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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 | ||
1da177e4 LT |
138 | spin_lock(&files->file_lock); |
139 | if (!(file = fcheck(oldfd))) | |
140 | goto out_unlock; | |
141 | err = newfd; | |
3c333937 UD |
142 | if (unlikely(newfd == oldfd)) { |
143 | if (flags & O_CLOEXEC) { | |
144 | fdt = files_fdtable(files); | |
145 | FD_SET(newfd, fdt->close_on_exec); | |
146 | } | |
1da177e4 | 147 | goto out_unlock; |
3c333937 | 148 | } |
1da177e4 LT |
149 | err = -EBADF; |
150 | if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
151 | goto out_unlock; | |
152 | get_file(file); /* We are now finished with oldfd */ | |
153 | ||
154 | err = expand_files(files, newfd); | |
155 | if (err < 0) | |
156 | goto out_fput; | |
157 | ||
158 | /* To avoid races with open() and dup(), we will mark the fd as | |
159 | * in-use in the open-file bitmap throughout the entire dup2() | |
160 | * process. This is quite safe: do_close() uses the fd array | |
161 | * entry, not the bitmap, to decide what work needs to be | |
162 | * done. --sct */ | |
163 | /* Doesn't work. open() might be there first. --AV */ | |
164 | ||
165 | /* Yes. It's a race. In user space. Nothing sane to do */ | |
166 | err = -EBUSY; | |
badf1662 DS |
167 | fdt = files_fdtable(files); |
168 | tofree = fdt->fd[newfd]; | |
169 | if (!tofree && FD_ISSET(newfd, fdt->open_fds)) | |
1da177e4 LT |
170 | goto out_fput; |
171 | ||
ab2af1f5 | 172 | rcu_assign_pointer(fdt->fd[newfd], file); |
badf1662 | 173 | FD_SET(newfd, fdt->open_fds); |
336dd1f7 UD |
174 | if (flags & O_CLOEXEC) |
175 | FD_SET(newfd, fdt->close_on_exec); | |
176 | else | |
177 | FD_CLR(newfd, fdt->close_on_exec); | |
1da177e4 LT |
178 | spin_unlock(&files->file_lock); |
179 | ||
180 | if (tofree) | |
181 | filp_close(tofree, files); | |
182 | err = newfd; | |
183 | out: | |
184 | return err; | |
185 | out_unlock: | |
186 | spin_unlock(&files->file_lock); | |
187 | goto out; | |
188 | ||
189 | out_fput: | |
190 | spin_unlock(&files->file_lock); | |
191 | fput(file); | |
192 | goto out; | |
193 | } | |
336dd1f7 UD |
194 | |
195 | asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd) | |
196 | { | |
197 | return sys_dup3(oldfd, newfd, 0); | |
198 | } | |
1da177e4 LT |
199 | |
200 | asmlinkage long sys_dup(unsigned int fildes) | |
201 | { | |
202 | int ret = -EBADF; | |
203 | struct file * file = fget(fildes); | |
204 | ||
205 | if (file) | |
22d2b35b | 206 | ret = dupfd(file, 0, 0); |
1da177e4 LT |
207 | return ret; |
208 | } | |
209 | ||
210 | #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME) | |
211 | ||
212 | static int setfl(int fd, struct file * filp, unsigned long arg) | |
213 | { | |
0f7fc9e4 | 214 | struct inode * inode = filp->f_path.dentry->d_inode; |
1da177e4 LT |
215 | int error = 0; |
216 | ||
7d95c8f2 | 217 | /* |
218 | * O_APPEND cannot be cleared if the file is marked as append-only | |
219 | * and the file is open for write. | |
220 | */ | |
221 | if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) | |
1da177e4 LT |
222 | return -EPERM; |
223 | ||
224 | /* O_NOATIME can only be set by the owner or superuser */ | |
225 | if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) | |
3bd858ab | 226 | if (!is_owner_or_cap(inode)) |
1da177e4 LT |
227 | return -EPERM; |
228 | ||
229 | /* required for strict SunOS emulation */ | |
