1 /*
2 Xen Store Daemon interface providing simple tree-like database.
3 Copyright (C) 2005 Rusty Russell IBM Corporation
4
5 This library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 This library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with this library; If not, see <http://www.gnu.org/licenses/>.
17 */
18
19 #define _GNU_SOURCE
20
21 #include <sys/types.h>
22 #include <sys/stat.h>
23 #include <fcntl.h>
24 #include <sys/uio.h>
25 #include <sys/socket.h>
26 #include <sys/un.h>
27 #include <string.h>
28 #include <unistd.h>
29 #include <stdbool.h>
30 #include <stdlib.h>
31 #include <assert.h>
32 #include <stdio.h>
33 #include <signal.h>
34 #include <stdint.h>
35 #include <errno.h>
36 #include "xenstore.h"
37 #include "list.h"
38 #include "utils.h"
39
40 #include <xentoolcore_internal.h>
41
42 struct xs_stored_msg {
43 struct list_head list;
44 struct xsd_sockmsg hdr;
45 char *body;
46 };
47
48 #ifdef USE_PTHREAD
49
50 #include <pthread.h>
51
52 #ifdef USE_DLSYM
53 #include <dlfcn.h>
54 #endif
55
56 struct xs_handle {
57 /* Communications channel to xenstore daemon. */
58 int fd;
59 Xentoolcore__Active_Handle tc_ah; /* for restrict */
60
61 /*
62 * A read thread which pulls messages off the comms channel and
63 * signals waiters.
64 */
65 pthread_t read_thr;
66 int read_thr_exists;
67
68 /*
69 * A list of fired watch messages, protected by a mutex. Users can
70 * wait on the conditional variable until a watch is pending.
71 */
72 struct list_head watch_list;
73 pthread_mutex_t watch_mutex;
74 pthread_cond_t watch_condvar;
75
76 /* Clients can select() on this pipe to wait for a watch to fire. */
77 int watch_pipe[2];
78 /* Filtering watch event in unwatch function? */
79 bool unwatch_filter;
80
81 /*
82 * A list of replies. Currently only one will ever be outstanding
83 * because we serialise requests. The requester can wait on the
84 * conditional variable for its response.
85 */
86 struct list_head reply_list;
87 pthread_mutex_t reply_mutex;
88 pthread_cond_t reply_condvar;
89
90 /* One request at a time. */
91 pthread_mutex_t request_mutex;
92
93 /* Lock discipline:
94 * Only holder of the request lock may write to h->fd.
95 * Only holder of the request lock may access read_thr_exists.
96 * If read_thr_exists==0, only holder of request lock may read h->fd;
97 * If read_thr_exists==1, only the read thread may read h->fd.
98 * Only holder of the reply lock may access reply_list.
99 * Only holder of the watch lock may access watch_list.
100 * Lock hierarchy:
101 * The order in which to acquire locks is
102 * request_mutex
103 * reply_mutex
104 * watch_mutex
105 */
106 };
107
108 #define mutex_lock(m) pthread_mutex_lock(m)
109 #define mutex_unlock(m) pthread_mutex_unlock(m)
110 #define condvar_signal(c) pthread_cond_signal(c)
111 #define condvar_wait(c,m) pthread_cond_wait(c,m)
112 #define cleanup_push(f, a) \
113 pthread_cleanup_push((void (*)(void *))(f), (void *)(a))
114 /*
115 * Some definitions of pthread_cleanup_pop() are a macro starting with an
116 * end-brace. GCC then complains if we immediately precede that with a label.
117 * Hence we insert a dummy statement to appease the compiler in this situation.
118 */
119 #define cleanup_pop(run) ((void)0); pthread_cleanup_pop(run)
120
121 #define read_thread_exists(h) (h->read_thr_exists)
122
123 /* Because pthread_cleanup_p* are not available when USE_PTHREAD is
124 * disabled, use these macros which convert appropriately. */
125 #define cleanup_push_heap(p) cleanup_push(free, p)
126 #define cleanup_pop_heap(run, p) cleanup_pop((run))
127
128 static void *read_thread(void *arg);
129
130 #else /* !defined(USE_PTHREAD) */
131
132 struct xs_handle {
133 int fd;
134 Xentoolcore__Active_Handle tc_ah; /* for restrict */
135 struct list_head reply_list;
136 struct list_head watch_list;
137 /* Clients can select() on this pipe to wait for a watch to fire. */
138 int watch_pipe[2];
139 /* Filtering watch event in unwatch function? */
140 bool unwatch_filter;
141 };
142
143 #define mutex_lock(m) ((void)0)
144 #define mutex_unlock(m) ((void)0)
145 #define condvar_signal(c) ((void)0)
146 #define condvar_wait(c,m) ((void)0)
147 #define cleanup_push(f, a) ((void)0)
148 #define cleanup_pop(run) ((void)0)
149 #define read_thread_exists(h) (0)
150
151 #define cleanup_push_heap(p) ((void)0)
152 #define cleanup_pop_heap(run, p) do { if ((run)) free(p); } while(0)
153
154 #endif
155
156 static int read_message(struct xs_handle *h, int nonblocking);
157
setnonblock(int fd,int nonblock)158 static bool setnonblock(int fd, int nonblock) {
159 int flags = fcntl(fd, F_GETFL);
160 if (flags == -1)
161 return false;
162
163 if (nonblock)
164 flags |= O_NONBLOCK;
165 else
166 flags &= ~O_NONBLOCK;
167
168 if (fcntl(fd, F_SETFL, flags) == -1)
169 return false;
170
171 return true;
172 }
173
xs_fileno(struct xs_handle * h)174 int xs_fileno(struct xs_handle *h)
175 {
176 char c = 0;
177
178 mutex_lock(&h->watch_mutex);
179
180 if ((h->watch_pipe[0] == -1) && (pipe(h->watch_pipe) != -1)) {
181 /* Kick things off if the watch list is already non-empty. */
182 if (!list_empty(&h->watch_list))
