1 /* File descriptors.
2 Copyright (C) 1993-2022 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 <https://www.gnu.org/licenses/>. */
18
19 #ifndef _HURD_FD_H
20
21 #define _HURD_FD_H 1
22 #include <features.h>
23
24 #include <hurd/hurd_types.h>
25 #include <hurd/port.h>
26 #include <sys/socket.h>
27 #include <sys/select.h>
28 #include <fcntl.h>
29 #include <bits/types/sigset_t.h>
30
31
32 /* Structure representing a file descriptor. */
33
34 struct hurd_fd
35 {
36 struct hurd_port port; /* io server port. */
37 int flags; /* fcntl flags; locked by port.lock. */
38
39 /* Normal port to the ctty. When `port' is our ctty, this is a port to
40 the same io object but which never returns EBACKGROUND; when not,
41 this is nil. */
42 struct hurd_port ctty;
43 };
44
45
46 /* Current file descriptor table. */
47
48 #if defined __USE_EXTERN_INLINES && defined _LIBC
49 #include <lock-intern.h>
50 extern int _hurd_dtablesize;
51 extern struct hurd_fd **_hurd_dtable;
52 extern struct mutex _hurd_dtable_lock; /* Locks those two variables. */
53 #endif
54
55 #include <hurd/signal.h>
56
57 #ifndef _HURD_FD_H_EXTERN_INLINE
58 #define _HURD_FD_H_EXTERN_INLINE __extern_inline
59 #endif
60
61 /* Returns the descriptor cell for FD. If FD is invalid or unused, return
62 NULL. The cell is unlocked; when ready to use it, lock it and check for
63 it being unused. */
64
65 extern struct hurd_fd *_hurd_fd_get (int fd);
66
67 #if defined __USE_EXTERN_INLINES && defined _LIBC
68 # if IS_IN (libc)
69 _HURD_FD_H_EXTERN_INLINE struct hurd_fd *
_hurd_fd_get(int fd)70 _hurd_fd_get (int fd)
71 {
72 struct hurd_fd *descriptor;
73
74 HURD_CRITICAL_BEGIN;
75 __mutex_lock (&_hurd_dtable_lock);
76 if (fd < 0 || fd >= _hurd_dtablesize)
77 descriptor = NULL;
78 else
79 {
80 struct hurd_fd *cell = _hurd_dtable[fd];
81 if (cell == NULL)
82 /* No descriptor allocated at this index. */
83 descriptor = NULL;
84 else
85 {
86 __spin_lock (&cell->port.lock);
87 if (cell->port.port == MACH_PORT_NULL)
88 /* The descriptor at this index has no port in it.
89 This happens if it existed before but was closed. */
90 descriptor = NULL;
91 else
92 descriptor = cell;
93 __spin_unlock (&cell->port.lock);
94 }
95 }
96 __mutex_unlock (&_hurd_dtable_lock);
97 HURD_CRITICAL_END;
98
99 return descriptor;
100 }
101 # endif
102 #endif
103
104
105 /* Evaluate EXPR with the variable `descriptor' bound to a pointer to the
106 file descriptor structure for FD. */
107
108 #define HURD_FD_USE(fd, expr) \
109 ({ struct hurd_fd *descriptor = _hurd_fd_get (fd); \
110 descriptor == NULL ? EBADF : (expr); })
111
112 /* Evaluate EXPR with the variable `port' bound to the port to FD, and
113 `ctty' bound to the ctty port. */
114
115 #define HURD_DPORT_USE(fd, expr) \
116 HURD_FD_USE ((fd), HURD_FD_PORT_USE (descriptor, (expr)))
117
118 /* Likewise, but FD is a pointer to the file descriptor structure. */
119 /* Also see HURD_FD_PORT_USE_CANCEL. */
120
121 #define HURD_FD_PORT_USE(fd, expr) \
122 ({ error_t __result; \
123 struct hurd_fd *const __d = (fd); \
124 struct hurd_userlink __ulink, __ctty_ulink; \
125 io_t port, ctty; \
126 void *crit = _hurd_critical_section_lock (); \
127 __spin_lock (&__d->port.lock); \
128 if (__d->port.port == MACH_PORT_NULL) \
129 { \
130 __spin_unlock (&__d->port.lock); \
131 _hurd_critical_section_unlock (crit); \
132 __result = EBADF; \
133 } \
134 else \
135 { \
136 ctty = _hurd_port_get (&__d->ctty, &__ctty_ulink); \
137 port = _hurd_port_locked_get (&__d->port, &__ulink); \
138 _hurd_critical_section_unlock (crit); \
139 __result = (expr); \
140 _hurd_port_free (&__d->port, &__ulink, port); \
141 if (ctty != MACH_PORT_NULL) \
142 _hurd_port_free (&__d->ctty, &__ctty_ulink, ctty); \
143 } \
144 __result; })
145
146 #include <errno.h>
147 #include <bits/types/error_t.h>
148
149 /* Check if ERR should generate a signal.
