[PATCH] uml: Fix SIGWINCH relaying
[linux-2.6] / arch / um / kernel / sigio_user.c
1 /* 
2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
3  * Licensed under the GPL
4  */
5
6 #include <unistd.h>
7 #include <stdlib.h>
8 #include <termios.h>
9 #include <pty.h>
10 #include <signal.h>
11 #include <errno.h>
12 #include <string.h>
13 #include <sched.h>
14 #include <sys/socket.h>
15 #include <sys/poll.h>
16 #include "init.h"
17 #include "user.h"
18 #include "kern_util.h"
19 #include "user_util.h"
20 #include "sigio.h"
21 #include "helper.h"
22 #include "os.h"
23
24 /* Changed during early boot */
25 int pty_output_sigio = 0;
26 int pty_close_sigio = 0;
27
28 /* Used as a flag during SIGIO testing early in boot */
29 static volatile int got_sigio = 0;
30
31 void __init handler(int sig)
32 {
33         got_sigio = 1;
34 }
35
36 struct openpty_arg {
37         int master;
38         int slave;
39         int err;
40 };
41
42 static void openpty_cb(void *arg)
43 {
44         struct openpty_arg *info = arg;
45
46         info->err = 0;
47         if(openpty(&info->master, &info->slave, NULL, NULL, NULL))
48                 info->err = -errno;
49 }
50
51 void __init check_one_sigio(void (*proc)(int, int))
52 {
53         struct sigaction old, new;
54         struct openpty_arg pty = { .master = -1, .slave = -1 };
55         int master, slave, err;
56
57         initial_thread_cb(openpty_cb, &pty);
58         if(pty.err){
59                 printk("openpty failed, errno = %d\n", -pty.err);
60                 return;
61         }
62
63         master = pty.master;
64         slave = pty.slave;
65
66         if((master == -1) || (slave == -1)){
67                 printk("openpty failed to allocate a pty\n");
68                 return;
69         }
70
71         /* Not now, but complain so we now where we failed. */
72         err = raw(master);
73         if (err < 0)
74                 panic("check_sigio : __raw failed, errno = %d\n", -err);
75
76         err = os_sigio_async(master, slave);
77         if(err < 0)
78                 panic("tty_fds : sigio_async failed, err = %d\n", -err);
79
80         if(sigaction(SIGIO, NULL, &old) < 0)
81                 panic("check_sigio : sigaction 1 failed, errno = %d\n", errno);
82         new = old;
83         new.sa_handler = handler;
84         if(sigaction(SIGIO, &new, NULL) < 0)
85                 panic("check_sigio : sigaction 2 failed, errno = %d\n", errno);
86
87         got_sigio = 0;
88         (*proc)(master, slave);
89                 
90         os_close_file(master);
91         os_close_file(slave);
92
93         if(sigaction(SIGIO, &old, NULL) < 0)
94                 panic("check_sigio : sigaction 3 failed, errno = %d\n", errno);
95 }
96
97 static void tty_output(int master, int slave)
98 {
99         int n;
100         char buf[512];
101
102         printk("Checking that host ptys support output SIGIO...");
103
104         memset(buf, 0, sizeof(buf));
105
106         while(os_write_file(master, buf, sizeof(buf)) > 0) ;
107         if(errno != EAGAIN)
108                 panic("check_sigio : write failed, errno = %d\n", errno);
109         while(((n = os_read_file(slave, buf, sizeof(buf))) > 0) && !got_sigio) ;
110
111         if (got_sigio) {
112                 printk("Yes\n");
113                 pty_output_sigio = 1;
114         } else if (n == -EAGAIN) {
115                 printk("No, enabling workaround\n");
116         } else {
117                 panic("check_sigio : read failed, err = %d\n", n);
118         }
119 }
120
121 static void tty_close(int master, int slave)
122 {
123         printk("Checking that host ptys support SIGIO on close...");
124
125         os_close_file(slave);
126         if(got_sigio){
127                 printk("Yes\n");
128                 pty_close_sigio = 1;
129         }
130         else printk("No, enabling workaround\n");
131 }
132
133 void __init check_sigio(void)
134 {
135         if((os_access("/dev/ptmx", OS_ACC_R_OK) < 0) &&
136            (os_access("/dev/ptyp0", OS_ACC_R_OK) < 0)){
137                 printk("No pseudo-terminals available - skipping pty SIGIO "
138                        "check\n");
139                 return;
140         }
141         check_one_sigio(tty_output);
142         check_one_sigio(tty_close);
143 }
144
145 /* Protected by sigio_lock(), also used by sigio_cleanup, which is an 
146  * exitcall.