183 while (write(h->watch_pipe[1], &c, 1) != 1)
184 continue;
185 }
186
187 mutex_unlock(&h->watch_mutex);
188
189 return h->watch_pipe[0];
190 }
191
get_socket(const char * connect_to)192 static int get_socket(const char *connect_to)
193 {
194 struct sockaddr_un addr;
195 int sock, saved_errno, flags;
196
197 sock = socket(PF_UNIX, SOCK_STREAM, 0);
198 if (sock < 0)
199 return -1;
200
201 if ((flags = fcntl(sock, F_GETFD)) < 0)
202 goto error;
203 flags |= FD_CLOEXEC;
204 if (fcntl(sock, F_SETFD, flags) < 0)
205 goto error;
206
207 addr.sun_family = AF_UNIX;
208 if(strlen(connect_to) >= sizeof(addr.sun_path)) {
209 errno = EINVAL;
210 goto error;
211 }
212 strcpy(addr.sun_path, connect_to);
213
214 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) != 0)
215 goto error;
216
217 return sock;
218
219 error:
220 saved_errno = errno;
221 close(sock);
222 errno = saved_errno;
223 return -1;
224 }
225
get_dev(const char * connect_to)226 static int get_dev(const char *connect_to)
227 {
228 /* We cannot open read-only because requests are writes */
229 return open(connect_to, O_RDWR);
230 }
231
all_restrict_cb(Xentoolcore__Active_Handle * ah,domid_t domid)232 static int all_restrict_cb(Xentoolcore__Active_Handle *ah, domid_t domid) {
233 struct xs_handle *h = CONTAINER_OF(ah, *h, tc_ah);
234 return xentoolcore__restrict_by_dup2_null(h->fd);
235 }
236
get_handle(const char * connect_to)237 static struct xs_handle *get_handle(const char *connect_to)
238 {
239 struct stat buf;
240 struct xs_handle *h = NULL;
241 int saved_errno;
242
243 h = malloc(sizeof(*h));
244 if (h == NULL)
245 goto err;
246
247 memset(h, 0, sizeof(*h));
248 h->fd = -1;
249
250 h->tc_ah.restrict_callback = all_restrict_cb;
251 xentoolcore__register_active_handle(&h->tc_ah);
252
253 if (stat(connect_to, &buf) != 0)
254 goto err;
255
256 if (S_ISSOCK(buf.st_mode))
257 h->fd = get_socket(connect_to);
258 else
259 h->fd = get_dev(connect_to);
260
261 if (h->fd == -1)
262 goto err;
263
264 INIT_LIST_HEAD(&h->reply_list);
265 INIT_LIST_HEAD(&h->watch_list);
266
267 /* Watch pipe is allocated on demand in xs_fileno(). */
268 h->watch_pipe[0] = h->watch_pipe[1] = -1;
269
270 h->unwatch_filter = false;
271
272 #ifdef USE_PTHREAD
273 pthread_mutex_init(&h->watch_mutex, NULL);
274 pthread_cond_init(&h->watch_condvar, NULL);
275
276 pthread_mutex_init(&h->reply_mutex, NULL);
277 pthread_cond_init(&h->reply_condvar, NULL);
278
279 pthread_mutex_init(&h->request_mutex, NULL);
280 #endif
281
282 return h;
283
284 err:
285 saved_errno = errno;
286
287 if (h) {
288 xentoolcore__deregister_active_handle(&h->tc_ah);
289 if (h->fd >= 0)
290 close(h->fd);
291 }
292 free(h);
293
294 errno = saved_errno;
295 return NULL;
296 }
297
xs_daemon_open(void)298 struct xs_handle *xs_daemon_open(void)
299 {
300 return xs_open(0);
301 }
302
xs_daemon_open_readonly(void)303 struct xs_handle *xs_daemon_open_readonly(void)
304 {
305 return xs_open(XS_OPEN_READONLY);
306 }
307
xs_domain_open(void)308 struct xs_handle *xs_domain_open(void)
309 {
310 return xs_open(0);
311 }
312
xs_open(unsigned long flags)313 struct xs_handle *xs_open(unsigned long flags)
314 {
315 struct xs_handle *xsh = NULL;
316
317 if (flags & XS_OPEN_READONLY)
318 xsh = get_handle(xs_daemon_socket_ro());
319 else
320 xsh = get_handle(xs_daemon_socket());
321
322 if (!xsh && !(flags & XS_OPEN_SOCKETONLY))
323 xsh = get_handle(xs_domain_dev());
324
325 if (xsh && (flags & XS_UNWATCH_FILTER))
326 xsh->unwatch_filter = true;
327
328 return xsh;
329 }
330
close_free_msgs(struct xs_handle * h)331 static void close_free_msgs(struct xs_handle *h) {
332 struct xs_stored_msg *msg, *tmsg;
333
334 list_for_each_entry_safe(msg, tmsg, &h->reply_list, list) {
335 free(msg->body);
336 free(msg);
337 }
338
339 list_for_each_entry_safe(msg, tmsg, &h->watch_list, list) {
340 free(msg->body);
341 free(msg);
342 }
343 }
344
close_fds_free(struct xs_handle * h)345 static void close_fds_free(struct xs_handle *h) {
346 if (h->watch_pipe[0] != -1) {
347 close(h->watch_pipe[0]);
348 close(h->watch_pipe[1]);
349 }
350
351 xentoolcore__deregister_active_handle(&h->tc_ah);
352 close(h->fd);
353
354 free(h);
355 }
356
xs_daemon_destroy_postfork(struct xs_handle * h)357 void xs_daemon_destroy_postfork(struct xs_handle *h)
358 {
359 close_free_msgs(h);
360 close_fds_free(h);
361 }
362
xs_daemon_close(struct xs_handle * h)363 void xs_daemon_close(struct xs_handle *h)
364 {
365 #ifdef USE_PTHREAD
366 if (h->read_thr_exists) {
367 pthread_cancel(h->read_thr);
368 pthread_join(h->read_thr, NULL);
369 }
370 #endif
371
372 mutex_lock(&h->request_mutex);
373 mutex_lock(&h->reply_mutex);
374 mutex_lock(&h->watch_mutex);
375
376 close_free_msgs(h);
377
378 mutex_unlock(&h->request_mutex);
379 mutex_unlock(&h->reply_mutex);
380 mutex_unlock(&h->watch_mutex);
381
382 close_fds_free(h);
383 }
384
xs_close(struct xs_handle * xsh)385 void xs_close(struct xs_handle* xsh)
386 {
387 if (xsh)
388 xs_daemon_close(xsh);
389 }
390
read_all(int fd,void * data,unsigned int len,int nonblocking)391 static bool read_all(int fd, void *data, unsigned int len, int nonblocking)
