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
25 #include <sys/types.h>
30 #include <sys/select.h>
31 #include <sys/resource.h>
37 #include <urcu/compiler.h>
38 #include <urcu/tls-compat.h>
39 #include <urcu/system.h>
43 #include <lttng/ust-error.h>
44 #include <usterr-signal-safe.h>
46 #include "../liblttng-ust/compat.h"
48 /* Operations on the fd set. */
49 #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd)
50 #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE]))
51 #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE)
52 #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO)
54 /* Check fd validity before calling these. */
55 #define ADD_FD_TO_SET(fd, fd_sets) \
56 FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
57 #define IS_FD_SET(fd, fd_sets) \
58 FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
59 #define DEL_FD_FROM_SET(fd, fd_sets) \
60 FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
63 * Protect the lttng_fd_set. Nests within the ust_lock, and therefore
64 * within the libc dl lock. Therefore, we need to fixup the TLS before
65 * nesting into this lock.
67 * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex
68 * is also held across fork.
70 static pthread_mutex_t ust_safe_guard_fd_mutex
= PTHREAD_MUTEX_INITIALIZER
;
73 * Cancel state when grabbing the ust_safe_guard_fd_mutex. Saved when
74 * locking, restored on unlock. Protected by ust_safe_guard_fd_mutex.
76 static int ust_safe_guard_saved_cancelstate
;
79 * Track whether we are within lttng-ust or application, for close
80 * system call override by LD_PRELOAD library. Threads registered
81 * as being lttng-ust listener threads need to perform fd tracker
82 * locking explicitly around their use of file descriptor manipulation
85 static DEFINE_URCU_TLS(int, thread_fd_tracking
);
88 * Track whether we are invoking close() from a signal handler nested on
89 * an application thread.
91 static DEFINE_URCU_TLS(int, ust_fd_mutex_nest
);
94 /* fd_set used to book keep fd being used by lttng-ust. */
95 static fd_set
*lttng_fd_set
;
96 static int lttng_ust_max_fd
;
97 static int num_fd_sets
;
101 * Force a read (imply TLS fixup for dlopen) of TLS variables.
103 void lttng_ust_fixup_fd_tracker_tls(void)
105 asm volatile ("" : : "m" (URCU_TLS(thread_fd_tracking
)));
106 asm volatile ("" : : "m" (URCU_TLS(ust_fd_mutex_nest
)));
110 * Allocate the fd set array based on the hard limit set for this
111 * process. This will be called during the constructor execution
112 * and will also be called in the child after fork via lttng_ust_init.
114 void lttng_ust_init_fd_tracker(void)
119 if (CMM_LOAD_SHARED(init_done
))
122 memset(&rlim
, 0, sizeof(rlim
));
123 /* Get the current possible max number of fd for this process. */
124 if (getrlimit(RLIMIT_NOFILE
, &rlim
) < 0)
127 * FD set array size determined using the hard limit. Even if
128 * the process wishes to increase its limit using setrlimit, it
129 * can only do so with the softlimit which will be less than the
132 lttng_ust_max_fd
= rlim
.rlim_max
;
133 num_fd_sets
= lttng_ust_max_fd
/ FD_SETSIZE
;
134 if (lttng_ust_max_fd
% FD_SETSIZE
)
136 if (lttng_fd_set
!= NULL
) {
140 lttng_fd_set
= malloc(num_fd_sets
* (sizeof(fd_set
)));
143 for (i
= 0; i
< num_fd_sets
; i
++)
144 FD_ZERO((<tng_fd_set
[i
]));
145 CMM_STORE_SHARED(init_done
, 1);
148 void lttng_ust_lock_fd_tracker(void)
150 sigset_t sig_all_blocked
, orig_mask
;
153 ret
= pthread_setcancelstate(PTHREAD_CANCEL_DISABLE
, &oldstate
);
155 ERR("pthread_setcancelstate: %s", strerror(ret
));
157 sigfillset(&sig_all_blocked
);
158 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
160 ERR("pthread_sigmask: %s", strerror(ret
));
162 if (!URCU_TLS(ust_fd_mutex_nest
)++) {
164 * Ensure the compiler don't move the store after the close()
165 * call in case close() would be marked as leaf.
