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1 | /* |
2 | * linux/fs/fcntl.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | */ |
6 | |
7 | #include <linux/syscalls.h> |
8 | #include <linux/init.h> |
9 | #include <linux/mm.h> |
10 | #include <linux/fs.h> |
11 | #include <linux/file.h> |
12 | #include <linux/fdtable.h> |
13 | #include <linux/capability.h> |
14 | #include <linux/dnotify.h> |
15 | #include <linux/slab.h> |
16 | #include <linux/module.h> |
17 | #include <linux/security.h> |
18 | #include <linux/ptrace.h> |
19 | #include <linux/signal.h> |
20 | #include <linux/rcupdate.h> |
21 | #include <linux/pid_namespace.h> |
22 | |
23 | #include <asm/poll.h> |
24 | #include <asm/siginfo.h> |
25 | #include <asm/uaccess.h> |
26 | |
27 | void set_close_on_exec(unsigned int fd, int flag) |
28 | { |
29 | struct files_struct *files = current->files; |
30 | struct fdtable *fdt; |
31 | spin_lock(&files->file_lock); |
32 | fdt = files_fdtable(files); |
33 | if (flag) |
34 | FD_SET(fd, fdt->close_on_exec); |
35 | else |
36 | FD_CLR(fd, fdt->close_on_exec); |
37 | spin_unlock(&files->file_lock); |
38 | } |
39 | |
40 | static int get_close_on_exec(unsigned int fd) |
41 | { |
42 | struct files_struct *files = current->files; |
43 | struct fdtable *fdt; |
44 | int res; |
45 | rcu_read_lock(); |
46 | fdt = files_fdtable(files); |
47 | res = FD_ISSET(fd, fdt->close_on_exec); |
48 | rcu_read_unlock(); |
49 | return res; |
50 | } |
51 | |
52 | SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags) |
53 | { |
54 | int err = -EBADF; |
55 | struct file * file, *tofree; |
56 | struct files_struct * files = current->files; |
57 | struct fdtable *fdt; |
58 | |
59 | if ((flags & ~O_CLOEXEC) != 0) |
60 | return -EINVAL; |
61 | |
62 | if (unlikely(oldfd == newfd)) |
63 | return -EINVAL; |
64 | |
65 | spin_lock(&files->file_lock); |
66 | err = expand_files(files, newfd); |
67 | file = fcheck(oldfd); |
68 | if (unlikely(!file)) |
69 | goto Ebadf; |
70 | if (unlikely(err < 0)) { |
71 | if (err == -EMFILE) |
72 | goto Ebadf; |
73 | goto out_unlock; |
74 | } |
75 | /* |
76 | * We need to detect attempts to do dup2() over allocated but still |
77 | * not finished descriptor. NB: OpenBSD avoids that at the price of |
78 | * extra work in their equivalent of fget() - they insert struct |
79 | * file immediately after grabbing descriptor, mark it larval if |
80 | * more work (e.g. actual opening) is needed and make sure that |
81 | * fget() treats larval files as absent. Potentially interesting, |
82 | * but while extra work in fget() is trivial, locking implications |
83 | * and amount of surgery on open()-related paths in VFS are not. |
84 | * FreeBSD fails with -EBADF in the same situation, NetBSD "solution" |
85 | * deadlocks in rather amusing ways, AFAICS. All of that is out of |
86 | * scope of POSIX or SUS, since neither considers shared descriptor |
87 | * tables and this condition does not arise without those. |
88 | */ |
89 | err = -EBUSY; |
90 | fdt = files_fdtable(files); |
91 | tofree = fdt->fd[newfd]; |
92 | if (!tofree && FD_ISSET(newfd, fdt->open_fds)) |
93 | goto out_unlock; |
94 | get_file(file); |
95 | rcu_assign_pointer(fdt->fd[newfd], file); |
96 | FD_SET(newfd, fdt->open_fds); |
97 | if (flags & O_CLOEXEC) |
98 | FD_SET(newfd, fdt->close_on_exec); |
99 | else |
100 | FD_CLR(newfd, fdt->close_on_exec); |
101 | spin_unlock(&files->file_lock); |
102 | |
103 | if (tofree) |
104 | filp_close(tofree, files); |
105 | |
106 | return newfd; |
107 | |
108 | Ebadf: |
109 | err = -EBADF; |
110 | out_unlock: |
111 | spin_unlock(&files->file_lock); |
112 | return err; |