392 /* With nonblocking, either reads either everything requested,
393 * or nothing. */
394 {
395 if (!len)
396 return true;
397
398 if (nonblocking && !setnonblock(fd, 1))
399 return false;
400
401 while (len) {
402 int done;
403
404 done = read(fd, data, len);
405 if (done < 0) {
406 if (errno == EINTR)
407 continue;
408 goto out_false;
409 }
410 if (done == 0) {
411 /* It closed fd on us? EBADF is appropriate. */
412 errno = EBADF;
413 goto out_false;
414 }
415 data += done;
416 len -= done;
417
418 if (nonblocking) {
419 nonblocking = 0;
420 if (!setnonblock(fd, 0))
421 goto out_false;
422 }
423 }
424
425 return true;
426
427 out_false:
428 if (nonblocking)
429 setnonblock(fd, 0);
430 return false;
431 }
432
433 #ifdef XSTEST
434 #define read_all read_all_choice
435 #define xs_write_all write_all_choice
436 #endif
437
get_error(const char * errorstring)438 static int get_error(const char *errorstring)
439 {
440 unsigned int i;
441
442 for (i = 0; !streq(errorstring, xsd_errors[i].errstring); i++)
443 if (i == ARRAY_SIZE(xsd_errors) - 1)
444 return EINVAL;
445 return xsd_errors[i].errnum;
446 }
447
448 /* Adds extra nul terminator, because we generally (always?) hold strings. */
read_reply(struct xs_handle * h,enum xsd_sockmsg_type * type,unsigned int * len)449 static void *read_reply(
450 struct xs_handle *h, enum xsd_sockmsg_type *type, unsigned int *len)
451 {
452 struct xs_stored_msg *msg;
453 char *body;
454 int read_from_thread;
455
456 read_from_thread = read_thread_exists(h);
457
458 /* Read from comms channel ourselves if there is no reader thread. */
459 if (!read_from_thread && (read_message(h, 0) == -1))
460 return NULL;
461
462 mutex_lock(&h->reply_mutex);
463 #ifdef USE_PTHREAD
464 while (list_empty(&h->reply_list) && read_from_thread && h->fd != -1)
465 condvar_wait(&h->reply_condvar, &h->reply_mutex);
466 #endif
467 if (list_empty(&h->reply_list)) {
468 mutex_unlock(&h->reply_mutex);
469 errno = EINVAL;
470 return NULL;
471 }
472 msg = list_top(&h->reply_list, struct xs_stored_msg, list);
473 list_del(&msg->list);
474 assert(list_empty(&h->reply_list));
475 mutex_unlock(&h->reply_mutex);
476
477 *type = msg->hdr.type;
478 if (len)
479 *len = msg->hdr.len;
480 body = msg->body;
481
482 free(msg);
483
484 return body;
485 }
486
487 /* Send message to xs, get malloc'ed reply. NULL and set errno on error. */
xs_talkv(struct xs_handle * h,xs_transaction_t t,enum xsd_sockmsg_type type,const struct iovec * iovec,unsigned int num_vecs,unsigned int * len)488 static void *xs_talkv(struct xs_handle *h, xs_transaction_t t,
489 enum xsd_sockmsg_type type,
490 const struct iovec *iovec,
491 unsigned int num_vecs,
492 unsigned int *len)
493 {
494 struct xsd_sockmsg msg;
495 void *ret = NULL;
496 int saved_errno;
497 unsigned int i;
498 struct sigaction ignorepipe, oldact;
499
500 msg.tx_id = t;
501 msg.req_id = 0;
502 msg.type = type;
503 msg.len = 0;
504 for (i = 0; i < num_vecs; i++)
505 msg.len += iovec[i].iov_len;
506
507 if (msg.len > XENSTORE_PAYLOAD_MAX) {
508 errno = E2BIG;
509 return 0;
510 }
511
512 ignorepipe.sa_handler = SIG_IGN;
513 sigemptyset(&ignorepipe.sa_mask);
514 ignorepipe.sa_flags = 0;
515 sigaction(SIGPIPE, &ignorepipe, &oldact);
516
517 mutex_lock(&h->request_mutex);
518
519 if (!xs_write_all(h->fd, &msg, sizeof(msg)))
520 goto fail;
521
522 for (i = 0; i < num_vecs; i++)
523 if (!xs_write_all(h->fd, iovec[i].iov_base, iovec[i].iov_len))
524 goto fail;
525
526 ret = read_reply(h, &msg.type, len);
527 if (!ret)
528 goto fail;
529
530 mutex_unlock(&h->request_mutex);
531
532 sigaction(SIGPIPE, &oldact, NULL);
533 if (msg.type == XS_ERROR) {
534 saved_errno = get_error(ret);
535 free(ret);
536 errno = saved_errno;
537 return NULL;
538 }
539
540 if (msg.type != type) {
541 free(ret);
542 saved_errno = EBADF;
543 goto close_fd;
544 }
545 return ret;
546
547 fail:
548 /* We're in a bad state, so close fd. */
549 saved_errno = errno;
550 mutex_unlock(&h->request_mutex);
551 sigaction(SIGPIPE, &oldact, NULL);
552 close_fd:
553 close(h->fd);
554 h->fd = -1;
555 errno = saved_errno;
556 return NULL;
557 }
558
559 /* free(), but don't change errno. */
free_no_errno(void * p)560 static void free_no_errno(void *p)
561 {
562 int saved_errno = errno;
563 free(p);
564 errno = saved_errno;
565 }
566
567 /* Simplified version of xs_talkv: single message. */
xs_single(struct xs_handle * h,xs_transaction_t t,enum xsd_sockmsg_type type,const char * string,unsigned int * len)568 static void *xs_single(struct xs_handle *h, xs_transaction_t t,
569 enum xsd_sockmsg_type type,
570 const char *string,
571 unsigned int *len)
572 {
573 struct iovec iovec;
574
575 iovec.iov_base = (void *)string;
576 iovec.iov_len = strlen(string) + 1;
577 return xs_talkv(h, t, type, &iovec, 1, len);
578 }
579
xs_bool(char * reply)580 static bool xs_bool(char *reply)
581 {
582 if (!reply)
583 return false;
584 free(reply);
585 return true;
586 }
587
xs_directory_common(char * strings,unsigned int len,unsigned int * num)588 static char **xs_directory_common(char *strings, unsigned int len,
589 unsigned int *num)
590 {
591 char *p, **ret;
592