147  */
148 static int write_sigio_pid = -1;
149
150 /* These arrays are initialized before the sigio thread is started, and
151  * the descriptors closed after it is killed.  So, it can't see them change.
152  * On the UML side, they are changed under the sigio_lock.
153  */
154 static int write_sigio_fds[2] = { -1, -1 };
155 static int sigio_private[2] = { -1, -1 };
156
157 struct pollfds {
158         struct pollfd *poll;
159         int size;
160         int used;
161 };
162
163 /* Protected by sigio_lock().  Used by the sigio thread, but the UML thread
164  * synchronizes with it.
165  */
166 struct pollfds current_poll = {
167         .poll           = NULL,
168         .size           = 0,
169         .used           = 0
170 };
171
172 struct pollfds next_poll = {
173         .poll           = NULL,
174         .size           = 0,
175         .used           = 0
176 };
177
178 static int write_sigio_thread(void *unused)
179 {
180         struct pollfds *fds, tmp;
181         struct pollfd *p;
182         int i, n, respond_fd;
183         char c;
184
185         signal(SIGWINCH, SIG_IGN);
186         fds = &current_poll;
187         while(1){
188                 n = poll(fds->poll, fds->used, -1);
189                 if(n < 0){
190                         if(errno == EINTR) continue;
191                         printk("write_sigio_thread : poll returned %d, "
192                                "errno = %d\n", n, errno);
193                 }
194                 for(i = 0; i < fds->used; i++){
195                         p = &fds->poll[i];
196                         if(p->revents == 0) continue;
197                         if(p->fd == sigio_private[1]){
198                                 n = os_read_file(sigio_private[1], &c, sizeof(c));
199                                 if(n != sizeof(c))
200                                         printk("write_sigio_thread : "
201                                                "read failed, err = %d\n", -n);
202                                 tmp = current_poll;
203                                 current_poll = next_poll;
204                                 next_poll = tmp;
205                                 respond_fd = sigio_private[1];
206                         }
207                         else {
208                                 respond_fd = write_sigio_fds[1];
209                                 fds->used--;
210                                 memmove(&fds->poll[i], &fds->poll[i + 1],
211                                         (fds->used - i) * sizeof(*fds->poll));
212                         }
213
214                         n = os_write_file(respond_fd, &c, sizeof(c));
215                         if(n != sizeof(c))
216                                 printk("write_sigio_thread : write failed, "
217                                        "err = %d\n", -n);
218                 }
219         }
220 }
221
222 static int need_poll(int n)
223 {
224         if(n <= next_poll.size){
225                 next_poll.used = n;
226                 return(0);
227         }
228         if(next_poll.poll != NULL) kfree(next_poll.poll);
229         next_poll.poll = um_kmalloc_atomic(n * sizeof(struct pollfd));
230         if(next_poll.poll == NULL){
231                 printk("need_poll : failed to allocate new pollfds\n");
232                 next_poll.size = 0;
233                 next_poll.used = 0;
234                 return(-1);
235         }
236         next_poll.size = n;
237         next_poll.used = n;
238         return(0);
239 }
240
241 /* Must be called with sigio_lock held, because it's needed by the marked
242  * critical section. */
243 static void update_thread(void)
244 {
245         unsigned long flags;
246         int n;
247         char c;
248
249         flags = set_signals(0);
250         n = os_write_file(sigio_private[0], &c, sizeof(c));
251         if(n != sizeof(c)){
252                 printk("update_thread : write failed, err = %d\n", -n);
253                 goto fail;
254         }
255
256         n = os_read_file(sigio_private[0], &c, sizeof(c));
257         if(n != sizeof(c)){
258                 printk("update_thread : read failed, err = %d\n", -n);
259                 goto fail;
260         }
261
262         set_signals(flags);
263         return;
264  fail:
265         /* Critical section start */
266         if(write_sigio_pid != -1) 
267                 os_kill_process(write_sigio_pid, 1);
268         write_sigio_pid = -1;
269         os_close_file(sigio_private[0]);
270         os_close_file(sigio_private[1]);
271         os_close_file(write_sigio_fds[0]);
272         os_close_file(write_sigio_fds[1]);
273         /* Critical section end */
274         set_signals(flags);
275 }
276
277 int add_sigio_fd(int fd, int read)
