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Commit | Line | Data |
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1da177e4 LT |
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> | |
9f3acc31 | 12 | #include <linux/fdtable.h> |
16f7e0fe | 13 | #include <linux/capability.h> |
1da177e4 | 14 | #include <linux/dnotify.h> |
1da177e4 LT |
15 | #include <linux/slab.h> |
16 | #include <linux/module.h> | |
17 | #include <linux/security.h> | |
18 | #include <linux/ptrace.h> | |
7ed20e1a | 19 | #include <linux/signal.h> |
ab2af1f5 | 20 | #include <linux/rcupdate.h> |
b488893a | 21 | #include <linux/pid_namespace.h> |
1da177e4 LT |
22 | |
23 | #include <asm/poll.h> | |
24 | #include <asm/siginfo.h> | |
25 | #include <asm/uaccess.h> | |
26 | ||
fc9b52cd | 27 | void set_close_on_exec(unsigned int fd, int flag) |
1da177e4 LT |
28 | { |
29 | struct files_struct *files = current->files; | |
badf1662 | 30 | struct fdtable *fdt; |
1da177e4 | 31 | spin_lock(&files->file_lock); |
badf1662 | 32 | fdt = files_fdtable(files); |
1da177e4 | 33 | if (flag) |
badf1662 | 34 | FD_SET(fd, fdt->close_on_exec); |
1da177e4 | 35 | else |
badf1662 | 36 | FD_CLR(fd, fdt->close_on_exec); |
1da177e4 LT |
37 | spin_unlock(&files->file_lock); |
38 | } | |
39 | ||
858119e1 | 40 | static int get_close_on_exec(unsigned int fd) |
1da177e4 LT |
41 | { |
42 | struct files_struct *files = current->files; | |
badf1662 | 43 | struct fdtable *fdt; |
1da177e4 | 44 | int res; |
b835996f | 45 | rcu_read_lock(); |
badf1662 DS |
46 | fdt = files_fdtable(files); |
47 | res = FD_ISSET(fd, fdt->close_on_exec); | |
b835996f | 48 | rcu_read_unlock(); |
1da177e4 LT |
49 | return res; |
50 | } | |
51 | ||
52 | /* | |
53 | * locate_fd finds a free file descriptor in the open_fds fdset, | |
54 | * expanding the fd arrays if necessary. Must be called with the | |
55 | * file_lock held for write. | |
56 | */ | |
57 | ||
f8f95702 | 58 | static int locate_fd(unsigned int orig_start, int cloexec) |
1da177e4 | 59 | { |
f8f95702 | 60 | struct files_struct *files = current->files; |
1da177e4 LT |
61 | unsigned int newfd; |
62 | unsigned int start; | |
63 | int error; | |
badf1662 | 64 | struct fdtable *fdt; |
1da177e4 | 65 | |
f8f95702 AV |
66 | spin_lock(&files->file_lock); |
67 | ||
1da177e4 LT |
68 | error = -EINVAL; |
69 | if (orig_start >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
70 | goto out; | |
71 | ||
72 | repeat: | |
ab2af1f5 | 73 | fdt = files_fdtable(files); |
1da177e4 LT |
74 | /* |
75 | * Someone might have closed fd's in the range | |
badf1662 | 76 | * orig_start..fdt->next_fd |
1da177e4 LT |
77 | */ |
78 | start = orig_start; | |
0c9e63fd ED |
79 | if (start < files->next_fd) |
80 | start = files->next_fd; | |
1da177e4 LT |
81 | |
82 | newfd = start; | |
bbea9f69 | 83 | if (start < fdt->max_fds) |
badf1662 | 84 | newfd = find_next_zero_bit(fdt->open_fds->fds_bits, |
bbea9f69 | 85 | fdt->max_fds, start); |
1da177e4 LT |
86 | |
87 | error = -EMFILE; | |
88 | if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
89 | goto out; | |
