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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 | 66 | spin_lock(&files->file_lock); |
1da177e4 | 67 | repeat: |
ab2af1f5 | 68 | fdt = files_fdtable(files); |
1da177e4 LT |
69 | /* |
70 | * Someone might have closed fd's in the range | |
badf1662 | 71 | * orig_start..fdt->next_fd |
1da177e4 LT |
72 | */ |
73 | start = orig_start; | |
0c9e63fd ED |
74 | if (start < files->next_fd) |
75 | start = files->next_fd; | |
1da177e4 LT |
76 | |
77 | newfd = start; | |
bbea9f69 | 78 | if (start < fdt->max_fds) |
badf1662 | 79 | newfd = find_next_zero_bit(fdt->open_fds->fds_bits, |
bbea9f69 | 80 | fdt->max_fds, start); |
1da177e4 LT |
81 | |
82 | error = expand_files(files, newfd); | |
83 | if (error < 0) | |
84 | goto out; | |
85 | ||
86 | /* | |
87 | * If we needed to expand the fs array we | |
88 | * might have blocked - try again. | |
89 | */ | |
90 | if (error) | |
91 | goto repeat; | |
92 | ||
0c9e63fd ED |
93 | if (start <= files->next_fd) |
94 | files->next_fd = newfd + 1; | |
ab2af1f5 | 95 | |
f8f95702 AV |
96 | FD_SET(newfd, fdt->open_fds); |
97 | if (cloexec) | |
98 | FD_SET(newfd, fdt->close_on_exec); | |
99 | else | |
100 | FD_CLR(newfd, fdt->close_on_exec); | |
1da177e4 | 101 | error = newfd; |
f8f95702 | 102 | |
1da177e4 | 103 | out: |
f8f95702 | 104 | spin_unlock(&files->file_lock); |
1da177e4 LT |
105 | return error; |
106 | } | |
107 | ||
22d2b35b | 108 | static int dupfd(struct file *file, unsigned int start, int cloexec) |
1da177e4 | 109 | { |
f8f95702 AV |
110 | int fd = locate_fd(start, cloexec); |
111 | if (fd >= 0) | |
1da177e4 | 112 | fd_install(fd, file); |
f8f95702 | 113 | else |
1da177e4 | 114 | fput(file); |
1da177e4 LT |
115 | |
116 | return fd; | |
117 | } | |
118 | ||
336dd1f7 | 119 | asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags) |
1da177e4 LT |
120 | { |
121 | int err = -EBADF; | |
122 | struct file * file, *tofree; | |
123 | struct files_struct * files = current->files; | |
badf1662 | 124 | struct fdtable *fdt; |
1da177e4 | 125 | |
336dd1f7 UD |
126 | if ((flags & ~O_CLOEXEC) != 0) |
127 | return -EINVAL; | |
128 | ||
6c5d0512 AV |
129 | if (unlikely(oldfd == newfd)) |
130 | return -EINVAL; | |
131 | ||
1da177e4 LT |
132 | spin_lock(&files->file_lock); |
133 | if (!(file = fcheck(oldfd))) | |
134 | goto out_unlock; | |
1da177e4 LT |
135 | get_file(file); /* We are now finished with oldfd */ |
136 | ||
137 | err = expand_files(files, newfd); | |
4e1e018e AV |
138 | if (unlikely(err < 0)) { |
139 | if (err == -EMFILE) | |
140 | err = -EBADF; | |
1da177e4 | 141 | goto out_fput; |
4e1e018e | 142 | } |
1da177e4 LT |
143 | |
144 | /* To avoid races with open() and dup(), we will mark the fd as | |
145 | * in-use in the open-file bitmap throughout the entire dup2() | |
146 | * process. This is quite safe: do_close() uses the fd array | |
147 | * entry, not the bitmap, to decide what work needs to be | |
148 | * done. --sct */ | |
149 | /* Doesn't work. open() might be there first. --AV */ | |
150 | ||
151 | /* Yes. It's a race. In user space. Nothing sane to do */ | |
152 | err = -EBUSY; | |
badf1662 DS |
153 | fdt = files_fdtable(files); |
