2 * Copyright (C) 2016 - Aravind HT <aravind.ht@gmail.com>
3 * 2016 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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; only
8 * version 2.1 of the License.
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.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #include <sys/types.h>
29 #include <sys/select.h>
30 #include <sys/resource.h>
36 #include <urcu/compiler.h>
37 #include <urcu/tls-compat.h>
38 #include <urcu/system.h>
42 #include <lttng/ust-error.h>
43 #include <usterr-signal-safe.h>
45 #include "../liblttng-ust/compat.h"
47 /* Operations on the fd set. */
48 #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd)
49 #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE]))
50 #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE)
51 #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO)
53 /* Check fd validity before calling these. */
54 #define ADD_FD_TO_SET(fd, fd_sets) \
55 FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
56 #define IS_FD_SET(fd, fd_sets) \
57 FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
58 #define DEL_FD_FROM_SET(fd, fd_sets) \
59 FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
62 * Protect the lttng_fd_set. Nests within the ust_lock, and therefore
63 * within the libc dl lock. Therefore, we need to fixup the TLS before
64 * nesting into this lock.
66 * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex
67 * is also held across fork.
69 static pthread_mutex_t ust_safe_guard_fd_mutex
= PTHREAD_MUTEX_INITIALIZER
;
72 * Cancel state when grabbing the ust_safe_guard_fd_mutex. Saved when
73 * locking, restored on unlock. Protected by ust_safe_guard_fd_mutex.
75 static int ust_safe_guard_saved_cancelstate
;
78 * Track whether we are within lttng-ust or application, for close
79 * system call override by LD_PRELOAD library. This also tracks whether
80 * we are invoking close() from a signal handler nested on an
83 static DEFINE_URCU_TLS(int, ust_fd_mutex_nest
);
85 /* fd_set used to book keep fd being used by lttng-ust. */
86 static fd_set
*lttng_fd_set
;
87 static int lttng_ust_max_fd
;
88 static int num_fd_sets
;
92 * Force a read (imply TLS fixup for dlopen) of TLS variables.
94 void lttng_ust_fixup_fd_tracker_tls(void)
96 asm volatile ("" : : "m" (URCU_TLS(ust_fd_mutex_nest
)));
100 * Allocate the fd set array based on the hard limit set for this
101 * process. This will be called during the constructor execution
102 * and will also be called in the child after fork via lttng_ust_init.
104 void lttng_ust_init_fd_tracker(void)
109 if (CMM_LOAD_SHARED(init_done
))
112 memset(&rlim
, 0, sizeof(rlim
));
113 /* Get the current possible max number of fd for this process. */
114 if (getrlimit(RLIMIT_NOFILE
, &rlim
) < 0)
117 * FD set array size determined using the hard limit. Even if
118 * the process wishes to increase its limit using setrlimit, it
119 * can only do so with the softlimit which will be less than the
122 lttng_ust_max_fd
= rlim
.rlim_max
;
123 num_fd_sets
= lttng_ust_max_fd
/ FD_SETSIZE
;
124 if (lttng_ust_max_fd
% FD_SETSIZE
)
126 if (lttng_fd_set
!= NULL
) {
130 lttng_fd_set
= malloc(num_fd_sets
* (sizeof(fd_set
)));
133 for (i
= 0; i
< num_fd_sets
; i
++)
134 FD_ZERO((<tng_fd_set
[i
]));
135 CMM_STORE_SHARED(init_done
, 1);
138 void lttng_ust_lock_fd_tracker(void)
140 sigset_t sig_all_blocked
, orig_mask
;
143 ret
= pthread_setcancelstate(PTHREAD_CANCEL_DISABLE
, &oldstate
);
145 ERR("pthread_setcancelstate: %s", strerror(ret
));
147 sigfillset(&sig_all_blocked
);
148 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
150 ERR("pthread_sigmask: %s", strerror(ret
));
152 if (!URCU_TLS(ust_fd_mutex_nest
)++) {
154 * Ensure the compiler don't move the store after the close()
155 * call in case close() would be marked as leaf.
158 pthread_mutex_lock(&ust_safe_guard_fd_mutex
);
159 ust_safe_guard_saved_cancelstate
= oldstate
;
161 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
163 ERR("pthread_sigmask: %s", strerror(ret
));
167 void lttng_ust_unlock_fd_tracker(void)
169 sigset_t sig_all_blocked
, orig_mask
;
170 int ret
, newstate
, oldstate
;
171 bool restore_cancel
= false;
173 sigfillset(&sig_all_blocked
);
174 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
176 ERR("pthread_sigmask: %s", strerror(ret
));
179 * Ensure the compiler don't move the store before the close()
180 * call, in case close() would be marked as leaf.
183 if (!--URCU_TLS(ust_fd_mutex_nest
)) {
184 newstate
= ust_safe_guard_saved_cancelstate
;
185 restore_cancel
= true;
186 pthread_mutex_unlock(&ust_safe_guard_fd_mutex
);
188 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
190 ERR("pthread_sigmask: %s", strerror(ret
));
192 if (restore_cancel
) {
193 ret
= pthread_setcancelstate(newstate
, &oldstate
);
195 ERR("pthread_setcancelstate: %s", strerror(ret
));
200 static int dup_std_fd(int fd
)
203 int fd_to_close
[STDERR_FILENO
+ 1];
204 int fd_to_close_count
= 0;
205 int dup_cmd
= F_DUPFD
; /* Default command */
208 if (!(IS_FD_STD(fd
))) {
209 /* Should not be here */
214 /* Check for FD_CLOEXEC flag */
215 ret
= fcntl(fd
, F_GETFD
);
217 PERROR("fcntl on f_getfd");
222 if (ret
& FD_CLOEXEC
) {
223 dup_cmd
= F_DUPFD_CLOEXEC
;
227 for (i
= 0; i
< STDERR_FILENO
+ 1; i
++) {
228 ret
= fcntl(fd
, dup_cmd
, 0);
230 PERROR("fcntl dup fd");
234 if (!(IS_FD_STD(ret
))) {
235 /* fd is outside of STD range, use it. */
237 /* Close fd received as argument. */
243 fd_to_close
[i
] = ret
;
247 /* Close intermediary fds */
248 for (i
= 0; i
< fd_to_close_count
; i
++) {
249 ret
= close(fd_to_close
[i
]);
251 PERROR("close on temporary fd: %d.", fd_to_close
[i
]);
253 * Not using an abort here would yield a complicated
254 * error handling for the caller. If a failure occurs
255 * here, the system is already in a bad state.