90 | ||
91 | error = expand_files(files, newfd); | |
92 | if (error < 0) | |
93 | goto out; | |
94 | ||
95 | /* | |
96 | * If we needed to expand the fs array we | |
97 | * might have blocked - try again. | |
98 | */ | |
99 | if (error) | |
100 | goto repeat; | |
101 | ||
0c9e63fd ED |
102 | if (start <= files->next_fd) |
103 | files->next_fd = newfd + 1; | |
ab2af1f5 | 104 | |
f8f95702 AV |
105 | FD_SET(newfd, fdt->open_fds); |
106 | if (cloexec) | |
107 | FD_SET(newfd, fdt->close_on_exec); | |
108 | else | |
109 | FD_CLR(newfd, fdt->close_on_exec); | |
1da177e4 | 110 | error = newfd; |
f8f95702 | 111 | |
1da177e4 | 112 | out: |
f8f95702 | 113 | spin_unlock(&files->file_lock); |
1da177e4 LT |
114 | return error; |
115 | } | |
116 | ||
22d2b35b | 117 | static int dupfd(struct file *file, unsigned int start, int cloexec) |
1da177e4 | 118 | { |
f8f95702 AV |
119 | int fd = locate_fd(start, cloexec); |
120 | if (fd >= 0) | |
1da177e4 | 121 | fd_install(fd, file); |
f8f95702 | 122 | else |
1da177e4 | 123 | fput(file); |
1da177e4 LT |
124 | |
125 | return fd; | |
126 | } | |
127 | ||
336dd1f7 | 128 | asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags) |
1da177e4 LT |
129 | { |
130 | int err = -EBADF; | |
131 | struct file * file, *tofree; | |
132 | struct files_struct * files = current->files; | |
badf1662 | 133 | struct fdtable *fdt; |
1da177e4 | 134 | |
336dd1f7 UD |
135 | if ((flags & ~O_CLOEXEC) != 0) |
136 | return -EINVAL; | |
137 | ||
6c5d0512 AV |
138 | if (unlikely(oldfd == newfd)) |
139 | return -EINVAL; | |
140 | ||
1da177e4 LT |
141 | spin_lock(&files->file_lock); |
142 | if (!(file = fcheck(oldfd))) | |
143 | goto out_unlock; | |
1da177e4 LT |
144 | if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) |
145 | goto out_unlock; | |
146 | get_file(file); /* We are now finished with oldfd */ | |
147 | ||
148 | err = expand_files(files, newfd); | |
149 | if (err < 0) | |
150 | goto out_fput; | |
151 | ||
152 | /* To avoid races with open() and dup(), we will mark the fd as | |
153 | * in-use in the open-file bitmap throughout the entire dup2() | |
154 | * process. This is quite safe: do_close() uses the fd array | |
155 | * entry, not the bitmap, to decide what work needs to be | |
156 | * done. --sct */ | |
157 | /* Doesn't work. open() might be there first. --AV */ | |
158 | ||
159 | /* Yes. It's a race. In user space. Nothing sane to do */ | |
160 | err = -EBUSY; | |
badf1662 DS |
161 | fdt = files_fdtable(files); |
162 | tofree = fdt->fd[newfd]; | |
163 | if (!tofree && FD_ISSET(newfd, fdt->open_fds)) | |
1da177e4 LT |
164 | goto out_fput; |
165 | ||
ab2af1f5 | 166 | rcu_assign_pointer(fdt->fd[newfd], file); |
badf1662 | 167 | FD_SET(newfd, fdt->open_fds); |
336dd1f7 UD |
168 | if (flags & O_CLOEXEC) |
169 | FD_SET(newfd, fdt->close_on_exec); | |
170 | else | |
171 | FD_CLR(newfd, fdt->close_on_exec); | |
1da177e4 LT |
172 | spin_unlock(&files->file_lock); |
173 | ||
174 | if (tofree) | |
175 | filp_close(tofree, files); | |
176 | err = newfd; | |
177 | out: | |
178 | return err; | |