113 | } |
114 | |
115 | SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) |
116 | { |
117 | if (unlikely(newfd == oldfd)) { /* corner case */ |
118 | struct files_struct *files = current->files; |
119 | int retval = oldfd; |
120 | |
121 | rcu_read_lock(); |
122 | if (!fcheck_files(files, oldfd)) |
123 | retval = -EBADF; |
124 | rcu_read_unlock(); |
125 | return retval; |
126 | } |
127 | return sys_dup3(oldfd, newfd, 0); |
128 | } |
129 | |
130 | SYSCALL_DEFINE1(dup, unsigned int, fildes) |
131 | { |
132 | int ret = -EBADF; |
133 | struct file *file = fget(fildes); |
134 | |
135 | if (file) { |
136 | ret = get_unused_fd(); |
137 | if (ret >= 0) |
138 | fd_install(ret, file); |
139 | else |
140 | fput(file); |
141 | } |
142 | return ret; |
143 | } |
144 | |
145 | #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) |
146 | |
147 | static int setfl(int fd, struct file * filp, unsigned long arg) |
148 | { |
149 | struct inode * inode = filp->f_path.dentry->d_inode; |
150 | int error = 0; |
151 | |
152 | /* |
153 | * O_APPEND cannot be cleared if the file is marked as append-only |
154 | * and the file is open for write. |
155 | */ |
156 | if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) |
157 | return -EPERM; |
158 | |
159 | /* O_NOATIME can only be set by the owner or superuser */ |
160 | if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) |
161 | if (!is_owner_or_cap(inode)) |
162 | return -EPERM; |
163 | |
164 | /* required for strict SunOS emulation */ |
165 | if (O_NONBLOCK != O_NDELAY) |
166 | if (arg & O_NDELAY) |
167 | arg |= O_NONBLOCK; |
168 | |
169 | if (arg & O_DIRECT) { |
170 | if (!filp->f_mapping || !filp->f_mapping->a_ops || |
171 | !filp->f_mapping->a_ops->direct_IO) |
172 | return -EINVAL; |
173 | } |
174 | |
175 | if (filp->f_op && filp->f_op->check_flags) |
176 | error = filp->f_op->check_flags(arg); |
177 | if (error) |
178 | return error; |
179 | |
180 | /* |
181 | * ->fasync() is responsible for setting the FASYNC bit. |
182 | */ |
183 | if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op && |
184 | filp->f_op->fasync) { |
185 | error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); |
186 | if (error < 0) |
187 | goto out; |
188 | if (error > 0) |
189 | error = 0; |
190 | } |
191 | spin_lock(&filp->f_lock); |
192 | filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); |
193 | spin_unlock(&filp->f_lock); |
194 | |
195 | out: |
196 | return error; |
197 | } |
198 | |
199 | static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, |
200 | int force) |
201 | { |
202 | write_lock_irq(&filp->f_owner.lock); |
203 | if (force || !filp->f_owner.pid) { |
204 | put_pid(filp->f_owner.pid); |
205 | filp->f_owner.pid = get_pid(pid); |
206 | filp->f_owner.pid_type = type; |
207 | |
208 | if (pid) { |
209 | const struct cred *cred = current_cred(); |
210 | filp->f_owner.uid = cred->uid; |
211 | filp->f_owner.euid = cred->euid; |
212 | } |
213 | } |
214 | write_unlock_irq(&filp->f_owner.lock); |
215 | } |
216 | |
217 | int __f_setown(struct file *filp, struct pid *pid, enum pid_type type, |
218 | int force) |
219 | { |
220 | int err; |
221 | |
222 | err = security_file_set_fowner(filp); |
223 | if (err) |
224 | return err; |
225 | |
226 | f_modown(filp, pid, type, force); |
227 | return 0; |
228 | } |
229 | EXPORT_SYMBOL(__f_setown); |
230 | |
231 | int f_setown(struct file *filp, unsigned long arg, int force) |
232 | { |
233 | enum pid_type type; |
234 | struct pid *pid; |
235 | int who = arg; |
236 | int result; |
237 | type = PIDTYPE_PID; |
238 | if (who < 0) { |
239 | type = PIDTYPE_PGID; |
240 | who = -who; |
