text: /*
   * Server-side file descriptor management
   *
   * Copyright (C) 2000, 2003 Alexandre Julliard
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
   */
  
  
  #include "config.h"
  #include "wine/port.h"
  
  #include <assert.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <limits.h>
  #include <signal.h>
  #include <stdarg.h>
  #include <stdio.h>
  #include <string.h>
  #include <stdlib.h>
  #ifdef HAVE_POLL_H
  #include <poll.h>
  #endif
  #ifdef HAVE_SYS_POLL_H
  #include <sys/poll.h>
  #endif
  #ifdef HAVE_LINUX_MAJOR_H
  #include <linux/major.h>
  #endif
  #ifdef HAVE_SYS_STATVFS_H
  #include <sys/statvfs.h>
  #endif
  #ifdef HAVE_SYS_VFS_H
  /* Work around a conflict with Solaris' system list defined in sys/list.h. */
  #define list SYSLIST
  #define list_next SYSLIST_NEXT
  #define list_prev SYSLIST_PREV
  #define list_head SYSLIST_HEAD
  #define list_tail SYSLIST_TAIL
  #define list_move_tail SYSLIST_MOVE_TAIL
  #define list_remove SYSLIST_REMOVE
  #include <sys/vfs.h>
  #undef list
  #undef list_next
  #undef list_prev
  #undef list_head
  #undef list_tail
  #undef list_move_tail
  #undef list_remove
  #endif
  #ifdef HAVE_SYS_PARAM_H
  #include <sys/param.h>
  #endif
  #ifdef HAVE_SYS_MOUNT_H
  #include <sys/mount.h>
  #endif
  #ifdef HAVE_SYS_STATFS_H
  #include <sys/statfs.h>
  #endif
  #ifdef HAVE_SYS_SYSCTL_H
  #include <sys/sysctl.h>
  #endif
  #ifdef HAVE_SYS_EVENT_H
  #include <sys/event.h>
  #undef LIST_INIT
  #undef LIST_ENTRY
  #endif
  #ifdef HAVE_STDINT_H
  #include <stdint.h>
  #endif
  #include <sys/stat.h>
  #include <sys/time.h>
  #ifdef MAJOR_IN_MKDEV
  #include <sys/mkdev.h>
  #elif defined(MAJOR_IN_SYSMACROS)
  #include <sys/sysmacros.h>
  #endif
  #include <sys/types.h>
  #include <unistd.h>
  #ifdef HAVE_SYS_SYSCALL_H
  #include <sys/syscall.h>
  #endif
  
  #include "ntstatus.h"
  #define WIN32_NO_STATUS
  #include "object.h"
  #include "file.h"
  #include "handle.h"
  #include "process.h"
  #include "request.h"
  
  #include "winternl.h"
  #include "winioctl.h"
  
  #if defined(HAVE_SYS_EPOLL_H) && defined(HAVE_EPOLL_CREATE)
  # include <sys/epoll.h>
  # define USE_EPOLL
  #elif defined(linux) && defined(__i386__) && defined(HAVE_STDINT_H)
  # define USE_EPOLL
  # define EPOLLIN POLLIN
  # define EPOLLOUT POLLOUT
  # define EPOLLERR POLLERR
  # define EPOLLHUP POLLHUP
  # define EPOLL_CTL_ADD 1
  # define EPOLL_CTL_DEL 2
  # define EPOLL_CTL_MOD 3
  
  typedef union epoll_data
  {
    void *ptr;
    int fd;
    uint32_t u32;
    uint64_t u64;
  } epoll_data_t;
  
  struct epoll_event
  {
    uint32_t events;
    epoll_data_t data;
  };
  
  static inline int epoll_create( int size )
  {
      return syscall( 254 /*NR_epoll_create*/, size );
  }
  
  static inline int epoll_ctl( int epfd, int op, int fd, const struct epoll_event *event )
  {
      return syscall( 255 /*NR_epoll_ctl*/, epfd, op, fd, event );
  }
  
  static inline int epoll_wait( int epfd, struct epoll_event *events, int maxevents, int timeout )
  {
      return syscall( 256 /*NR_epoll_wait*/, epfd, events, maxevents, timeout );
  }
  
  #endif /* linux && __i386__ && HAVE_STDINT_H */
  
  #if defined(HAVE_PORT_H) && defined(HAVE_PORT_CREATE)
  # include <port.h>
  # define USE_EVENT_PORTS
  #endif /* HAVE_PORT_H && HAVE_PORT_CREATE */
  
  /* Because of the stupid Posix locking semantics, we need to keep
   * track of all file descriptors referencing a given file, and not
   * close a single one until all the locks are gone (sigh).
   */
  
  /* file descriptor object */
  
  /* closed_fd is used to keep track of the unix fd belonging to a closed fd object */
  struct closed_fd
  {
      struct list entry;       /* entry in inode closed list */
      int         unix_fd;     /* the unix file descriptor */
      int         unlink;      /* whether to unlink on close */
      char       *unix_name;   /* name to unlink on close, points to parent fd unix_name */
  };
  
  struct fd
  {
      struct object        obj;         /* object header */
      const struct fd_ops *fd_ops;      /* file descriptor operations */
      struct inode        *inode;       /* inode that this fd belongs to */
      struct list          inode_entry; /* entry in inode fd list */
      struct closed_fd    *closed;      /* structure to store the unix fd at destroy time */
      struct object       *user;        /* object using this file descriptor */
      struct list          locks;       /* list of locks on this fd */
      unsigned int         access;      /* file access (FILE_READ_DATA etc.) */
      unsigned int         options;     /* file options (FILE_DELETE_ON_CLOSE, FILE_SYNCHRONOUS...) */
      unsigned int         sharing;     /* file sharing mode */
      char                *unix_name;   /* unix file name */
      int                  unix_fd;     /* unix file descriptor */
      unsigned int         no_fd_status;/* status to return when unix_fd is -1 */
      unsigned int         cacheable :1;/* can the fd be cached on the client side? */
      unsigned int         signaled :1; /* is the fd signaled? */
      unsigned int         fs_locks :1; /* can we use filesystem locks for this fd? */
      int                  poll_index;  /* index of fd in poll array */
      struct async_queue  *read_q;      /* async readers of this fd */
      struct async_queue  *write_q;     /* async writers of this fd */
      struct async_queue  *wait_q;      /* other async waiters of this fd */
      struct completion   *completion;  /* completion object attached to this fd */
      apc_param_t          comp_key;    /* completion key to set in completion events */
  };
  
  static void fd_dump( struct object *obj, int verbose );
  static void fd_destroy( struct object *obj );
  
  static const struct object_ops fd_ops =
  {
      sizeof(struct fd),        /* size */
      fd_dump,                  /* dump */
      no_get_type,              /* get_type */
      no_add_queue,             /* add_queue */
      NULL,                     /* remove_queue */
      NULL,                     /* signaled */
      NULL,                     /* satisfied */
      no_signal,                /* signal */
      no_get_fd,                /* get_fd */
      no_map_access,            /* map_access */
      default_get_sd,           /* get_sd */
      default_set_sd,           /* set_sd */
      no_lookup_name,           /* lookup_name */
      no_link_name,             /* link_name */
      NULL,                     /* unlink_name */
      no_open_file,             /* open_file */
      no_close_handle,          /* close_handle */
      fd_destroy                /* destroy */
  };
  
  /* device object */
  
  #define DEVICE_HASH_SIZE 7
  #define INODE_HASH_SIZE 17
  
  struct device
  {
      struct object       obj;        /* object header */
      struct list         entry;      /* entry in device hash list */
      dev_t               dev;        /* device number */
      int                 removable;  /* removable device? (or -1 if unknown) */
      struct list         inode_hash[INODE_HASH_SIZE];  /* inodes hash table */
  };
  
  static void device_dump( struct object *obj, int verbose );
  static void device_destroy( struct object *obj );
  
  static const struct object_ops device_ops =
  {
      sizeof(struct device),    /* size */
      device_dump,              /* dump */
      no_get_type,              /* get_type */
      no_add_queue,             /* add_queue */
      NULL,                     /* remove_queue */
      NULL,                     /* signaled */
      NULL,                     /* satisfied */
      no_signal,                /* signal */
      no_get_fd,                /* get_fd */
      no_map_access,            /* map_access */
      default_get_sd,           /* get_sd */
      default_set_sd,           /* set_sd */
      no_lookup_name,           /* lookup_name */
      no_link_name,             /* link_name */
      NULL,                     /* unlink_name */
      no_open_file,             /* open_file */
      no_close_handle,          /* close_handle */
      device_destroy            /* destroy */
  };
  
  /* inode object */
  
  struct inode
  {
      struct object       obj;        /* object header */
      struct list         entry;      /* inode hash list entry */
      struct device      *device;     /* device containing this inode */
      ino_t               ino;        /* inode number */
      struct list         open;       /* list of open file descriptors */
      struct list         locks;      /* list of file locks */
      struct list         closed;     /* list of file descriptors to close at destroy time */
  };
  
  static void inode_dump( struct object *obj, int verbose );
  static void inode_destroy( struct object *obj );
  
  static const struct object_ops inode_ops =
  {
      sizeof(struct inode),     /* size */
      inode_dump,               /* dump */
      no_get_type,              /* get_type */
      no_add_queue,             /* add_queue */
      NULL,                     /* remove_queue */
      NULL,                     /* signaled */
      NULL,                     /* satisfied */
      no_signal,                /* signal */
      no_get_fd,                /* get_fd */
      no_map_access,            /* map_access */
      default_get_sd,           /* get_sd */
      default_set_sd,           /* set_sd */
      no_lookup_name,           /* lookup_name */
      no_link_name,             /* link_name */
      NULL,                     /* unlink_name */
      no_open_file,             /* open_file */
      no_close_handle,          /* close_handle */
      inode_destroy             /* destroy */
  };
  
