Add public iterator API to p11-kit

1 files changed, 829 insertions, 0 deletions

diff --git a/p11-kit/iter.c b/p11-kit/iter.c
new file mode 100644
index 0000000..4a4dbd3
--- /dev/null
+++ b/p11-kit/iter.c
@@ -0,0 +1,829 @@
+/*
+ * Copyright (C) 2013 Red Hat Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *     * Redistributions of source code must retain the above
+ *       copyright notice, this list of conditions and the
+ *       following disclaimer.
+ *     * Redistributions in binary form must reproduce the
+ *       above copyright notice, this list of conditions and
+ *       the following disclaimer in the documentation and/or
+ *       other materials provided with the distribution.
+ *     * The names of contributors to this software may not be
+ *       used to endorse or promote products derived from this
+ *       software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * Author: Stef Walter <stefw@redhat.com>
+ */
+
+#include "config.h"
+
+#include "array.h"
+#include "attrs.h"
+#include "debug.h"
+#include "iter.h"
+#include "pin.h"
+#include "private.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct _Callback {
+	p11_kit_iter_callback func;
+	void *callback_data;
+	p11_kit_destroyer destroyer;
+	struct _Callback *next;
+} Callback;
+
+#define MAX_OBJECTS 64
+
+/**
+ * P11KitIter:
+ *
+ * Used to iterate over PKCS\#11 objects.
+ */
+typedef struct p11_kit_iter {
+
+	/* Iterator matching data */
+	CK_INFO match_module;
+	CK_TOKEN_INFO match_token;
+	CK_ATTRIBUTE *match_attrs;
+	Callback *callbacks;
+	CK_FLAGS session_flags;
+
+	/* The input modules */
+	p11_array *modules;
+
+	/* The results of C_GetSlotList */
+	CK_SLOT_ID *slots;
+	CK_ULONG num_slots;
+	CK_ULONG saw_slots;
+
+	/* The results of C_FindObjects */
+	CK_OBJECT_HANDLE objects[MAX_OBJECTS];
+	CK_ULONG num_objects;
+	CK_ULONG saw_objects;
+
+	/* The current iteration */
+	CK_FUNCTION_LIST_PTR module;
+	CK_SLOT_ID slot;
+	CK_SESSION_HANDLE session;
+	CK_OBJECT_HANDLE object;
+
+	/* And various flags */
+	int searching : 1;
+	int searched : 1;
+	int iterating : 1;
+	int match_nothing : 1;
+	int keep_session : 1;
+} P11KitIter;
+
+/**
+ * p11_kit_iter_new:
+ * @uri: (allow-none): a PKCS\#11 URI to filter on, or %NULL
+ *
+ * Create a new PKCS\#11 iterator for iterating over objects. Only
+ * objects that match the @uri will be returned by the iterator.
+ * Relevant information in @uri is copied, and you need not keep
+ * @uri around.
+ *
+ * If no @uri is specified then the iterator will iterate over all
+ * objects, unless otherwise filtered.