593 /* Count the strings. */
594 *num = xs_count_strings(strings, len);
595
596 /* Transfer to one big alloc for easy freeing. */
597 ret = malloc(*num * sizeof(char *) + len);
598 if (!ret) {
599 free_no_errno(strings);
600 return NULL;
601 }
602 memcpy(&ret[*num], strings, len);
603 free_no_errno(strings);
604
605 strings = (char *)&ret[*num];
606 for (p = strings, *num = 0; p < strings + len; p += strlen(p) + 1)
607 ret[(*num)++] = p;
608 return ret;
609 }
610
xs_directory_part(struct xs_handle * h,xs_transaction_t t,const char * path,unsigned int * num)611 static char **xs_directory_part(struct xs_handle *h, xs_transaction_t t,
612 const char *path, unsigned int *num)
613 {
614 unsigned int off, result_len;
615 char gen[24], offstr[8];
616 struct iovec iovec[2];
617 char *result = NULL, *strings = NULL;
618
619 memset(gen, 0, sizeof(gen));
620 iovec[0].iov_base = (void *)path;
621 iovec[0].iov_len = strlen(path) + 1;
622
623 for (off = 0;;) {
624 snprintf(offstr, sizeof(offstr), "%u", off);
625 iovec[1].iov_base = (void *)offstr;
626 iovec[1].iov_len = strlen(offstr) + 1;
627 result = xs_talkv(h, t, XS_DIRECTORY_PART, iovec, 2,
628 &result_len);
629
630 /* If XS_DIRECTORY_PART isn't supported return E2BIG. */
631 if (!result) {
632 if (errno == ENOSYS)
633 errno = E2BIG;
634 return NULL;
635 }
636
637 if (off) {
638 if (strcmp(gen, result)) {
639 free(result);
640 free(strings);
641 strings = NULL;
642 off = 0;
643 continue;
644 }
645 } else
646 strncpy(gen, result, sizeof(gen) - 1);
647
648 result_len -= strlen(result) + 1;
649 strings = realloc(strings, off + result_len);
650 memcpy(strings + off, result + strlen(result) + 1, result_len);
651 free(result);
652 off += result_len;
653
654 if (off <= 1 || strings[off - 2] == 0)
655 break;
656 }
657
658 if (off > 1)
659 off--;
660
661 return xs_directory_common(strings, off, num);
662 }
663
xs_directory(struct xs_handle * h,xs_transaction_t t,const char * path,unsigned int * num)664 char **xs_directory(struct xs_handle *h, xs_transaction_t t,
665 const char *path, unsigned int *num)
666 {
667 char *strings;
668 unsigned int len;
669
670 strings = xs_single(h, t, XS_DIRECTORY, path, &len);
671 if (!strings) {
672 if (errno != E2BIG)
673 return NULL;
674 return xs_directory_part(h, t, path, num);
675 }
676
677 return xs_directory_common(strings, len, num);
678 }
679
680 /* Get the value of a single file, nul terminated.
681 * Returns a malloced value: call free() on it after use.
682 * len indicates length in bytes, not including the nul.
683 * Returns NULL on failure.
684 */
xs_read(struct xs_handle * h,xs_transaction_t t,const char * path,unsigned int * len)685 void *xs_read(struct xs_handle *h, xs_transaction_t t,
686 const char *path, unsigned int *len)
687 {
688 return xs_single(h, t, XS_READ, path, len);
689 }
690
691 /* Write the value of a single file.
692 * Returns false on failure.
693 */
xs_write(struct xs_handle * h,xs_transaction_t t,const char * path,const void * data,unsigned int len)694 bool xs_write(struct xs_handle *h, xs_transaction_t t,
695 const char *path, const void *data, unsigned int len)
696 {
697 struct iovec iovec[2];
698
699 iovec[0].iov_base = (void *)path;
700 iovec[0].iov_len = strlen(path) + 1;
701 iovec[1].iov_base = (void *)data;
702 iovec[1].iov_len = len;
703
704 return xs_bool(xs_talkv(h, t, XS_WRITE, iovec,
705 ARRAY_SIZE(iovec), NULL));
706 }
707
708 /* Create a new directory.
709 * Returns false on failure, or success if it already exists.
710 */
xs_mkdir(struct xs_handle * h,xs_transaction_t t,const char * path)711 bool xs_mkdir(struct xs_handle *h, xs_transaction_t t,
712 const char *path)
713 {
714 return xs_bool(xs_single(h, t, XS_MKDIR, path, NULL));
715 }
716
717 /* Destroy a file or directory (directories must be empty).
718 * Returns false on failure, or success if it doesn't exist.
719 */
xs_rm(struct xs_handle * h,xs_transaction_t t,const char * path)720 bool xs_rm(struct xs_handle *h, xs_transaction_t t,
721 const char *path)
722 {
723 return xs_bool(xs_single(h, t, XS_RM, path, NULL));
724 }
725
726 /* Get permissions of node (first element is owner).
727 * Returns malloced array, or NULL: call free() after use.
728 */
xs_get_permissions(struct xs_handle * h,xs_transaction_t t,const char * path,unsigned int * num)729 struct xs_permissions *xs_get_permissions(struct xs_handle *h,
730 xs_transaction_t t,
731 const char *path, unsigned int *num)
732 {
733 char *strings;
734 unsigned int len;
735 struct xs_permissions *ret;
736
737 strings = xs_single(h, t, XS_GET_PERMS, path, &len);
738 if (!strings)
739 return NULL;
740
741 /* Count the strings: each one perms then domid. */
742 *num = xs_count_strings(strings, len);
743
744 /* Transfer to one big alloc for easy freeing. */
745 ret = malloc(*num * sizeof(struct xs_permissions));
746 if (!ret) {
747 free_no_errno(strings);
748 return NULL;
749 }
750
751 if (!xs_strings_to_perms(ret, *num, strings)) {
752 free_no_errno(ret);
753 ret = NULL;
754 }
755
756 free(strings);
757 return ret;
758 }
759
760 /* Set permissions of node (must be owner).
761 * Returns false on failure.