230 | if (O_NONBLOCK != O_NDELAY) | |
231 | if (arg & O_NDELAY) | |
232 | arg |= O_NONBLOCK; | |
233 | ||
234 | if (arg & O_DIRECT) { | |
235 | if (!filp->f_mapping || !filp->f_mapping->a_ops || | |
236 | !filp->f_mapping->a_ops->direct_IO) | |
237 | return -EINVAL; | |
238 | } | |
239 | ||
240 | if (filp->f_op && filp->f_op->check_flags) | |
241 | error = filp->f_op->check_flags(arg); | |
242 | if (error) | |
243 | return error; | |
244 | ||
1da177e4 LT |
245 | if ((arg ^ filp->f_flags) & FASYNC) { |
246 | if (filp->f_op && filp->f_op->fasync) { | |
247 | error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); | |
248 | if (error < 0) | |
249 | goto out; | |
250 | } | |
251 | } | |
252 | ||
253 | filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); | |
254 | out: | |
1da177e4 LT |
255 | return error; |
256 | } | |
257 | ||
609d7fa9 | 258 | static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, |
1da177e4 LT |
259 | uid_t uid, uid_t euid, int force) |
260 | { | |
261 | write_lock_irq(&filp->f_owner.lock); | |
262 | if (force || !filp->f_owner.pid) { | |
609d7fa9 EB |
263 | put_pid(filp->f_owner.pid); |
264 | filp->f_owner.pid = get_pid(pid); | |
265 | filp->f_owner.pid_type = type; | |
1da177e4 LT |
266 | filp->f_owner.uid = uid; |
267 | filp->f_owner.euid = euid; | |
268 | } | |
269 | write_unlock_irq(&filp->f_owner.lock); | |
270 | } | |
271 | ||
609d7fa9 EB |
272 | int __f_setown(struct file *filp, struct pid *pid, enum pid_type type, |
273 | int force) | |
1da177e4 LT |
274 | { |
275 | int err; | |
276 | ||
277 | err = security_file_set_fowner(filp); | |
278 | if (err) | |
279 | return err; | |
280 | ||
609d7fa9 | 281 | f_modown(filp, pid, type, current->uid, current->euid, force); |
1da177e4 LT |
282 | return 0; |
283 | } | |
609d7fa9 | 284 | EXPORT_SYMBOL(__f_setown); |
1da177e4 | 285 | |
609d7fa9 EB |
286 | int f_setown(struct file *filp, unsigned long arg, int force) |
287 | { | |
288 | enum pid_type type; | |
289 | struct pid *pid; | |
290 | int who = arg; | |
291 | int result; | |
292 | type = PIDTYPE_PID; | |
293 | if (who < 0) { | |
294 | type = PIDTYPE_PGID; | |
295 | who = -who; | |
296 | } | |
297 | rcu_read_lock(); | |
b488893a | 298 | pid = find_vpid(who); |
609d7fa9 EB |
299 | result = __f_setown(filp, pid, type, force); |
300 | rcu_read_unlock(); | |
301 | return result; | |
302 | } | |
1da177e4 LT |
303 | EXPORT_SYMBOL(f_setown); |
304 | ||
305 | void f_delown(struct file *filp) | |
306 | { | |
609d7fa9 EB |
307 | f_modown(filp, NULL, PIDTYPE_PID, 0, 0, 1); |
308 | } | |
309 | ||
310 | pid_t f_getown(struct file *filp) | |
311 | { | |
312 | pid_t pid; | |
43fa1adb | 313 | read_lock(&filp->f_owner.lock); |
6c5f3e7b | 314 | pid = pid_vnr(filp->f_owner.pid); |
609d7fa9 EB |
315 | if (filp->f_owner.pid_type == PIDTYPE_PGID) |
316 | pid = -pid; | |
43fa1adb | 317 | read_unlock(&filp->f_owner.lock); |
609d7fa9 | 318 | return pid; |
1da177e4 LT |
319 | } |
320 | ||
321 | static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, | |
322 | struct file *filp) | |
323 | { | |
324 | long err = -EINVAL; | |
325 | ||
326 | switch (cmd) { | |
327 | case F_DUPFD: | |
22d2b35b | 328 | case F_DUPFD_CLOEXEC: |
1da177e4 | 329 | get_file(filp); |
22d2b35b | 330 | err = dupfd(filp, arg, cmd == F_DUPFD_CLOEXEC); |
1da177e4 LT |
331 | break; |
332 | case F_GETFD: | |