+ *
+ * Returns: (transfer full): a new iterator, which should be freed
+ *          with p11_kit_iter_free()
+ */
+P11KitIter *
+p11_kit_iter_new (P11KitUri *uri)
+{
+	P11KitIter *iter;
+	CK_ATTRIBUTE *attrs;
+	CK_TOKEN_INFO *tinfo;
+	CK_INFO *minfo;
+	CK_ULONG count;
+
+	iter = calloc (1, sizeof (P11KitIter));
+	return_val_if_fail (iter != NULL, NULL);
+
+	iter->modules = p11_array_new (NULL);
+	return_val_if_fail (iter->modules != NULL, NULL);
+
+	if (uri != NULL) {
+
+		if (p11_kit_uri_any_unrecognized (uri)) {
+			iter->match_nothing = 1;
+
+		} else {
+			attrs = p11_kit_uri_get_attributes (uri, &count);
+			iter->match_attrs = p11_attrs_buildn (NULL, attrs, count);
+
+			minfo = p11_kit_uri_get_module_info (uri);
+			if (minfo != NULL)
+				memcpy (&iter->match_module, minfo, sizeof (CK_INFO));
+
+			tinfo = p11_kit_uri_get_token_info (uri);
+			if (tinfo != NULL)
+				memcpy (&iter->match_token, tinfo, sizeof (CK_TOKEN_INFO));
+		}
+	} else {
+		/* Match any module version number*/
+		iter->match_module.libraryVersion.major = (CK_BYTE)-1;
+		iter->match_module.libraryVersion.minor = (CK_BYTE)-1;
+	}
+
+	iter->session_flags = CKF_SERIAL_SESSION;
+
+	return iter;
+}
+
+/**
+ * p11_kit_iter_set_session_flags:
+ * @iter: the iterator
+ * @flags: set of session flags
+ *
+ * Set the PKCS\#11 session flags to be used when the iterator opens
+ * new sessions.
+ */
+void
+p11_kit_iter_set_session_flags (P11KitIter *iter,
+                                CK_FLAGS flags)
+{
+	return_if_fail (iter != NULL);
+	return_if_fail (!iter->iterating);
+	iter->session_flags = flags | CKF_SERIAL_SESSION;
+}
+
+/**
+ * p11_kit_destroyer:
+ * @data: data to destroy
+ *
+ * A callback called to free a resource.
+ */
+
+/**
+ * p11_kit_iter_callback:
+ * @iter: the iterator
+ * @matches: (out): whether to match the current object
+ * @data: callback data
+ *
+ * A callback setup with p11_kit_iter_add_callback(). This callback is
+ * called for each object iterated.
+ *
+ * If the callback sets @matches to CK_FALSE, then this object is
+ * skipped and not matched by p11_kit_iter_next(). If you return
+ * anything but CKR_OK, then the iteration is stopped, and
+ * p11_kit_iter_next() returns the result code.
+ *
+ * Returns: CKR_OK to continue iterating, CKR_CANCEL to stop, or
+ *          anything else to fail
+ */
+
+/**
+ * p11_kit_iter_add_callback:
+ * @iter: the iterator
+ * @callback: a function to call for each iteration
+ * @callback_data: (allow-none): data to pass to the function
+ * @callback_destroy: (allow-none): used to cleanup the data
+ *
+ * Adds a callback to the iterator which will be called each time
+ * that an object is iterated.
+ *
+ * These callbacks can also perform filtering. If any callback
+ * indicates through it's <literal>matches</literal> argument that
+ * the object should not match, then that object will not be iterated
+ * as far as p11_kit_iter_next() is concerned.
+ */
+void
+p11_kit_iter_add_callback (P11KitIter *iter,
+                           p11_kit_iter_callback callback,
+                           void *callback_data,
+                           p11_kit_destroyer callback_destroy)
+{
+	Callback *cb;
+
+	return_if_fail (iter != NULL);
+	return_if_fail (callback != NULL);
+
+	cb = calloc (1, sizeof (Callback));
+	return_if_fail (cb != NULL);
+
+	cb->func = callback;
+	cb->destroyer = callback_destroy;
+	cb->callback_data = callback_data;
+	cb->next = iter->callbacks;
+	iter->callbacks = cb;
+}
+
+/**
+ * p11_kit_iter_add_filter:
+ * @iter: the iterator
+ * @matching: (array length=count): the attributes that the objects should match
+ * @count: the number of attributes
+ *
+ * Add a filter to limit the objects that the iterator iterates over.
+ *
+ * Only objects matching the passed in attributes will be iterated.
+ * This function can be called multiple times.
+ *
+ * The @matching attributes are copied.