179 | out_unlock: | |
180 | spin_unlock(&files->file_lock); | |
181 | goto out; | |
182 | ||
183 | out_fput: | |
184 | spin_unlock(&files->file_lock); | |
185 | fput(file); | |
186 | goto out; | |
187 | } | |
336dd1f7 UD |
188 | |
189 | asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd) | |
190 | { | |
6c5d0512 AV |
191 | if (unlikely(newfd == oldfd)) { /* corner case */ |
192 | struct files_struct *files = current->files; | |
193 | rcu_read_lock(); | |
194 | if (!fcheck_files(files, oldfd)) | |
195 | oldfd = -EBADF; | |
196 | rcu_read_unlock(); | |
197 | return oldfd; | |
198 | } | |
336dd1f7 UD |
199 | return sys_dup3(oldfd, newfd, 0); |
200 | } | |
1da177e4 LT |
201 | |
202 | asmlinkage long sys_dup(unsigned int fildes) | |
203 | { | |
204 | int ret = -EBADF; | |
205 | struct file * file = fget(fildes); | |
206 | ||
207 | if (file) | |
22d2b35b | 208 | ret = dupfd(file, 0, 0); |
1da177e4 LT |
209 | return ret; |
210 | } | |
211 | ||
212 | #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME) | |
213 | ||
214 | static int setfl(int fd, struct file * filp, unsigned long arg) | |
215 | { | |
0f7fc9e4 | 216 | struct inode * inode = filp->f_path.dentry->d_inode; |
1da177e4 LT |
217 | int error = 0; |
218 | ||
7d95c8f2 | 219 | /* |
220 | * O_APPEND cannot be cleared if the file is marked as append-only | |
221 | * and the file is open for write. | |
222 | */ | |
223 | if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) | |
1da177e4 LT |
224 | return -EPERM; |
225 | ||
226 | /* O_NOATIME can only be set by the owner or superuser */ | |
227 | if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) | |
3bd858ab | 228 | if (!is_owner_or_cap(inode)) |
1da177e4 LT |
229 | return -EPERM; |
230 | ||
231 | /* required for strict SunOS emulation */ | |
232 | if (O_NONBLOCK != O_NDELAY) | |
233 | if (arg & O_NDELAY) | |
234 | arg |= O_NONBLOCK; | |
235 | ||
236 | if (arg & O_DIRECT) { | |
237 | if (!filp->f_mapping || !filp->f_mapping->a_ops || | |
238 | !filp->f_mapping->a_ops->direct_IO) | |
239 | return -EINVAL; | |
240 | } | |
241 | ||
242 | if (filp->f_op && filp->f_op->check_flags) | |
243 | error = filp->f_op->check_flags(arg); | |
244 | if (error) | |
245 | return error; | |
246 | ||
1da177e4 LT |
247 | if ((arg ^ filp->f_flags) & FASYNC) { |
248 | if (filp->f_op && filp->f_op->fasync) { | |
249 | error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); | |
250 | if (error < 0) | |
251 | goto out; | |
252 | } | |
253 | } | |
254 | ||
255 | filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); | |
256 | out: | |
1da177e4 LT |
257 | return error; |
258 | } | |
259 | ||
609d7fa9 | 260 | static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, |
1da177e4 LT |
261 | uid_t uid, uid_t euid, int force) |
262 | { | |
263 | write_lock_irq(&filp->f_owner.lock); | |
264 | if (force || !filp->f_owner.pid) { | |
609d7fa9 EB |
265 | put_pid(filp->f_owner.pid); |
266 | filp->f_owner.pid = get_pid(pid); | |
267 | filp->f_owner.pid_type = type; | |
1da177e4 LT |
268 | filp->f_owner.uid = uid; |