  /* file lock object */
  
  struct file_lock
  {
      struct object       obj;         /* object header */
      struct fd          *fd;          /* fd owning this lock */
      struct list         fd_entry;    /* entry in list of locks on a given fd */
      struct list         inode_entry; /* entry in inode list of locks */
      int                 shared;      /* shared lock? */
      file_pos_t          start;       /* locked region is interval [start;end) */
      file_pos_t          end;
      struct process     *process;     /* process owning this lock */
      struct list         proc_entry;  /* entry in list of locks owned by the process */
  };
  
  static void file_lock_dump( struct object *obj, int verbose );
  static int file_lock_signaled( struct object *obj, struct wait_queue_entry *entry );
  
  static const struct object_ops file_lock_ops =
  {
      sizeof(struct file_lock),   /* size */
      file_lock_dump,             /* dump */
      no_get_type,                /* get_type */
      add_queue,                  /* add_queue */
      remove_queue,               /* remove_queue */
      file_lock_signaled,         /* signaled */
      no_satisfied,               /* satisfied */
      no_signal,                  /* signal */
      no_get_fd,                  /* get_fd */
      no_map_access,              /* map_access */
      default_get_sd,             /* get_sd */
      default_set_sd,             /* set_sd */
      no_lookup_name,             /* lookup_name */
      no_link_name,               /* link_name */
      NULL,                       /* unlink_name */
      no_open_file,               /* open_file */
      no_close_handle,            /* close_handle */
      no_destroy                  /* destroy */
  };
  
  
  #define OFF_T_MAX       (~((file_pos_t)1 << (8*sizeof(off_t)-1)))
  #define FILE_POS_T_MAX  (~(file_pos_t)0)
  
  static file_pos_t max_unix_offset = OFF_T_MAX;
  
  #define DUMP_LONG_LONG(val) do { \
      if (sizeof(val) > sizeof(unsigned long) && (val) > ~0UL) \
          fprintf( stderr, "%lx%08lx", (unsigned long)((unsigned long long)(val) >> 32), (unsigned long)(val) ); \
      else \
          fprintf( stderr, "%lx", (unsigned long)(val) ); \
    } while (0)
  
  
  
  /****************************************************************/
  /* timeouts support */
  
  struct timeout_user
  {
      struct list           entry;      /* entry in sorted timeout list */
      timeout_t             when;       /* timeout expiry (absolute time) */
      timeout_callback      callback;   /* callback function */
      void                 *private;    /* callback private data */
  };
  
  static struct list timeout_list = LIST_INIT(timeout_list);   /* sorted timeouts list */
  timeout_t current_time;
  
  static inline void set_current_time(void)
  {
      static const timeout_t ticks_1601_to_1970 = (timeout_t)86400 * (369 * 365 + 89) * TICKS_PER_SEC;
      struct timeval now;
      gettimeofday( &now, NULL );
      current_time = (timeout_t)now.tv_sec * TICKS_PER_SEC + now.tv_usec * 10 + ticks_1601_to_1970;
  }
  
  /* add a timeout user */
  struct timeout_user *add_timeout_user( timeout_t when, timeout_callback func, void *private )
  {
      struct timeout_user *user;
      struct list *ptr;
  
      if (!(user = mem_alloc( sizeof(*user) ))) return NULL;
      user->when     = (when > 0) ? when : current_time - when;
      user->callback = func;
      user->private  = private;
  
      /* Now insert it in the linked list */
  
      LIST_FOR_EACH( ptr, &timeout_list )
      {
          struct timeout_user *timeout = LIST_ENTRY( ptr, struct timeout_user, entry );
          if (timeout->when >= user->when) break;
      }
      list_add_before( ptr, &user->entry );
      return user;
  }
  
  /* remove a timeout user */
  void remove_timeout_user( struct timeout_user *user )
  {
      list_remove( &user->entry );
      free( user );
  }
  
  /* return a text description of a timeout for debugging purposes */
  const char *get_timeout_str( timeout_t timeout )
  {
      static char buffer[64];
      long secs, nsecs;
  
      if (!timeout) return "0";
      if (timeout == TIMEOUT_INFINITE) return "infinite";
  
      if (timeout < 0)  /* relative */
      {
          secs = -timeout / TICKS_PER_SEC;
          nsecs = -timeout % TICKS_PER_SEC;
          sprintf( buffer, "+%ld.%07ld", secs, nsecs );
      }
      else  /* absolute */
      {
          secs = (timeout - current_time) / TICKS_PER_SEC;
          nsecs = (timeout - current_time) % TICKS_PER_SEC;
          if (nsecs < 0)
          {
              nsecs += TICKS_PER_SEC;
              secs--;
          }
          if (secs >= 0)
              sprintf( buffer, "%x%08x (+%ld.%07ld)",
                       (unsigned int)(timeout >> 32), (unsigned int)timeout, secs, nsecs );
          else
              sprintf( buffer, "%x%08x (-%ld.%07ld)",
                       (unsigned int)(timeout >> 32), (unsigned int)timeout,
                       -(secs + 1), TICKS_PER_SEC - nsecs );
      }
      return buffer;
  }
  
  
  /****************************************************************/
  /* poll support */
  
  static struct fd **poll_users;              /* users array */
  static struct pollfd *pollfd;               /* poll fd array */
  static int nb_users;                        /* count of array entries actually in use */
  static int active_users;                    /* current number of active users */
  static int allocated_users;                 /* count of allocated entries in the array */
  static struct fd **freelist;                /* list of free entries in the array */
  
  static int get_next_timeout(void);
  
  static inline void fd_poll_event( struct fd *fd, int event )
  {
      fd->fd_ops->poll_event( fd, event );
  }
  
  #ifdef USE_EPOLL
  
  static int epoll_fd = -1;
  
  static inline void init_epoll(void)
  {
      epoll_fd = epoll_create( 128 );
  }
  
  /* set the events that epoll waits for on this fd; helper for set_fd_events */
  static inline void set_fd_epoll_events( struct fd *fd, int user, int events )
  {
      struct epoll_event ev;
      int ctl;
  
      if (epoll_fd == -1) return;
  
      if (events == -1)  /* stop waiting on this fd completely */
      {
          if (pollfd[user].fd == -1) return;  /* already removed */
          ctl = EPOLL_CTL_DEL;
      }
      else if (pollfd[user].fd == -1)
      {
          if (pollfd[user].events) return;  /* stopped waiting on it, don't restart */
          ctl = EPOLL_CTL_ADD;
      }
      else
      {
          if (pollfd[user].events == events) return;  /* nothing to do */
          ctl = EPOLL_CTL_MOD;
      }
  
      ev.events = events;
      memset(&ev.data, 0, sizeof(ev.data));
      ev.data.u32 = user;
  
      if (epoll_ctl( epoll_fd, ctl, fd->unix_fd, &ev ) == -1)
      {
          if (errno == ENOMEM)  /* not enough memory, give up on epoll */
          {
              close( epoll_fd );
              epoll_fd = -1;
          }
          else perror( "epoll_ctl" );  /* should not happen */
      }
  }
  
  static inline void remove_epoll_user( struct fd *fd, int user )
  {
      if (epoll_fd == -1) return;
  
      if (pollfd[user].fd != -1)
      {
          struct epoll_event dummy;
          epoll_ctl( epoll_fd, EPOLL_CTL_DEL, fd->unix_fd, &dummy );
      }
  }
  
  static inline void main_loop_epoll(void)
  {
      int i, ret, timeout;
      struct epoll_event events[128];
  
      assert( POLLIN == EPOLLIN );
      assert( POLLOUT == EPOLLOUT );
      assert( POLLERR == EPOLLERR );
      assert( POLLHUP == EPOLLHUP );
  
      if (epoll_fd == -1) return;
  
      while (active_users)
      {
          timeout = get_next_timeout();
  
          if (!active_users) break;  /* last user removed by a timeout */
          if (epoll_fd == -1) break;  /* an error occurred with epoll */
  
          ret = epoll_wait( epoll_fd, events, sizeof(events)/sizeof(events[0]), timeout );
          set_current_time();
  
          /* put the events into the pollfd array first, like poll does */
          for (i = 0; i < ret; i++)
          {
              int user = events[i].data.u32;
              pollfd[user].revents = events[i].events;
          }
  
          /* read events from the pollfd array, as set_fd_events may modify them */
          for (i = 0; i < ret; i++)
          {
              int user = events[i].data.u32;
              if (pollfd[user].revents) fd_poll_event( poll_users[user], pollfd[user].revents );
          }
      }
  }
  
  #elif defined(HAVE_KQUEUE)
  
  static int kqueue_fd = -1;
  
  static inline void init_epoll(void)
  {
  #ifdef __APPLE__ /* kqueue support is broken in Mac OS < 10.5 */
      int mib[2];
      char release[32];
      size_t len = sizeof(release);
  
      mib[0] = CTL_KERN;
      mib[1] = KERN_OSRELEASE;
      if (sysctl( mib, 2, release, &len, NULL, 0 ) == -1) return;
      if (atoi(release) < 9) return;
  #endif
      kqueue_fd = kqueue();
  }
  
  static inline void set_fd_epoll_events( struct fd *fd, int user, int events )
  {
      struct kevent ev[2];
  
      if (kqueue_fd == -1) return;
  
      EV_SET( &ev[0], fd->unix_fd, EVFILT_READ, 0, NOTE_LOWAT, 1, (void *)(long)user );
      EV_SET( &ev[1], fd->unix_fd, EVFILT_WRITE, 0, NOTE_LOWAT, 1, (void *)(long)user );
  
      if (events == -1)  /* stop waiting on this fd completely */
      {
          if (pollfd[user].fd == -1) return;  /* already removed */
          ev[0].flags |= EV_DELETE;
          ev[1].flags |= EV_DELETE;
      }
      else if (pollfd[user].fd == -1)
      {
          if (pollfd[user].events) return;  /* stopped waiting on it, don't restart */
          ev[0].flags |= EV_ADD | ((events & POLLIN) ? EV_ENABLE : EV_DISABLE);
          ev[1].flags |= EV_ADD | ((events & POLLOUT) ? EV_ENABLE : EV_DISABLE);
      }
      else
      {
          if (pollfd[user].events == events) return;  /* nothing to do */
          ev[0].flags |= (events & POLLIN) ? EV_ENABLE : EV_DISABLE;
          ev[1].flags |= (events & POLLOUT) ? EV_ENABLE : EV_DISABLE;
      }
  
      if (kevent( kqueue_fd, ev, 2, NULL, 0, NULL ) == -1)
      {
          if (errno == ENOMEM)  /* not enough memory, give up on kqueue */
          {
              close( kqueue_fd );
              kqueue_fd = -1;
          }
          else perror( "kevent" );  /* should not happen */
      }
  }
  
  static inline void remove_epoll_user( struct fd *fd, int user )
  {
      if (kqueue_fd == -1) return;
  
      if (pollfd[user].fd != -1)
      {
          struct kevent ev[2];
  