+ */
+void
+p11_kit_iter_add_filter (P11KitIter *iter,
+                         CK_ATTRIBUTE *matching,
+                         CK_ULONG count)
+{
+	return_if_fail (iter != NULL);
+	return_if_fail (!iter->iterating);
+
+	iter->match_attrs = p11_attrs_buildn (iter->match_attrs, matching, count);
+	return_if_fail (iter->match_attrs != NULL);
+}
+
+static void
+finish_object (P11KitIter *iter)
+{
+	iter->object = 0;
+}
+
+static void
+finish_slot (P11KitIter *iter)
+{
+	if (iter->session && !iter->keep_session) {
+		assert (iter->module != NULL);
+		(iter->module->C_CloseSession) (iter->session);
+	}
+
+	iter->keep_session = 0;
+	iter->session = 0;
+	iter->searched = 0;
+	iter->searching = 0;
+	iter->slot = 0;
+}
+
+static void
+finish_module (P11KitIter *iter)
+{
+	iter->num_slots = 0;
+	iter->saw_slots = 0;
+	iter->module = NULL;
+}
+
+static CK_RV
+finish_iterating (P11KitIter *iter,
+                  CK_RV rv)
+{
+	finish_object (iter);
+	finish_slot (iter);
+	finish_module (iter);
+	p11_array_clear (iter->modules);
+
+	iter->iterating = 0;
+	return rv;
+}
+
+/**
+ * p11_kit_iter_begin:
+ * @iter: the iterator
+ * @modules: (array zero-terminated=1): null-terminated list of
+ *           modules to iterate over
+ *
+ * Begin iterating PKCS\#11 objects in the given @modules.
+ *
+ * The @modules arguments should be a null-terminated list of
+ * pointers to the modules' PKCS\#11 function pointers.
+ *
+ * For each module, all initialized slots will be iterated over,
+ * having sessions opened for each of them in turn, and searched
+ * for objects matching the search criteria.
+ */
+void
+p11_kit_iter_begin (P11KitIter *iter,
+                    CK_FUNCTION_LIST_PTR *modules)
+{
+	int i;
+
+	return_if_fail (modules != NULL);
+
+	finish_iterating (iter, CKR_OK);
+
+	/* Use this module */
+	for (i = 0; modules[i] != NULL; i++) {
+		if (!p11_array_push (iter->modules, modules[i]))
+			return_if_reached ();
+	}
+
+	iter->iterating = 1;
+	iter->searched = 1;
+}
+
+/**
+ * p11_kit_iter_begin_with:
+ * @iter: the iterator
+ * @module: the module to iterate over
+ * @slot: (allow-none): the slot to iterate objects in, or zero
+ * @session: (allow-none): the session to search for objects on, or zero
+ *
+ * Begin iterating PKCS\#11 objects in the given @module.
+ *
+ * If @slot is non-zero then the iteration will be limited to that
+ * slot.
+ *
+ * If @session is non-zero then the iteration will be limited to
+ * objects visible through that session, which implies that they
+ * are also limited to the slot which the session was opened for.
+ */
+void
+p11_kit_iter_begin_with (P11KitIter *iter,
+                         CK_FUNCTION_LIST_PTR module,
+                         CK_SLOT_ID slot,
+                         CK_SESSION_HANDLE session)
+{
+	CK_SESSION_INFO info;
+	CK_RV rv;
+
+	finish_iterating (iter, CKR_OK);
+
+	return_if_fail (module != NULL);
+
+	if (session != 0) {
+		/*
+		 * A currently active session. Initialize as if we're ready
+		 * to search using this session.
+		 */
+
+		/* If we have a session, but no slot, then look it up */
+		if (slot == 0) {
+			assert (module != NULL);
+			rv = (module->C_GetSessionInfo) (session, &info);
+			if (rv == CKR_OK)
+				slot = info.slotID;
+		}
+
+		/* So initialize as if we're ready to search */
+		iter->session = session;
+		iter->slot = slot;
+		iter->module = module;
+		iter->keep_session = 1;
+
+	} else if (slot != 0) {
+
+		/*
+		 * Limit to this slot. Initialize as if we're ready to use the
+		 * slot from the slots list.