269 | filp->f_owner.euid = euid; | |
270 | } | |
271 | write_unlock_irq(&filp->f_owner.lock); | |
272 | } | |
273 | ||
609d7fa9 EB |
274 | int __f_setown(struct file *filp, struct pid *pid, enum pid_type type, |
275 | int force) | |
1da177e4 LT |
276 | { |
277 | int err; | |
278 | ||
279 | err = security_file_set_fowner(filp); | |
280 | if (err) | |
281 | return err; | |
282 | ||
609d7fa9 | 283 | f_modown(filp, pid, type, current->uid, current->euid, force); |
1da177e4 LT |
284 | return 0; |
285 | } | |
609d7fa9 | 286 | EXPORT_SYMBOL(__f_setown); |
1da177e4 | 287 | |
609d7fa9 EB |
288 | int f_setown(struct file *filp, unsigned long arg, int force) |
289 | { | |
290 | enum pid_type type; | |
291 | struct pid *pid; | |
292 | int who = arg; | |
293 | int result; | |
294 | type = PIDTYPE_PID; | |
295 | if (who < 0) { | |
296 | type = PIDTYPE_PGID; | |
297 | who = -who; | |
298 | } | |
299 | rcu_read_lock(); | |
b488893a | 300 | pid = find_vpid(who); |
609d7fa9 EB |
301 | result = __f_setown(filp, pid, type, force); |
302 | rcu_read_unlock(); | |
303 | return result; | |
304 | } | |
1da177e4 LT |
305 | EXPORT_SYMBOL(f_setown); |
306 | ||
307 | void f_delown(struct file *filp) | |
308 | { | |
609d7fa9 EB |
309 | f_modown(filp, NULL, PIDTYPE_PID, 0, 0, 1); |
310 | } | |
311 | ||
312 | pid_t f_getown(struct file *filp) | |
313 | { | |
314 | pid_t pid; | |
43fa1adb | 315 | read_lock(&filp->f_owner.lock); |
6c5f3e7b | 316 | pid = pid_vnr(filp->f_owner.pid); |
609d7fa9 EB |
317 | if (filp->f_owner.pid_type == PIDTYPE_PGID) |
318 | pid = -pid; | |
43fa1adb | 319 | read_unlock(&filp->f_owner.lock); |
609d7fa9 | 320 | return pid; |
1da177e4 LT |
321 | } |
322 | ||
323 | static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, | |
324 | struct file *filp) | |
325 | { | |
326 | long err = -EINVAL; | |
327 | ||
328 | switch (cmd) { | |
329 | case F_DUPFD: | |
22d2b35b | 330 | case F_DUPFD_CLOEXEC: |
1da177e4 | 331 | get_file(filp); |
22d2b35b | 332 | err = dupfd(filp, arg, cmd == F_DUPFD_CLOEXEC); |
1da177e4 LT |
333 | break; |
334 | case F_GETFD: | |
335 | err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; | |
336 | break; | |
337 | case F_SETFD: | |
338 | err = 0; | |
339 | set_close_on_exec(fd, arg & FD_CLOEXEC); | |
340 | break; | |
341 | case F_GETFL: | |
342 | err = filp->f_flags; | |
343 | break; | |
344 | case F_SETFL: | |
345 | err = setfl(fd, filp, arg); | |
346 | break; | |
347 | case F_GETLK: | |
348 | err = fcntl_getlk(filp, (struct flock __user *) arg); | |
349 | break; | |
350 | case F_SETLK: | |
351 | case F_SETLKW: | |
c293621b | 352 | err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg); |
1da177e4 LT |
353 | break; |
354 | case F_GETOWN: | |
355 | /* | |
356 | * XXX If f_owner is a process group, the | |
357 | * negative return value will get converted | |
358 | * into an error. Oops. If we keep the | |
359 | * current syscall conventions, the only way | |
360 | * to fix this will be in libc. | |
361 | */ | |
609d7fa9 | 362 | err = f_getown(filp); |
1da177e4 LT |
