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>
35 #include <urcu/compiler.h>
36 #include <urcu/tls-compat.h>
37 #include <urcu/system.h>
41 #include <lttng/ust-error.h>
42 #include <usterr-signal-safe.h>
44 #include "../liblttng-ust/compat.h"
46 /* Operations on the fd set. */
47 #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd)
48 #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE]))
49 #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE)
50 #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO)
52 /* Check fd validity before calling these. */
53 #define ADD_FD_TO_SET(fd, fd_sets) \
54 FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
55 #define IS_FD_SET(fd, fd_sets) \
56 FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
57 #define DEL_FD_FROM_SET(fd, fd_sets) \
58 FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets))
61 * Protect the lttng_fd_set. Nests within the ust_lock, and therefore
62 * within the libc dl lock. Therefore, we need to fixup the TLS before
63 * nesting into this lock.
65 static pthread_mutex_t ust_safe_guard_fd_mutex
= PTHREAD_MUTEX_INITIALIZER
;
67 * Track whether we are within lttng-ust or application, for close
68 * system call override by LD_PRELOAD library.
70 static DEFINE_URCU_TLS(int, thread_fd_tracking
);
72 /* fd_set used to book keep fd being used by lttng-ust. */
73 static fd_set
*lttng_fd_set
;
74 static int lttng_ust_max_fd
;
75 static int num_fd_sets
;
79 * Force a read (imply TLS fixup for dlopen) of TLS variables.
81 void lttng_ust_fixup_fd_tracker_tls(void)
83 asm volatile ("" : : "m" (URCU_TLS(thread_fd_tracking
)));
87 * Allocate the fd set array based on the hard limit set for this
88 * process. This will be called during the constructor execution
89 * and will also be called in the child after fork via lttng_ust_init.
91 void lttng_ust_init_fd_tracker(void)
96 if (CMM_LOAD_SHARED(init_done
))
99 memset(&rlim
, 0, sizeof(rlim
));
100 /* Get the current possible max number of fd for this process. */
101 if (getrlimit(RLIMIT_NOFILE
, &rlim
) < 0)
104 * FD set array size determined using the hard limit. Even if
105 * the process wishes to increase its limit using setrlimit, it
106 * can only do so with the softlimit which will be less than the
109 lttng_ust_max_fd
= rlim
.rlim_max
;
110 num_fd_sets
= lttng_ust_max_fd
/ FD_SETSIZE
;
111 if (lttng_ust_max_fd
% FD_SETSIZE
)
113 if (lttng_fd_set
!= NULL
) {
117 lttng_fd_set
= malloc(num_fd_sets
* (sizeof(fd_set
)));
120 for (i
= 0; i
< num_fd_sets
; i
++)
121 FD_ZERO((<tng_fd_set
[i
]));
122 CMM_STORE_SHARED(init_done
, 1);
125 void lttng_ust_lock_fd_tracker(void)
127 URCU_TLS(thread_fd_tracking
) = 1;
129 * Ensure the compiler don't move the store after the close()
130 * call in case close() would be marked as leaf.
133 pthread_mutex_lock(&ust_safe_guard_fd_mutex
);
136 void lttng_ust_unlock_fd_tracker(void)
138 pthread_mutex_unlock(&ust_safe_guard_fd_mutex
);
140 * Ensure the compiler don't move the store before the close()
141 * call, in case close() would be marked as leaf.
144 URCU_TLS(thread_fd_tracking
) = 0;
147 static int dup_std_fd(int fd
)
150 int fd_to_close
[STDERR_FILENO
+ 1];
151 int fd_to_close_count
= 0;
152 int dup_cmd
= F_DUPFD
; /* Default command */
155 if (!(IS_FD_STD(fd
))) {
156 /* Should not be here */
161 /* Check for FD_CLOEXEC flag */
162 ret
= fcntl(fd
, F_GETFD
);
164 PERROR("fcntl on f_getfd");
169 if (ret
& FD_CLOEXEC
) {
170 dup_cmd
= F_DUPFD_CLOEXEC
;
174 for (i
= 0; i
< STDERR_FILENO
+ 1; i
++) {
175 ret
= fcntl(fd
, dup_cmd
, 0);
177 PERROR("fcntl dup fd");
181 if (!(IS_FD_STD(ret
))) {
182 /* fd is outside of STD range, use it. */
184 /* Close fd received as argument. */
190 fd_to_close
[i
] = ret
;
194 /* Close intermediary fds */
195 for (i
= 0; i
< fd_to_close_count
; i
++) {
196 ret
= close(fd_to_close
[i
]);
198 PERROR("close on temporary fd: %d.", fd_to_close
[i
]);
200 * Not using an abort here would yield a complicated
201 * error handling for the caller. If a failure occurs
202 * here, the system is already in a bad state.