+		 */
+
+		iter->module = module;
+		iter->slots = realloc (iter->slots, sizeof (CK_SLOT_ID));
+		return_if_fail (iter->slots != NULL);
+		iter->slots[0] = slot;
+		iter->num_slots = 1;
+		iter->searched = 1;
+
+	} else {
+
+		/*
+		 * Limit to this module. Initialize as if we're ready to use
+		 * the module from the modules array.
+		 */
+
+		assert (module != NULL);
+		p11_array_push (iter->modules, module);
+		iter->session = 0;
+		iter->slot = 0;
+		iter->searched = 1;
+	}
+
+	iter->iterating = 1;
+}
+
+static CK_RV
+call_all_filters (P11KitIter *iter,
+                  CK_BBOOL *matches)
+{
+	Callback *cb;
+	CK_RV rv;
+
+	*matches = CK_TRUE;
+
+	for (cb = iter->callbacks; cb != NULL; cb = cb->next) {
+		rv = (cb->func) (iter, matches, cb->callback_data);
+		if (rv != CKR_OK || !*matches)
+			return rv;
+	}
+
+	return CKR_OK;
+}
+
+static CK_RV
+move_next_session (P11KitIter *iter)
+{
+	CK_TOKEN_INFO tinfo;
+	CK_ULONG num_slots;
+	CK_INFO minfo;
+	CK_RV rv;
+
+	finish_slot (iter);
+
+	/* If we have no more slots, then move to next module */
+	while (iter->saw_slots >= iter->num_slots) {
+		finish_module (iter);
+
+		/* Iter is finished */
+		if (iter->modules->num == 0)
+			return finish_iterating (iter, CKR_CANCEL);
+
+		iter->module = iter->modules->elem[0];
+		p11_array_remove (iter->modules, 0);
+
+		/* Skip module if it doesn't match uri */
+		assert (iter->module != NULL);
+		rv = (iter->module->C_GetInfo) (&minfo);
+		if (rv != CKR_OK || !p11_match_uri_module_info (&iter->match_module, &minfo))
+			continue;
+
+		rv = (iter->module->C_GetSlotList) (CK_TRUE, NULL, &num_slots);
+		if (rv != CKR_OK)
+			return finish_iterating (iter, rv);
+
+		iter->slots = realloc (iter->slots, sizeof (CK_SLOT_ID) * (num_slots + 1));
+		return_val_if_fail (iter->slots != NULL, CKR_HOST_MEMORY);
+
+		rv = (iter->module->C_GetSlotList) (CK_TRUE, iter->slots, &num_slots);
+		if (rv != CKR_OK)
+			return finish_iterating (iter, rv);
+
+		iter->num_slots = num_slots;
+		assert (iter->saw_slots == 0);
+	}
+
+	/* Move to the next slot, and open a session on it */
+	while (iter->saw_slots < iter->num_slots) {
+		iter->slot = iter->slots[iter->saw_slots++];
+
+		assert (iter->module != NULL);
+		rv = (iter->module->C_GetTokenInfo) (iter->slot, &tinfo);
+		if (rv != CKR_OK || !p11_match_uri_token_info (&iter->match_token, &tinfo))
+			continue;
+
+		/* Token is not initialized, we're not going to get further, so skip */
+		if (!(tinfo.flags & CKF_TOKEN_INITIALIZED))
+			continue;
+
+		rv = (iter->module->C_OpenSession) (iter->slot, iter->session_flags,
+		                                    NULL, NULL, &iter->session);
+		if (rv != CKR_OK)
+			return finish_iterating (iter, rv);
+
+		if (iter->session != 0)
+			return CKR_OK;
+	}
+
+	/* Otherwise try again */
+	return move_next_session (iter);
+}
+
+/**
+ * p11_kit_iter_next:
+ * @iter: the iterator
+ *
+ * Iterate to the next matching object.