363 | force_successful_syscall_return(); |
364 | break; | |
365 | case F_SETOWN: | |
366 | err = f_setown(filp, arg, 1); | |
367 | break; | |
368 | case F_GETSIG: | |
369 | err = filp->f_owner.signum; | |
370 | break; | |
371 | case F_SETSIG: | |
372 | /* arg == 0 restores default behaviour. */ | |
7ed20e1a | 373 | if (!valid_signal(arg)) { |
1da177e4 LT |
374 | break; |
375 | } | |
376 | err = 0; | |
377 | filp->f_owner.signum = arg; | |
378 | break; | |
379 | case F_GETLEASE: | |
380 | err = fcntl_getlease(filp); | |
381 | break; | |
382 | case F_SETLEASE: | |
383 | err = fcntl_setlease(fd, filp, arg); | |
384 | break; | |
385 | case F_NOTIFY: | |
386 | err = fcntl_dirnotify(fd, filp, arg); | |
387 | break; | |
388 | default: | |
389 | break; | |
390 | } | |
391 | return err; | |
392 | } | |
393 | ||
394 | asmlinkage long sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg) | |
395 | { | |
396 | struct file *filp; | |
397 | long err = -EBADF; | |
398 | ||
399 | filp = fget(fd); | |
400 | if (!filp) | |
401 | goto out; | |
402 | ||
403 | err = security_file_fcntl(filp, cmd, arg); | |
404 | if (err) { | |
405 | fput(filp); | |
406 | return err; | |
407 | } | |
408 | ||
409 | err = do_fcntl(fd, cmd, arg, filp); | |
410 | ||
411 | fput(filp); | |
412 | out: | |
413 | return err; | |
414 | } | |
415 | ||
416 | #if BITS_PER_LONG == 32 | |
417 | asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg) | |
418 | { | |
419 | struct file * filp; | |
420 | long err; | |
421 | ||
422 | err = -EBADF; | |
423 | filp = fget(fd); | |
424 | if (!filp) | |
425 | goto out; | |
426 | ||
427 | err = security_file_fcntl(filp, cmd, arg); | |
428 | if (err) { | |
429 | fput(filp); | |
430 | return err; | |
431 | } | |
432 | err = -EBADF; | |
433 | ||
434 | switch (cmd) { | |
435 | case F_GETLK64: | |
436 | err = fcntl_getlk64(filp, (struct flock64 __user *) arg); | |
437 | break; | |
438 | case F_SETLK64: | |
439 | case F_SETLKW64: | |
c293621b PS |
440 | err = fcntl_setlk64(fd, filp, cmd, |
441 | (struct flock64 __user *) arg); | |
1da177e4 LT |
442 | break; |
443 | default: | |
444 | err = do_fcntl(fd, cmd, arg, filp); | |
445 | break; | |
446 | } | |
447 | fput(filp); | |
448 | out: | |
449 | return err; | |
450 | } | |
451 | #endif | |
452 | ||
453 | /* Table to convert sigio signal codes into poll band bitmaps */ | |
454 | ||
fa3536cc | 455 | static const long band_table[NSIGPOLL] = { |
1da177e4 LT |
456 | POLLIN | POLLRDNORM, /* POLL_IN */ |
457 | POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */ | |
458 | POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */ | |
459 | POLLERR, /* POLL_ERR */ | |
460 | POLLPRI | POLLRDBAND, /* POLL_PRI */ | |
461 | POLLHUP | POLLERR /* POLL_HUP */ | |
462 | }; | |
463 | ||
464 | static inline int sigio_perm(struct task_struct *p, | |
465 | struct fown_struct *fown, int sig) | |
466 | { | |
467 | return (((fown->euid == 0) || | |
468 | (fown->euid == p->suid) || (fown->euid == p->uid) || | |
469 | (fown->uid == p->suid) || (fown->uid == p->uid)) && | |
470 | !security_file_send_sigiotask(p, fown, sig)); | |