          EV_SET( &ev[0], fd->unix_fd, EVFILT_READ, EV_DELETE, 0, 0, 0 );
          EV_SET( &ev[1], fd->unix_fd, EVFILT_WRITE, EV_DELETE, 0, 0, 0 );
          kevent( kqueue_fd, ev, 2, NULL, 0, NULL );
      }
  }
  
  static inline void main_loop_epoll(void)
  {
      int i, ret, timeout;
      struct kevent events[128];
  
      if (kqueue_fd == -1) return;
  
      while (active_users)
      {
          timeout = get_next_timeout();
  
          if (!active_users) break;  /* last user removed by a timeout */
          if (kqueue_fd == -1) break;  /* an error occurred with kqueue */
  
          if (timeout != -1)
          {
              struct timespec ts;
  
              ts.tv_sec = timeout / 1000;
              ts.tv_nsec = (timeout % 1000) * 1000000;
              ret = kevent( kqueue_fd, NULL, 0, events, sizeof(events)/sizeof(events[0]), &ts );
          }
          else ret = kevent( kqueue_fd, NULL, 0, events, sizeof(events)/sizeof(events[0]), NULL );
  
          set_current_time();
  
          /* put the events into the pollfd array first, like poll does */
          for (i = 0; i < ret; i++)
          {
              long user = (long)events[i].udata;
              pollfd[user].revents = 0;
          }
          for (i = 0; i < ret; i++)
          {
              long user = (long)events[i].udata;
              if (events[i].filter == EVFILT_READ) pollfd[user].revents |= POLLIN;
              else if (events[i].filter == EVFILT_WRITE) pollfd[user].revents |= POLLOUT;
              if (events[i].flags & EV_EOF) pollfd[user].revents |= POLLHUP;
              if (events[i].flags & EV_ERROR) pollfd[user].revents |= POLLERR;
          }
  
          /* read events from the pollfd array, as set_fd_events may modify them */
          for (i = 0; i < ret; i++)
          {
              long user = (long)events[i].udata;
              if (pollfd[user].revents) fd_poll_event( poll_users[user], pollfd[user].revents );
              pollfd[user].revents = 0;
          }
      }
  }
  
  #elif defined(USE_EVENT_PORTS)
  
  static int port_fd = -1;
  
  static inline void init_epoll(void)
  {
      port_fd = port_create();
  }
  
  static inline void set_fd_epoll_events( struct fd *fd, int user, int events )
  {
      int ret;
  
      if (port_fd == -1) return;
  
      if (events == -1)  /* stop waiting on this fd completely */
      {
          if (pollfd[user].fd == -1) return;  /* already removed */
          port_dissociate( port_fd, PORT_SOURCE_FD, fd->unix_fd );
      }
      else if (pollfd[user].fd == -1)
      {
          if (pollfd[user].events) return;  /* stopped waiting on it, don't restart */
          ret = port_associate( port_fd, PORT_SOURCE_FD, fd->unix_fd, events, (void *)user );
      }
      else
      {
          if (pollfd[user].events == events) return;  /* nothing to do */
          ret = port_associate( port_fd, PORT_SOURCE_FD, fd->unix_fd, events, (void *)user );
      }
  
      if (ret == -1)
      {
          if (errno == ENOMEM)  /* not enough memory, give up on port_associate */
          {
              close( port_fd );
              port_fd = -1;
          }
          else perror( "port_associate" );  /* should not happen */
      }
  }
  
  static inline void remove_epoll_user( struct fd *fd, int user )
  {
      if (port_fd == -1) return;
  
      if (pollfd[user].fd != -1)
      {
          port_dissociate( port_fd, PORT_SOURCE_FD, fd->unix_fd );
      }
  }
  
  static inline void main_loop_epoll(void)
  {
      int i, nget, ret, timeout;
      port_event_t events[128];
  
      if (port_fd == -1) return;
  
      while (active_users)
      {
          timeout = get_next_timeout();
          nget = 1;
  
          if (!active_users) break;  /* last user removed by a timeout */
          if (port_fd == -1) break;  /* an error occurred with event completion */
  
          if (timeout != -1)
          {
              struct timespec ts;
  
              ts.tv_sec = timeout / 1000;
              ts.tv_nsec = (timeout % 1000) * 1000000;
              ret = port_getn( port_fd, events, sizeof(events)/sizeof(events[0]), &nget, &ts );
          }
          else ret = port_getn( port_fd, events, sizeof(events)/sizeof(events[0]), &nget, NULL );
  
  	if (ret == -1) break;  /* an error occurred with event completion */
  
          set_current_time();
  
          /* put the events into the pollfd array first, like poll does */
          for (i = 0; i < nget; i++)
          {
              long user = (long)events[i].portev_user;
              pollfd[user].revents = events[i].portev_events;
          }
  
          /* read events from the pollfd array, as set_fd_events may modify them */
          for (i = 0; i < nget; i++)
          {
              long user = (long)events[i].portev_user;
              if (pollfd[user].revents) fd_poll_event( poll_users[user], pollfd[user].revents );
              /* if we are still interested, reassociate the fd */
              if (pollfd[user].fd != -1) {
                  port_associate( port_fd, PORT_SOURCE_FD, pollfd[user].fd, pollfd[user].events, (void *)user );
              }
          }
      }
  }
  
  #else /* HAVE_KQUEUE */
  
  static inline void init_epoll(void) { }
  static inline void set_fd_epoll_events( struct fd *fd, int user, int events ) { }
  static inline void remove_epoll_user( struct fd *fd, int user ) { }
  static inline void main_loop_epoll(void) { }
  
  #endif /* USE_EPOLL */
  
  
  /* add a user in the poll array and return its index, or -1 on failure */
  static int add_poll_user( struct fd *fd )
  {
      int ret;
      if (freelist)
      {
          ret = freelist - poll_users;
          freelist = (struct fd **)poll_users[ret];
      }
      else
      {
          if (nb_users == allocated_users)
          {
              struct fd **newusers;
              struct pollfd *newpoll;
              int new_count = allocated_users ? (allocated_users + allocated_users / 2) : 16;
              if (!(newusers = realloc( poll_users, new_count * sizeof(*poll_users) ))) return -1;
              if (!(newpoll = realloc( pollfd, new_count * sizeof(*pollfd) )))
              {
                  if (allocated_users)
                      poll_users = newusers;
                  else
                      free( newusers );
                  return -1;
              }
              poll_users = newusers;
              pollfd = newpoll;
              if (!allocated_users) init_epoll();
              allocated_users = new_count;
          }
          ret = nb_users++;
      }
      pollfd[ret].fd = -1;
      pollfd[ret].events = 0;
      pollfd[ret].revents = 0;
      poll_users[ret] = fd;
      active_users++;
      return ret;
  }
  
  /* remove a user from the poll list */
  static void remove_poll_user( struct fd *fd, int user )
  {
      assert( user >= 0 );
      assert( poll_users[user] == fd );
  
      remove_epoll_user( fd, user );
      pollfd[user].fd = -1;
      pollfd[user].events = 0;
      pollfd[user].revents = 0;
      poll_users[user] = (struct fd *)freelist;
      freelist = &poll_users[user];
      active_users--;
  }
  
  /* process pending timeouts and return the time until the next timeout, in milliseconds */
  static int get_next_timeout(void)
  {
      if (!list_empty( &timeout_list ))
      {
          struct list expired_list, *ptr;
  
          /* first remove all expired timers from the list */
  
          list_init( &expired_list );
          while ((ptr = list_head( &timeout_list )) != NULL)
          {
              struct timeout_user *timeout = LIST_ENTRY( ptr, struct timeout_user, entry );
  
              if (timeout->when <= current_time)
              {
                  list_remove( &timeout->entry );
                  list_add_tail( &expired_list, &timeout->entry );
              }
              else break;
          }
  
          /* now call the callback for all the removed timers */
  
          while ((ptr = list_head( &expired_list )) != NULL)
          {
              struct timeout_user *timeout = LIST_ENTRY( ptr, struct timeout_user, entry );
              list_remove( &timeout->entry );
              timeout->callback( timeout->private );
              free( timeout );
          }
  
          if ((ptr = list_head( &timeout_list )) != NULL)
          {
              struct timeout_user *timeout = LIST_ENTRY( ptr, struct timeout_user, entry );
              int diff = (timeout->when - current_time + 9999) / 10000;
              if (diff < 0) diff = 0;
              return diff;
          }
      }
      return -1;  /* no pending timeouts */
  }
  
  /* server main poll() loop */
  void main_loop(void)
  {
      int i, ret, timeout;
  
      set_current_time();
      server_start_time = current_time;
  
      main_loop_epoll();
      /* fall through to normal poll loop */
  
      while (active_users)
      {
          timeout = get_next_timeout();
  
          if (!active_users) break;  /* last user removed by a timeout */
  
          ret = poll( pollfd, nb_users, timeout );
          set_current_time();
  
          if (ret > 0)
          {
              for (i = 0; i < nb_users; i++)
              {
                  if (pollfd[i].revents)
                  {
                      fd_poll_event( poll_users[i], pollfd[i].revents );
                      if (!--ret) break;
                  }
              }
          }
      }
  }
  
  
  /****************************************************************/
  /* device functions */
  
  static struct list device_hash[DEVICE_HASH_SIZE];
  
  static int is_device_removable( dev_t dev, int unix_fd )
  {
  #if defined(linux) && defined(HAVE_FSTATFS)
      struct statfs stfs;
  
      /* check for floppy disk */
      if (major(dev) == FLOPPY_MAJOR) return 1;
  
      if (fstatfs( unix_fd, &stfs ) == -1) return 0;
      return (stfs.f_type == 0x9660 ||    /* iso9660 */
              stfs.f_type == 0x9fa1 ||    /* supermount */
              stfs.f_type == 0x15013346); /* udf */
  #elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__) || defined(__APPLE__)
      struct statfs stfs;
  
      if (fstatfs( unix_fd, &stfs ) == -1) return 0;
      return (!strcmp("cd9660", stfs.f_fstypename) || !strcmp("udf", stfs.f_fstypename));
  #elif defined(__NetBSD__)
      struct statvfs stfs;
  
      if (fstatvfs( unix_fd, &stfs ) == -1) return 0;
      return (!strcmp("cd9660", stfs.f_fstypename) || !strcmp("udf", stfs.f_fstypename));
  #elif defined(sun)
  # include <sys/dkio.h>
  # include <sys/vtoc.h>
      struct dk_cinfo dkinf;
      if (ioctl( unix_fd, DKIOCINFO, &dkinf ) == -1) return 0;
      return (dkinf.dki_ctype == DKC_CDROM ||
              dkinf.dki_ctype == DKC_NCRFLOPPY ||
              dkinf.dki_ctype == DKC_SMSFLOPPY ||
              dkinf.dki_ctype == DKC_INTEL82072 ||
              dkinf.dki_ctype == DKC_INTEL82077);
  #else
      return 0;
  #endif
  }
  