154 | tofree = fdt->fd[newfd]; | |
155 | if (!tofree && FD_ISSET(newfd, fdt->open_fds)) | |
1da177e4 LT |
156 | goto out_fput; |
157 | ||
ab2af1f5 | 158 | rcu_assign_pointer(fdt->fd[newfd], file); |
badf1662 | 159 | FD_SET(newfd, fdt->open_fds); |
336dd1f7 UD |
160 | if (flags & O_CLOEXEC) |
161 | FD_SET(newfd, fdt->close_on_exec); | |
162 | else | |
163 | FD_CLR(newfd, fdt->close_on_exec); | |
1da177e4 LT |
164 | spin_unlock(&files->file_lock); |
165 | ||
166 | if (tofree) | |
167 | filp_close(tofree, files); | |
168 | err = newfd; | |
169 | out: | |
170 | return err; | |
171 | out_unlock: | |
172 | spin_unlock(&files->file_lock); | |
173 | goto out; | |
174 | ||
175 | out_fput: | |
176 | spin_unlock(&files->file_lock); | |
177 | fput(file); | |
178 | goto out; | |
179 | } | |
336dd1f7 UD |
180 | |
181 | asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd) | |
182 | { | |
6c5d0512 AV |
183 | if (unlikely(newfd == oldfd)) { /* corner case */ |
184 | struct files_struct *files = current->files; | |
185 | rcu_read_lock(); | |
186 | if (!fcheck_files(files, oldfd)) | |
187 | oldfd = -EBADF; | |
188 | rcu_read_unlock(); | |
189 | return oldfd; | |
190 | } | |
336dd1f7 UD |
191 | return sys_dup3(oldfd, newfd, 0); |
192 | } | |
1da177e4 LT |
193 | |
194 | asmlinkage long sys_dup(unsigned int fildes) | |
195 | { | |
196 | int ret = -EBADF; | |
197 | struct file * file = fget(fildes); | |
198 | ||
199 | if (file) | |
22d2b35b | 200 | ret = dupfd(file, 0, 0); |
1da177e4 LT |
201 | return ret; |
202 | } | |
203 | ||
204 | #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME) | |
205 | ||
206 | static int setfl(int fd, struct file * filp, unsigned long arg) | |
207 | { | |
0f7fc9e4 | 208 | struct inode * inode = filp->f_path.dentry->d_inode; |
1da177e4 LT |
209 | int error = 0; |
210 | ||
7d95c8f2 | 211 | /* |
212 | * O_APPEND cannot be cleared if the file is marked as append-only | |
213 | * and the file is open for write. | |
214 | */ | |
215 | if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) | |
1da177e4 LT |
216 | return -EPERM; |
217 | ||
218 | /* O_NOATIME can only be set by the owner or superuser */ | |
219 | if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) | |
3bd858ab | 220 | if (!is_owner_or_cap(inode)) |
1da177e4 LT |
221 | return -EPERM; |
222 | ||
223 | /* required for strict SunOS emulation */ | |
224 | if (O_NONBLOCK != O_NDELAY) | |
225 | if (arg & O_NDELAY) | |
226 | arg |= O_NONBLOCK; | |
227 | ||
228 | if (arg & O_DIRECT) { | |
229 | if (!filp->f_mapping || !filp->f_mapping->a_ops || | |
230 | !filp->f_mapping->a_ops->direct_IO) | |
231 | return -EINVAL; | |
232 | } | |
233 | ||
234 | if (filp->f_op && filp->f_op->check_flags) | |
235 | error = filp->f_op->check_flags(arg); | |
236 | if (error) | |
237 | return error; | |
238 | ||
1da177e4 LT |
239 | if ((arg ^ filp->f_flags) & FASYNC) { |
240 | if (filp->f_op && filp->f_op->fasync) { | |
241 | error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); | |
242 | if (error < 0) | |
243 | goto out; | |
244 | } | |
245 | } | |
246 | ||
247 | filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); | |
248 | out: | |
1da177e4 LT |
249 | return error; |
250 | } | |
