[Pkg-gnupg-commit] [gnupg2] 223/241: scd: Simplify saving application context.
Daniel Kahn Gillmor
dkg at fifthhorseman.net
Wed Dec 9 20:32:20 UTC 2015
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dkg pushed a commit to branch master
in repository gnupg2.
commit 9639af5f16a7ed908cbce2415330b9fcd88edc90
Author: NIIBE Yutaka <gniibe at fsij.org>
Date: Fri Dec 4 14:13:23 2015 +0900
scd: Simplify saving application context.
* scd/app.c (lock_table): Remove LAST_APP field.
(lock_reader, app_dump_state, application_notify_card_reset)
(release_application): Follow the change.
(check_conflict): New.
(check_application_conflict): Lock the slot and call check_conflict.
(select_application): Call check_conflict and not use LAST_APP.
--
We don't need LAST_APP field but just keep the application context by
APP field. Since we have a reference counter, it is possible if we
can deallocate or not.
---
scd/app.c | 103 +++++++++++++++++++++++++-------------------------------------
1 file changed, 41 insertions(+), 62 deletions(-)
diff --git a/scd/app.c b/scd/app.c
index 5e6751e..51464a2 100644
--- a/scd/app.c
+++ b/scd/app.c
@@ -39,7 +39,6 @@ static struct
int initialized;
npth_mutex_t lock;
app_t app; /* Application context in use or NULL. */
- app_t last_app; /* Last application object used as this slot or NULL. */
} lock_table[10];
@@ -87,7 +86,6 @@ lock_reader (int slot, ctrl_t ctrl)
}
lock_table[slot].initialized = 1;
lock_table[slot].app = NULL;
- lock_table[slot].last_app = NULL;
}
res = npth_mutex_lock (&lock_table[slot].lock);
@@ -139,12 +137,6 @@ app_dump_state (void)
if (lock_table[slot].app->apptype)
log_printf (" type='%s'", lock_table[slot].app->apptype);
}
- if (lock_table[slot].last_app)
- {
- log_printf (" lastapp=%p", lock_table[slot].last_app);
- if (lock_table[slot].last_app->apptype)
- log_printf (" type='%s'", lock_table[slot].last_app->apptype);
- }
log_printf ("\n");
}
}
@@ -167,8 +159,6 @@ is_app_allowed (const char *name)
void
application_notify_card_reset (int slot)
{
- app_t app;
-
if (slot < 0 || slot >= DIM (lock_table))
return;
@@ -182,20 +172,35 @@ application_notify_card_reset (int slot)
lock_table[slot].app = NULL;
}
- /* Deallocate a saved application for that slot, so that we won't
- try to reuse it. If there is no saved application, set a flag so
- that we won't save the current state. */
- app = lock_table[slot].last_app;
+ unlock_reader (slot);
+}
- if (app)
+
+/*
+ * This function is called with lock held.
+ */
+static gpg_error_t
+check_conflict (int slot, const char *name)
+{
+ app_t app = lock_table[slot].app;
+
+ if (!app || !name || (app->apptype && !ascii_strcasecmp (app->apptype, name)))
+ return 0;
+
+ if (!app->ref_count)
{
- lock_table[slot].last_app = NULL;
+ lock_table[slot].app = NULL;
deallocate_app (app);
+ return 0;
+ }
+ else
+ {
+ log_info ("application '%s' in use by reader %d - can't switch\n",
+ app->apptype? app->apptype : "<null>", slot);
+ return gpg_error (GPG_ERR_CONFLICT);
}
- unlock_reader (slot);
}
-
/* This function is used by the serialno command to check for an
application conflict which may appear if the serialno command is
used to request a specific application and the connection has
@@ -203,18 +208,18 @@ application_notify_card_reset (int slot)
gpg_error_t
check_application_conflict (ctrl_t ctrl, int slot, const char *name)
{
- app_t app;
-
- (void)ctrl;
+ gpg_error_t err;
if (slot < 0 || slot >= DIM (lock_table))
return gpg_error (GPG_ERR_INV_VALUE);
- app = lock_table[slot].initialized ? lock_table[slot].app : NULL;
- if (app && app->apptype && name)
- if ( ascii_strcasecmp (app->apptype, name))
- return gpg_error (GPG_ERR_CONFLICT);
- return 0;
+ err = lock_reader (slot, ctrl);
+ if (err)
+ return err;
+
+ err = check_conflict (slot, name);
+ unlock_reader (slot);
+ return err;
}
@@ -243,41 +248,15 @@ select_application (ctrl_t ctrl, int slot, const char *name, app_t *r_app)
return err;
/* First check whether we already have an application to share. */
- app = lock_table[slot].initialized ? lock_table[slot].app : NULL;
- if (app && name)
- if (!app->apptype || ascii_strcasecmp (app->apptype, name))
- {
- unlock_reader (slot);
- if (app->apptype)
- log_info ("application '%s' in use by reader %d - can't switch\n",
- app->apptype, slot);
- return gpg_error (GPG_ERR_CONFLICT);
- }
-
- /* If we don't have an app, check whether we have a saved
- application for that slot. This is useful so that a card does
- not get reset even if only one session is using the card - this
- way the PIN cache and other cached data are preserved. */
- if (!app && lock_table[slot].initialized && lock_table[slot].last_app)
+ err = check_conflict (slot, name);
+ if (err)
{
- app = lock_table[slot].last_app;
- if (!name || (app->apptype && !ascii_strcasecmp (app->apptype, name)) )
- {
- /* Yes, we can reuse this application - either the caller
- requested an unspecific one or the requested one matches
- the saved one. */
- lock_table[slot].app = app;
- lock_table[slot].last_app = NULL;
- }
- else
- {
- /* No, this saved application can't be used - deallocate it. */
- lock_table[slot].last_app = NULL;
- deallocate_app (app);
- app = NULL;
- }
+ unlock_reader (slot);
+ return err;
}
+ app = lock_table[slot].app;
+
/* If we can reuse an application, bump the reference count and
return it. */
if (app)
@@ -486,10 +465,10 @@ release_application (app_t app)
return;
}
- if (lock_table[slot].last_app)
- deallocate_app (lock_table[slot].last_app);
- lock_table[slot].last_app = lock_table[slot].app;
- lock_table[slot].app = NULL;
+ /* We don't deallocate app here. Instead, we keep it. This is
+ useful so that a card does not get reset even if only one session
+ is using the card - this way the PIN cache and other cached data
+ are preserved. */
unlock_reader (slot);
}
--
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