  /* retrieve the device object for a given fd, creating it if needed */
  static struct device *get_device( dev_t dev, int unix_fd )
  {
      struct device *device;
      unsigned int i, hash = dev % DEVICE_HASH_SIZE;
  
      if (device_hash[hash].next)
      {
          LIST_FOR_EACH_ENTRY( device, &device_hash[hash], struct device, entry )
              if (device->dev == dev) return (struct device *)grab_object( device );
      }
      else list_init( &device_hash[hash] );
  
      /* not found, create it */
  
      if (unix_fd == -1) return NULL;
      if ((device = alloc_object( &device_ops )))
      {
          device->dev = dev;
          device->removable = is_device_removable( dev, unix_fd );
          for (i = 0; i < INODE_HASH_SIZE; i++) list_init( &device->inode_hash[i] );
          list_add_head( &device_hash[hash], &device->entry );
      }
      return device;
  }
  
  static void device_dump( struct object *obj, int verbose )
  {
      struct device *device = (struct device *)obj;
      fprintf( stderr, "Device dev=" );
      DUMP_LONG_LONG( device->dev );
      fprintf( stderr, "\n" );
  }
  
  static void device_destroy( struct object *obj )
  {
      struct device *device = (struct device *)obj;
      unsigned int i;
  
      for (i = 0; i < INODE_HASH_SIZE; i++)
          assert( list_empty(&device->inode_hash[i]) );
  
      list_remove( &device->entry );  /* remove it from the hash table */
  }
  
  
  /****************************************************************/
  /* inode functions */
  
  /* close all pending file descriptors in the closed list */
  static void inode_close_pending( struct inode *inode, int keep_unlinks )
  {
      struct list *ptr = list_head( &inode->closed );
  
      while (ptr)
      {
          struct closed_fd *fd = LIST_ENTRY( ptr, struct closed_fd, entry );
          struct list *next = list_next( &inode->closed, ptr );
  
          if (fd->unix_fd != -1)
          {
              close( fd->unix_fd );
              fd->unix_fd = -1;
          }
          if (!keep_unlinks || !fd->unlink)  /* get rid of it unless there's an unlink pending on that file */
          {
              list_remove( ptr );
              free( fd->unix_name );
              free( fd );
          }
          ptr = next;
      }
  }
  
  static void inode_dump( struct object *obj, int verbose )
  {
      struct inode *inode = (struct inode *)obj;
      fprintf( stderr, "Inode device=%p ino=", inode->device );
      DUMP_LONG_LONG( inode->ino );
      fprintf( stderr, "\n" );
  }
  
  static void inode_destroy( struct object *obj )
  {
      struct inode *inode = (struct inode *)obj;
      struct list *ptr;
  
      assert( list_empty(&inode->open) );
      assert( list_empty(&inode->locks) );
  
      list_remove( &inode->entry );
  
      while ((ptr = list_head( &inode->closed )))
      {
          struct closed_fd *fd = LIST_ENTRY( ptr, struct closed_fd, entry );
          list_remove( ptr );
          if (fd->unix_fd != -1) close( fd->unix_fd );
          if (fd->unlink)
          {
              /* make sure it is still the same file */
              struct stat st;
              if (!stat( fd->unix_name, &st ) && st.st_dev == inode->device->dev && st.st_ino == inode->ino)
              {
                  if (S_ISDIR(st.st_mode)) rmdir( fd->unix_name );
                  else unlink( fd->unix_name );
              }
          }
          free( fd->unix_name );
          free( fd );
      }
      release_object( inode->device );
  }
  
  /* retrieve the inode object for a given fd, creating it if needed */
  static struct inode *get_inode( dev_t dev, ino_t ino, int unix_fd )
  {
      struct device *device;
      struct inode *inode;
      unsigned int hash = ino % INODE_HASH_SIZE;
  
      if (!(device = get_device( dev, unix_fd ))) return NULL;
  
      LIST_FOR_EACH_ENTRY( inode, &device->inode_hash[hash], struct inode, entry )
      {
          if (inode->ino == ino)
          {
              release_object( device );
              return (struct inode *)grab_object( inode );
          }
      }
  
      /* not found, create it */
      if ((inode = alloc_object( &inode_ops )))
      {
          inode->device = device;
          inode->ino    = ino;
          list_init( &inode->open );
          list_init( &inode->locks );
          list_init( &inode->closed );
          list_add_head( &device->inode_hash[hash], &inode->entry );
      }
      else release_object( device );
  
      return inode;
  }
  
  /* add fd to the inode list of file descriptors to close */
  static void inode_add_closed_fd( struct inode *inode, struct closed_fd *fd )
  {
      if (!list_empty( &inode->locks ))
      {
          list_add_head( &inode->closed, &fd->entry );
      }
      else if (fd->unlink)  /* close the fd but keep the structure around for unlink */
      {
          if (fd->unix_fd != -1) close( fd->unix_fd );
          fd->unix_fd = -1;
          list_add_head( &inode->closed, &fd->entry );
      }
      else  /* no locks on this inode and no unlink, get rid of the fd */
      {
          if (fd->unix_fd != -1) close( fd->unix_fd );
          free( fd->unix_name );
          free( fd );
      }
  }
  
  
  /****************************************************************/
  /* file lock functions */
  
  static void file_lock_dump( struct object *obj, int verbose )
  {
      struct file_lock *lock = (struct file_lock *)obj;
      fprintf( stderr, "Lock %s fd=%p proc=%p start=",
               lock->shared ? "shared" : "excl", lock->fd, lock->process );
      DUMP_LONG_LONG( lock->start );
      fprintf( stderr, " end=" );
      DUMP_LONG_LONG( lock->end );
      fprintf( stderr, "\n" );
  }
  
  static int file_lock_signaled( struct object *obj, struct wait_queue_entry *entry )
  {
      struct file_lock *lock = (struct file_lock *)obj;
      /* lock is signaled if it has lost its owner */
      return !lock->process;
  }
  
  /* set (or remove) a Unix lock if possible for the given range */
  static int set_unix_lock( struct fd *fd, file_pos_t start, file_pos_t end, int type )
  {
      struct flock fl;
  
      if (!fd->fs_locks) return 1;  /* no fs locks possible for this fd */
      for (;;)
      {
          if (start == end) return 1;  /* can't set zero-byte lock */
          if (start > max_unix_offset) return 1;  /* ignore it */
          fl.l_type   = type;
          fl.l_whence = SEEK_SET;
          fl.l_start  = start;
          if (!end || end > max_unix_offset) fl.l_len = 0;
          else fl.l_len = end - start;
          if (fcntl( fd->unix_fd, F_SETLK, &fl ) != -1) return 1;
  
          switch(errno)
          {
          case EACCES:
              /* check whether locks work at all on this file system */
              if (fcntl( fd->unix_fd, F_GETLK, &fl ) != -1)
              {
                  set_error( STATUS_FILE_LOCK_CONFLICT );
                  return 0;
              }
              /* fall through */
          case EIO:
          case ENOLCK:
          case ENOTSUP:
              /* no locking on this fs, just ignore it */
              fd->fs_locks = 0;
              return 1;
          case EAGAIN:
              set_error( STATUS_FILE_LOCK_CONFLICT );
              return 0;
          case EBADF:
              /* this can happen if we try to set a write lock on a read-only file */
              /* try to at least grab a read lock */
              if (fl.l_type == F_WRLCK)
              {
                  type = F_RDLCK;
                  break; /* retry */
              }
              set_error( STATUS_ACCESS_DENIED );
              return 0;
  #ifdef EOVERFLOW
          case EOVERFLOW:
  #endif
          case EINVAL:
              /* this can happen if off_t is 64-bit but the kernel only supports 32-bit */
              /* in that case we shrink the limit and retry */
              if (max_unix_offset > INT_MAX)
              {
                  max_unix_offset = INT_MAX;
                  break;  /* retry */
              }
              /* fall through */
          default:
              file_set_error();
              return 0;
          }
      }
  }
  
  /* check if interval [start;end) overlaps the lock */
  static inline int lock_overlaps( struct file_lock *lock, file_pos_t start, file_pos_t end )
  {
      if (lock->end && start >= lock->end) return 0;
      if (end && lock->start >= end) return 0;
      return 1;
  }
  
  /* remove Unix locks for all bytes in the specified area that are no longer locked */
  static void remove_unix_locks( struct fd *fd, file_pos_t start, file_pos_t end )
  {
      struct hole
      {
          struct hole *next;
          struct hole *prev;
          file_pos_t   start;
          file_pos_t   end;
      } *first, *cur, *next, *buffer;
  
      struct list *ptr;
      int count = 0;
  
      if (!fd->inode) return;
      if (!fd->fs_locks) return;
      if (start == end || start > max_unix_offset) return;
      if (!end || end > max_unix_offset) end = max_unix_offset + 1;
  
      /* count the number of locks overlapping the specified area */
  
      LIST_FOR_EACH( ptr, &fd->inode->locks )
      {
          struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, inode_entry );
          if (lock->start == lock->end) continue;
          if (lock_overlaps( lock, start, end )) count++;
      }
  
      if (!count)  /* no locks at all, we can unlock everything */
      {
          set_unix_lock( fd, start, end, F_UNLCK );
          return;
      }
  
      /* allocate space for the list of holes */
      /* max. number of holes is number of locks + 1 */
  
      if (!(buffer = malloc( sizeof(*buffer) * (count+1) ))) return;
      first = buffer;
      first->next  = NULL;
      first->prev  = NULL;
      first->start = start;
      first->end   = end;
      next = first + 1;
  
      /* build a sorted list of unlocked holes in the specified area */
  
      LIST_FOR_EACH( ptr, &fd->inode->locks )
      {
          struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, inode_entry );
          if (lock->start == lock->end) continue;
          if (!lock_overlaps( lock, start, end )) continue;
  
