mirror of git://git.gnupg.org/gnupg.git
scd: Fix access to list of cards (1/3).
* scd/app.c (card_list_lock): Use MRSW lock. (lock_r_card_list, unlock_r_card_list): New. (lock_w_card_list, unlock_w_card_list): New. (app_dump_state, app_send_devinfo): Use the MRSW lock. (select_application, app_switch_current_card): Likewise. (scd_update_reader_status_file): Likewise. (initialize_module_command, send_card_and_app_list): Likewise. (app_do_with_keygrip, app_wait): Likewise. -- GnuPG-bug-id: 5524 Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka
parent
5a93acbc7a
commit
216945a80e
137
scd/app.c
137
scd/app.c
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@ -39,9 +39,40 @@ static gpg_error_t
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send_serialno_and_app_status (card_t card, int with_apps, ctrl_t ctrl);
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static gpg_error_t run_reselect (ctrl_t ctrl, card_t c, app_t a, app_t a_prev);
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/* Lock to protect the list of cards and its associated
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* applications. */
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static npth_mutex_t card_list_lock;
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/*
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* Multiple readers, single writer (MRSW) lock.
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*/
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struct mrsw_lock
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{
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npth_mutex_t lock;
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npth_cond_t cond;
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int num_readers_active;
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int num_writers_waiting;
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int writer_active;
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};
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#define CARD_LIST_LOCK_WAIT 0
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#define CARD_LIST_LOCK_UPDATE 1
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/* MRSW lock to protect the list of cards.
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*
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* This structure is used for serializing access to the list of cards
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* (by CARD_TOP). While allowing multiple accesses by different
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* connections as "r" access (for a CARD in the list), "w" access to
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* update the list is only possible with a single thread.
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*
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* Each use of a CARD (in the list) does "r" access.
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*
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* For "w" access, the app_wait function, which waits on any change of
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* the list, it uses CARD_LIST_LOCK_WAIT. For other cases of "w"
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* access (opening new card or removal of card), CARD_LIST_LOCK_UPDATE
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* is used.
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*
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* Note that for serializing access to each CARD (and its associated
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* applications) itself, it is done separately by another mutex with
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* lock_card/unlock_card.
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*/
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static struct mrsw_lock card_list_lock;
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/* Notification to threads which keep watching the status change. */
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static npth_cond_t notify_cond;
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@ -293,6 +324,56 @@ unlock_card (card_t card)
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}
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static void
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lock_r_card_list (void)
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{
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npth_mutex_lock (&card_list_lock.lock);
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while (card_list_lock.num_writers_waiting
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|| card_list_lock.writer_active)
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npth_cond_wait (&card_list_lock.cond, &card_list_lock.lock);
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card_list_lock.num_readers_active++;
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npth_mutex_unlock (&card_list_lock.lock);
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}
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static void
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unlock_r_card_list (void)
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{
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npth_mutex_lock (&card_list_lock.lock);
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if (--card_list_lock.num_readers_active == 0)
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npth_cond_broadcast (&card_list_lock.cond);
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npth_mutex_unlock (&card_list_lock.lock);
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}
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static void
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lock_w_card_list (int for_update)
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{
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npth_mutex_lock (&card_list_lock.lock);
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card_list_lock.num_writers_waiting++;
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while (card_list_lock.num_readers_active
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|| card_list_lock.writer_active)
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npth_cond_wait (&card_list_lock.cond, &card_list_lock.lock);
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card_list_lock.num_writers_waiting--;
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if (for_update)
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{
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card_list_lock.writer_active++;
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npth_mutex_unlock (&card_list_lock.lock);
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}
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}
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static void
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unlock_w_card_list (int for_update)
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{
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if (for_update)
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{
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npth_mutex_lock (&card_list_lock.lock);
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card_list_lock.writer_active--;
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}
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npth_cond_broadcast (&card_list_lock.cond);
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npth_mutex_unlock (&card_list_lock.lock);
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}
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/* This function may be called to print information pertaining to the
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* current state of this module to the log. */
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void
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@ -301,7 +382,7 @@ app_dump_state (void)
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card_t c;
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app_t a;
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npth_mutex_lock (&card_list_lock);
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lock_r_card_list ();
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for (c = card_top; c; c = c->next)
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{
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log_info ("app_dump_state: card=%p slot=%d type=%s refcount=%u\n",
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@ -311,7 +392,7 @@ app_dump_state (void)
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log_info ("app_dump_state: app=%p type='%s'\n",
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a, strapptype (a->apptype));
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}
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npth_mutex_unlock (&card_list_lock);
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unlock_r_card_list ();
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}
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@ -324,7 +405,7 @@ app_send_devinfo (ctrl_t ctrl)
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send_status_direct (ctrl, "DEVINFO_START", "");
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npth_mutex_lock (&card_list_lock);
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lock_r_card_list ();
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no_device = (card_top == NULL);
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for (c = card_top; c; c = c->next)
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{
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@ -339,7 +420,7 @@ app_send_devinfo (ctrl_t ctrl)