762 */
xs_set_permissions(struct xs_handle * h,xs_transaction_t t,const char * path,struct xs_permissions * perms,unsigned int num_perms)763 bool xs_set_permissions(struct xs_handle *h,
764 xs_transaction_t t,
765 const char *path,
766 struct xs_permissions *perms,
767 unsigned int num_perms)
768 {
769 unsigned int i;
770 struct iovec iov[1+num_perms];
771
772 iov[0].iov_base = (void *)path;
773 iov[0].iov_len = strlen(path) + 1;
774
775 for (i = 0; i < num_perms; i++) {
776 char buffer[MAX_STRLEN(unsigned int)+1];
777
778 if (!xs_perm_to_string(&perms[i], buffer, sizeof(buffer)))
779 goto unwind;
780
781 iov[i+1].iov_base = strdup(buffer);
782 iov[i+1].iov_len = strlen(buffer) + 1;
783 if (!iov[i+1].iov_base)
784 goto unwind;
785 }
786
787 if (!xs_bool(xs_talkv(h, t, XS_SET_PERMS, iov, 1+num_perms, NULL)))
788 goto unwind;
789 for (i = 0; i < num_perms; i++)
790 free(iov[i+1].iov_base);
791 return true;
792
793 unwind:
794 num_perms = i;
795 for (i = 0; i < num_perms; i++)
796 free_no_errno(iov[i+1].iov_base);
797 return false;
798 }
799
800 /* Always return false a functionality has been removed in Xen 4.9 */
xs_restrict(struct xs_handle * h,unsigned domid)801 bool xs_restrict(struct xs_handle *h, unsigned domid)
802 {
803 return false;
804 }
805
806 /* Watch a node for changes (poll on fd to detect, or call read_watch()).
807 * When the node (or any child) changes, fd will become readable.
808 * Token is returned when watch is read, to allow matching.
809 * Returns false on failure.
810 */
xs_watch(struct xs_handle * h,const char * path,const char * token)811 bool xs_watch(struct xs_handle *h, const char *path, const char *token)
812 {
813 struct iovec iov[2];
814
815 #ifdef USE_PTHREAD
816 #define DEFAULT_THREAD_STACKSIZE (16 * 1024)
817 #define READ_THREAD_STACKSIZE \
818 ((DEFAULT_THREAD_STACKSIZE < PTHREAD_STACK_MIN) ? \
819 PTHREAD_STACK_MIN : DEFAULT_THREAD_STACKSIZE)
820
821 /* We dynamically create a reader thread on demand. */
822 mutex_lock(&h->request_mutex);
823 if (!h->read_thr_exists) {
824 sigset_t set, old_set;
825 pthread_attr_t attr;
826 static size_t stack_size;
827 #ifdef USE_DLSYM
828 size_t (*getsz)(pthread_attr_t *attr);
829 #endif
830
831 if (pthread_attr_init(&attr) != 0) {
832 mutex_unlock(&h->request_mutex);
833 return false;
834 }
835 if (!stack_size) {
836 #ifdef USE_DLSYM
837 getsz = dlsym(RTLD_DEFAULT, "__pthread_get_minstack");
838 if (getsz)
839 stack_size = getsz(&attr);
840 #endif
841 if (stack_size < READ_THREAD_STACKSIZE)
842 stack_size = READ_THREAD_STACKSIZE;
843 }
844 if (pthread_attr_setstacksize(&attr, stack_size) != 0) {
845 pthread_attr_destroy(&attr);
846 mutex_unlock(&h->request_mutex);
847 return false;
848 }
849
850 sigfillset(&set);
851 pthread_sigmask(SIG_SETMASK, &set, &old_set);
852
853 if (pthread_create(&h->read_thr, &attr, read_thread, h) != 0) {
854 pthread_sigmask(SIG_SETMASK, &old_set, NULL);
855 pthread_attr_destroy(&attr);
856 mutex_unlock(&h->request_mutex);
857 return false;
858 }
859 h->read_thr_exists = 1;
860 pthread_sigmask(SIG_SETMASK, &old_set, NULL);
861 pthread_attr_destroy(&attr);
862 }
863 mutex_unlock(&h->request_mutex);
864 #endif
865
866 iov[0].iov_base = (void *)path;
867 iov[0].iov_len = strlen(path) + 1;
868 iov[1].iov_base = (void *)token;
869 iov[1].iov_len = strlen(token) + 1;
870
871 return xs_bool(xs_talkv(h, XBT_NULL, XS_WATCH, iov,
872 ARRAY_SIZE(iov), NULL));
873 }
874
875
876 /* Clear the pipe token if there are no more pending watchs.
877 * We suppose the watch_mutex is already taken.
878 */
xs_maybe_clear_watch_pipe(struct xs_handle * h)879 static void xs_maybe_clear_watch_pipe(struct xs_handle *h)
880 {
881 char c;
882
883 if (list_empty(&h->watch_list) && (h->watch_pipe[0] != -1))
884 while (read(h->watch_pipe[0], &c, 1) != 1)
885 continue;
886 }
887
888 /* Find out what node change was on (will block if nothing pending).
889 * Returns array of two pointers: path and token, or NULL.
890 * Call free() after use.
891 */
read_watch_internal(struct xs_handle * h,unsigned int * num,int nonblocking)892 static char **read_watch_internal(struct xs_handle *h, unsigned int *num,
893 int nonblocking)
894 {
895 struct xs_stored_msg *msg;
896 char **ret, *strings;
897 unsigned int num_strings, i;
898
899 mutex_lock(&h->watch_mutex);
900
901 #ifdef USE_PTHREAD
902 /* Wait on the condition variable for a watch to fire.
903 * If the reader thread doesn't exist yet, then that's because
904 * we haven't called xs_watch. Presumably the application
905 * will do so later; in the meantime we just block.
906 */
907 while (list_empty(&h->watch_list) && h->fd != -1) {
908 if (nonblocking) {
909 mutex_unlock(&h->watch_mutex);
910 errno = EAGAIN;
911 return 0;
912 }
913 condvar_wait(&h->watch_condvar, &h->watch_mutex);
914 }
915 #else /* !defined(USE_PTHREAD) */
916 /* Read from comms channel ourselves if there are no threads
917 * and therefore no reader thread. */
918
919 assert(!read_thread_exists(h)); /* not threadsafe but worth a check */
920 if ((read_message(h, nonblocking) == -1))
921 return NULL;
922
923 #endif /* !defined(USE_PTHREAD) */
924
925 if (list_empty(&h->watch_list)) {
926 mutex_unlock(&h->watch_mutex);
927 errno = EINVAL;
928 return NULL;
929 }
930 msg = list_top(&h->watch_list, struct xs_stored_msg, list);
931 list_del(&msg->list);
932
933 xs_maybe_clear_watch_pipe(h);
934 mutex_unlock(&h->watch_mutex);
935
936 assert(msg->hdr.type == XS_WATCH_EVENT);
937
938 strings = msg->body;
939 num_strings = xs_count_strings(strings, msg->hdr.len);
940
941 ret = malloc(sizeof(char*) * num_strings + msg->hdr.len);
942 if (!ret) {
943 free_no_errno(strings);
944 free_no_errno(msg);
945 return NULL;
946 }
947
948 ret[0] = (char *)(ret + num_strings);
949 memcpy(ret[0], strings, msg->hdr.len);
950
951 free(strings);
952 free(msg);
953
954 for (i = 1; i < num_strings; i++)
955 ret[i] = ret[i - 1] + strlen(ret[i - 1]) + 1;
956
957 *num = num_strings;
958
959 return ret;
960 }
961
xs_check_watch(struct xs_handle * h)962 char **xs_check_watch(struct xs_handle *h)
963 {
964 unsigned int num;
965 char **ret;
966 ret = read_watch_internal(h, &num, 1);
967 if (ret) assert(num >= 2);
968 return ret;
969 }
970
971 /* Find out what node change was on (will block if nothing pending).