          /* go through all the holes touched by this lock */
          for (cur = first; cur; cur = cur->next)
          {
              if (cur->end <= lock->start) continue; /* hole is before start of lock */
              if (lock->end && cur->start >= lock->end) break;  /* hole is after end of lock */
  
              /* now we know that lock is overlapping hole */
  
              if (cur->start >= lock->start)  /* lock starts before hole, shrink from start */
              {
                  cur->start = lock->end;
                  if (cur->start && cur->start < cur->end) break;  /* done with this lock */
                  /* now hole is empty, remove it */
                  if (cur->next) cur->next->prev = cur->prev;
                  if (cur->prev) cur->prev->next = cur->next;
                  else if (!(first = cur->next)) goto done;  /* no more holes at all */
              }
              else if (!lock->end || cur->end <= lock->end)  /* lock larger than hole, shrink from end */
              {
                  cur->end = lock->start;
                  assert( cur->start < cur->end );
              }
              else  /* lock is in the middle of hole, split hole in two */
              {
                  next->prev = cur;
                  next->next = cur->next;
                  cur->next = next;
                  next->start = lock->end;
                  next->end = cur->end;
                  cur->end = lock->start;
                  assert( next->start < next->end );
                  assert( cur->end < next->start );
                  next++;
                  break;  /* done with this lock */
              }
          }
      }
  
      /* clear Unix locks for all the holes */
  
      for (cur = first; cur; cur = cur->next)
          set_unix_lock( fd, cur->start, cur->end, F_UNLCK );
  
   done:
      free( buffer );
  }
  
  /* create a new lock on a fd */
  static struct file_lock *add_lock( struct fd *fd, int shared, file_pos_t start, file_pos_t end )
  {
      struct file_lock *lock;
  
      if (!(lock = alloc_object( &file_lock_ops ))) return NULL;
      lock->shared  = shared;
      lock->start   = start;
      lock->end     = end;
      lock->fd      = fd;
      lock->process = current->process;
  
      /* now try to set a Unix lock */
      if (!set_unix_lock( lock->fd, lock->start, lock->end, lock->shared ? F_RDLCK : F_WRLCK ))
      {
          release_object( lock );
          return NULL;
      }
      list_add_tail( &fd->locks, &lock->fd_entry );
      list_add_tail( &fd->inode->locks, &lock->inode_entry );
      list_add_tail( &lock->process->locks, &lock->proc_entry );
      return lock;
  }
  
  /* remove an existing lock */
  static void remove_lock( struct file_lock *lock, int remove_unix )
  {
      struct inode *inode = lock->fd->inode;
  
      list_remove( &lock->fd_entry );
      list_remove( &lock->inode_entry );
      list_remove( &lock->proc_entry );
      if (remove_unix) remove_unix_locks( lock->fd, lock->start, lock->end );
      if (list_empty( &inode->locks )) inode_close_pending( inode, 1 );
      lock->process = NULL;
      wake_up( &lock->obj, 0 );
      release_object( lock );
  }
  
  /* remove all locks owned by a given process */
  void remove_process_locks( struct process *process )
  {
      struct list *ptr;
  
      while ((ptr = list_head( &process->locks )))
      {
          struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, proc_entry );
          remove_lock( lock, 1 );  /* this removes it from the list */
      }
  }
  
  /* remove all locks on a given fd */
  static void remove_fd_locks( struct fd *fd )
  {
      file_pos_t start = FILE_POS_T_MAX, end = 0;
      struct list *ptr;
  
      while ((ptr = list_head( &fd->locks )))
      {
          struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, fd_entry );
          if (lock->start < start) start = lock->start;
          if (!lock->end || lock->end > end) end = lock->end - 1;
          remove_lock( lock, 0 );
      }
      if (start < end) remove_unix_locks( fd, start, end + 1 );
  }
  
  /* add a lock on an fd */
  /* returns handle to wait on */
  obj_handle_t lock_fd( struct fd *fd, file_pos_t start, file_pos_t count, int shared, int wait )
  {
      struct list *ptr;
      file_pos_t end = start + count;
  
      if (!fd->inode)  /* not a regular file */
      {
          set_error( STATUS_INVALID_DEVICE_REQUEST );
          return 0;
      }
  
      /* don't allow wrapping locks */
      if (end && end < start)
      {
          set_error( STATUS_INVALID_PARAMETER );
          return 0;
      }
  
      /* check if another lock on that file overlaps the area */
      LIST_FOR_EACH( ptr, &fd->inode->locks )
      {
          struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, inode_entry );
          if (!lock_overlaps( lock, start, end )) continue;
          if (shared && (lock->shared || lock->fd == fd)) continue;
          /* found one */
          if (!wait)
          {
              set_error( STATUS_FILE_LOCK_CONFLICT );
              return 0;
          }
          set_error( STATUS_PENDING );
          return alloc_handle( current->process, lock, SYNCHRONIZE, 0 );
      }
  
      /* not found, add it */
      if (add_lock( fd, shared, start, end )) return 0;
      if (get_error() == STATUS_FILE_LOCK_CONFLICT)
      {
          /* Unix lock conflict -> tell client to wait and retry */
          if (wait) set_error( STATUS_PENDING );
      }
      return 0;
  }
  
  /* remove a lock on an fd */
  void unlock_fd( struct fd *fd, file_pos_t start, file_pos_t count )
  {
      struct list *ptr;
      file_pos_t end = start + count;
  
      /* find an existing lock with the exact same parameters */
      LIST_FOR_EACH( ptr, &fd->locks )
      {
          struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, fd_entry );
          if ((lock->start == start) && (lock->end == end))
          {
              remove_lock( lock, 1 );
              return;
          }
      }
      set_error( STATUS_FILE_LOCK_CONFLICT );
  }
  
  
  /****************************************************************/
  /* file descriptor functions */
  
  static void fd_dump( struct object *obj, int verbose )
  {
      struct fd *fd = (struct fd *)obj;
      fprintf( stderr, "Fd unix_fd=%d user=%p options=%08x", fd->unix_fd, fd->user, fd->options );
      if (fd->inode) fprintf( stderr, " inode=%p unlink=%d", fd->inode, fd->closed->unlink );
      fprintf( stderr, "\n" );
  }
  
  static void fd_destroy( struct object *obj )
  {
      struct fd *fd = (struct fd *)obj;
  
      free_async_queue( fd->read_q );
      free_async_queue( fd->write_q );
      free_async_queue( fd->wait_q );
  
      if (fd->completion) release_object( fd->completion );
      remove_fd_locks( fd );
      list_remove( &fd->inode_entry );
      if (fd->poll_index != -1) remove_poll_user( fd, fd->poll_index );
      if (fd->inode)
      {
          inode_add_closed_fd( fd->inode, fd->closed );
          release_object( fd->inode );
      }
      else  /* no inode, close it right away */
      {
          if (fd->unix_fd != -1) close( fd->unix_fd );
          free( fd->unix_name );
      }
  }
  
  /* check if the desired access is possible without violating */
  /* the sharing mode of other opens of the same file */
  static unsigned int check_sharing( struct fd *fd, unsigned int access, unsigned int sharing,
                                     unsigned int open_flags, unsigned int options )
  {
      /* only a few access bits are meaningful wrt sharing */
      const unsigned int read_access = FILE_READ_DATA | FILE_EXECUTE;
      const unsigned int write_access = FILE_WRITE_DATA | FILE_APPEND_DATA;
      const unsigned int all_access = read_access | write_access | DELETE;
  
      unsigned int existing_sharing = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
      unsigned int existing_access = 0;
      struct list *ptr;
  
      fd->access = access;
      fd->sharing = sharing;
  
      LIST_FOR_EACH( ptr, &fd->inode->open )
      {
          struct fd *fd_ptr = LIST_ENTRY( ptr, struct fd, inode_entry );
          if (fd_ptr != fd)
          {
              /* if access mode is 0, sharing mode is ignored */
              if (fd_ptr->access & all_access) existing_sharing &= fd_ptr->sharing;
              existing_access |= fd_ptr->access;
          }
      }
  
      if (((access & read_access) && !(existing_sharing & FILE_SHARE_READ)) ||
          ((access & write_access) && !(existing_sharing & FILE_SHARE_WRITE)) ||
          ((access & DELETE) && !(existing_sharing & FILE_SHARE_DELETE)))
          return STATUS_SHARING_VIOLATION;
      if (((existing_access & FILE_MAPPING_WRITE) && !(sharing & FILE_SHARE_WRITE)) ||
          ((existing_access & FILE_MAPPING_IMAGE) && (access & FILE_WRITE_DATA)))
          return STATUS_SHARING_VIOLATION;
      if ((existing_access & FILE_MAPPING_IMAGE) && (options & FILE_DELETE_ON_CLOSE))
          return STATUS_CANNOT_DELETE;
      if ((existing_access & FILE_MAPPING_ACCESS) && (open_flags & O_TRUNC))
          return STATUS_USER_MAPPED_FILE;
      if (!(access & all_access))
          return 0;  /* if access mode is 0, sharing mode is ignored (except for mappings) */
      if (((existing_access & read_access) && !(sharing & FILE_SHARE_READ)) ||
          ((existing_access & write_access) && !(sharing & FILE_SHARE_WRITE)) ||
          ((existing_access & DELETE) && !(sharing & FILE_SHARE_DELETE)))
          return STATUS_SHARING_VIOLATION;
      return 0;
  }
  
  /* set the events that select waits for on this fd */
  void set_fd_events( struct fd *fd, int events )
  {
      int user = fd->poll_index;
      assert( poll_users[user] == fd );
  
      set_fd_epoll_events( fd, user, events );
  
      if (events == -1)  /* stop waiting on this fd completely */
      {
          pollfd[user].fd = -1;
          pollfd[user].events = POLLERR;
          pollfd[user].revents = 0;
      }
      else if (pollfd[user].fd != -1 || !pollfd[user].events)
      {
          pollfd[user].fd = fd->unix_fd;
          pollfd[user].events = events;
      }
  }
  
  /* prepare an fd for unmounting its corresponding device */
  static inline void unmount_fd( struct fd *fd )
  {
      assert( fd->inode );
  
      async_wake_up( fd->read_q, STATUS_VOLUME_DISMOUNTED );
      async_wake_up( fd->write_q, STATUS_VOLUME_DISMOUNTED );
  
      if (fd->poll_index != -1) set_fd_events( fd, -1 );
  
      if (fd->unix_fd != -1) close( fd->unix_fd );
  
      fd->unix_fd = -1;
      fd->no_fd_status = STATUS_VOLUME_DISMOUNTED;
      fd->closed->unix_fd = -1;
      fd->closed->unlink = 0;
  