471 | } | |
472 | ||
473 | static void send_sigio_to_task(struct task_struct *p, | |
474 | struct fown_struct *fown, | |
475 | int fd, | |
476 | int reason) | |
477 | { | |
478 | if (!sigio_perm(p, fown, fown->signum)) | |
479 | return; | |
480 | ||
481 | switch (fown->signum) { | |
482 | siginfo_t si; | |
483 | default: | |
484 | /* Queue a rt signal with the appropriate fd as its | |
485 | value. We use SI_SIGIO as the source, not | |
486 | SI_KERNEL, since kernel signals always get | |
487 | delivered even if we can't queue. Failure to | |
488 | queue in this case _should_ be reported; we fall | |
489 | back to SIGIO in that case. --sct */ | |
490 | si.si_signo = fown->signum; | |
491 | si.si_errno = 0; | |
492 | si.si_code = reason; | |
493 | /* Make sure we are called with one of the POLL_* | |
494 | reasons, otherwise we could leak kernel stack into | |
495 | userspace. */ | |
f6298aab | 496 | BUG_ON((reason & __SI_MASK) != __SI_POLL); |
1da177e4 LT |
497 | if (reason - POLL_IN >= NSIGPOLL) |
498 | si.si_band = ~0L; | |
499 | else | |
500 | si.si_band = band_table[reason - POLL_IN]; | |
501 | si.si_fd = fd; | |
850d6fbe | 502 | if (!group_send_sig_info(fown->signum, &si, p)) |
1da177e4 LT |
503 | break; |
504 | /* fall-through: fall back on the old plain SIGIO signal */ | |
505 | case 0: | |
850d6fbe | 506 | group_send_sig_info(SIGIO, SEND_SIG_PRIV, p); |
1da177e4 LT |
507 | } |
508 | } | |
509 | ||
510 | void send_sigio(struct fown_struct *fown, int fd, int band) | |
511 | { | |
512 | struct task_struct *p; | |
609d7fa9 EB |
513 | enum pid_type type; |
514 | struct pid *pid; | |
1da177e4 LT |
515 | |
516 | read_lock(&fown->lock); | |
609d7fa9 | 517 | type = fown->pid_type; |
1da177e4 LT |
518 | pid = fown->pid; |
519 | if (!pid) | |
520 | goto out_unlock_fown; | |
521 | ||
522 | read_lock(&tasklist_lock); | |
609d7fa9 EB |
523 | do_each_pid_task(pid, type, p) { |
524 | send_sigio_to_task(p, fown, fd, band); | |
525 | } while_each_pid_task(pid, type, p); | |
1da177e4 LT |
526 | read_unlock(&tasklist_lock); |
527 | out_unlock_fown: | |
528 | read_unlock(&fown->lock); | |
529 | } | |
530 | ||
531 | static void send_sigurg_to_task(struct task_struct *p, | |
532 | struct fown_struct *fown) | |
533 | { | |
534 | if (sigio_perm(p, fown, SIGURG)) | |
850d6fbe | 535 | group_send_sig_info(SIGURG, SEND_SIG_PRIV, p); |
1da177e4 LT |
536 | } |
537 | ||
538 | int send_sigurg(struct fown_struct *fown) | |
539 | { | |
540 | struct task_struct *p; | |
609d7fa9 EB |
541 | enum pid_type type; |
542 | struct pid *pid; | |
543 | int ret = 0; | |
1da177e4 LT |
544 | |
545 | read_lock(&fown->lock); | |
609d7fa9 | 546 | type = fown->pid_type; |
1da177e4 LT |
547 | pid = fown->pid; |
548 | if (!pid) | |
549 | goto out_unlock_fown; | |
550 | ||
551 | ret = 1; | |
552 | ||
553 | read_lock(&tasklist_lock); | |
609d7fa9 EB |
554 | do_each_pid_task(pid, type, p) { |
555 | send_sigurg_to_task(p, fown); | |
556 | } while_each_pid_task(pid, type, p); | |
1da177e4 LT |
557 | read_unlock(&tasklist_lock); |