168 pthread_mutex_lock(&ust_safe_guard_fd_mutex
);
169 ust_safe_guard_saved_cancelstate
= oldstate
;
171 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
173 ERR("pthread_sigmask: %s", strerror(ret
));
177 void lttng_ust_unlock_fd_tracker(void)
179 sigset_t sig_all_blocked
, orig_mask
;
180 int ret
, newstate
, oldstate
;
181 bool restore_cancel
= false;
183 sigfillset(&sig_all_blocked
);
184 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
186 ERR("pthread_sigmask: %s", strerror(ret
));
189 * Ensure the compiler don't move the store before the close()
190 * call, in case close() would be marked as leaf.
193 if (!--URCU_TLS(ust_fd_mutex_nest
)) {
194 newstate
= ust_safe_guard_saved_cancelstate
;
195 restore_cancel
= true;
196 pthread_mutex_unlock(&ust_safe_guard_fd_mutex
);
198 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
200 ERR("pthread_sigmask: %s", strerror(ret
));
202 if (restore_cancel
) {
203 ret
= pthread_setcancelstate(newstate
, &oldstate
);
205 ERR("pthread_setcancelstate: %s", strerror(ret
));
210 static int dup_std_fd(int fd
)
213 int fd_to_close
[STDERR_FILENO
+ 1];
214 int fd_to_close_count
= 0;
215 int dup_cmd
= F_DUPFD
; /* Default command */
218 if (!(IS_FD_STD(fd
))) {
219 /* Should not be here */
224 /* Check for FD_CLOEXEC flag */
225 ret
= fcntl(fd
, F_GETFD
);
227 PERROR("fcntl on f_getfd");
232 if (ret
& FD_CLOEXEC
) {
233 dup_cmd
= F_DUPFD_CLOEXEC
;
237 for (i
= 0; i
< STDERR_FILENO
+ 1; i
++) {
238 ret
= fcntl(fd
, dup_cmd
, 0);
240 PERROR("fcntl dup fd");
244 if (!(IS_FD_STD(ret
))) {
245 /* fd is outside of STD range, use it. */
247 /* Close fd received as argument. */
253 fd_to_close
[i
] = ret
;
257 /* Close intermediary fds */
258 for (i
= 0; i
< fd_to_close_count
; i
++) {
259 ret
= close(fd_to_close
[i
]);
261 PERROR("close on temporary fd: %d.", fd_to_close
[i
]);
263 * Not using an abort here would yield a complicated
264 * error handling for the caller. If a failure occurs
265 * here, the system is already in a bad state.
277 * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd.
278 * Has strict checking of fd validity.
280 * If fd <= 2, dup the fd until fd > 2. This enables us to bypass
281 * problems that can be encountered if UST uses stdin, stdout, stderr
282 * fds for internal use (daemon etc.). This can happen if the
283 * application closes either of those file descriptors. Intermediary fds
284 * are closed as needed.
286 * Return -1 on error.
289 int lttng_ust_add_fd_to_tracker(int fd
)
293 * Ensure the tracker is initialized when called from
296 lttng_ust_init_fd_tracker();
297 assert(URCU_TLS(ust_fd_mutex_nest
));
300 ret
= dup_std_fd(fd
);
307 /* Trying to add an fd which we can not accommodate. */
308 assert(IS_FD_VALID(fd
));
309 /* Setting an fd thats already set. */
310 assert(!IS_FD_SET(fd
, lttng_fd_set
));
312 ADD_FD_TO_SET(fd
, lttng_fd_set
);
319 * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd.
320 * Has strict checking for fd validity.