150 Returns the signal to take, or zero if none. */
151
152 extern int _hurd_fd_error_signal (error_t err);
153
154 #ifdef __USE_EXTERN_INLINES
155 _HURD_FD_H_EXTERN_INLINE int
_hurd_fd_error_signal(error_t err)156 _hurd_fd_error_signal (error_t err)
157 {
158 switch (err)
159 {
160 case EMACH_SEND_INVALID_DEST:
161 case EMIG_SERVER_DIED:
162 /* The server has disappeared! */
163 return SIGLOST;
164 case EPIPE:
165 return SIGPIPE;
166 default:
167 /* Having a default case avoids -Wenum-switch warnings. */
168 return 0;
169 }
170 }
171 #endif
172
173 /* Handle an error from an RPC on a file descriptor's port. You should
174 always use this function to handle errors from RPCs made on file
175 descriptor ports. Some errors are translated into signals. */
176
177 extern error_t _hurd_fd_error (int fd, error_t err);
178
179 #ifdef __USE_EXTERN_INLINES
180 _HURD_FD_H_EXTERN_INLINE error_t
_hurd_fd_error(int fd,error_t err)181 _hurd_fd_error (int fd, error_t err)
182 {
183 int signo = _hurd_fd_error_signal (err);
184 if (signo)
185 {
186 const struct hurd_signal_detail detail
187 = { exc: 0, exc_code: 0, exc_subcode: 0, code: fd, error: err };
188 _hurd_raise_signal (NULL, signo, &detail);
189 }
190 return err;
191 }
192 #endif
193
194 /* Handle error code ERR from an RPC on file descriptor FD's port.
195 Set `errno' to the appropriate error code, and always return -1. */
196
197 extern int __hurd_dfail (int fd, error_t err);
198
199 #ifdef __USE_EXTERN_INLINES
200 _HURD_FD_H_EXTERN_INLINE int
__hurd_dfail(int fd,error_t err)201 __hurd_dfail (int fd, error_t err)
202 {
203 errno = _hurd_fd_error (fd, err);
204 return -1;
205 }
206 #endif
207
208 /* Likewise, but do not raise SIGPIPE on EPIPE if flags contain
209 MSG_NOSIGNAL. */
210
211 extern int __hurd_sockfail (int fd, int flags, error_t err);
212
213 #ifdef __USE_EXTERN_INLINES
214 _HURD_FD_H_EXTERN_INLINE int
__hurd_sockfail(int fd,int flags,error_t err)215 __hurd_sockfail (int fd, int flags, error_t err)
216 {
217 if (!(flags & MSG_NOSIGNAL) || err != EPIPE)
218 err = _hurd_fd_error (fd, err);
219 errno = err;
220 return -1;
221 }
222 #endif
223
224 /* Set up *FD to have PORT its server port, doing appropriate ctty magic.
225 Does no locking or unlocking. */
226
227 extern void _hurd_port2fd (struct hurd_fd *fd, io_t port, int flags);
228
229 /* Allocate a new file descriptor and install PORT in it (doing any
230 appropriate ctty magic); consumes a user reference on PORT. FLAGS are
231 as for `open'; only O_IGNORE_CTTY and O_CLOEXEC are meaningful, but all are
232 saved.