972 * Returns array of two pointers: path and token, or NULL.
973 * Call free() after use.
974 */
xs_read_watch(struct xs_handle * h,unsigned int * num)975 char **xs_read_watch(struct xs_handle *h, unsigned int *num)
976 {
977 return read_watch_internal(h, num, 0);
978 }
979
980 /* Remove a watch on a node.
981 * Returns false on failure (no watch on that node).
982 */
xs_unwatch(struct xs_handle * h,const char * path,const char * token)983 bool xs_unwatch(struct xs_handle *h, const char *path, const char *token)
984 {
985 struct iovec iov[2];
986 struct xs_stored_msg *msg, *tmsg;
987 bool res;
988 char *s, *p;
989 unsigned int i;
990 char *l_token, *l_path;
991
992 iov[0].iov_base = (char *)path;
993 iov[0].iov_len = strlen(path) + 1;
994 iov[1].iov_base = (char *)token;
995 iov[1].iov_len = strlen(token) + 1;
996
997 res = xs_bool(xs_talkv(h, XBT_NULL, XS_UNWATCH, iov,
998 ARRAY_SIZE(iov), NULL));
999
1000 if (!h->unwatch_filter) /* Don't filter the watch list */
1001 return res;
1002
1003
1004 /* Filter the watch list to remove potential message */
1005 mutex_lock(&h->watch_mutex);
1006
1007 if (list_empty(&h->watch_list)) {
1008 mutex_unlock(&h->watch_mutex);
1009 return res;
1010 }
1011
1012 list_for_each_entry_safe(msg, tmsg, &h->watch_list, list) {
1013 assert(msg->hdr.type == XS_WATCH_EVENT);
1014
1015 s = msg->body;
1016
1017 l_token = NULL;
1018 l_path = NULL;
1019
1020 for (p = s, i = 0; p < msg->body + msg->hdr.len; p++) {
1021 if (*p == '\0')
1022 {
1023 if (i == XS_WATCH_TOKEN)
1024 l_token = s;
1025 else if (i == XS_WATCH_PATH)
1026 l_path = s;
1027 i++;
1028 s = p + 1;
1029 }
1030 }
1031
1032 if (l_token && !strcmp(token, l_token) &&
1033 l_path && xs_path_is_subpath(path, l_path)) {
1034 list_del(&msg->list);
1035 free(msg);
1036 }
1037 }
1038
1039 xs_maybe_clear_watch_pipe(h);
1040
1041 mutex_unlock(&h->watch_mutex);
1042
1043 return res;
1044 }
1045
1046 /* Start a transaction: changes by others will not be seen during this
1047 * transaction, and changes will not be visible to others until end.
1048 * Returns XBT_NULL on failure.
1049 */
xs_transaction_start(struct xs_handle * h)1050 xs_transaction_t xs_transaction_start(struct xs_handle *h)
1051 {
1052 char *id_str;
1053 xs_transaction_t id;
1054
1055 id_str = xs_single(h, XBT_NULL, XS_TRANSACTION_START, "", NULL);
1056 if (id_str == NULL)
1057 return XBT_NULL;
1058
1059 id = strtoul(id_str, NULL, 0);
1060 free(id_str);
1061
1062 return id;
1063 }
1064
1065 /* End a transaction.
1066 * If abandon is true, transaction is discarded instead of committed.
1067 * Returns false on failure, which indicates an error: transactions will
1068 * not fail spuriously.
1069 */
xs_transaction_end(struct xs_handle * h,xs_transaction_t t,bool abort)1070 bool xs_transaction_end(struct xs_handle *h, xs_transaction_t t,
1071 bool abort)
1072 {
1073 char abortstr[2];
1074
1075 if (abort)
1076 strcpy(abortstr, "F");
1077 else
1078 strcpy(abortstr, "T");
1079
1080 return xs_bool(xs_single(h, t, XS_TRANSACTION_END, abortstr, NULL));
1081 }
1082
1083 /* Introduce a new domain.
1084 * This tells the store daemon about a shared memory page and event channel
1085 * associated with a domain: the domain uses these to communicate.