251 | ||
609d7fa9 | 252 | static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, |
1da177e4 LT |
253 | uid_t uid, uid_t euid, int force) |
254 | { | |
255 | write_lock_irq(&filp->f_owner.lock); | |
256 | if (force || !filp->f_owner.pid) { | |
609d7fa9 EB |
257 | put_pid(filp->f_owner.pid); |
258 | filp->f_owner.pid = get_pid(pid); | |
259 | filp->f_owner.pid_type = type; | |
1da177e4 LT |
260 | filp->f_owner.uid = uid; |
261 | filp->f_owner.euid = euid; | |
262 | } | |
263 | write_unlock_irq(&filp->f_owner.lock); | |
264 | } | |
265 | ||
609d7fa9 EB |
266 | int __f_setown(struct file *filp, struct pid *pid, enum pid_type type, |
267 | int force) | |
1da177e4 LT |
268 | { |
269 | int err; | |
270 | ||
271 | err = security_file_set_fowner(filp); | |
272 | if (err) | |
273 | return err; | |
274 | ||
609d7fa9 | 275 | f_modown(filp, pid, type, current->uid, current->euid, force); |
1da177e4 LT |
276 | return 0; |
277 | } | |
609d7fa9 | 278 | EXPORT_SYMBOL(__f_setown); |
1da177e4 | 279 | |
609d7fa9 EB |
280 | int f_setown(struct file *filp, unsigned long arg, int force) |
281 | { | |
282 | enum pid_type type; | |
283 | struct pid *pid; | |
284 | int who = arg; | |
285 | int result; | |
286 | type = PIDTYPE_PID; | |
287 | if (who < 0) { | |
288 | type = PIDTYPE_PGID; | |
289 | who = -who; | |
290 | } | |
291 | rcu_read_lock(); | |
b488893a | 292 | pid = find_vpid(who); |
609d7fa9 EB |
293 | result = __f_setown(filp, pid, type, force); |
294 | rcu_read_unlock(); | |
295 | return result; | |
296 | } | |
1da177e4 LT |
297 | EXPORT_SYMBOL(f_setown); |
298 | ||
299 | void f_delown(struct file *filp) | |
300 | { | |
609d7fa9 EB |
301 | f_modown(filp, NULL, PIDTYPE_PID, 0, 0, 1); |
302 | } | |
303 | ||
304 | pid_t f_getown(struct file *filp) | |
305 | { | |
306 | pid_t pid; | |
43fa1adb | 307 | read_lock(&filp->f_owner.lock); |
6c5f3e7b | 308 | pid = pid_vnr(filp->f_owner.pid); |
609d7fa9 EB |
309 | if (filp->f_owner.pid_type == PIDTYPE_PGID) |
310 | pid = -pid; | |
43fa1adb | 311 | read_unlock(&filp->f_owner.lock); |
609d7fa9 | 312 | return pid; |
1da177e4 LT |
313 | } |
314 | ||
315 | static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, | |
316 | struct file *filp) | |
317 | { | |
318 | long err = -EINVAL; | |
319 | ||
320 | switch (cmd) { | |
321 | case F_DUPFD: | |
22d2b35b | 322 | case F_DUPFD_CLOEXEC: |
4e1e018e AV |
323 | if (arg >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) |
324 | break; | |
1da177e4 | 325 | get_file(filp); |
22d2b35b | 326 | err = dupfd(filp, arg, cmd == F_DUPFD_CLOEXEC); |
1da177e4 LT |
327 | break; |
328 | case F_GETFD: | |
329 | err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; | |
330 | break; | |
331 | case F_SETFD: | |
332 | err = 0; | |
333 | set_close_on_exec(fd, arg & FD_CLOEXEC); | |
334 | break; | |
335 | case F_GETFL: | |
336 | err = filp->f_flags; | |
337 | break; | |
338 | case F_SETFL: | |
339 | err = setfl(fd, filp, arg); | |
340 | break; | |
341 | case F_GETLK: | |
342 | err = fcntl_getlk(filp, (struct flock __user *) arg); | |
343 | break; | |
344 | case F_SETLK: | |
345 | case F_SETLKW: | |
c293621b | 346 | err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg); |