278 {
279         int err = 0, i, n, events;
280
281         sigio_lock();
282         for(i = 0; i < current_poll.used; i++){
283                 if(current_poll.poll[i].fd == fd) 
284                         goto out;
285         }
286
287         n = current_poll.used + 1;
288         err = need_poll(n);
289         if(err) 
290                 goto out;
291
292         for(i = 0; i < current_poll.used; i++)
293                 next_poll.poll[i] = current_poll.poll[i];
294
295         if(read) events = POLLIN;
296         else events = POLLOUT;
297
298         next_poll.poll[n - 1] = ((struct pollfd) { .fd          = fd,
299                                                    .events      = events,
300                                                    .revents     = 0 });
301         update_thread();
302  out:
303         sigio_unlock();
304         return(err);
305 }
306
307 int ignore_sigio_fd(int fd)
308 {
309         struct pollfd *p;
310         int err = 0, i, n = 0;
311
312         sigio_lock();
313         for(i = 0; i < current_poll.used; i++){
314                 if(current_poll.poll[i].fd == fd) break;
315         }
316         if(i == current_poll.used)
317                 goto out;
318         
319         err = need_poll(current_poll.used - 1);
320         if(err)
321                 goto out;
322
323         for(i = 0; i < current_poll.used; i++){
324                 p = &current_poll.poll[i];
325                 if(p->fd != fd) next_poll.poll[n++] = current_poll.poll[i];
326         }
327         if(n == i){
328                 printk("ignore_sigio_fd : fd %d not found\n", fd);
329                 err = -1;
330                 goto out;
331         }
332
333         update_thread();
334  out:
335         sigio_unlock();
336         return(err);
337 }
338
339 static int setup_initial_poll(int fd)
340 {
341         struct pollfd *p;
342
343         p = um_kmalloc(sizeof(struct pollfd));
344         if(p == NULL){
345                 printk("setup_initial_poll : failed to allocate poll\n");
346                 return(-1);
347         }
348         *p = ((struct pollfd) { .fd     = fd,
349                                 .events         = POLLIN,
350                                 .revents        = 0 });
351         current_poll = ((struct pollfds) { .poll        = p,
352                                            .used        = 1,
353                                            .size        = 1 });
354         return(0);
355 }
356
357 void write_sigio_workaround(void)
358 {
359         unsigned long stack;
360         int err;
361
362         sigio_lock();
363         if(write_sigio_pid != -1)
364                 goto out;
365
366         err = os_pipe(write_sigio_fds, 1, 1);
367         if(err < 0){
368                 printk("write_sigio_workaround - os_pipe 1 failed, "
369                        "err = %d\n", -err);
370                 goto out;
371         }
372         err = os_pipe(sigio_private, 1, 1);
373         if(err < 0){
374                 printk("write_sigio_workaround - os_pipe 2 failed, "
375                        "err = %d\n", -err);
376                 goto out_close1;
377         }
378         if(setup_initial_poll(sigio_private[1]))
379                 goto out_close2;
380
381         write_sigio_pid = run_helper_thread(write_sigio_thread, NULL, 
382                                             CLONE_FILES | CLONE_VM, &stack, 0);
383
384         if(write_sigio_pid < 0) goto out_close2;
385
386         if(write_sigio_irq(write_sigio_fds[0])) 
387                 goto out_kill;
388
389  out:
390         sigio_unlock();
391         return;
392
393  out_kill:
394         os_kill_process(write_sigio_pid, 1);
395         write_sigio_pid = -1;
396  out_close2:
397         os_close_file(sigio_private[0]);
398         os_close_file(sigio_private[1]);
399  out_close1:
400         os_close_file(write_sigio_fds[0]);
401         os_close_file(write_sigio_fds[1]);
402         sigio_unlock();
403 }
404
405 int read_sigio_fd(int fd)
406 {
407         int n;
408         char c;
409
410         n = os_read_file(fd, &c, sizeof(c));
411         if(n != sizeof(c)){
412                 if(n < 0) {
413                         printk("read_sigio_fd - read failed, err = %d\n", -n);
414                         return(n);
415                 }
416                 else {
417                         printk("read_sigio_fd - short read, bytes = %d\n", n);
418                         return(-EIO);
419                 }
420         }
421         return(n);
422 }
423
424 static void sigio_cleanup(void)
425 {
426         if (write_sigio_pid != -1) {
427                 os_kill_process(write_sigio_pid, 1);
428                 write_sigio_pid = -1;
429         }
430 }
431
432 __uml_exitcall(sigio_cleanup);