1086 */
xs_introduce_domain(struct xs_handle * h,unsigned int domid,unsigned long mfn,unsigned int eventchn)1087 bool xs_introduce_domain(struct xs_handle *h,
1088 unsigned int domid, unsigned long mfn,
1089 unsigned int eventchn)
1090 {
1091 char domid_str[MAX_STRLEN(domid)];
1092 char mfn_str[MAX_STRLEN(mfn)];
1093 char eventchn_str[MAX_STRLEN(eventchn)];
1094 struct iovec iov[3];
1095
1096 snprintf(domid_str, sizeof(domid_str), "%u", domid);
1097 snprintf(mfn_str, sizeof(mfn_str), "%lu", mfn);
1098 snprintf(eventchn_str, sizeof(eventchn_str), "%u", eventchn);
1099
1100 iov[0].iov_base = domid_str;
1101 iov[0].iov_len = strlen(domid_str) + 1;
1102 iov[1].iov_base = mfn_str;
1103 iov[1].iov_len = strlen(mfn_str) + 1;
1104 iov[2].iov_base = eventchn_str;
1105 iov[2].iov_len = strlen(eventchn_str) + 1;
1106
1107 return xs_bool(xs_talkv(h, XBT_NULL, XS_INTRODUCE, iov,
1108 ARRAY_SIZE(iov), NULL));
1109 }
1110
xs_set_target(struct xs_handle * h,unsigned int domid,unsigned int target)1111 bool xs_set_target(struct xs_handle *h,
1112 unsigned int domid, unsigned int target)
1113 {
1114 char domid_str[MAX_STRLEN(domid)];
1115 char target_str[MAX_STRLEN(target)];
1116 struct iovec iov[2];
1117
1118 snprintf(domid_str, sizeof(domid_str), "%u", domid);
1119 snprintf(target_str, sizeof(target_str), "%u", target);
1120
1121 iov[0].iov_base = domid_str;
1122 iov[0].iov_len = strlen(domid_str) + 1;
1123 iov[1].iov_base = target_str;
1124 iov[1].iov_len = strlen(target_str) + 1;
1125
1126 return xs_bool(xs_talkv(h, XBT_NULL, XS_SET_TARGET, iov,
1127 ARRAY_SIZE(iov), NULL));
1128 }
1129
single_with_domid(struct xs_handle * h,enum xsd_sockmsg_type type,unsigned int domid)1130 static void * single_with_domid(struct xs_handle *h,
1131 enum xsd_sockmsg_type type,
1132 unsigned int domid)
1133 {
1134 char domid_str[MAX_STRLEN(domid)];
1135
1136 snprintf(domid_str, sizeof(domid_str), "%u", domid);
1137
1138 return xs_single(h, XBT_NULL, type, domid_str, NULL);
1139 }
1140
xs_release_domain(struct xs_handle * h,unsigned int domid)1141 bool xs_release_domain(struct xs_handle *h, unsigned int domid)
1142 {
1143 return xs_bool(single_with_domid(h, XS_RELEASE, domid));
1144 }
1145
1146 /* clear the shutdown bit for the given domain */
xs_resume_domain(struct xs_handle * h,unsigned int domid)1147 bool xs_resume_domain(struct xs_handle *h, unsigned int domid)
1148 {
1149 return xs_bool(single_with_domid(h, XS_RESUME, domid));
1150 }
1151
xs_get_domain_path(struct xs_handle * h,unsigned int domid)1152 char *xs_get_domain_path(struct xs_handle *h, unsigned int domid)
1153 {
1154 char domid_str[MAX_STRLEN(domid)];
1155
1156 snprintf(domid_str, sizeof(domid_str), "%u", domid);
1157
1158 return xs_single(h, XBT_NULL, XS_GET_DOMAIN_PATH, domid_str, NULL);
1159 }
1160
xs_path_is_subpath(const char * parent,const char * child)1161 bool xs_path_is_subpath(const char *parent, const char *child)
1162 {
1163 size_t childlen = strlen(child);
1164 size_t parentlen = strlen(parent);
1165
1166 if (childlen < parentlen)
1167 return false;
1168
1169 if (memcmp(child, parent, parentlen))
1170 return false;
1171
1172 if (childlen > parentlen && child[parentlen] != '/')
1173 return false;
1174
1175 return true;
1176 }
1177
xs_is_domain_introduced(struct xs_handle * h,unsigned int domid)1178 bool xs_is_domain_introduced(struct xs_handle *h, unsigned int domid)
1179 {
1180 char *domain = single_with_domid(h, XS_IS_DOMAIN_INTRODUCED, domid);
1181 int rc = strcmp("F", domain);
1182
1183 free(domain);
1184 return rc;
1185 }
1186
xs_suspend_evtchn_port(int domid)1187 int xs_suspend_evtchn_port(int domid)
1188 {
1189 char path[128];
1190 char *portstr;
1191 int port;
1192 unsigned int plen;
1193 struct xs_handle *xs;
1194
1195 xs = xs_daemon_open();
1196 if (!xs)
1197 return -1;
1198
1199 sprintf(path, "/local/domain/%d/device/suspend/event-channel", domid);
1200 portstr = xs_read(xs, XBT_NULL, path, &plen);
1201 xs_daemon_close(xs);
1202
1203 if (!portstr || !plen) {
1204 port = -1;
1205 goto out;
1206 }
1207
1208 port = atoi(portstr);
1209
1210 out:
1211 free(portstr);
1212 return port;
1213 }
1214
xs_control_command(struct xs_handle * h,const char * cmd,void * data,unsigned int len)1215 char *xs_control_command(struct xs_handle *h, const char *cmd,
1216 void *data, unsigned int len)
1217 {
1218 struct iovec iov[2];
1219
1220 iov[0].iov_base = (void *)cmd;
1221 iov[0].iov_len = strlen(cmd) + 1;
1222 iov[1].iov_base = data;
1223 iov[1].iov_len = len;
1224
1225 return xs_talkv(h, XBT_NULL, XS_CONTROL, iov,
1226 ARRAY_SIZE(iov), NULL);
1227 }
1228
xs_debug_command(struct xs_handle * h,const char * cmd,void * data,unsigned int len)1229 char *xs_debug_command(struct xs_handle *h, const char *cmd,
1230 void *data, unsigned int len)
1231 {
1232 return xs_control_command(h, cmd, data, len);
1233 }
1234
read_message(struct xs_handle * h,int nonblocking)1235 static int read_message(struct xs_handle *h, int nonblocking)
1236 {
1237 /* IMPORTANT: It is forbidden to call this function without
1238 * acquiring the request lock and checking that h->read_thr_exists
1239 * is false. See "Lock discipline" in struct xs_handle, above. */
1240
1241 /* If nonblocking==1, this function will always read either
1242 * nothing, returning -1 and setting errno==EAGAIN, or we read
1243 * whole amount requested. Ie as soon as we have the start of
1244 * the message we block until we get all of it.