333 | err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; | |
334 | break; | |
335 | case F_SETFD: | |
336 | err = 0; | |
337 | set_close_on_exec(fd, arg & FD_CLOEXEC); | |
338 | break; | |
339 | case F_GETFL: | |
340 | err = filp->f_flags; | |
341 | break; | |
342 | case F_SETFL: | |
343 | err = setfl(fd, filp, arg); | |
344 | break; | |
345 | case F_GETLK: | |
346 | err = fcntl_getlk(filp, (struct flock __user *) arg); | |
347 | break; | |
348 | case F_SETLK: | |
349 | case F_SETLKW: | |
c293621b | 350 | err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg); |
1da177e4 LT |
351 | break; |
352 | case F_GETOWN: | |
353 | /* | |
354 | * XXX If f_owner is a process group, the | |
355 | * negative return value will get converted | |
356 | * into an error. Oops. If we keep the | |
357 | * current syscall conventions, the only way | |
358 | * to fix this will be in libc. | |
359 | */ | |
609d7fa9 | 360 | err = f_getown(filp); |
1da177e4 LT |
361 | force_successful_syscall_return(); |
362 | break; | |
363 | case F_SETOWN: | |
364 | err = f_setown(filp, arg, 1); | |
365 | break; | |
366 | case F_GETSIG: | |
367 | err = filp->f_owner.signum; | |
368 | break; | |
369 | case F_SETSIG: | |
370 | /* arg == 0 restores default behaviour. */ | |
7ed20e1a | 371 | if (!valid_signal(arg)) { |
1da177e4 LT |
372 | break; |
373 | } | |
374 | err = 0; | |
375 | filp->f_owner.signum = arg; | |
376 | break; | |
377 | case F_GETLEASE: | |
378 | err = fcntl_getlease(filp); | |
379 | break; | |
380 | case F_SETLEASE: | |
381 | err = fcntl_setlease(fd, filp, arg); | |
382 | break; | |
383 | case F_NOTIFY: | |
384 | err = fcntl_dirnotify(fd, filp, arg); | |
385 | break; | |
386 | default: | |
387 | break; | |
388 | } | |
389 | return err; | |
390 | } | |
391 | ||
392 | asmlinkage long sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg) | |
393 | { | |
394 | struct file *filp; | |
395 | long err = -EBADF; | |
396 | ||
397 | filp = fget(fd); | |
398 | if (!filp) | |
399 | goto out; | |
400 | ||
401 | err = security_file_fcntl(filp, cmd, arg); | |
402 | if (err) { | |
403 | fput(filp); | |
404 | return err; | |
405 | } | |
406 | ||
407 | err = do_fcntl(fd, cmd, arg, filp); | |
408 | ||
409 | fput(filp); | |
410 | out: | |
411 | return err; | |
412 | } | |
413 | ||
414 | #if BITS_PER_LONG == 32 | |
415 | asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg) | |
416 | { | |
417 | struct file * filp; | |
418 | long err; | |
419 | ||
420 | err = -EBADF; | |
421 | filp = fget(fd); | |
422 | if (!filp) | |
423 | goto out; | |
424 | ||
425 | err = security_file_fcntl(filp, cmd, arg); | |
426 | if (err) { | |
427 | fput(filp); | |
428 | return err; | |
429 | } | |
430 | err = -EBADF; | |
431 | ||
432 | switch (cmd) { | |
433 | case F_GETLK64: | |
434 | err = fcntl_getlk64(filp, (struct flock64 __user *) arg); | |
435 | break; | |
436 | case F_SETLK64: | |
437 | case F_SETLKW64: | |
c293621b PS |
438 | err = fcntl_setlk64(fd, filp, cmd, |
439 | (struct flock64 __user *) arg); | |
1da177e4 LT |
440 | break; |
441 | default: | |
442 | err = do_fcntl(fd, cmd, arg, filp); | |
443 | break; | |
444 | } | |
445 | fput(filp); | |
446 | out: | |
447 | return err; | |
448 | } | |
449 | #endif | |
450 | ||
451 | /* Table to convert sigio signal codes into poll band bitmaps */ | |
452 | ||
fa3536cc | 453 | static const long band_table[NSIGPOLL] = { |
1da177e4 LT |