      /* stop using Unix locks on this fd (existing locks have been removed by close) */
      fd->fs_locks = 0;
  }
  
  /* allocate an fd object, without setting the unix fd yet */
  static struct fd *alloc_fd_object(void)
  {
      struct fd *fd = alloc_object( &fd_ops );
  
      if (!fd) return NULL;
  
      fd->fd_ops     = NULL;
      fd->user       = NULL;
      fd->inode      = NULL;
      fd->closed     = NULL;
      fd->access     = 0;
      fd->options    = 0;
      fd->sharing    = 0;
      fd->unix_fd    = -1;
      fd->unix_name  = NULL;
      fd->cacheable  = 0;
      fd->signaled   = 1;
      fd->fs_locks   = 1;
      fd->poll_index = -1;
      fd->read_q     = NULL;
      fd->write_q    = NULL;
      fd->wait_q     = NULL;
      fd->completion = NULL;
      list_init( &fd->inode_entry );
      list_init( &fd->locks );
  
      if ((fd->poll_index = add_poll_user( fd )) == -1)
      {
          release_object( fd );
          return NULL;
      }
      return fd;
  }
  
  /* allocate a pseudo fd object, for objects that need to behave like files but don't have a unix fd */
  struct fd *alloc_pseudo_fd( const struct fd_ops *fd_user_ops, struct object *user, unsigned int options )
  {
      struct fd *fd = alloc_object( &fd_ops );
  
      if (!fd) return NULL;
  
      fd->fd_ops     = fd_user_ops;
      fd->user       = user;
      fd->inode      = NULL;
      fd->closed     = NULL;
      fd->access     = 0;
      fd->options    = options;
      fd->sharing    = 0;
      fd->unix_name  = NULL;
      fd->unix_fd    = -1;
      fd->cacheable  = 0;
      fd->signaled   = 0;
      fd->fs_locks   = 0;
      fd->poll_index = -1;
      fd->read_q     = NULL;
      fd->write_q    = NULL;
      fd->wait_q     = NULL;
      fd->completion = NULL;
      fd->no_fd_status = STATUS_BAD_DEVICE_TYPE;
      list_init( &fd->inode_entry );
      list_init( &fd->locks );
      return fd;
  }
  
  /* duplicate an fd object for a different user */
  struct fd *dup_fd_object( struct fd *orig, unsigned int access, unsigned int sharing, unsigned int options )
  {
      unsigned int err;
      struct fd *fd = alloc_fd_object();
  
      if (!fd) return NULL;
  
      fd->options    = options;
      fd->cacheable  = orig->cacheable;
  
      if (orig->unix_name)
      {
          if (!(fd->unix_name = mem_alloc( strlen(orig->unix_name) + 1 ))) goto failed;
          strcpy( fd->unix_name, orig->unix_name );
      }
  
      if (orig->inode)
      {
          struct closed_fd *closed = mem_alloc( sizeof(*closed) );
          if (!closed) goto failed;
          if ((fd->unix_fd = dup( orig->unix_fd )) == -1)
          {
              file_set_error();
              free( closed );
              goto failed;
          }
          closed->unix_fd = fd->unix_fd;
          closed->unlink = 0;
          closed->unix_name = fd->unix_name;
          fd->closed = closed;
          fd->inode = (struct inode *)grab_object( orig->inode );
          list_add_head( &fd->inode->open, &fd->inode_entry );
          if ((err = check_sharing( fd, access, sharing, 0, options )))
          {
              set_error( err );
              goto failed;
          }
      }
      else if ((fd->unix_fd = dup( orig->unix_fd )) == -1)
      {
          file_set_error();
          goto failed;
      }
      return fd;
  
  failed:
      release_object( fd );
      return NULL;
  }
  
  /* find an existing fd object that can be reused for a mapping */
  struct fd *get_fd_object_for_mapping( struct fd *fd, unsigned int access, unsigned int sharing )
  {
      struct fd *fd_ptr;
  
      if (!fd->inode) return NULL;
  
      LIST_FOR_EACH_ENTRY( fd_ptr, &fd->inode->open, struct fd, inode_entry )
          if (fd_ptr->access == access && fd_ptr->sharing == sharing)
              return (struct fd *)grab_object( fd_ptr );
  
      return NULL;
  }
  
  /* set the status to return when the fd has no associated unix fd */
  void set_no_fd_status( struct fd *fd, unsigned int status )
  {
      fd->no_fd_status = status;
  }
  
  /* sets the user of an fd that previously had no user */
  void set_fd_user( struct fd *fd, const struct fd_ops *user_ops, struct object *user )
  {
      assert( fd->fd_ops == NULL );
      fd->fd_ops = user_ops;
      fd->user   = user;
  }
  
  char *dup_fd_name( struct fd *root, const char *name )
  {
      char *ret;
  
      if (!root) return strdup( name );
      if (!root->unix_name) return NULL;
  
      /* skip . prefix */
      if (name[0] == '.' && (!name[1] || name[1] == '/')) name++;
  
      if ((ret = malloc( strlen(root->unix_name) + strlen(name) + 2 )))
      {
          strcpy( ret, root->unix_name );
          if (name[0] && name[0] != '/') strcat( ret, "/" );
          strcat( ret, name );
      }
      return ret;
  }
  
  /* open() wrapper that returns a struct fd with no fd user set */
  struct fd *open_fd( struct fd *root, const char *name, int flags, mode_t *mode, unsigned int access,
                      unsigned int sharing, unsigned int options )
  {
      struct stat st;
      struct closed_fd *closed_fd;
      struct fd *fd;
      int root_fd = -1;
      int rw_mode;
  
      if (((options & FILE_DELETE_ON_CLOSE) && !(access & DELETE)) ||
          ((options & FILE_DIRECTORY_FILE) && (flags & O_TRUNC)))
      {
          set_error( STATUS_INVALID_PARAMETER );
          return NULL;
      }
  
      if (!(fd = alloc_fd_object())) return NULL;
  
      fd->options = options;
      if (!(closed_fd = mem_alloc( sizeof(*closed_fd) )))
      {
          release_object( fd );
          return NULL;
      }
  
      if (root)
      {
          if ((root_fd = get_unix_fd( root )) == -1) goto error;
          if (fchdir( root_fd ) == -1)
          {
              file_set_error();
              root_fd = -1;
              goto error;
          }
      }
  
      /* create the directory if needed */
      if ((options & FILE_DIRECTORY_FILE) && (flags & O_CREAT))
      {
          if (mkdir( name, *mode ) == -1)
          {
              if (errno != EEXIST || (flags & O_EXCL))
              {
                  file_set_error();
                  goto error;
              }
          }
          flags &= ~(O_CREAT | O_EXCL | O_TRUNC);
      }
  
      if ((access & FILE_UNIX_WRITE_ACCESS) && !(options & FILE_DIRECTORY_FILE))
      {
          if (access & FILE_UNIX_READ_ACCESS) rw_mode = O_RDWR;
          else rw_mode = O_WRONLY;
      }
      else rw_mode = O_RDONLY;
  
      fd->unix_name = dup_fd_name( root, name );
  
      if ((fd->unix_fd = open( name, rw_mode | (flags & ~O_TRUNC), *mode )) == -1)
      {
          /* if we tried to open a directory for write access, retry read-only */
          if (errno == EISDIR)
          {
              if ((access & FILE_UNIX_WRITE_ACCESS) || (flags & O_CREAT))
                  fd->unix_fd = open( name, O_RDONLY | (flags & ~(O_TRUNC | O_CREAT | O_EXCL)), *mode );
          }
  
          if (fd->unix_fd == -1)
          {
              file_set_error();
              goto error;
          }
      }
  
      closed_fd->unix_fd = fd->unix_fd;
      closed_fd->unlink = 0;
      closed_fd->unix_name = fd->unix_name;
      fstat( fd->unix_fd, &st );
      *mode = st.st_mode;
  
      /* only bother with an inode for normal files and directories */
      if (S_ISREG(st.st_mode) || S_ISDIR(st.st_mode))
      {
          unsigned int err;
          struct inode *inode = get_inode( st.st_dev, st.st_ino, fd->unix_fd );
  
          if (!inode)
          {
              /* we can close the fd because there are no others open on the same file,
               * otherwise we wouldn't have failed to allocate a new inode
               */
              goto error;
          }
          fd->inode = inode;
          fd->closed = closed_fd;
          fd->cacheable = !inode->device->removable;
          list_add_head( &inode->open, &fd->inode_entry );
          closed_fd = NULL;
  
          /* check directory options */
          if ((options & FILE_DIRECTORY_FILE) && !S_ISDIR(st.st_mode))
          {
              set_error( STATUS_NOT_A_DIRECTORY );
              goto error;
          }
          if ((options & FILE_NON_DIRECTORY_FILE) && S_ISDIR(st.st_mode))
          {
              set_error( STATUS_FILE_IS_A_DIRECTORY );
              goto error;
          }
          if ((err = check_sharing( fd, access, sharing, flags, options )))
          {
              set_error( err );
              goto error;
          }
  
          /* can't unlink files if we don't have permission to access */
          if ((options & FILE_DELETE_ON_CLOSE) && !(flags & O_CREAT) &&
              !(st.st_mode & (S_IWUSR | S_IWGRP | S_IWOTH)))
          {
              set_error( STATUS_CANNOT_DELETE );
              goto error;
          }
  
          fd->closed->unlink = (options & FILE_DELETE_ON_CLOSE) != 0;
          if (flags & O_TRUNC)
          {
              if (S_ISDIR(st.st_mode))
              {
                  set_error( STATUS_OBJECT_NAME_COLLISION );
                  goto error;
              }
              ftruncate( fd->unix_fd, 0 );
          }
      }
      else  /* special file */
      {
          if (options & FILE_DELETE_ON_CLOSE)  /* we can't unlink special files */
          {
              set_error( STATUS_INVALID_PARAMETER );
              goto error;
          }
          free( closed_fd );
          fd->cacheable = 1;
      }
      if (root_fd != -1) fchdir( server_dir_fd ); /* go back to the server dir */
      return fd;
  
  error:
      release_object( fd );
      free( closed_fd );
      if (root_fd != -1) fchdir( server_dir_fd ); /* go back to the server dir */
      return NULL;
  }
  
