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 * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex
66 * is also held across fork.
68 static pthread_mutex_t ust_safe_guard_fd_mutex
= PTHREAD_MUTEX_INITIALIZER
;
70 * Track whether we are within lttng-ust or application, for close
71 * system call override by LD_PRELOAD library.
73 static DEFINE_URCU_TLS(int, thread_fd_tracking
);
75 /* fd_set used to book keep fd being used by lttng-ust. */
76 static fd_set
*lttng_fd_set
;
77 static int lttng_ust_max_fd
;
78 static int num_fd_sets
;
82 * Force a read (imply TLS fixup for dlopen) of TLS variables.
84 void lttng_ust_fixup_fd_tracker_tls(void)
86 asm volatile ("" : : "m" (URCU_TLS(thread_fd_tracking
)));
90 * Allocate the fd set array based on the hard limit set for this
91 * process. This will be called during the constructor execution
92 * and will also be called in the child after fork via lttng_ust_init.
94 void lttng_ust_init_fd_tracker(void)
99 if (CMM_LOAD_SHARED(init_done
))
102 memset(&rlim
, 0, sizeof(rlim
));
103 /* Get the current possible max number of fd for this process. */
104 if (getrlimit(RLIMIT_NOFILE
, &rlim
) < 0)
107 * FD set array size determined using the hard limit. Even if
108 * the process wishes to increase its limit using setrlimit, it
109 * can only do so with the softlimit which will be less than the
112 lttng_ust_max_fd
= rlim
.rlim_max
;
113 num_fd_sets
= lttng_ust_max_fd
/ FD_SETSIZE
;
114 if (lttng_ust_max_fd
% FD_SETSIZE
)
116 if (lttng_fd_set
!= NULL
) {
120 lttng_fd_set
= malloc(num_fd_sets
* (sizeof(fd_set
)));
123 for (i
= 0; i
< num_fd_sets
; i
++)
124 FD_ZERO((<tng_fd_set
[i
]));
125 CMM_STORE_SHARED(init_done
, 1);
128 void lttng_ust_lock_fd_tracker(void)
130 URCU_TLS(thread_fd_tracking
) = 1;
132 * Ensure the compiler don't move the store after the close()
133 * call in case close() would be marked as leaf.
136 pthread_mutex_lock(&ust_safe_guard_fd_mutex
);
139 void lttng_ust_unlock_fd_tracker(void)
141 pthread_mutex_unlock(&ust_safe_guard_fd_mutex
);
143 * Ensure the compiler don't move the store before the close()
144 * call, in case close() would be marked as leaf.
147 URCU_TLS(thread_fd_tracking
) = 0;
150 static int dup_std_fd(int fd
)
153 int fd_to_close
[STDERR_FILENO
+ 1];
154 int fd_to_close_count
= 0;
155 int dup_cmd
= F_DUPFD
; /* Default command */
158 if (!(IS_FD_STD(fd
))) {
159 /* Should not be here */
164 /* Check for FD_CLOEXEC flag */
165 ret
= fcntl(fd
, F_GETFD
);
167 PERROR("fcntl on f_getfd");
172 if (ret
& FD_CLOEXEC
) {
173 dup_cmd
= F_DUPFD_CLOEXEC
;
177 for (i
= 0; i
< STDERR_FILENO
+ 1; i
++) {
178 ret
= fcntl(fd
, dup_cmd
, 0);
180 PERROR("fcntl dup fd");
184 if (!(IS_FD_STD(ret
))) {
185 /* fd is outside of STD range, use it. */
187 /* Close fd received as argument. */
193 fd_to_close
[i
] = ret
;
197 /* Close intermediary fds */
198 for (i
= 0; i
< fd_to_close_count
; i
++) {
199 ret
= close(fd_to_close
[i
]);
201 PERROR("close on temporary fd: %d.", fd_to_close
[i
]);
203 * Not using an abort here would yield a complicated
204 * error handling for the caller. If a failure occurs
205 * here, the system is already in a bad state.
217 * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd.
218 * Has strict checking of fd validity.
220 * If fd <= 2, dup the fd until fd > 2. This enables us to bypass
221 * problems that can be encountered if UST uses stdin, stdout, stderr
222 * fds for internal use (daemon etc.). This can happen if the
223 * application closes either of those file descriptors. Intermediary fds
224 * are closed as needed.
226 * Return -1 on error.