1245 */
1246
1247 struct xs_stored_msg *msg = NULL;
1248 char *body = NULL;
1249 int saved_errno = 0;
1250 int ret = -1;
1251
1252 /* Allocate message structure and read the message header. */
1253 msg = malloc(sizeof(*msg));
1254 if (msg == NULL)
1255 goto error;
1256 cleanup_push_heap(msg);
1257 if (!read_all(h->fd, &msg->hdr, sizeof(msg->hdr), nonblocking)) { /* Cancellation point */
1258 saved_errno = errno;
1259 goto error_freemsg;
1260 }
1261
1262 /* Sanity check message body length. */
1263 if (msg->hdr.len > XENSTORE_PAYLOAD_MAX) {
1264 saved_errno = E2BIG;
1265 goto error_freemsg;
1266 }
1267
1268 /* Allocate and read the message body. */
1269 body = msg->body = malloc(msg->hdr.len + 1);
1270 if (body == NULL)
1271 goto error_freemsg;
1272 cleanup_push_heap(body);
1273 if (!read_all(h->fd, body, msg->hdr.len, 0)) { /* Cancellation point */
1274 saved_errno = errno;
1275 goto error_freebody;
1276 }
1277
1278 body[msg->hdr.len] = '\0';
1279
1280 if (msg->hdr.type == XS_WATCH_EVENT) {
1281 mutex_lock(&h->watch_mutex);
1282 cleanup_push(pthread_mutex_unlock, &h->watch_mutex);
1283
1284 /* Kick users out of their select() loop. */
1285 if (list_empty(&h->watch_list) &&
1286 (h->watch_pipe[1] != -1))
1287 while (write(h->watch_pipe[1], body, 1) != 1) /* Cancellation point */
1288 continue;
1289
1290 list_add_tail(&msg->list, &h->watch_list);
1291
1292 condvar_signal(&h->watch_condvar);
1293
1294 cleanup_pop(1);
1295 } else {
1296 mutex_lock(&h->reply_mutex);
1297
1298 /* There should only ever be one response pending! */
1299 if (!list_empty(&h->reply_list)) {
1300 mutex_unlock(&h->reply_mutex);
1301 saved_errno = EEXIST;
1302 goto error_freebody;
1303 }
1304
1305 list_add_tail(&msg->list, &h->reply_list);
1306 condvar_signal(&h->reply_condvar);
1307
1308 mutex_unlock(&h->reply_mutex);
1309 }
1310
1311 ret = 0;
1312
1313 error_freebody:
1314 cleanup_pop_heap(ret == -1, body);
1315 error_freemsg:
1316 cleanup_pop_heap(ret == -1, msg);
1317 error:
1318 errno = saved_errno;
1319
1320 return ret;
1321 }
1322
1323 #ifdef USE_PTHREAD
read_thread(void * arg)1324 static void *read_thread(void *arg)
1325 {
1326 struct xs_handle *h = arg;
1327 int fd;
1328
1329 while (read_message(h, 0) != -1)
1330 continue;
1331
1332 /* An error return from read_message leaves the socket in an undefined
1333 * state; we might have read only the header and not the message after
1334 * it, or (more commonly) the other end has closed the connection.
1335 * Since further communication is unsafe, close the socket.
1336 */
1337 fd = h->fd;
1338 h->fd = -1;
1339 close(fd);
1340
1341 /* wake up all waiters */
1342 pthread_mutex_lock(&h->reply_mutex);
1343 pthread_cond_broadcast(&h->reply_condvar);
1344 pthread_mutex_unlock(&h->reply_mutex);
1345
1346 pthread_mutex_lock(&h->watch_mutex);
1347 pthread_cond_broadcast(&h->watch_condvar);
1348 pthread_mutex_unlock(&h->watch_mutex);
1349
1350 return NULL;
1351 }
1352 #endif
1353
expanding_buffer_ensure(struct expanding_buffer * ebuf,int min_avail)1354 char *expanding_buffer_ensure(struct expanding_buffer *ebuf, int min_avail)
1355 {
1356 int want;
1357 char *got;
1358
1359 if (ebuf->avail >= min_avail)
1360 return ebuf->buf;
1361
1362 if (min_avail >= INT_MAX/3)
1363 return 0;
1364
1365 want = ebuf->avail + min_avail + 10;
1366 got = realloc(ebuf->buf, want);
1367 if (!got)
1368 return 0;
1369
1370 ebuf->buf = got;
1371 ebuf->avail = want;
1372 return ebuf->buf;
1373 }
1374
sanitise_value(struct expanding_buffer * ebuf,const char * val,unsigned len)1375 char *sanitise_value(struct expanding_buffer *ebuf,
1376 const char *val, unsigned len)
1377 {
1378 int used, remain, c;
1379 unsigned char *ip;
1380
1381 #define ADD(c) (ebuf->buf[used++] = (c))
1382 #define ADDF(f,c) (used += sprintf(ebuf->buf+used, (f), (c)))
1383
1384 assert(len < INT_MAX/5);
1385
1386 ip = (unsigned char *)val;
1387 used = 0;
1388 remain = len;
1389
1390 if (!expanding_buffer_ensure(ebuf, remain + 1))
1391 return NULL;
1392
1393 while (remain-- > 0) {
1394 c= *ip++;
1395
1396 if (c >= ' ' && c <= '~' && c != '\\') {
1397 ADD(c);
1398 continue;
1399 }
1400
1401 if (!expanding_buffer_ensure(ebuf, used + remain + 5))
1402 /* for "<used>\\nnn<remain>\0" */
1403 return 0;
1404
1405 ADD('\\');
1406 switch (c) {
1407 case '\t': ADD('t'); break;
1408 case '\n': ADD('n'); break;
1409 case '\r': ADD('r'); break;
1410 case '\\': ADD('\\'); break;
1411 default:
1412 if (c < 010) ADDF("%03o", c);
1413 else ADDF("x%02x", c);
1414 }
1415 }
1416
1417 ADD(0);
1418 assert(used <= ebuf->avail);
1419 return ebuf->buf;
1420
1421 #undef ADD
1422 #undef ADDF
1423 }
1424
unsanitise_value(char * out,unsigned * out_len_r,const char * in)1425 void unsanitise_value(char *out, unsigned *out_len_r, const char *in)
1426 {
1427 const char *ip;
1428 char *op;
1429 unsigned c;
1430 int n;
1431
1432 for (ip = in, op = out; (c = *ip++); *op++ = c) {
1433 if (c == '\\') {
1434 c = *ip++;
1435
1436 #define GETF(f) do { \
1437 n = 0; \
1438 sscanf(ip, f "%n", &c, &n); \
1439 ip += n; \
1440 } while (0)
1441
1442 switch (c) {
1443 case 't': c= '\t'; break;
1444 case 'n': c= '\n'; break;
1445 case 'r': c= '\r'; break;
1446 case '\\': c= '\\'; break;
1447 case 'x': GETF("%2x"); break;
1448 case '0': case '4':
1449 case '1': case '5':
1450 case '2': case '6':
1451 case '3': case '7': --ip; GETF("%3o"); break;
1452 case 0: --ip; break;
1453 default:;
1454 }
1455 #undef GETF
1456 }
1457 }
1458
1459 *op = 0;
1460
1461 if (out_len_r)
1462 *out_len_r = op - out;
1463 }
1464
1465 /*
1466 * Local variables:
1467 * mode: C
1468 * c-file-style: "linux"
1469 * indent-tabs-mode: t
1470 * c-basic-offset: 8
1471 * tab-width: 8
1472 * End:
1473 */
1474