241 | } |
242 | rcu_read_lock(); |
243 | pid = find_vpid(who); |
244 | result = __f_setown(filp, pid, type, force); |
245 | rcu_read_unlock(); |
246 | return result; |
247 | } |
248 | EXPORT_SYMBOL(f_setown); |
249 | |
250 | void f_delown(struct file *filp) |
251 | { |
252 | f_modown(filp, NULL, PIDTYPE_PID, 1); |
253 | } |
254 | |
255 | pid_t f_getown(struct file *filp) |
256 | { |
257 | pid_t pid; |
258 | read_lock(&filp->f_owner.lock); |
259 | pid = pid_vnr(filp->f_owner.pid); |
260 | if (filp->f_owner.pid_type == PIDTYPE_PGID) |
261 | pid = -pid; |
262 | read_unlock(&filp->f_owner.lock); |
263 | return pid; |
264 | } |
265 | |
266 | static int f_setown_ex(struct file *filp, unsigned long arg) |
267 | { |
268 | struct f_owner_ex * __user owner_p = (void * __user)arg; |
269 | struct f_owner_ex owner; |
270 | struct pid *pid; |
271 | int type; |
272 | int ret; |
273 | |
274 | ret = copy_from_user(&owner, owner_p, sizeof(owner)); |
275 | if (ret) |
276 | return ret; |
277 | |
278 | switch (owner.type) { |
279 | case F_OWNER_TID: |
280 | type = PIDTYPE_MAX; |
281 | break; |
282 | |
283 | case F_OWNER_PID: |
284 | type = PIDTYPE_PID; |
285 | break; |
286 | |
287 | case F_OWNER_PGRP: |
288 | type = PIDTYPE_PGID; |
289 | break; |
290 | |
291 | default: |
292 | return -EINVAL; |
293 | } |
294 | |
295 | rcu_read_lock(); |
296 | pid = find_vpid(owner.pid); |
297 | if (owner.pid && !pid) |
298 | ret = -ESRCH; |
299 | else |
300 | ret = __f_setown(filp, pid, type, 1); |
301 | rcu_read_unlock(); |
302 | |
303 | return ret; |
304 | } |
305 | |
306 | static int f_getown_ex(struct file *filp, unsigned long arg) |
307 | { |
308 | struct f_owner_ex * __user owner_p = (void * __user)arg; |
309 | struct f_owner_ex owner; |
310 | int ret = 0; |
311 | |
312 | read_lock(&filp->f_owner.lock); |
313 | owner.pid = pid_vnr(filp->f_owner.pid); |
314 | switch (filp->f_owner.pid_type) { |
315 | case PIDTYPE_MAX: |
316 | owner.type = F_OWNER_TID; |
317 | break; |
318 | |
319 | case PIDTYPE_PID: |
320 | owner.type = F_OWNER_PID; |
321 | break; |
322 | |
323 | case PIDTYPE_PGID: |
324 | owner.type = F_OWNER_PGRP; |
325 | break; |
326 | |
327 | default: |
328 | WARN_ON(1); |
329 | ret = -EINVAL; |
330 | break; |
331 | } |
332 | read_unlock(&filp->f_owner.lock); |
333 | |
334 | if (!ret) |
335 | ret = copy_to_user(owner_p, &owner, sizeof(owner)); |
336 | return ret; |
337 | } |
338 | |
339 | static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, |
340 | struct file *filp) |
341 | { |
342 | long err = -EINVAL; |
343 | |
344 | switch (cmd) { |
345 | case F_DUPFD: |
346 | case F_DUPFD_CLOEXEC: |
347 | if (arg >= rlimit(RLIMIT_NOFILE)) |
348 | break; |
349 | err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0); |
350 | if (err >= 0) { |
351 | get_file(filp); |
352 | fd_install(err, filp); |
353 | } |
354 | break; |
355 | case F_GETFD: |
356 | err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; |
357 | break; |
358 | case F_SETFD: |
359 | err = 0; |
360 | set_close_on_exec(fd, arg & FD_CLOEXEC); |
361 | break; |
362 | case F_GETFL: |
363 | err = filp->f_flags; |
364 | break; |
365 | case F_SETFL: |
366 | err = setfl(fd, filp, arg); |
367 | break; |
368 | case F_GETLK: |
369 | err = fcntl_getlk(filp, (struct flock __user *) arg); |
370 | break; |
371 | case F_SETLK: |
372 | case F_SETLKW: |
373 | err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg); |
374 | break; |
375 | case F_GETOWN: |
376 | /* |
377 | * XXX If f_owner is a process group, the |
378 | * negative return value will get converted |
379 | * into an error. Oops. If we keep the |