  /* create an fd for an anonymous file */
  /* if the function fails the unix fd is closed */
  struct fd *create_anonymous_fd( const struct fd_ops *fd_user_ops, int unix_fd, struct object *user,
                                  unsigned int options )
  {
      struct fd *fd = alloc_fd_object();
  
      if (fd)
      {
          set_fd_user( fd, fd_user_ops, user );
          fd->unix_fd = unix_fd;
          fd->options = options;
          return fd;
      }
      close( unix_fd );
      return NULL;
  }
  
  /* retrieve the object that is using an fd */
  void *get_fd_user( struct fd *fd )
  {
      return fd->user;
  }
  
  /* retrieve the opening options for the fd */
  unsigned int get_fd_options( struct fd *fd )
  {
      return fd->options;
  }
  
  /* retrieve the unix fd for an object */
  int get_unix_fd( struct fd *fd )
  {
      if (fd->unix_fd == -1) set_error( fd->no_fd_status );
      return fd->unix_fd;
  }
  
  /* check if two file descriptors point to the same file */
  int is_same_file_fd( struct fd *fd1, struct fd *fd2 )
  {
      return fd1->inode == fd2->inode;
  }
  
  /* allow the fd to be cached (can't be reset once set) */
  void allow_fd_caching( struct fd *fd )
  {
      fd->cacheable = 1;
  }
  
  /* check if fd is on a removable device */
  int is_fd_removable( struct fd *fd )
  {
      return (fd->inode && fd->inode->device->removable);
  }
  
  /* set or clear the fd signaled state */
  void set_fd_signaled( struct fd *fd, int signaled )
  {
      fd->signaled = signaled;
      if (signaled) wake_up( fd->user, 0 );
  }
  
  /* check if fd is signaled */
  int is_fd_signaled( struct fd *fd )
  {
      return fd->signaled;
  }
  
  /* handler for close_handle that refuses to close fd-associated handles in other processes */
  int fd_close_handle( struct object *obj, struct process *process, obj_handle_t handle )
  {
      return (!current || current->process == process);
  }
  
  /* check if events are pending and if yes return which one(s) */
  int check_fd_events( struct fd *fd, int events )
  {
      struct pollfd pfd;
  
      if (fd->unix_fd == -1) return POLLERR;
      if (fd->inode) return events;  /* regular files are always signaled */
  
      pfd.fd     = fd->unix_fd;
      pfd.events = events;
      if (poll( &pfd, 1, 0 ) <= 0) return 0;
      return pfd.revents;
  }
  
  /* default signaled() routine for objects that poll() on an fd */
  int default_fd_signaled( struct object *obj, struct wait_queue_entry *entry )
  {
      struct fd *fd = get_obj_fd( obj );
      int ret = fd->signaled;
      release_object( fd );
      return ret;
  }
  
  /* default map_access() routine for objects that behave like an fd */
  unsigned int default_fd_map_access( struct object *obj, unsigned int access )
  {
      if (access & GENERIC_READ)    access |= FILE_GENERIC_READ;
      if (access & GENERIC_WRITE)   access |= FILE_GENERIC_WRITE;
      if (access & GENERIC_EXECUTE) access |= FILE_GENERIC_EXECUTE;
      if (access & GENERIC_ALL)     access |= FILE_ALL_ACCESS;
      return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
  }
  
  int default_fd_get_poll_events( struct fd *fd )
  {
      int events = 0;
  
      if (async_waiting( fd->read_q )) events |= POLLIN;
      if (async_waiting( fd->write_q )) events |= POLLOUT;
      return events;
  }
  
  /* default handler for poll() events */
  void default_poll_event( struct fd *fd, int event )
  {
      if (event & (POLLIN | POLLERR | POLLHUP)) async_wake_up( fd->read_q, STATUS_ALERTED );
      if (event & (POLLOUT | POLLERR | POLLHUP)) async_wake_up( fd->write_q, STATUS_ALERTED );
  
      /* if an error occurred, stop polling this fd to avoid busy-looping */
      if (event & (POLLERR | POLLHUP)) set_fd_events( fd, -1 );
      else if (!fd->inode) set_fd_events( fd, fd->fd_ops->get_poll_events( fd ) );
  }
  
  struct async *fd_queue_async( struct fd *fd, const async_data_t *data, int type )
  {
      struct async_queue *queue;
      struct async *async;
  
      switch (type)
      {
      case ASYNC_TYPE_READ:
          if (!fd->read_q && !(fd->read_q = create_async_queue( fd ))) return NULL;
          queue = fd->read_q;
          break;
      case ASYNC_TYPE_WRITE:
          if (!fd->write_q && !(fd->write_q = create_async_queue( fd ))) return NULL;
          queue = fd->write_q;
          break;
      case ASYNC_TYPE_WAIT:
          if (!fd->wait_q && !(fd->wait_q = create_async_queue( fd ))) return NULL;
          queue = fd->wait_q;
          break;
      default:
          queue = NULL;
          assert(0);
      }
  
      if ((async = create_async( current, queue, data )) && type != ASYNC_TYPE_WAIT)
      {
          if (!fd->inode)
              set_fd_events( fd, fd->fd_ops->get_poll_events( fd ) );
          else  /* regular files are always ready for read and write */
              async_wake_up( queue, STATUS_ALERTED );
      }
      return async;
  }
  
  void fd_async_wake_up( struct fd *fd, int type, unsigned int status )
  {
      switch (type)
      {
      case ASYNC_TYPE_READ:
          async_wake_up( fd->read_q, status );
          break;
      case ASYNC_TYPE_WRITE:
          async_wake_up( fd->write_q, status );
          break;
      case ASYNC_TYPE_WAIT:
          async_wake_up( fd->wait_q, status );
          break;
      default:
          assert(0);
      }
  }
  
  void fd_reselect_async( struct fd *fd, struct async_queue *queue )
  {
      fd->fd_ops->reselect_async( fd, queue );
  }
  
  void no_fd_queue_async( struct fd *fd, const async_data_t *data, int type, int count )
  {
      set_error( STATUS_OBJECT_TYPE_MISMATCH );
  }
  
  void default_fd_queue_async( struct fd *fd, const async_data_t *data, int type, int count )
  {
      struct async *async;
  
      if ((async = fd_queue_async( fd, data, type )))
      {
          release_object( async );
          set_error( STATUS_PENDING );
      }
  }
  
  /* default reselect_async() fd routine */
  void default_fd_reselect_async( struct fd *fd, struct async_queue *queue )
  {
      if (queue != fd->wait_q)
      {
          int poll_events = fd->fd_ops->get_poll_events( fd );
          int events = check_fd_events( fd, poll_events );
          if (events) fd->fd_ops->poll_event( fd, events );
          else set_fd_events( fd, poll_events );
      }
  }
  
  /* default cancel_async() fd routine */
  int default_fd_cancel_async( struct fd *fd, struct process *process, struct thread *thread, client_ptr_t iosb )
  {
      int n = 0;
  
      n += async_wake_up_by( fd->read_q, process, thread, iosb, STATUS_CANCELLED );
      n += async_wake_up_by( fd->write_q, process, thread, iosb, STATUS_CANCELLED );
      n += async_wake_up_by( fd->wait_q, process, thread, iosb, STATUS_CANCELLED );
      return n;
  }
  
  static inline int is_valid_mounted_device( struct stat *st )
  {
  #if defined(linux) || defined(__sun__)
      return S_ISBLK( st->st_mode );
  #else
      /* disks are char devices on *BSD */
      return S_ISCHR( st->st_mode );
  #endif
  }
  
  /* close all Unix file descriptors on a device to allow unmounting it */
  static void unmount_device( struct fd *device_fd )
  {
      unsigned int i;
      struct stat st;
      struct device *device;
      struct inode *inode;
      struct fd *fd;
      int unix_fd = get_unix_fd( device_fd );
  
      if (unix_fd == -1) return;
  
      if (fstat( unix_fd, &st ) == -1 || !is_valid_mounted_device( &st ))
      {
          set_error( STATUS_INVALID_PARAMETER );
          return;
      }
  
      if (!(device = get_device( st.st_rdev, -1 ))) return;
  
      for (i = 0; i < INODE_HASH_SIZE; i++)
      {
          LIST_FOR_EACH_ENTRY( inode, &device->inode_hash[i], struct inode, entry )
          {
              LIST_FOR_EACH_ENTRY( fd, &inode->open, struct fd, inode_entry )
              {
                  unmount_fd( fd );
              }
              inode_close_pending( inode, 0 );
          }
      }
      /* remove it from the hash table */
      list_remove( &device->entry );
      list_init( &device->entry );
      release_object( device );
  }
  
  /* default read() routine */
  obj_handle_t no_fd_read( struct fd *fd, const async_data_t *async, int blocking, file_pos_t pos )
  {
      set_error( STATUS_OBJECT_TYPE_MISMATCH );
      return 0;
  }
  
  /* default write() routine */
  obj_handle_t no_fd_write( struct fd *fd, const async_data_t *async, int blocking,
                            file_pos_t pos, data_size_t *written )
  {
      set_error( STATUS_OBJECT_TYPE_MISMATCH );
      return 0;
  }
  
  /* default flush() routine */
  obj_handle_t no_fd_flush( struct fd *fd, const async_data_t *async, int blocking )
  {
      set_error( STATUS_OBJECT_TYPE_MISMATCH );
      return 0;
  }
  
  /* default ioctl() routine */
  obj_handle_t no_fd_ioctl( struct fd *fd, ioctl_code_t code, const async_data_t *async, int blocking )
  {
      set_error( STATUS_OBJECT_TYPE_MISMATCH );
      return 0;
  }
  
  /* default ioctl() routine */
  obj_handle_t default_fd_ioctl( struct fd *fd, ioctl_code_t code, const async_data_t *async, int blocking )
  {
      switch(code)
      {
      case FSCTL_DISMOUNT_VOLUME:
          unmount_device( fd );
          return 0;
      default:
          set_error( STATUS_NOT_SUPPORTED );
          return 0;
      }
  }
  
  /* same as get_handle_obj but retrieve the struct fd associated to the object */
  static struct fd *get_handle_fd_obj( struct process *process, obj_handle_t handle,
                                       unsigned int access )
  {
      struct fd *fd = NULL;
      struct object *obj;
  
      if ((obj = get_handle_obj( process, handle, access, NULL )))
      {
          fd = get_obj_fd( obj );
          release_object( obj );
      }
      return fd;
  }
  