229 int lttng_ust_add_fd_to_tracker(int fd
)
233 * Ensure the tracker is initialized when called from
236 lttng_ust_init_fd_tracker();
237 assert(URCU_TLS(thread_fd_tracking
));
240 ret
= dup_std_fd(fd
);
247 /* Trying to add an fd which we can not accommodate. */
248 assert(IS_FD_VALID(fd
));
249 /* Setting an fd thats already set. */
250 assert(!IS_FD_SET(fd
, lttng_fd_set
));
252 ADD_FD_TO_SET(fd
, lttng_fd_set
);
259 * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd.
260 * Has strict checking for fd validity.
262 void lttng_ust_delete_fd_from_tracker(int fd
)
265 * Ensure the tracker is initialized when called from
268 lttng_ust_init_fd_tracker();
270 assert(URCU_TLS(thread_fd_tracking
));
271 /* Not a valid fd. */
272 assert(IS_FD_VALID(fd
));
273 /* Deleting an fd which was not set. */
274 assert(IS_FD_SET(fd
, lttng_fd_set
));
276 DEL_FD_FROM_SET(fd
, lttng_fd_set
);
280 * Interface allowing applications to close arbitrary file descriptors.
281 * We check if it is owned by lttng-ust, and return -1, errno=EBADF
282 * instead of closing it if it is the case.
284 int lttng_ust_safe_close_fd(int fd
, int (*close_cb
)(int fd
))
288 lttng_ust_fixup_fd_tracker_tls();
291 * Ensure the tracker is initialized when called from
294 lttng_ust_init_fd_tracker();
297 * If called from lttng-ust, we directly call close without
298 * validating whether the FD is part of the tracked set.
300 if (URCU_TLS(thread_fd_tracking
))
303 lttng_ust_lock_fd_tracker();
304 if (IS_FD_VALID(fd
) && IS_FD_SET(fd
, lttng_fd_set
)) {
310 lttng_ust_unlock_fd_tracker();
316 * Interface allowing applications to close arbitrary streams.
317 * We check if it is owned by lttng-ust, and return -1, errno=EBADF
318 * instead of closing it if it is the case.
320 int lttng_ust_safe_fclose_stream(FILE *stream
, int (*fclose_cb
)(FILE *stream
))
324 lttng_ust_fixup_fd_tracker_tls();
327 * Ensure the tracker is initialized when called from
330 lttng_ust_init_fd_tracker();
333 * If called from lttng-ust, we directly call fclose without
334 * validating whether the FD is part of the tracked set.
336 if (URCU_TLS(thread_fd_tracking
))
337 return fclose_cb(stream
);
341 lttng_ust_lock_fd_tracker();
342 if (IS_FD_VALID(fd
) && IS_FD_SET(fd
, lttng_fd_set
)) {
346 ret
= fclose_cb(stream
);
348 lttng_ust_unlock_fd_tracker();
354 static void set_close_success(int *p
)
358 static int test_close_success(const int *p
)
363 static void set_close_success(int *p
__attribute__((unused
)))
366 static int test_close_success(const int *p
__attribute__((unused
)))
373 * Implement helper for closefrom() override.
375 int lttng_ust_safe_closefrom_fd(int lowfd
, int (*close_cb
)(int fd
))
377 int ret
= 0, close_success
= 0, i
;
379 lttng_ust_fixup_fd_tracker_tls();
382 * Ensure the tracker is initialized when called from
385 lttng_ust_init_fd_tracker();
389 * NetBSD return EBADF if fd is invalid.
396 * If called from lttng-ust, we directly call close without
397 * validating whether the FD is part of the tracked set.
399 if (URCU_TLS(thread_fd_tracking
)) {
400 for (i
= lowfd
; i
< lttng_ust_max_fd
; i
++) {
401 if (close_cb(i
) < 0) {
411 set_close_success(&close_success
);
414 lttng_ust_lock_fd_tracker();
415 for (i
= lowfd
; i
< lttng_ust_max_fd
; i
++) {
416 if (IS_FD_VALID(i
) && IS_FD_SET(i
, lttng_fd_set
))
418 if (close_cb(i
) < 0) {
425 lttng_ust_unlock_fd_tracker();
429 set_close_success(&close_success
);
431 lttng_ust_unlock_fd_tracker();
433 if (!test_close_success(&close_success
)) {
435 * OpenBSD return EBADF if fd is greater than all open