1da177e4 LT |
347 | break; |
348 | case F_GETOWN: | |
349 | /* | |
350 | * XXX If f_owner is a process group, the | |
351 | * negative return value will get converted | |
352 | * into an error. Oops. If we keep the | |
353 | * current syscall conventions, the only way | |
354 | * to fix this will be in libc. | |
355 | */ | |
609d7fa9 | 356 | err = f_getown(filp); |
1da177e4 LT |
357 | force_successful_syscall_return(); |
358 | break; | |
359 | case F_SETOWN: | |
360 | err = f_setown(filp, arg, 1); | |
361 | break; | |
362 | case F_GETSIG: | |
363 | err = filp->f_owner.signum; | |
364 | break; | |
365 | case F_SETSIG: | |
366 | /* arg == 0 restores default behaviour. */ | |
7ed20e1a | 367 | if (!valid_signal(arg)) { |
1da177e4 LT |
368 | break; |
369 | } | |
370 | err = 0; | |
371 | filp->f_owner.signum = arg; | |
372 | break; | |
373 | case F_GETLEASE: | |
374 | err = fcntl_getlease(filp); | |
375 | break; | |
376 | case F_SETLEASE: | |
377 | err = fcntl_setlease(fd, filp, arg); | |
378 | break; | |
379 | case F_NOTIFY: | |
380 | err = fcntl_dirnotify(fd, filp, arg); | |
381 | break; | |
382 | default: | |
383 | break; | |
384 | } | |
385 | return err; | |
386 | } | |
387 | ||
388 | asmlinkage long sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg) | |
389 | { | |
390 | struct file *filp; | |
391 | long err = -EBADF; | |
392 | ||
393 | filp = fget(fd); | |
394 | if (!filp) | |
395 | goto out; | |
396 | ||
397 | err = security_file_fcntl(filp, cmd, arg); | |
398 | if (err) { | |
399 | fput(filp); | |
400 | return err; | |
401 | } | |
402 | ||
403 | err = do_fcntl(fd, cmd, arg, filp); | |
404 | ||
405 | fput(filp); | |
406 | out: | |
407 | return err; | |
408 | } | |
409 | ||
410 | #if BITS_PER_LONG == 32 | |
411 | asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg) | |
412 | { | |
413 | struct file * filp; | |
414 | long err; | |
415 | ||
416 | err = -EBADF; | |
417 | filp = fget(fd); | |
418 | if (!filp) | |
419 | goto out; | |
420 | ||
421 | err = security_file_fcntl(filp, cmd, arg); | |
422 | if (err) { | |
423 | fput(filp); | |
424 | return err; | |
425 | } | |
426 | err = -EBADF; | |
427 | ||
428 | switch (cmd) { | |
429 | case F_GETLK64: | |
430 | err = fcntl_getlk64(filp, (struct flock64 __user *) arg); | |
431 | break; | |
432 | case F_SETLK64: | |
433 | case F_SETLKW64: | |
c293621b PS |
434 | err = fcntl_setlk64(fd, filp, cmd, |
435 | (struct flock64 __user *) arg); | |
1da177e4 LT |
436 | break; |
437 | default: | |
438 | err = do_fcntl(fd, cmd, arg, filp); | |
439 | break; | |
440 | } | |
441 | fput(filp); | |
442 | out: | |
443 | return err; | |
444 | } | |
445 | #endif | |
446 | ||
447 | /* Table to convert sigio signal codes into poll band bitmaps */ | |
448 | ||
fa3536cc | 449 | static const long band_table[NSIGPOLL] = { |
1da177e4 LT |
450 | POLLIN | POLLRDNORM, /* POLL_IN */ |
451 | POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */ | |
452 | POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */ | |
453 | POLLERR, /* POLL_ERR */ | |
454 | POLLPRI | POLLRDBAND, /* POLL_PRI */ | |
455 | POLLHUP | POLLERR /* POLL_HUP */ | |
456 | }; | |
457 | ||
458 | static inline int sigio_perm(struct task_struct *p, | |