380 | * current syscall conventions, the only way |
381 | * to fix this will be in libc. |
382 | */ |
383 | err = f_getown(filp); |
384 | force_successful_syscall_return(); |
385 | break; |
386 | case F_SETOWN: |
387 | err = f_setown(filp, arg, 1); |
388 | break; |
389 | case F_GETOWN_EX: |
390 | err = f_getown_ex(filp, arg); |
391 | break; |
392 | case F_SETOWN_EX: |
393 | err = f_setown_ex(filp, arg); |
394 | break; |
395 | case F_GETSIG: |
396 | err = filp->f_owner.signum; |
397 | break; |
398 | case F_SETSIG: |
399 | /* arg == 0 restores default behaviour. */ |
400 | if (!valid_signal(arg)) { |
401 | break; |
402 | } |
403 | err = 0; |
404 | filp->f_owner.signum = arg; |
405 | break; |
406 | case F_GETLEASE: |
407 | err = fcntl_getlease(filp); |
408 | break; |
409 | case F_SETLEASE: |
410 | err = fcntl_setlease(fd, filp, arg); |
411 | break; |
412 | case F_NOTIFY: |
413 | err = fcntl_dirnotify(fd, filp, arg); |
414 | break; |
415 | default: |
416 | break; |
417 | } |
418 | return err; |
419 | } |
420 | |
421 | SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) |
422 | { |
423 | struct file *filp; |
424 | long err = -EBADF; |
425 | |
426 | filp = fget(fd); |
427 | if (!filp) |
428 | goto out; |
429 | |
430 | err = security_file_fcntl(filp, cmd, arg); |
431 | if (err) { |
432 | fput(filp); |
433 | return err; |
434 | } |
435 | |
436 | err = do_fcntl(fd, cmd, arg, filp); |
437 | |
438 | fput(filp); |
439 | out: |
440 | return err; |
441 | } |
442 | |
443 | #if BITS_PER_LONG == 32 |
444 | SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, |
445 | unsigned long, arg) |
446 | { |
447 | struct file * filp; |
448 | long err; |
449 | |
450 | err = -EBADF; |
451 | filp = fget(fd); |
452 | if (!filp) |
453 | goto out; |
454 | |
455 | err = security_file_fcntl(filp, cmd, arg); |
456 | if (err) { |
457 | fput(filp); |
458 | return err; |
459 | } |
460 | err = -EBADF; |
461 | |
462 | switch (cmd) { |
463 | case F_GETLK64: |
464 | err = fcntl_getlk64(filp, (struct flock64 __user *) arg); |
465 | break; |
466 | case F_SETLK64: |
467 | case F_SETLKW64: |
468 | err = fcntl_setlk64(fd, filp, cmd, |
469 | (struct flock64 __user *) arg); |
470 | break; |
471 | default: |
472 | err = do_fcntl(fd, cmd, arg, filp); |
473 | break; |
474 | } |
475 | fput(filp); |
476 | out: |
477 | return err; |
478 | } |
479 | #endif |
480 | |
481 | /* Table to convert sigio signal codes into poll band bitmaps */ |
482 | |
483 | static const long band_table[NSIGPOLL] = { |
484 | POLLIN | POLLRDNORM, /* POLL_IN */ |
485 | POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */ |
486 | POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */ |
487 | POLLERR, /* POLL_ERR */ |
488 | POLLPRI | POLLRDBAND, /* POLL_PRI */ |
489 | POLLHUP | POLLERR /* POLL_HUP */ |
490 | }; |
491 | |
492 | static inline int sigio_perm(struct task_struct *p, |
493 | struct fown_struct *fown, int sig) |
494 | { |
495 | const struct cred *cred; |
496 | int ret; |
497 | |
498 | rcu_read_lock(); |
499 | cred = __task_cred(p); |
500 | ret = ((fown->euid == 0 || |
501 | fown->euid == cred->suid || fown->euid == cred->uid || |
502 | fown->uid == cred->suid || fown->uid == cred->uid) && |
503 | !security_file_send_sigiotask(p, fown, sig)); |
504 | rcu_read_unlock(); |
505 | return ret; |
506 | } |
507 | |
508 | static void send_sigio_to_task(struct task_struct *p, |
509 | struct fown_struct *fown, |
510 | int fd, int reason, int group) |
511 | { |
512 | /* |
513 | * F_SETSIG can change ->signum lockless in parallel, make |
514 | * sure we read it once and use the same value throughout. |
515 | */ |
516 | int signum = ACCESS_ONCE(fown->signum); |
