hurd/hurd/fd.h

   1 /* File descriptors.
   2    Copyright (C) 1993-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _HURD_FD_H
  20
  21 #define _HURD_FD_H      1
  22 #include <features.h>
  23
  24 #include <cthreads.h>
  25
  26 #include <hurd/hurd_types.h>
  27 #include <hurd/port.h>
  28 #include <sys/socket.h>
  29
  30
  31 /* Structure representing a file descriptor.  */
  32
  33 struct hurd_fd
  34   {
  35     struct hurd_port port;      /* io server port.  */
  36     int flags;                  /* fcntl flags; locked by port.lock.  */
  37
  38     /* Normal port to the ctty.  When `port' is our ctty, this is a port to
  39        the same io object but which never returns EBACKGROUND; when not,
  40        this is nil.  */
  41     struct hurd_port ctty;
  42   };
  43
  44
  45 /* Current file descriptor table.  */
  46
  47 extern int _hurd_dtablesize;
  48 extern struct hurd_fd **_hurd_dtable;
  49 extern struct mutex _hurd_dtable_lock; /* Locks those two variables.  */
  50 \f
  51 #include <hurd/signal.h>
  52
  53 #ifndef _HURD_FD_H_EXTERN_INLINE
  54 #define _HURD_FD_H_EXTERN_INLINE __extern_inline
  55 #endif
  56
  57 /* Returns the descriptor cell for FD.  If FD is invalid or unused, return
  58    NULL.  The cell is unlocked; when ready to use it, lock it and check for
  59    it being unused.  */
  60
  61 _HURD_FD_H_EXTERN_INLINE struct hurd_fd *
  62 _hurd_fd_get (int fd)
  63 {
  64   struct hurd_fd *descriptor;
  65
  66   HURD_CRITICAL_BEGIN;
  67   __mutex_lock (&_hurd_dtable_lock);
  68   if (fd < 0 || fd >= _hurd_dtablesize)
  69     descriptor = NULL;
  70   else
  71     {
  72       struct hurd_fd *cell = _hurd_dtable[fd];
  73       if (cell == NULL)
  74         /* No descriptor allocated at this index.  */
  75         descriptor = NULL;
  76       else
  77         {
  78           __spin_lock (&cell->port.lock);
  79           if (cell->port.port == MACH_PORT_NULL)
  80             /* The descriptor at this index has no port in it.
  81                This happens if it existed before but was closed.  */
  82             descriptor = NULL;
  83           else
  84             descriptor = cell;
  85           __spin_unlock (&cell->port.lock);
  86         }
  87     }
  88   __mutex_unlock (&_hurd_dtable_lock);
  89   HURD_CRITICAL_END;
  90
  91   return descriptor;
  92 }
  93
  94
  95 /* Evaluate EXPR with the variable `descriptor' bound to a pointer to the
  96    file descriptor structure for FD.   */
  97
  98 #define HURD_FD_USE(fd, expr)                                                 \
  99   ({ struct hurd_fd *descriptor = _hurd_fd_get (fd);                          \
 100      descriptor == NULL ? EBADF : (expr); })
 101
 102 /* Evaluate EXPR with the variable `port' bound to the port to FD, and
 103    `ctty' bound to the ctty port.  */
 104
 105 #define HURD_DPORT_USE(fd, expr) \
 106   HURD_FD_USE ((fd), HURD_FD_PORT_USE (descriptor, (expr)))
 107
 108 /* Likewise, but FD is a pointer to the file descriptor structure.  */
 109
 110 #define HURD_FD_PORT_USE(fd, expr)                                            \
 111   ({ error_t __result;                                                        \
 112      struct hurd_fd *const __d = (fd);                                        \
 113      struct hurd_userlink __ulink, __ctty_ulink;                              \
 114      io_t port, ctty;                                                         \
 115      void *crit = _hurd_critical_section_lock ();                             \
 116      __spin_lock (&__d->port.lock);                                           \
 117      if (__d->port.port == MACH_PORT_NULL)                                    \
 118        {                                                                      \
 119          __spin_unlock (&__d->port.lock);                                     \
 120          _hurd_critical_section_unlock (crit);                                \
 121          __result = EBADF;                                                    \
 122        }                                                                      \
 123      else                                                                     \
 124        {                                                                      \
 125          ctty = _hurd_port_get (&__d->ctty, &__ctty_ulink);                   \
 126          port = _hurd_port_locked_get (&__d->port, &__ulink);                 \
 127          _hurd_critical_section_unlock (crit);                                \
 128          __result = (expr);                                                   \
 129          _hurd_port_free (&__d->port, &__ulink, port);                        \
 130          if (ctty != MACH_PORT_NULL)                                          \
 131            _hurd_port_free (&__d->ctty, &__ctty_ulink, ctty);                 \
 132        }                                                                      \
 133      __result; })
 134 \f
 135 #include <errno.h>
 136
 137 /* Check if ERR should generate a signal.
 138    Returns the signal to take, or zero if none.  */
 139
 140 _HURD_FD_H_EXTERN_INLINE int
 141 _hurd_fd_error_signal (error_t err)
 142 {
 143   switch (err)
 144     {
 145     case EMACH_SEND_INVALID_DEST:
 146     case EMIG_SERVER_DIED:
 147       /* The server has disappeared!  */
 148       return SIGLOST;
 149     case EPIPE:
 150       return SIGPIPE;
 151     default:
 152       /* Having a default case avoids -Wenum-switch warnings.  */
 153       return 0;
 154     }
 155 }
 156
 157 /* Handle an error from an RPC on a file descriptor's port.  You should
 158    always use this function to handle errors from RPCs made on file
 159    descriptor ports.  Some errors are translated into signals.  */
 160
 161 _HURD_FD_H_EXTERN_INLINE error_t
 162 _hurd_fd_error (int fd, error_t err)
 163 {
 164   int signo = _hurd_fd_error_signal (err);
 165   if (signo)
 166     {
 167       const struct hurd_signal_detail detail
 168         = { code: fd, error: err, exc: 0 };
 169       _hurd_raise_signal (NULL, signo, &detail);
 170     }
 171   return err;
 172 }
 173
 174 /* Handle error code ERR from an RPC on file descriptor FD's port.