558 | out_unlock_fown: | |
559 | read_unlock(&fown->lock); | |
560 | return ret; | |
561 | } | |
562 | ||
563 | static DEFINE_RWLOCK(fasync_lock); | |
e18b890b | 564 | static struct kmem_cache *fasync_cache __read_mostly; |
1da177e4 LT |
565 | |
566 | /* | |
567 | * fasync_helper() is used by some character device drivers (mainly mice) | |
568 | * to set up the fasync queue. It returns negative on error, 0 if it did | |
569 | * no changes and positive if it added/deleted the entry. | |
570 | */ | |
571 | int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) | |
572 | { | |
573 | struct fasync_struct *fa, **fp; | |
574 | struct fasync_struct *new = NULL; | |
575 | int result = 0; | |
576 | ||
577 | if (on) { | |
e94b1766 | 578 | new = kmem_cache_alloc(fasync_cache, GFP_KERNEL); |
1da177e4 LT |
579 | if (!new) |
580 | return -ENOMEM; | |
581 | } | |
582 | write_lock_irq(&fasync_lock); | |
583 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { | |
584 | if (fa->fa_file == filp) { | |
585 | if(on) { | |
586 | fa->fa_fd = fd; | |
587 | kmem_cache_free(fasync_cache, new); | |
588 | } else { | |
589 | *fp = fa->fa_next; | |
590 | kmem_cache_free(fasync_cache, fa); | |
591 | result = 1; | |
592 | } | |
593 | goto out; | |
594 | } | |
595 | } | |
596 | ||
597 | if (on) { | |
598 | new->magic = FASYNC_MAGIC; | |
599 | new->fa_file = filp; | |
600 | new->fa_fd = fd; | |
601 | new->fa_next = *fapp; | |
602 | *fapp = new; | |
603 | result = 1; | |
604 | } | |
605 | out: | |
606 | write_unlock_irq(&fasync_lock); | |
607 | return result; | |
608 | } | |
609 | ||
610 | EXPORT_SYMBOL(fasync_helper); | |
611 | ||
612 | void __kill_fasync(struct fasync_struct *fa, int sig, int band) | |
613 | { | |
614 | while (fa) { | |
615 | struct fown_struct * fown; | |
616 | if (fa->magic != FASYNC_MAGIC) { | |
617 | printk(KERN_ERR "kill_fasync: bad magic number in " | |
618 | "fasync_struct!\n"); | |
619 | return; | |
620 | } | |
621 | fown = &fa->fa_file->f_owner; | |
622 | /* Don't send SIGURG to processes which have not set a | |
623 | queued signum: SIGURG has its own default signalling | |
624 | mechanism. */ | |
625 | if (!(sig == SIGURG && fown->signum == 0)) | |
626 | send_sigio(fown, fa->fa_fd, band); | |
627 | fa = fa->fa_next; | |
628 | } | |
629 | } | |
630 | ||
631 | EXPORT_SYMBOL(__kill_fasync); | |
632 | ||
633 | void kill_fasync(struct fasync_struct **fp, int sig, int band) | |
634 | { | |
635 | /* First a quick test without locking: usually | |
636 | * the list is empty. | |
637 | */ | |
638 | if (*fp) { | |
639 | read_lock(&fasync_lock); | |
640 | /* reread *fp after obtaining the lock */ | |
641 | __kill_fasync(*fp, sig, band); | |
642 | read_unlock(&fasync_lock); | |
643 | } | |
644 | } | |
645 | EXPORT_SYMBOL(kill_fasync); | |
646 | ||
647 | static int __init fasync_init(void) | |
648 | { | |
649 | fasync_cache = kmem_cache_create("fasync_cache", | |
20c2df83 | 650 | sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); |
1da177e4 LT |
651 | return 0; |
652 | } | |
653 | ||
654 | module_init(fasync_init) |