233
234 If the descriptor table is full, set errno, and return -1.
235 If DEALLOC is nonzero, deallocate PORT first. */
236
237 extern int _hurd_intern_fd (io_t port, int flags, int dealloc);
238
239 /* Allocate a new file descriptor in the table and return it, locked. The
240 new descriptor number will be no less than FIRST_FD. If the table is
241 full, set errno to EMFILE and return NULL. If FIRST_FD is negative or
242 bigger than the size of the table, set errno to EINVAL and return NULL. */
243
244 extern struct hurd_fd *_hurd_alloc_fd (int *fd_ptr, int first_fd);
245
246 /* Allocate a new file descriptor structure and initialize its port cells
247 with PORT and CTTY. (This does not affect the descriptor table.) */
248
249 extern struct hurd_fd *_hurd_new_fd (io_t port, io_t ctty);
250
251 /* Close a file descriptor, making it available for future reallocation. */
252
253 extern error_t _hurd_fd_close (struct hurd_fd *fd);
254
255 /* Read and write data from a file descriptor; just like `read' and `write'
256 if OFFSET is -1, or like `pread' and `pwrite' if OFFSET is not -1.
257 If successful, stores the amount actually read or written in *NBYTES. */
258
259 extern error_t _hurd_fd_read (struct hurd_fd *fd,
260 void *buf, size_t *nbytes, __loff_t offset);
261 extern error_t _hurd_fd_write (struct hurd_fd *fd,
262 const void *buf, size_t *nbytes, __loff_t offset);
263
264
265 /* Call *RPC on PORT and/or CTTY; if a call on CTTY returns EBACKGROUND,
266 generate SIGTTIN/SIGTTOU or EIO as appropriate. */
267
268 extern error_t _hurd_ctty_input (io_t port, io_t ctty, error_t (*rpc) (io_t));
269 extern error_t _hurd_ctty_output (io_t port, io_t ctty, error_t (*rpc) (io_t));
270
271
272 /* The guts of `select' and `poll'. Check the first NFDS descriptors
273 either in POLLFDS (if nonnull) or in each of READFDS, WRITEFDS,
274 EXCEPTFDS that is nonnull. If TIMEOUT is not NULL, time out after
275 waiting the interval specified therein. If SIGMASK is nonnull,
276 the set of blocked signals is temporarily set to that during this call.
277 Returns the number of ready descriptors, or -1 for errors. */
278 struct pollfd;
279 struct timespec;
280 extern int _hurd_select (int nfds, struct pollfd *pollfds,
281 fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
282 const struct timespec *timeout,
283 const sigset_t *sigmask);
284
285 /* Apply AT_FLAGS on FLAGS, in preparation for calling
286 __hurd_file_name_lookup. */
287
288 #if defined __USE_EXTERN_INLINES && defined _LIBC
289 # if IS_IN (libc)
290 _HURD_FD_H_EXTERN_INLINE error_t
__hurd_at_flags(int * at_flags,int * flags)291 __hurd_at_flags (int *at_flags, int *flags)
292 {
293 if ((*at_flags & AT_SYMLINK_FOLLOW) && (*at_flags & AT_SYMLINK_NOFOLLOW))
294 return EINVAL;
295
296 *flags |= (*at_flags & AT_SYMLINK_NOFOLLOW) ? O_NOLINK : 0;
297 *at_flags &= ~AT_SYMLINK_NOFOLLOW;
298
299 if (*at_flags & AT_SYMLINK_FOLLOW)
300 *flags &= ~O_NOLINK;
301 *at_flags &= ~AT_SYMLINK_FOLLOW;
302
303 if (*at_flags & AT_NO_AUTOMOUNT)
304 *flags |= O_NOTRANS;
305 *at_flags &= ~AT_NO_AUTOMOUNT;
306
307 if (*at_flags != 0)
308 return EINVAL;
309
310 return 0;
311 }
312 # endif
313 #endif
314
315 /* Variant of file_name_lookup used in *at function implementations.
316 AT_FLAGS may only contain AT_SYMLINK_FOLLOW or AT_SYMLINK_NOFOLLOW,
317 which will remove and add O_NOLINK from FLAGS respectively.
318 Other bits cause EINVAL. */
319 extern file_t __file_name_lookup_at (int fd, int at_flags,
320 const char *file_name,
321 int flags, mode_t mode);
322
323 /* Variant of file_name_split used in *at function implementations. */
324 extern file_t __file_name_split_at (int fd, const char *file_name,
325 char **name);
326
327 /* Variant of directory_name_split used in *at function implementations. */
328 extern file_t __directory_name_split_at (int fd, const char *directory_name,
329 char **name);
330
331
332
333 #endif /* hurd/fd.h */
334