517 | |
518 | if (!sigio_perm(p, fown, signum)) |
519 | return; |
520 | |
521 | switch (signum) { |
522 | siginfo_t si; |
523 | default: |
524 | /* Queue a rt signal with the appropriate fd as its |
525 | value. We use SI_SIGIO as the source, not |
526 | SI_KERNEL, since kernel signals always get |
527 | delivered even if we can't queue. Failure to |
528 | queue in this case _should_ be reported; we fall |
529 | back to SIGIO in that case. --sct */ |
530 | si.si_signo = signum; |
531 | si.si_errno = 0; |
532 | si.si_code = reason; |
533 | /* Make sure we are called with one of the POLL_* |
534 | reasons, otherwise we could leak kernel stack into |
535 | userspace. */ |
536 | BUG_ON((reason & __SI_MASK) != __SI_POLL); |
537 | if (reason - POLL_IN >= NSIGPOLL) |
538 | si.si_band = ~0L; |
539 | else |
540 | si.si_band = band_table[reason - POLL_IN]; |
541 | si.si_fd = fd; |
542 | if (!do_send_sig_info(signum, &si, p, group)) |
543 | break; |
544 | /* fall-through: fall back on the old plain SIGIO signal */ |
545 | case 0: |
546 | do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group); |
547 | } |
548 | } |
549 | |
550 | void send_sigio(struct fown_struct *fown, int fd, int band) |
551 | { |
552 | struct task_struct *p; |
553 | enum pid_type type; |
554 | struct pid *pid; |
555 | int group = 1; |
556 | |
557 | read_lock(&fown->lock); |
558 | |
559 | type = fown->pid_type; |
560 | if (type == PIDTYPE_MAX) { |
561 | group = 0; |
562 | type = PIDTYPE_PID; |
563 | } |
564 | |
565 | pid = fown->pid; |
566 | if (!pid) |
567 | goto out_unlock_fown; |
568 | |
569 | read_lock(&tasklist_lock); |
570 | do_each_pid_task(pid, type, p) { |
571 | send_sigio_to_task(p, fown, fd, band, group); |
572 | } while_each_pid_task(pid, type, p); |
573 | read_unlock(&tasklist_lock); |
574 | out_unlock_fown: |
575 | read_unlock(&fown->lock); |
576 | } |
577 | |
578 | static void send_sigurg_to_task(struct task_struct *p, |
579 | struct fown_struct *fown, int group) |
580 | { |
581 | if (sigio_perm(p, fown, SIGURG)) |
582 | do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group); |
583 | } |
584 | |
585 | int send_sigurg(struct fown_struct *fown) |
586 | { |
587 | struct task_struct *p; |
588 | enum pid_type type; |
589 | struct pid *pid; |
590 | int group = 1; |
591 | int ret = 0; |
592 | |
593 | read_lock(&fown->lock); |
594 | |
595 | type = fown->pid_type; |
596 | if (type == PIDTYPE_MAX) { |
597 | group = 0; |
598 | type = PIDTYPE_PID; |
599 | } |
600 | |
601 | pid = fown->pid; |
602 | if (!pid) |
603 | goto out_unlock_fown; |
604 | |
605 | ret = 1; |
606 | |
607 | read_lock(&tasklist_lock); |
608 | do_each_pid_task(pid, type, p) { |
609 | send_sigurg_to_task(p, fown, group); |
610 | } while_each_pid_task(pid, type, p); |
611 | read_unlock(&tasklist_lock); |
612 | out_unlock_fown: |
613 | read_unlock(&fown->lock); |
614 | return ret; |
615 | } |
616 | |
617 | static DEFINE_RWLOCK(fasync_lock); |
618 | static struct kmem_cache *fasync_cache __read_mostly; |
619 | |
620 | /* |
621 | * Remove a fasync entry. If successfully removed, return |
622 | * positive and clear the FASYNC flag. If no entry exists, |
623 | * do nothing and return 0. |
624 | * |
625 | * NOTE! It is very important that the FASYNC flag always |
626 | * match the state "is the filp on a fasync list". |
627 | * |
628 | * We always take the 'filp->f_lock', in since fasync_lock |
629 | * needs to be irq-safe. |
630 | */ |
631 | static int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) |
632 | { |
633 | struct fasync_struct *fa, **fp; |
634 | int result = 0; |
635 | |