+ *
+ * To access the object, session and so on, use the p11_kit_iter_get_object(),
+ * p11_kit_iter_get_session(), and p11_kit_iter_get_module() functions.
+ *
+ * This call must only be called after either p11_kit_iter_begin()
+ * or p11_kit_iter_begin_with() have been called.
+ *
+ * Objects which are skipped by callbacks will not be returned here
+ * as matching objects.
+ *
+ * Returns: CKR_OK if an object matched, CKR_CANCEL if no more objects, or another error
+ */
+CK_RV
+p11_kit_iter_next (P11KitIter *iter)
+{
+	CK_ULONG count;
+	CK_BBOOL matches;
+	CK_RV rv;
+
+	return_val_if_fail (iter->iterating, CKR_OPERATION_NOT_INITIALIZED);
+
+	iter->object = 0;
+
+	if (iter->match_nothing)
+		return finish_iterating (iter, CKR_CANCEL);
+
+	/*
+	 * If we have outstanding objects, then iterate one through those
+	 * Note that we pass each object through the filters, and only
+	 * assume it's iterated if it matches
+	 */
+	while (iter->saw_objects < iter->num_objects) {
+		iter->object = iter->objects[iter->saw_objects++];
+
+		rv = call_all_filters (iter, &matches);
+		if (rv != CKR_OK)
+			return finish_iterating (iter, rv);
+
+		if (matches)
+			return CKR_OK;
+	}
+
+	/* If we have finished searching then move to next session */
+	if (iter->searched) {
+		rv = move_next_session (iter);
+		if (rv != CKR_OK)
+			return finish_iterating (iter, rv);
+	}
+
+	/* Ready to start searching */
+	if (!iter->searching && !iter->searched) {
+		count = p11_attrs_count (iter->match_attrs);
+		rv = (iter->module->C_FindObjectsInit) (iter->session, iter->match_attrs, count);
+		if (rv != CKR_OK)
+			return finish_iterating (iter, rv);
+		iter->searching = 1;
+		iter->searched = 0;
+	}
+
+	/* If we have searched on this session then try to continue */
+	if (iter->searching) {
+		assert (iter->module != NULL);
+		assert (iter->session != 0);
+		iter->num_objects = 0;
+		iter->saw_objects = 0;
+
+		rv = (iter->module->C_FindObjects) (iter->session, iter->objects,
+		                                    MAX_OBJECTS, &iter->num_objects);
+		if (rv != CKR_OK)
+			return finish_iterating (iter, rv);
+
+		/*
+		 * Done searching on this session, although there are still
+		 * objects outstanding, which will be returned on next
+		 * iterations.
+		 */
+		if (iter->num_objects != MAX_OBJECTS) {
+			iter->searching = 0;
+			iter->searched = 1;
+			(iter->module->C_FindObjectsFinal) (iter->session);
+		}
+	}
+
+	/* Try again */
+	return p11_kit_iter_next (iter);
+}
+
+/**
+ * p11_kit_iter_get_module:
+ * @iter: the iterator
+ *
+ * Get the module function pointers for the current matching object.
+ *
+ * This can only be called after p11_kit_iter_next() succeeds.
+ *
+ * Returns: the module which the current matching object is in
+ */
+CK_FUNCTION_LIST_PTR
+p11_kit_iter_get_module (P11KitIter *iter)
+{
+	return_val_if_fail (iter != NULL, NULL);
+	return_val_if_fail (iter->iterating, 0);
+	return iter->module;
+}
+
+/**
+ * p11_kit_iter_get_slot:
+ * @iter: the iterator
+ *
+ * Get the slot which the current matching object is on.
+ *
+ * This can only be called after p11_kit_iter_next() succeeds.
