  cxx::Ref_ptr<File> create(L4::Cap<void> file) override
  { return cxx::make_ref_obj<IMPL>(L4::cap_cast<IFACE>(file)); }
};

class File_system
{
protected:
  File_system *_next;
 
public:
  File_system() noexcept : _next(0) {}
  virtual char const *type() const noexcept = 0;

  virtual int mount(char const *source, unsigned long mountflags,
                    void const *data, cxx::Ref_ptr<File> *dir) noexcept = 0;
 
  virtual ~File_system() noexcept = 0;

  File_system *next() const noexcept { return _next; }
  File_system *&next() noexcept { return _next; }
  void next(File_system *n) noexcept { _next = n; }
};
 
inline
File_system::~File_system() noexcept
{}
 
class File_system_list
{
public:
  class Iterator
  {
  public:
    explicit constexpr Iterator(File_system *c = nullptr) : _c(c) {}
 
    Iterator &operator++()
    {
      if (_c)
        _c = _c->next();
      return *this;
    }
 
    bool operator==(Iterator const &other) const { return _c == other._c; }
    bool operator!=(Iterator const &other) const { return _c != other._c; }
    File_system *operator*() const { return _c; }
    File_system *operator->() const { return _c; }
 
  private:
    File_system *_c;
  };
 
  File_system_list(File_system *head) : _head(head) {}
 
  constexpr Iterator begin() const
  { return Iterator(_head); }
 
  constexpr Iterator end() const
  { return Iterator(); }
 
private:
  File_system *_head;
};

class Fs
{
public:
  virtual cxx::Ref_ptr<File> get_file(int fd) noexcept = 0;

  virtual cxx::Ref_ptr<File> get_root() noexcept = 0;

  virtual cxx::Ref_ptr<File> get_cwd() noexcept { return get_root(); }

  virtual void set_cwd(cxx::Ref_ptr<File> const &) noexcept {}

  virtual int alloc_fd(cxx::Ref_ptr<File> const &f = cxx::Ref_ptr<>::Nil) noexcept = 0;

  virtual cxx::Pair<cxx::Ref_ptr<File>, int>
    set_fd(int fd, cxx::Ref_ptr<File> const &f = cxx::Ref_ptr<>::Nil) noexcept = 0;

  virtual cxx::Ref_ptr<File> free_fd(int fd) noexcept = 0;

  virtual int mount(char const *path, cxx::Ref_ptr<File> const &dir) noexcept = 0;

  virtual int register_file_system(File_system *f) noexcept = 0;

  virtual int unregister_file_system(File_system *f) noexcept = 0;

  virtual File_system *get_file_system(char const *fstype) noexcept = 0;

  virtual File_system_list file_system_list() noexcept = 0;

  int mount(char const *source, char const *target,
            char const *fstype, unsigned long mountflags,
            void const *data) noexcept;
 
  virtual int register_file_factory(cxx::Ref_ptr<File_factory> f) noexcept = 0;
  virtual int unregister_file_factory(cxx::Ref_ptr<File_factory> f) noexcept = 0;
  virtual cxx::Ref_ptr<File_factory> get_file_factory(int proto) noexcept = 0;
  virtual cxx::Ref_ptr<File_factory> get_file_factory(char const *proto_name) noexcept = 0;
 
  virtual ~Fs() = 0;
 
private:
  int mount_one(char const *source, char const *target,
                File_system *fs, unsigned long mountflags,
                void const *data) noexcept;
};
 
inline int
Fs::mount_one(char const *source, char const *target,
              File_system *fs, unsigned long mountflags,
              void const *data) noexcept
{
  cxx::Ref_ptr<File> dir;
  int res = fs->mount(source, mountflags, data, &dir);
 
  if (res < 0)
    return res;
 
  return mount(target, dir);
}
 
inline int
Fs::mount(char const *source, char const *target,
          char const *fstype, unsigned long mountflags,
          void const *data) noexcept
{
  if (   fstype[0] == 'a'
      && fstype[1] == 'u'
      && fstype[2] == 't'
      && fstype[3] == 'o'
      && fstype[4] == 0)
    {
      File_system_list fsl = file_system_list();
      for (File_system_list::Iterator c = fsl.begin(); c != fsl.end(); ++c)
        if (mount_one(source, target, *c, mountflags, data) == 0)
          return 0;
 
      return -ENODEV;
    }
 
  File_system *fs = get_file_system(fstype);
 
  if (!fs)
    return -ENODEV;
 
  return mount_one(source, target, fs, mountflags, data);
}
 
inline
Fs::~Fs()
{}

class Ops : public Mman, public Fs
{
public:
  virtual void *malloc(size_t bytes) noexcept = 0;
  virtual void free(void *mem) noexcept = 0;
  virtual ~Ops() noexcept = 0;
 
  char *strndup(char const *str, unsigned l) noexcept
  {
    unsigned len;
    for (len = 0; str[len] && len < l; ++len)
      ;
 
    if (len == 0)
      return nullptr;
 
    ++len;
 
    char *b = static_cast<char *>(this->malloc(len));
    if (b == nullptr)
      return nullptr;
 
    char *r = b;
    for (; len - 1 > 0 && *str; --len, ++b, ++str)
      *b = *str;
 
    *b = 0;
    return r;
  }
 
};
 
inline
Ops::~Ops() noexcept
{}
 
}}
 
#endif