454 | POLLIN | POLLRDNORM, /* POLL_IN */ |
455 | POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */ | |
456 | POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */ | |
457 | POLLERR, /* POLL_ERR */ | |
458 | POLLPRI | POLLRDBAND, /* POLL_PRI */ | |
459 | POLLHUP | POLLERR /* POLL_HUP */ | |
460 | }; | |
461 | ||
462 | static inline int sigio_perm(struct task_struct *p, | |
463 | struct fown_struct *fown, int sig) | |
464 | { | |
465 | return (((fown->euid == 0) || | |
466 | (fown->euid == p->suid) || (fown->euid == p->uid) || | |
467 | (fown->uid == p->suid) || (fown->uid == p->uid)) && | |
468 | !security_file_send_sigiotask(p, fown, sig)); | |
469 | } | |
470 | ||
471 | static void send_sigio_to_task(struct task_struct *p, | |
472 | struct fown_struct *fown, | |
473 | int fd, | |
474 | int reason) | |
475 | { | |
476 | if (!sigio_perm(p, fown, fown->signum)) | |
477 | return; | |
478 | ||
479 | switch (fown->signum) { | |
480 | siginfo_t si; | |
481 | default: | |
482 | /* Queue a rt signal with the appropriate fd as its | |
483 | value. We use SI_SIGIO as the source, not | |
484 | SI_KERNEL, since kernel signals always get | |
485 | delivered even if we can't queue. Failure to | |
486 | queue in this case _should_ be reported; we fall | |
487 | back to SIGIO in that case. --sct */ | |
488 | si.si_signo = fown->signum; | |
489 | si.si_errno = 0; | |
490 | si.si_code = reason; | |
491 | /* Make sure we are called with one of the POLL_* | |
492 | reasons, otherwise we could leak kernel stack into | |
493 | userspace. */ | |
f6298aab | 494 | BUG_ON((reason & __SI_MASK) != __SI_POLL); |
1da177e4 LT |
495 | if (reason - POLL_IN >= NSIGPOLL) |
496 | si.si_band = ~0L; | |
497 | else | |
498 | si.si_band = band_table[reason - POLL_IN]; | |
499 | si.si_fd = fd; | |
850d6fbe | 500 | if (!group_send_sig_info(fown->signum, &si, p)) |
1da177e4 LT |
501 | break; |
502 | /* fall-through: fall back on the old plain SIGIO signal */ | |
503 | case 0: | |
850d6fbe | 504 | group_send_sig_info(SIGIO, SEND_SIG_PRIV, p); |
1da177e4 LT |
505 | } |
506 | } | |
507 | ||
508 | void send_sigio(struct fown_struct *fown, int fd, int band) | |
509 | { | |
510 | struct task_struct *p; | |
609d7fa9 EB |
511 | enum pid_type type; |
512 | struct pid *pid; | |
1da177e4 LT |
513 | |
514 | read_lock(&fown->lock); | |
609d7fa9 | 515 | type = fown->pid_type; |
1da177e4 LT |
516 | pid = fown->pid; |
517 | if (!pid) | |
518 | goto out_unlock_fown; | |
519 | ||
520 | read_lock(&tasklist_lock); | |
609d7fa9 EB |
521 | do_each_pid_task(pid, type, p) { |
522 | send_sigio_to_task(p, fown, fd, band); | |
523 | } while_each_pid_task(pid, type, p); | |
1da177e4 LT |
524 | read_unlock(&tasklist_lock); |
525 | out_unlock_fown: | |
526 | read_unlock(&fown->lock); | |
527 | } | |
528 | ||
529 | static void send_sigurg_to_task(struct task_struct *p, | |
530 | struct fown_struct *fown) | |
531 | { | |
532 | if (sigio_perm(p, fown, SIGURG)) | |
850d6fbe | 533 | group_send_sig_info(SIGURG, SEND_SIG_PRIV, p); |
1da177e4 LT |
534 | } |
535 | ||
536 | int send_sigurg(struct fown_struct *fown) | |
537 | { | |
538 | struct task_struct *p; | |
609d7fa9 EB |
539 | enum pid_type type; |
540 | struct pid *pid; | |
541 | int ret = 0; | |
1da177e4 LT |
542 | |
543 | read_lock(&fown->lock); | |
609d7fa9 | 544 | type = fown->pid_type; |
1da177e4 LT |
545 | pid = fown->pid; |