459 | struct fown_struct *fown, int sig) | |
460 | { | |
461 | return (((fown->euid == 0) || | |
462 | (fown->euid == p->suid) || (fown->euid == p->uid) || | |
463 | (fown->uid == p->suid) || (fown->uid == p->uid)) && | |
464 | !security_file_send_sigiotask(p, fown, sig)); | |
465 | } | |
466 | ||
467 | static void send_sigio_to_task(struct task_struct *p, | |
468 | struct fown_struct *fown, | |
469 | int fd, | |
470 | int reason) | |
471 | { | |
472 | if (!sigio_perm(p, fown, fown->signum)) | |
473 | return; | |
474 | ||
475 | switch (fown->signum) { | |
476 | siginfo_t si; | |
477 | default: | |
478 | /* Queue a rt signal with the appropriate fd as its | |
479 | value. We use SI_SIGIO as the source, not | |
480 | SI_KERNEL, since kernel signals always get | |
481 | delivered even if we can't queue. Failure to | |
482 | queue in this case _should_ be reported; we fall | |
483 | back to SIGIO in that case. --sct */ | |
484 | si.si_signo = fown->signum; | |
485 | si.si_errno = 0; | |
486 | si.si_code = reason; | |
487 | /* Make sure we are called with one of the POLL_* | |
488 | reasons, otherwise we could leak kernel stack into | |
489 | userspace. */ | |
f6298aab | 490 | BUG_ON((reason & __SI_MASK) != __SI_POLL); |
1da177e4 LT |
491 | if (reason - POLL_IN >= NSIGPOLL) |
492 | si.si_band = ~0L; | |
493 | else | |
494 | si.si_band = band_table[reason - POLL_IN]; | |
495 | si.si_fd = fd; | |
850d6fbe | 496 | if (!group_send_sig_info(fown->signum, &si, p)) |
1da177e4 LT |
497 | break; |
498 | /* fall-through: fall back on the old plain SIGIO signal */ | |
499 | case 0: | |
850d6fbe | 500 | group_send_sig_info(SIGIO, SEND_SIG_PRIV, p); |
1da177e4 LT |
501 | } |
502 | } | |
503 | ||
504 | void send_sigio(struct fown_struct *fown, int fd, int band) | |
505 | { | |
506 | struct task_struct *p; | |
609d7fa9 EB |
507 | enum pid_type type; |
508 | struct pid *pid; | |
1da177e4 LT |
509 | |
510 | read_lock(&fown->lock); | |
609d7fa9 | 511 | type = fown->pid_type; |
1da177e4 LT |
512 | pid = fown->pid; |
513 | if (!pid) | |
514 | goto out_unlock_fown; | |
515 | ||
516 | read_lock(&tasklist_lock); | |
609d7fa9 EB |
517 | do_each_pid_task(pid, type, p) { |
518 | send_sigio_to_task(p, fown, fd, band); | |
519 | } while_each_pid_task(pid, type, p); | |
1da177e4 LT |
520 | read_unlock(&tasklist_lock); |
521 | out_unlock_fown: | |
522 | read_unlock(&fown->lock); | |
523 | } | |
524 | ||
525 | static void send_sigurg_to_task(struct task_struct *p, | |
526 | struct fown_struct *fown) | |
527 | { | |
528 | if (sigio_perm(p, fown, SIGURG)) | |
850d6fbe | 529 | group_send_sig_info(SIGURG, SEND_SIG_PRIV, p); |
1da177e4 LT |
530 | } |
531 | ||
532 | int send_sigurg(struct fown_struct *fown) | |
533 | { | |
534 | struct task_struct *p; | |
609d7fa9 EB |
535 | enum pid_type type; |
536 | struct pid *pid; | |
537 | int ret = 0; | |
1da177e4 LT |
538 | |
539 | read_lock(&fown->lock); | |
609d7fa9 | 540 | type = fown->pid_type; |
1da177e4 LT |
541 | pid = fown->pid; |
542 | if (!pid) | |
543 | goto out_unlock_fown; | |
544 | ||
545 | ret = 1; | |
546 | ||
547 | read_lock(&tasklist_lock); | |
609d7fa9 EB |
548 | do_each_pid_task(pid, type, p) { |