  /* set disposition for the fd */
  static void set_fd_disposition( struct fd *fd, int unlink )
  {
      struct stat st;
  
      if (!fd->inode)
      {
          set_error( STATUS_OBJECT_TYPE_MISMATCH );
          return;
      }
  
      if (fd->unix_fd == -1)
      {
          set_error( fd->no_fd_status );
          return;
      }
  
      if (fstat( fd->unix_fd, &st ) == -1)
      {
          file_set_error();
          return;
      }
  
      /* can't unlink special files */
      if (unlink && !S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
      {
          set_error( STATUS_INVALID_PARAMETER );
          return;
      }
  
      /* can't unlink files we don't have permission to access */
      if (unlink && !(st.st_mode & (S_IWUSR | S_IWGRP | S_IWOTH)))
      {
          set_error( STATUS_CANNOT_DELETE );
          return;
      }
  
      fd->closed->unlink = unlink || (fd->options & FILE_DELETE_ON_CLOSE);
  }
  
  /* set new name for the fd */
  static void set_fd_name( struct fd *fd, struct fd *root, const char *nameptr,
                           data_size_t len, int create_link )
  {
      struct inode *inode;
      struct stat st;
      char *name;
  
      if (!fd->inode || !fd->unix_name)
      {
          set_error( STATUS_OBJECT_TYPE_MISMATCH );
          return;
      }
      if (!len || ((nameptr[0] == '/') ^ !root))
      {
          set_error( STATUS_OBJECT_PATH_SYNTAX_BAD );
          return;
      }
      if (!(name = mem_alloc( len + 1 ))) return;
      memcpy( name, nameptr, len );
      name[len] = 0;
  
      if (root)
      {
          char *combined_name = dup_fd_name( root, name );
          if (!combined_name)
          {
              set_error( STATUS_NO_MEMORY );
              goto failed;
          }
          free( name );
          name = combined_name;
      }
  
      /* when creating a hard link, source cannot be a dir */
      if (create_link && fd->unix_fd != -1 &&
          !fstat( fd->unix_fd, &st ) && S_ISDIR( st.st_mode ))
      {
          set_error( STATUS_FILE_IS_A_DIRECTORY );
          goto failed;
      }
  
      if (!stat( name, &st ))
      {
          /* can't replace directories or special files */
          if (!S_ISREG( st.st_mode ))
          {
              set_error( STATUS_ACCESS_DENIED );
              goto failed;
          }
  
          /* can't replace an opened file */
          if ((inode = get_inode( st.st_dev, st.st_ino, -1 )))
          {
              int is_empty = list_empty( &inode->open );
              release_object( inode );
              if (!is_empty)
              {
                  set_error( STATUS_ACCESS_DENIED );
                  goto failed;
              }
          }
  
          /* link() expects that the target doesn't exist */
          /* rename() cannot replace files with directories */
          if (create_link || (fd->unix_fd != -1 &&
              !fstat( fd->unix_fd, &st ) && S_ISDIR( st.st_mode )))
          {
              if (unlink( name ))
              {
                  file_set_error();
                  goto failed;
              }
          }
      }
  
      if (create_link)
      {
          if (link( fd->unix_name, name ))
              file_set_error();
          free( name );
          return;
      }
  
      if (rename( fd->unix_name, name ))
      {
          file_set_error();
          goto failed;
      }
  
      free( fd->unix_name );
      fd->unix_name = name;
      fd->closed->unix_name = name;
      return;
  
  failed:
      free( name );
  }
  
  struct completion *fd_get_completion( struct fd *fd, apc_param_t *p_key )
  {
      *p_key = fd->comp_key;
      return fd->completion ? (struct completion *)grab_object( fd->completion ) : NULL;
  }
  
  void fd_copy_completion( struct fd *src, struct fd *dst )
  {
      assert( !dst->completion );
      dst->completion = fd_get_completion( src, &dst->comp_key );
  }
  
  /* flush a file buffers */
  DECL_HANDLER(flush)
  {
      struct fd *fd = get_handle_fd_obj( current->process, req->async.handle, 0 );
  
      if (fd)
      {
          reply->event = fd->fd_ops->flush( fd, &req->async, req->blocking );
          release_object( fd );
      }
  }
  
  /* open a file object */
  DECL_HANDLER(open_file_object)
  {
      struct unicode_str name = get_req_unicode_str();
      struct object *obj, *result, *root = NULL;
  
      if (req->rootdir && !(root = get_handle_obj( current->process, req->rootdir, 0, NULL ))) return;
  
      obj = open_named_object( root, NULL, &name, req->attributes );
      if (root) release_object( root );
      if (!obj) return;
  
      if ((result = obj->ops->open_file( obj, req->access, req->sharing, req->options )))
      {
          reply->handle = alloc_handle( current->process, result, req->access, req->attributes );
          release_object( result );
      }
      release_object( obj );
  }
  
  /* get the Unix name from a file handle */
  DECL_HANDLER(get_handle_unix_name)
  {
      struct fd *fd;
  
      if ((fd = get_handle_fd_obj( current->process, req->handle, 0 )))
      {
          if (fd->unix_name)
          {
              data_size_t name_len = strlen( fd->unix_name );
              reply->name_len = name_len;
              if (name_len <= get_reply_max_size()) set_reply_data( fd->unix_name, name_len );
              else set_error( STATUS_BUFFER_OVERFLOW );
          }
          else set_error( STATUS_OBJECT_TYPE_MISMATCH );
          release_object( fd );
      }
  }
  
  /* get a Unix fd to access a file */
  DECL_HANDLER(get_handle_fd)
  {
      struct fd *fd;
  
      if ((fd = get_handle_fd_obj( current->process, req->handle, 0 )))
      {
          int unix_fd = get_unix_fd( fd );
          reply->cacheable = fd->cacheable;
          if (unix_fd != -1)
          {
              reply->type = fd->fd_ops->get_fd_type( fd );
              reply->options = fd->options;
              reply->access = get_handle_access( current->process, req->handle );
              send_client_fd( current->process, unix_fd, req->handle );
          }
          release_object( fd );
      }
  }
  
  /* perform a read on a file object */
  DECL_HANDLER(read)
  {
      struct fd *fd = get_handle_fd_obj( current->process, req->async.handle, FILE_READ_DATA );
  
      if (fd)
      {
          reply->wait    = fd->fd_ops->read( fd, &req->async, req->blocking, req->pos );
          reply->options = fd->options;
          release_object( fd );
      }
  }
  
  /* perform a write on a file object */
  DECL_HANDLER(write)
  {
      struct fd *fd = get_handle_fd_obj( current->process, req->async.handle, FILE_WRITE_DATA );
  
      if (fd)
      {
          reply->wait    = fd->fd_ops->write( fd, &req->async, req->blocking, req->pos, &reply->size );
          reply->options = fd->options;
          release_object( fd );
      }
  }
  
  /* perform an ioctl on a file */
  DECL_HANDLER(ioctl)
  {
      unsigned int access = (req->code >> 14) & (FILE_READ_DATA|FILE_WRITE_DATA);
      struct fd *fd = get_handle_fd_obj( current->process, req->async.handle, access );
  
      if (fd)
      {
          reply->wait    = fd->fd_ops->ioctl( fd, req->code, &req->async, req->blocking );
          reply->options = fd->options;
          release_object( fd );
      }
  }
  
  /* create / reschedule an async I/O */
  DECL_HANDLER(register_async)
  {
      unsigned int access;
      struct fd *fd;
  
      switch(req->type)
      {
      case ASYNC_TYPE_READ:
          access = FILE_READ_DATA;
          break;
      case ASYNC_TYPE_WRITE:
          access = FILE_WRITE_DATA;
          break;
      default:
          set_error( STATUS_INVALID_PARAMETER );
          return;
      }
  
      if ((fd = get_handle_fd_obj( current->process, req->async.handle, access )))
      {
          if (get_unix_fd( fd ) != -1) fd->fd_ops->queue_async( fd, &req->async, req->type, req->count );
          release_object( fd );
      }
  }
  
  /* cancels all async I/O */
  DECL_HANDLER(cancel_async)
  {
      struct fd *fd = get_handle_fd_obj( current->process, req->handle, 0 );
      struct thread *thread = req->only_thread ? current : NULL;
  
      if (fd)
      {
          int count = fd->fd_ops->cancel_async( fd, current->process, thread, req->iosb );
          if (!count && req->iosb) set_error( STATUS_NOT_FOUND );
          release_object( fd );
      }
  }
  
  /* attach completion object to a fd */
  DECL_HANDLER(set_completion_info)
  {
      struct fd *fd = get_handle_fd_obj( current->process, req->handle, 0 );
  
      if (fd)
      {
          if (!(fd->options & (FILE_SYNCHRONOUS_IO_ALERT | FILE_SYNCHRONOUS_IO_NONALERT)) && !fd->completion)
          {
              fd->completion = get_completion_obj( current->process, req->chandle, IO_COMPLETION_MODIFY_STATE );
              fd->comp_key = req->ckey;
          }
          else set_error( STATUS_INVALID_PARAMETER );
          release_object( fd );
      }
  }
  
  /* push new completion msg into a completion queue attached to the fd */
  DECL_HANDLER(add_fd_completion)
  {
      struct fd *fd = get_handle_fd_obj( current->process, req->handle, 0 );
      if (fd)
      {
          if (fd->completion)
              add_completion( fd->completion, fd->comp_key, req->cvalue, req->status, req->information );
          release_object( fd );
      }
  }
  
  /* set fd disposition information */
  DECL_HANDLER(set_fd_disp_info)
  {
      struct fd *fd = get_handle_fd_obj( current->process, req->handle, DELETE );
      if (fd)
      {
          set_fd_disposition( fd, req->unlink );
          release_object( fd );
      }
  }
  
  /* set fd name information */
  DECL_HANDLER(set_fd_name_info)
  {
      struct fd *fd, *root_fd = NULL;
  
      if (req->rootdir)
      {
          struct dir *root;
  
          if (!(root = get_dir_obj( current->process, req->rootdir, 0 ))) return;
          root_fd = get_obj_fd( (struct object *)root );
          release_object( root );
          if (!root_fd) return;
      }
  
      if ((fd = get_handle_fd_obj( current->process, req->handle, 0 )))
      {
          set_fd_name( fd, root_fd, get_req_data(), get_req_data_size(), req->link );
          release_object( fd );
      }
      if (root_fd) release_object( root_fd );
  }
  