Fix: ensure fd tracker is initialized when called from constructors

[lttng-ust.git] / liblttng-ust-comm / lttng-ust-fd-tracker.c

diff --git a/liblttng-ust-comm/lttng-ust-fd-tracker.c b/liblttng-ust-comm/lttng-ust-fd-tracker.c
index 5a763ff2960550c094306d9d7d90de3d2bf9d037..8d2acb69f55f5cb32b7841ba7dafcdb96064326b 100644 (file)
--- a/liblttng-ust-comm/lttng-ust-fd-tracker.c
+++ b/liblttng-ust-comm/lttng-ust-fd-tracker.c
@@ -34,6 +34,7 @@
 #include <pthread.h>
 #include <urcu/compiler.h>
 #include <urcu/tls-compat.h>
+#include <urcu/system.h>
 
 #include <ust-fd.h>
 #include <helper.h>
@@ -71,6 +72,7 @@ static DEFINE_URCU_TLS(int, thread_fd_tracking);
 static fd_set *lttng_fd_set;
 static int lttng_ust_max_fd;
 static int num_fd_sets;
+static int init_done;
 
 /*
  * Force a read (imply TLS fixup for dlopen) of TLS variables.
@@ -90,6 +92,9 @@ void lttng_ust_init_fd_tracker(void)
        struct rlimit rlim;
        int i;
 
+       if (CMM_LOAD_SHARED(init_done))
+               return;
+
        memset(&rlim, 0, sizeof(rlim));
        /* Get the current possible max number of fd for this process. */
        if (getrlimit(RLIMIT_NOFILE, &rlim) < 0)
@@ -113,6 +118,7 @@ void lttng_ust_init_fd_tracker(void)
                abort();
        for (i = 0; i < num_fd_sets; i++)
                FD_ZERO((&lttng_fd_set[i]));
+       CMM_STORE_SHARED(init_done, 1);
 }
 
 void lttng_ust_lock_fd_tracker(void)
@@ -143,6 +149,12 @@ void lttng_ust_unlock_fd_tracker(void)
  */
 void lttng_ust_add_fd_to_tracker(int fd)
 {
+       /*
+        * Ensure the tracker is initialized when called from
+        * constructors.
+        */
+       lttng_ust_init_fd_tracker();
+
        assert(URCU_TLS(thread_fd_tracking));
        /* Trying to add an fd which we can not accommodate. */
        assert(IS_FD_VALID(fd));
@@ -158,6 +170,12 @@ void lttng_ust_add_fd_to_tracker(int fd)
  */
 void lttng_ust_delete_fd_from_tracker(int fd)
 {
+       /*
+        * Ensure the tracker is initialized when called from
+        * constructors.
+        */
+       lttng_ust_init_fd_tracker();
+
        assert(URCU_TLS(thread_fd_tracking));
        /* Not a valid fd. */
        assert(IS_FD_VALID(fd));
@@ -178,6 +196,12 @@ int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd))
 
        lttng_ust_fixup_fd_tracker_tls();
 
+       /*
+        * Ensure the tracker is initialized when called from
+        * constructors.
+        */
+       lttng_ust_init_fd_tracker();
+
        /*
         * If called from lttng-ust, we directly call close without
         * validating whether the FD is part of the tracked set.
@@ -197,6 +221,44 @@ int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd))
        return ret;
 }
 
+/*
+ * Interface allowing applications to close arbitrary streams.
+ * We check if it is owned by lttng-ust, and return -1, errno=EBADF
+ * instead of closing it if it is the case.
+ */
+int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream))
+{
+       int ret = 0, fd;
+
+       lttng_ust_fixup_fd_tracker_tls();
+
+       /*
+        * Ensure the tracker is initialized when called from
+        * constructors.
+        */
+       lttng_ust_init_fd_tracker();
+
+       /*
+        * If called from lttng-ust, we directly call fclose without
+        * validating whether the FD is part of the tracked set.
+        */
+       if (URCU_TLS(thread_fd_tracking))
+               return fclose_cb(stream);
+
+       fd = fileno(stream);
+
+       lttng_ust_lock_fd_tracker();
+       if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) {
+               ret = -1;
+               errno = EBADF;
+       } else {
+               ret = fclose_cb(stream);
+       }
+       lttng_ust_unlock_fd_tracker();
+
+       return ret;
+}
+
 #ifdef __OpenBSD__
 static void set_close_success(int *p)
 {
@@ -225,6 +287,12 @@ int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd))
 
        lttng_ust_fixup_fd_tracker_tls();
 
+       /*
+        * Ensure the tracker is initialized when called from
+        * constructors.
+        */
+       lttng_ust_init_fd_tracker();
+
        if (lowfd < 0) {
                /*
                 * NetBSD return EBADF if fd is invalid.