 175    Set `errno' to the appropriate error code, and always return -1.  */
 176
 177 _HURD_FD_H_EXTERN_INLINE int
 178 __hurd_dfail (int fd, error_t err)
 179 {
 180   errno = _hurd_fd_error (fd, err);
 181   return -1;
 182 }
 183
 184 /* Likewise, but do not raise SIGPIPE on EPIPE if flags contain
 185    MSG_NOSIGNAL.  */
 186
 187 _HURD_FD_H_EXTERN_INLINE int
 188 __hurd_sockfail (int fd, int flags, error_t err)
 189 {
 190   if (!(flags & MSG_NOSIGNAL) || err != EPIPE)
 191     err = _hurd_fd_error (fd, err);
 192   errno = err;
 193   return -1;
 194 }
 195 \f
 196 /* Set up *FD to have PORT its server port, doing appropriate ctty magic.
 197    Does no locking or unlocking.  */
 198
 199 extern void _hurd_port2fd (struct hurd_fd *fd, io_t port, int flags);
 200
 201 /* Allocate a new file descriptor and install PORT in it (doing any
 202    appropriate ctty magic); consumes a user reference on PORT.  FLAGS are
 203    as for `open'; only O_IGNORE_CTTY and O_CLOEXEC are meaningful, but all are
 204    saved.
 205
 206    If the descriptor table is full, set errno, and return -1.
 207    If DEALLOC is nonzero, deallocate PORT first.  */
 208
 209 extern int _hurd_intern_fd (io_t port, int flags, int dealloc);
 210
 211 /* Allocate a new file descriptor in the table and return it, locked.  The
 212    new descriptor number will be no less than FIRST_FD.  If the table is
 213    full, set errno to EMFILE and return NULL.  If FIRST_FD is negative or
 214    bigger than the size of the table, set errno to EINVAL and return NULL.  */
 215
 216 extern struct hurd_fd *_hurd_alloc_fd (int *fd_ptr, int first_fd);
 217
 218 /* Allocate a new file descriptor structure and initialize its port cells
 219    with PORT and CTTY.  (This does not affect the descriptor table.)  */
 220
 221 extern struct hurd_fd *_hurd_new_fd (io_t port, io_t ctty);
 222
 223 /* Close a file descriptor, making it available for future reallocation.  */
 224
 225 extern error_t _hurd_fd_close (struct hurd_fd *fd);
 226
 227 /* Read and write data from a file descriptor; just like `read' and `write'
 228    if OFFSET is -1, or like `pread' and `pwrite' if OFFSET is not -1.
 229    If successful, stores the amount actually read or written in *NBYTES.  */
 230
 231 extern error_t _hurd_fd_read (struct hurd_fd *fd,
 232                               void *buf, size_t *nbytes, loff_t offset);
 233 extern error_t _hurd_fd_write (struct hurd_fd *fd,
 234                                const void *buf, size_t *nbytes, loff_t offset);
 235
 236
 237 /* Call *RPC on PORT and/or CTTY; if a call on CTTY returns EBACKGROUND,
 238    generate SIGTTIN/SIGTTOU or EIO as appropriate.  */
 239
 240 extern error_t _hurd_ctty_input (io_t port, io_t ctty, error_t (*rpc) (io_t));
 241 extern error_t _hurd_ctty_output (io_t port, io_t ctty, error_t (*rpc) (io_t));
 242
 243
 244 /* The guts of `select' and `poll'.  Check the first NFDS descriptors
 245    either in POLLFDS (if nonnull) or in each of READFDS, WRITEFDS,
 246    EXCEPTFDS that is nonnull.  If TIMEOUT is not NULL, time out after
 247    waiting the interval specified therein.  If SIGMASK is nonnull,
 248    the set of blocked signals is temporarily set to that during this call.
 249    Returns the number of ready descriptors, or -1 for errors.  */
 250 struct pollfd;
 251 struct timespec;
 252 extern int _hurd_select (int nfds, struct pollfd *pollfds,
 253                          fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 254                          const struct timespec *timeout,
 255                          const sigset_t *sigmask);
 256
 257 /* Variant of file_name_lookup used in *at function implementations.
 258    AT_FLAGS may only contain AT_SYMLINK_FOLLOW or AT_SYMLINK_NOFOLLOW,
 259    which will remove and add O_NOLINK from FLAGS respectively.
 260    Other bits cause EINVAL.  */
 261 extern file_t __file_name_lookup_at (int fd, int at_flags,
 262                                      const char *file_name,
 263                                      int flags, mode_t mode);
 264
 265 /* Variant of file_name_split used in *at function implementations.  */
 266 extern file_t __file_name_split_at (int fd, const char *file_name,
 267                                     char **name);
 268
 269 /* Variant of directory_name_split used in *at function implementations.  */
 270 extern file_t __directory_name_split_at (int fd, const char *directory_name,
 271                                          char **name);
 272
 273
 274
 275 #endif  /* hurd/fd.h */