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for (a = c->app; a; a = a->next)
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send_status_direct (ctrl, card_info, strapptype (a->apptype));
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}
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npth_mutex_unlock (&card_list_lock);
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unlock_r_card_list ();
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send_status_direct (ctrl, "DEVINFO_END", "");
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@ -708,7 +789,7 @@ select_application (ctrl_t ctrl, const char *name, card_t *r_card,
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*r_card = NULL;
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npth_mutex_lock (&card_list_lock);
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lock_w_card_list (CARD_LIST_LOCK_UPDATE);
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if (scan || !card_top)
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{
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@ -719,7 +800,7 @@ select_application (ctrl_t ctrl, const char *name, card_t *r_card,
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err = apdu_dev_list_start (opt.reader_port, &l);
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if (err)
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{
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npth_mutex_unlock (&card_list_lock);
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unlock_w_card_list (CARD_LIST_LOCK_UPDATE);
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return err;
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}
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@ -807,7 +888,7 @@ select_application (ctrl_t ctrl, const char *name, card_t *r_card,
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else
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err = gpg_error (GPG_ERR_ENODEV);
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npth_mutex_unlock (&card_list_lock);
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unlock_w_card_list (CARD_LIST_LOCK_UPDATE);
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return err;
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}
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@ -823,7 +904,7 @@ app_switch_current_card (ctrl_t ctrl,
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gpg_error_t err;
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card_t card, cardtmp;
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npth_mutex_lock (&card_list_lock);
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lock_r_card_list ();
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if (!ctrl->card_ctx)
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{
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@ -858,7 +939,7 @@ app_switch_current_card (ctrl_t ctrl,
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err = send_serialno_and_app_status (ctrl->card_ctx, 0, ctrl);
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leave:
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npth_mutex_unlock (&card_list_lock);
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unlock_r_card_list ();
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return err;
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}
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@ -2290,7 +2371,7 @@ scd_update_reader_status_file (void)
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int periodical_check_needed = 0;
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int reported = 0;
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npth_mutex_lock (&card_list_lock);
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lock_w_card_list (CARD_LIST_LOCK_UPDATE);
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for (card = card_top; card; card = card_next)
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{
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int sw;
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@ -2356,7 +2437,7 @@ scd_update_reader_status_file (void)
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if (reported)
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npth_cond_broadcast (¬ify_cond);
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npth_mutex_unlock (&card_list_lock);
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unlock_w_card_list (CARD_LIST_LOCK_UPDATE);
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return periodical_check_needed;
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}
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@ -2370,13 +2451,25 @@ initialize_module_command (void)
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{
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gpg_error_t err;
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if (npth_mutex_init (&card_list_lock, NULL))
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card_list_lock.num_readers_active = 0;
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card_list_lock.num_writers_waiting = 0;
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card_list_lock.writer_active = 0;
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if (npth_mutex_init (&card_list_lock.lock, NULL))
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{
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err = gpg_error_from_syserror ();
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log_error ("app: error initializing mutex: %s\n", gpg_strerror (err));
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return err;
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}
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err = npth_cond_init (&card_list_lock.cond, NULL);
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if (err)
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{
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err = gpg_error_from_syserror ();
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log_error ("npth_cond_init failed: %s\n", gpg_strerror (err));
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return err;
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}
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err = npth_cond_init (¬ify_cond, NULL);
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if (err)
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{
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@ -2472,7 +2565,7 @@ send_card_and_app_list (ctrl_t ctrl, card_t wantcard, int with_apps)
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card_t *cardlist = NULL;
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int n, ncardlist;
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npth_mutex_lock (&card_list_lock);
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lock_r_card_list ();
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for (n=0, c = card_top; c; c = c->next)
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n++;
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if (!n)
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@ -2502,7 +2595,7 @@ send_card_and_app_list (ctrl_t ctrl, card_t wantcard, int with_apps)
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err = 0;
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leave:
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npth_mutex_unlock (&card_list_lock);
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unlock_r_card_list ();
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xfree (cardlist);
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return err;
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}
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@ -2604,7 +2697,7 @@ app_do_with_keygrip (ctrl_t ctrl, int action, const char *keygrip_str,
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card_t c;
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app_t a, a_prev;
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npth_mutex_lock (&card_list_lock);
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lock_r_card_list ();
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for (c = card_top; c; c = c->next)
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{
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@ -2661,14 +2754,14 @@ app_do_with_keygrip (ctrl_t ctrl, int action, const char *keygrip_str,
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unlock_card (c);
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locked = 0;
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}
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npth_mutex_unlock (&card_list_lock);
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unlock_r_card_list ();
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return c;
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}
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void
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app_wait (void)
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{
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npth_mutex_lock (&card_list_lock);
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npth_cond_wait (¬ify_cond, &card_list_lock);
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npth_mutex_unlock (&card_list_lock);
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lock_w_card_list (CARD_LIST_LOCK_WAIT);
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npth_cond_wait (¬ify_cond, &card_list_lock.lock);
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unlock_w_card_list (CARD_LIST_LOCK_WAIT);
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}
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