636 | spin_lock(&filp->f_lock); |
637 | write_lock_irq(&fasync_lock); |
638 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { |
639 | if (fa->fa_file != filp) |
640 | continue; |
641 | *fp = fa->fa_next; |
642 | kmem_cache_free(fasync_cache, fa); |
643 | filp->f_flags &= ~FASYNC; |
644 | result = 1; |
645 | break; |
646 | } |
647 | write_unlock_irq(&fasync_lock); |
648 | spin_unlock(&filp->f_lock); |
649 | return result; |
650 | } |
651 | |
652 | /* |
653 | * Add a fasync entry. Return negative on error, positive if |
654 | * added, and zero if did nothing but change an existing one. |
655 | * |
656 | * NOTE! It is very important that the FASYNC flag always |
657 | * match the state "is the filp on a fasync list". |
658 | */ |
659 | static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) |
660 | { |
661 | struct fasync_struct *new, *fa, **fp; |
662 | int result = 0; |
663 | |
664 | new = kmem_cache_alloc(fasync_cache, GFP_KERNEL); |
665 | if (!new) |
666 | return -ENOMEM; |
667 | |
668 | spin_lock(&filp->f_lock); |
669 | write_lock_irq(&fasync_lock); |
670 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { |
671 | if (fa->fa_file != filp) |
672 | continue; |
673 | fa->fa_fd = fd; |
674 | kmem_cache_free(fasync_cache, new); |
675 | goto out; |
676 | } |
677 | |
678 | new->magic = FASYNC_MAGIC; |
679 | new->fa_file = filp; |
680 | new->fa_fd = fd; |
681 | new->fa_next = *fapp; |
682 | *fapp = new; |
683 | result = 1; |
684 | filp->f_flags |= FASYNC; |
685 | |
686 | out: |
687 | write_unlock_irq(&fasync_lock); |
688 | spin_unlock(&filp->f_lock); |
689 | return result; |
690 | } |
691 | |
692 | /* |
693 | * fasync_helper() is used by almost all character device drivers |
694 | * to set up the fasync queue, and for regular files by the file |
695 | * lease code. It returns negative on error, 0 if it did no changes |
696 | * and positive if it added/deleted the entry. |
697 | */ |
698 | int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) |
699 | { |
700 | if (!on) |
701 | return fasync_remove_entry(filp, fapp); |
702 | return fasync_add_entry(fd, filp, fapp); |
703 | } |
704 | |
705 | EXPORT_SYMBOL(fasync_helper); |
706 | |
707 | void __kill_fasync(struct fasync_struct *fa, int sig, int band) |
708 | { |
709 | while (fa) { |
710 | struct fown_struct * fown; |
711 | if (fa->magic != FASYNC_MAGIC) { |
712 | printk(KERN_ERR "kill_fasync: bad magic number in " |
713 | "fasync_struct!\n"); |
714 | return; |
715 | } |
716 | fown = &fa->fa_file->f_owner; |
717 | /* Don't send SIGURG to processes which have not set a |
718 | queued signum: SIGURG has its own default signalling |
719 | mechanism. */ |
720 | if (!(sig == SIGURG && fown->signum == 0)) |
721 | send_sigio(fown, fa->fa_fd, band); |
722 | fa = fa->fa_next; |
723 | } |
724 | } |
725 | |
726 | EXPORT_SYMBOL(__kill_fasync); |
727 | |
728 | void kill_fasync(struct fasync_struct **fp, int sig, int band) |
729 | { |
730 | /* First a quick test without locking: usually |
731 | * the list is empty. |
732 | */ |
733 | if (*fp) { |
734 | read_lock(&fasync_lock); |
735 | /* reread *fp after obtaining the lock */ |
736 | __kill_fasync(*fp, sig, band); |
737 | read_unlock(&fasync_lock); |
738 | } |
739 | } |
740 | EXPORT_SYMBOL(kill_fasync); |
741 | |
742 | static int __init fasync_init(void) |
743 | { |
744 | fasync_cache = kmem_cache_create("fasync_cache", |
745 | sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); |
746 | return 0; |
747 | } |
748 | |
749 | module_init(fasync_init) |
750 |
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v2.6.34-rc5
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