322 void lttng_ust_delete_fd_from_tracker(int fd
)
325 * Ensure the tracker is initialized when called from
328 lttng_ust_init_fd_tracker();
330 assert(URCU_TLS(ust_fd_mutex_nest
));
331 /* Not a valid fd. */
332 assert(IS_FD_VALID(fd
));
333 /* Deleting an fd which was not set. */
334 assert(IS_FD_SET(fd
, lttng_fd_set
));
336 DEL_FD_FROM_SET(fd
, lttng_fd_set
);
340 * Interface allowing applications to close arbitrary file descriptors.
341 * We check if it is owned by lttng-ust, and return -1, errno=EBADF
342 * instead of closing it if it is the case.
344 int lttng_ust_safe_close_fd(int fd
, int (*close_cb
)(int fd
))
348 lttng_ust_fixup_fd_tracker_tls();
351 * Ensure the tracker is initialized when called from
354 lttng_ust_init_fd_tracker();
357 * If called from lttng-ust, we directly call close without
358 * validating whether the FD is part of the tracked set.
360 if (URCU_TLS(thread_fd_tracking
))
363 lttng_ust_lock_fd_tracker();
364 if (IS_FD_VALID(fd
) && IS_FD_SET(fd
, lttng_fd_set
)) {
370 lttng_ust_unlock_fd_tracker();
376 * Interface allowing applications to close arbitrary streams.
377 * We check if it is owned by lttng-ust, and return -1, errno=EBADF
378 * instead of closing it if it is the case.
380 int lttng_ust_safe_fclose_stream(FILE *stream
, int (*fclose_cb
)(FILE *stream
))
384 lttng_ust_fixup_fd_tracker_tls();
387 * Ensure the tracker is initialized when called from
390 lttng_ust_init_fd_tracker();
393 * If called from lttng-ust, we directly call fclose without
394 * validating whether the FD is part of the tracked set.
396 if (URCU_TLS(thread_fd_tracking
))
397 return fclose_cb(stream
);
401 lttng_ust_lock_fd_tracker();
402 if (IS_FD_VALID(fd
) && IS_FD_SET(fd
, lttng_fd_set
)) {
406 ret
= fclose_cb(stream
);
408 lttng_ust_unlock_fd_tracker();
414 static void set_close_success(int *p
)
418 static int test_close_success(const int *p
)
423 static void set_close_success(int *p
__attribute__((unused
)))
426 static int test_close_success(const int *p
__attribute__((unused
)))
433 * Implement helper for closefrom() override.
435 int lttng_ust_safe_closefrom_fd(int lowfd
, int (*close_cb
)(int fd
))
437 int ret
= 0, close_success
= 0, i
;
439 lttng_ust_fixup_fd_tracker_tls();
442 * Ensure the tracker is initialized when called from
445 lttng_ust_init_fd_tracker();
449 * NetBSD return EBADF if fd is invalid.
456 * If called from lttng-ust, we directly call close without
457 * validating whether the FD is part of the tracked set.
459 if (URCU_TLS(thread_fd_tracking
)) {
460 for (i
= lowfd
; i
< lttng_ust_max_fd
; i
++) {
461 if (close_cb(i
) < 0) {
471 set_close_success(&close_success
);
474 lttng_ust_lock_fd_tracker();
475 for (i
= lowfd
; i
< lttng_ust_max_fd
; i
++) {
476 if (IS_FD_VALID(i
) && IS_FD_SET(i
, lttng_fd_set
))
478 if (close_cb(i
) < 0) {
485 lttng_ust_unlock_fd_tracker();
489 set_close_success(&close_success
);
491 lttng_ust_unlock_fd_tracker();
493 if (!test_close_success(&close_success
)) {
495 * OpenBSD return EBADF if fd is greater than all open
505 void lttng_ust_fd_tracker_register_thread(void)
507 URCU_TLS(thread_fd_tracking
) = 1;