267 * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd.
268 * Has strict checking of fd validity.
270 * If fd <= 2, dup the fd until fd > 2. This enables us to bypass
271 * problems that can be encountered if UST uses stdin, stdout, stderr
272 * fds for internal use (daemon etc.). This can happen if the
273 * application closes either of those file descriptors. Intermediary fds
274 * are closed as needed.
276 * Return -1 on error.
279 int lttng_ust_add_fd_to_tracker(int fd
)
283 * Ensure the tracker is initialized when called from
286 lttng_ust_init_fd_tracker();
287 assert(URCU_TLS(ust_fd_mutex_nest
));
290 ret
= dup_std_fd(fd
);
297 /* Trying to add an fd which we can not accommodate. */
298 assert(IS_FD_VALID(fd
));
299 /* Setting an fd thats already set. */
300 assert(!IS_FD_SET(fd
, lttng_fd_set
));
302 ADD_FD_TO_SET(fd
, lttng_fd_set
);
309 * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd.
310 * Has strict checking for fd validity.
312 void lttng_ust_delete_fd_from_tracker(int fd
)
315 * Ensure the tracker is initialized when called from
318 lttng_ust_init_fd_tracker();
320 assert(URCU_TLS(ust_fd_mutex_nest
));
321 /* Not a valid fd. */
322 assert(IS_FD_VALID(fd
));
323 /* Deleting an fd which was not set. */
324 assert(IS_FD_SET(fd
, lttng_fd_set
));
326 DEL_FD_FROM_SET(fd
, lttng_fd_set
);
330 * Interface allowing applications to close arbitrary file descriptors.
331 * We check if it is owned by lttng-ust, and return -1, errno=EBADF
332 * instead of closing it if it is the case.
334 int lttng_ust_safe_close_fd(int fd
, int (*close_cb
)(int fd
))
338 lttng_ust_fixup_fd_tracker_tls();
341 * Ensure the tracker is initialized when called from
344 lttng_ust_init_fd_tracker();
347 * If called from lttng-ust, we directly call close without
348 * validating whether the FD is part of the tracked set.
350 if (URCU_TLS(ust_fd_mutex_nest
))
353 lttng_ust_lock_fd_tracker();
354 if (IS_FD_VALID(fd
) && IS_FD_SET(fd
, lttng_fd_set
)) {
360 lttng_ust_unlock_fd_tracker();
366 * Interface allowing applications to close arbitrary streams.
367 * We check if it is owned by lttng-ust, and return -1, errno=EBADF
368 * instead of closing it if it is the case.
370 int lttng_ust_safe_fclose_stream(FILE *stream
, int (*fclose_cb
)(FILE *stream
))
374 lttng_ust_fixup_fd_tracker_tls();
377 * Ensure the tracker is initialized when called from
380 lttng_ust_init_fd_tracker();
383 * If called from lttng-ust, we directly call fclose without
384 * validating whether the FD is part of the tracked set.
386 if (URCU_TLS(ust_fd_mutex_nest
))
387 return fclose_cb(stream
);
391 lttng_ust_lock_fd_tracker();
392 if (IS_FD_VALID(fd
) && IS_FD_SET(fd
, lttng_fd_set
)) {
396 ret
= fclose_cb(stream
);
398 lttng_ust_unlock_fd_tracker();
404 static void set_close_success(int *p
)
408 static int test_close_success(const int *p
)
413 static void set_close_success(int *p
__attribute__((unused
)))
416 static int test_close_success(const int *p
__attribute__((unused
)))
423 * Implement helper for closefrom() override.
425 int lttng_ust_safe_closefrom_fd(int lowfd
, int (*close_cb
)(int fd
))
427 int ret
= 0, close_success
= 0, i
;
429 lttng_ust_fixup_fd_tracker_tls();
432 * Ensure the tracker is initialized when called from
435 lttng_ust_init_fd_tracker();
439 * NetBSD return EBADF if fd is invalid.
446 * If called from lttng-ust, we directly call close without
447 * validating whether the FD is part of the tracked set.
449 if (URCU_TLS(ust_fd_mutex_nest
)) {
450 for (i
= lowfd
; i
< lttng_ust_max_fd
; i
++) {
451 if (close_cb(i
) < 0) {
461 set_close_success(&close_success
);
464 lttng_ust_lock_fd_tracker();
465 for (i
= lowfd
; i
< lttng_ust_max_fd
; i
++) {
466 if (IS_FD_VALID(i
) && IS_FD_SET(i
, lttng_fd_set
))
468 if (close_cb(i
) < 0) {
475 lttng_ust_unlock_fd_tracker();
479 set_close_success(&close_success
);
481 lttng_ust_unlock_fd_tracker();
483 if (!test_close_success(&close_success
)) {
485 * OpenBSD return EBADF if fd is greater than all open