546 | if (!pid) | |
547 | goto out_unlock_fown; | |
548 | ||
549 | ret = 1; | |
550 | ||
551 | read_lock(&tasklist_lock); | |
609d7fa9 EB |
552 | do_each_pid_task(pid, type, p) { |
553 | send_sigurg_to_task(p, fown); | |
554 | } while_each_pid_task(pid, type, p); | |
1da177e4 LT |
555 | read_unlock(&tasklist_lock); |
556 | out_unlock_fown: | |
557 | read_unlock(&fown->lock); | |
558 | return ret; | |
559 | } | |
560 | ||
561 | static DEFINE_RWLOCK(fasync_lock); | |
e18b890b | 562 | static struct kmem_cache *fasync_cache __read_mostly; |
1da177e4 LT |
563 | |
564 | /* | |
565 | * fasync_helper() is used by some character device drivers (mainly mice) | |
566 | * to set up the fasync queue. It returns negative on error, 0 if it did | |
567 | * no changes and positive if it added/deleted the entry. | |
568 | */ | |
569 | int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) | |
570 | { | |
571 | struct fasync_struct *fa, **fp; | |
572 | struct fasync_struct *new = NULL; | |
573 | int result = 0; | |
574 | ||
575 | if (on) { | |
e94b1766 | 576 | new = kmem_cache_alloc(fasync_cache, GFP_KERNEL); |
1da177e4 LT |
577 | if (!new) |
578 | return -ENOMEM; | |
579 | } | |
580 | write_lock_irq(&fasync_lock); | |
581 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { | |
582 | if (fa->fa_file == filp) { | |
583 | if(on) { | |
584 | fa->fa_fd = fd; | |
585 | kmem_cache_free(fasync_cache, new); | |
586 | } else { | |
587 | *fp = fa->fa_next; | |
588 | kmem_cache_free(fasync_cache, fa); | |
589 | result = 1; | |
590 | } | |
591 | goto out; | |
592 | } | |
593 | } | |
594 | ||
595 | if (on) { | |
596 | new->magic = FASYNC_MAGIC; | |
597 | new->fa_file = filp; | |
598 | new->fa_fd = fd; | |
599 | new->fa_next = *fapp; | |
600 | *fapp = new; | |
601 | result = 1; | |
602 | } | |
603 | out: | |
604 | write_unlock_irq(&fasync_lock); | |
605 | return result; | |
606 | } | |
607 | ||
608 | EXPORT_SYMBOL(fasync_helper); | |
609 | ||
610 | void __kill_fasync(struct fasync_struct *fa, int sig, int band) | |
611 | { | |
612 | while (fa) { | |
613 | struct fown_struct * fown; | |
614 | if (fa->magic != FASYNC_MAGIC) { | |
615 | printk(KERN_ERR "kill_fasync: bad magic number in " | |
616 | "fasync_struct!\n"); | |
617 | return; | |
618 | } | |
619 | fown = &fa->fa_file->f_owner; | |
620 | /* Don't send SIGURG to processes which have not set a | |
621 | queued signum: SIGURG has its own default signalling | |
622 | mechanism. */ | |
623 | if (!(sig == SIGURG && fown->signum == 0)) | |
624 | send_sigio(fown, fa->fa_fd, band); | |
625 | fa = fa->fa_next; | |
626 | } | |
627 | } | |
628 | ||
629 | EXPORT_SYMBOL(__kill_fasync); | |
630 | ||
631 | void kill_fasync(struct fasync_struct **fp, int sig, int band) | |
632 | { | |
633 | /* First a quick test without locking: usually | |
634 | * the list is empty. | |
635 | */ | |
636 | if (*fp) { | |
637 | read_lock(&fasync_lock); | |
638 | /* reread *fp after obtaining the lock */ | |
639 | __kill_fasync(*fp, sig, band); | |
640 | read_unlock(&fasync_lock); | |
641 | } | |
642 | } | |
643 | EXPORT_SYMBOL(kill_fasync); | |
644 | ||
645 | static int __init fasync_init(void) | |
646 | { | |
647 | fasync_cache = kmem_cache_create("fasync_cache", | |
20c2df83 | 648 | sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); |
1da177e4 LT |
649 | return 0; |
650 | } | |
651 | ||
652 | module_init(fasync_init) |