214 * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd.
215 * Has strict checking of fd validity.
217 * If fd <= 2, dup the fd until fd > 2. This enables us to bypass
218 * problems that can be encountered if UST uses stdin, stdout, stderr
219 * fds for internal use (daemon etc.). This can happen if the
220 * application closes either of those file descriptors. Intermediary fds
221 * are closed as needed.
223 * Return -1 on error.
226 int lttng_ust_add_fd_to_tracker(int fd
)
230 * Ensure the tracker is initialized when called from
233 lttng_ust_init_fd_tracker();
234 assert(URCU_TLS(thread_fd_tracking
));
237 ret
= dup_std_fd(fd
);
244 /* Trying to add an fd which we can not accommodate. */
245 assert(IS_FD_VALID(fd
));
246 /* Setting an fd thats already set. */
247 assert(!IS_FD_SET(fd
, lttng_fd_set
));
249 ADD_FD_TO_SET(fd
, lttng_fd_set
);
256 * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd.
257 * Has strict checking for fd validity.
259 void lttng_ust_delete_fd_from_tracker(int fd
)
262 * Ensure the tracker is initialized when called from
265 lttng_ust_init_fd_tracker();
267 assert(URCU_TLS(thread_fd_tracking
));
268 /* Not a valid fd. */
269 assert(IS_FD_VALID(fd
));
270 /* Deleting an fd which was not set. */
271 assert(IS_FD_SET(fd
, lttng_fd_set
));
273 DEL_FD_FROM_SET(fd
, lttng_fd_set
);
277 * Interface allowing applications to close arbitrary file descriptors.
278 * We check if it is owned by lttng-ust, and return -1, errno=EBADF
279 * instead of closing it if it is the case.
281 int lttng_ust_safe_close_fd(int fd
, int (*close_cb
)(int fd
))
285 lttng_ust_fixup_fd_tracker_tls();
288 * Ensure the tracker is initialized when called from
291 lttng_ust_init_fd_tracker();
294 * If called from lttng-ust, we directly call close without
295 * validating whether the FD is part of the tracked set.
297 if (URCU_TLS(thread_fd_tracking
))
300 lttng_ust_lock_fd_tracker();
301 if (IS_FD_VALID(fd
) && IS_FD_SET(fd
, lttng_fd_set
)) {
307 lttng_ust_unlock_fd_tracker();
313 * Interface allowing applications to close arbitrary streams.
314 * We check if it is owned by lttng-ust, and return -1, errno=EBADF
315 * instead of closing it if it is the case.
317 int lttng_ust_safe_fclose_stream(FILE *stream
, int (*fclose_cb
)(FILE *stream
))
321 lttng_ust_fixup_fd_tracker_tls();
324 * Ensure the tracker is initialized when called from
327 lttng_ust_init_fd_tracker();
330 * If called from lttng-ust, we directly call fclose without
331 * validating whether the FD is part of the tracked set.
333 if (URCU_TLS(thread_fd_tracking
))
334 return fclose_cb(stream
);
338 lttng_ust_lock_fd_tracker();
339 if (IS_FD_VALID(fd
) && IS_FD_SET(fd
, lttng_fd_set
)) {
343 ret
= fclose_cb(stream
);
345 lttng_ust_unlock_fd_tracker();
351 static void set_close_success(int *p
)
355 static int test_close_success(const int *p
)
360 static void set_close_success(int *p
__attribute__((unused
)))
363 static int test_close_success(const int *p
__attribute__((unused
)))
370 * Implement helper for closefrom() override.
372 int lttng_ust_safe_closefrom_fd(int lowfd
, int (*close_cb
)(int fd
))
374 int ret
= 0, close_success
= 0, i
;
376 lttng_ust_fixup_fd_tracker_tls();
379 * Ensure the tracker is initialized when called from
382 lttng_ust_init_fd_tracker();
386 * NetBSD return EBADF if fd is invalid.
393 * If called from lttng-ust, we directly call close without
394 * validating whether the FD is part of the tracked set.
396 if (URCU_TLS(thread_fd_tracking
)) {
397 for (i
= lowfd
; i
< lttng_ust_max_fd
; i
++) {
398 if (close_cb(i
) < 0) {
408 set_close_success(&close_success
);
411 lttng_ust_lock_fd_tracker();
412 for (i
= lowfd
; i
< lttng_ust_max_fd
; i
++) {
413 if (IS_FD_VALID(i
) && IS_FD_SET(i
, lttng_fd_set
))
415 if (close_cb(i
) < 0) {
422 lttng_ust_unlock_fd_tracker();
426 set_close_success(&close_success
);
428 lttng_ust_unlock_fd_tracker();
430 if (!test_close_success(&close_success
)) {
432 * OpenBSD return EBADF if fd is greater than all open