549 | send_sigurg_to_task(p, fown); | |
550 | } while_each_pid_task(pid, type, p); | |
1da177e4 LT |
551 | read_unlock(&tasklist_lock); |
552 | out_unlock_fown: | |
553 | read_unlock(&fown->lock); | |
554 | return ret; | |
555 | } | |
556 | ||
557 | static DEFINE_RWLOCK(fasync_lock); | |
e18b890b | 558 | static struct kmem_cache *fasync_cache __read_mostly; |
1da177e4 LT |
559 | |
560 | /* | |
561 | * fasync_helper() is used by some character device drivers (mainly mice) | |
562 | * to set up the fasync queue. It returns negative on error, 0 if it did | |
563 | * no changes and positive if it added/deleted the entry. | |
564 | */ | |
565 | int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) | |
566 | { | |
567 | struct fasync_struct *fa, **fp; | |
568 | struct fasync_struct *new = NULL; | |
569 | int result = 0; | |
570 | ||
571 | if (on) { | |
e94b1766 | 572 | new = kmem_cache_alloc(fasync_cache, GFP_KERNEL); |
1da177e4 LT |
573 | if (!new) |
574 | return -ENOMEM; | |
575 | } | |
576 | write_lock_irq(&fasync_lock); | |
577 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { | |
578 | if (fa->fa_file == filp) { | |
579 | if(on) { | |
580 | fa->fa_fd = fd; | |
581 | kmem_cache_free(fasync_cache, new); | |
582 | } else { | |
583 | *fp = fa->fa_next; | |
584 | kmem_cache_free(fasync_cache, fa); | |
585 | result = 1; | |
586 | } | |
587 | goto out; | |
588 | } | |
589 | } | |
590 | ||
591 | if (on) { | |
592 | new->magic = FASYNC_MAGIC; | |
593 | new->fa_file = filp; | |
594 | new->fa_fd = fd; | |
595 | new->fa_next = *fapp; | |
596 | *fapp = new; | |
597 | result = 1; | |
598 | } | |
599 | out: | |
600 | write_unlock_irq(&fasync_lock); | |
601 | return result; | |
602 | } | |
603 | ||
604 | EXPORT_SYMBOL(fasync_helper); | |
605 | ||
606 | void __kill_fasync(struct fasync_struct *fa, int sig, int band) | |
607 | { | |
608 | while (fa) { | |
609 | struct fown_struct * fown; | |
610 | if (fa->magic != FASYNC_MAGIC) { | |
611 | printk(KERN_ERR "kill_fasync: bad magic number in " | |
612 | "fasync_struct!\n"); | |
613 | return; | |
614 | } | |
615 | fown = &fa->fa_file->f_owner; | |
616 | /* Don't send SIGURG to processes which have not set a | |
617 | queued signum: SIGURG has its own default signalling | |
618 | mechanism. */ | |
619 | if (!(sig == SIGURG && fown->signum == 0)) | |
620 | send_sigio(fown, fa->fa_fd, band); | |
621 | fa = fa->fa_next; | |
622 | } | |
623 | } | |
624 | ||
625 | EXPORT_SYMBOL(__kill_fasync); | |
626 | ||
627 | void kill_fasync(struct fasync_struct **fp, int sig, int band) | |
628 | { | |
629 | /* First a quick test without locking: usually | |
630 | * the list is empty. | |
631 | */ | |
632 | if (*fp) { | |
633 | read_lock(&fasync_lock); | |
634 | /* reread *fp after obtaining the lock */ | |
635 | __kill_fasync(*fp, sig, band); | |
636 | read_unlock(&fasync_lock); | |
637 | } | |
638 | } | |
639 | EXPORT_SYMBOL(kill_fasync); | |
640 | ||
641 | static int __init fasync_init(void) | |
642 | { | |
643 | fasync_cache = kmem_cache_create("fasync_cache", | |
20c2df83 | 644 | sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); |
1da177e4 LT |
645 | return 0; |
646 | } | |
647 | ||
648 | module_init(fasync_init) |