+ *
+ * Returns: the slot of the current matching object
+ */
+CK_SLOT_ID
+p11_kit_iter_get_slot (P11KitIter *iter)
+{
+	return_val_if_fail (iter != NULL, 0);
+	return_val_if_fail (iter->iterating, 0);
+	return iter->slot;
+}
+
+/**
+ * p11_kit_iter_get_session:
+ * @iter: the iterator
+ *
+ * Get the session which the current matching object is acessible
+ * through.
+ *
+ * This can only be called after p11_kit_iter_next() succeeds.
+ *
+ * The session may be closed after the next p11_kit_iter_next() call
+ * unless p11_kit_iter_keep_session() is called.
+ *
+ * Returns: the slot of the current matching object
+ */
+CK_SESSION_HANDLE
+p11_kit_iter_get_session (P11KitIter *iter)
+{
+	return_val_if_fail (iter != NULL, 0);
+	return_val_if_fail (iter->iterating, 0);
+	return iter->session;
+}
+
+/**
+ * p11_kit_iter_get_object:
+ * @iter: the iterator
+ *
+ * Get the current matching object.
+ *
+ * This can only be called after p11_kit_iter_next() succeeds.
+ *
+ * Returns: the current matching object
+ */
+CK_OBJECT_HANDLE
+p11_kit_iter_get_object (P11KitIter *iter)
+{
+	return_val_if_fail (iter != NULL, 0);
+	return iter->object;
+}
+
+/**
+ * p11_kit_iter_load_attributes:
+ * @iter: the iterator
+ * @template: (array length=count) (inout): the attributes to load
+ * @count: the number of attributes
+ *
+ * Retrieve attributes for the current matching object.
+ *
+ * Each attribute in the array will be filled in with the value
+ * of that attribute retrieved from the object. After use the
+ * attribute value memory pointed to by the <literal>pValue</literal>
+ * of each attribute should be freed with the <literal>free<!-- -->()</literal>
+ * function.
+ *
+ * If the <literal>pValue</literal> of an attribute is not %NULL passed
+ * to this function, then it will be passed to
+ * <literal>realloc<!-- -->()</literal> to allocate the correct amount
+ * of space for the attribute value.
+ *
+ * If any attribute is not present on the object, or is sensitive and
+ * cannot be retrieved, then the <literal>pValue</literal> will be NULL.
+ * If <literal>pValue</literal> was not %NULL when passed to this function
+ * then it will be freed with <literal>free<!-- -->()</literal>. In these
+ * cases <literal>CKR_OK</literal> is returned.
+ *
+ * This can only be called after p11_kit_iter_next() succeeds.
+ *
+ * Returns: CKR_OK or a failure code
+ */
+CK_RV
+p11_kit_iter_load_attributes (P11KitIter *iter,
+                              CK_ATTRIBUTE *template,
+                              CK_ULONG count)
+{
+	CK_ATTRIBUTE *original = NULL;
+	CK_ULONG i;
+	CK_RV rv;
+
+	return_val_if_fail (iter != NULL, CKR_GENERAL_ERROR);
+	return_val_if_fail (iter->iterating, CKR_GENERAL_ERROR);
+	return_val_if_fail (iter->module != NULL, CKR_GENERAL_ERROR);
+	return_val_if_fail (iter->session != 0, CKR_GENERAL_ERROR);
+	return_val_if_fail (iter->object != 0, CKR_GENERAL_ERROR);
+
+	if (count == 0)
+		return CKR_OK;
+
+	original = memdup (template, count * sizeof (CK_ATTRIBUTE));
+	return_val_if_fail (original != NULL, CKR_HOST_MEMORY);
+
+	for (i = 0; i < count; i++)
+		template[i].pValue = NULL;
+
+	rv = (iter->module->C_GetAttributeValue) (iter->session, iter->object, template, count);
+
+	switch (rv) {
+	case CKR_OK:
+	case CKR_ATTRIBUTE_TYPE_INVALID:
+	case CKR_ATTRIBUTE_SENSITIVE:
+	case CKR_BUFFER_TOO_SMALL:
+		break;
+	default:
+		free (original);
+		return rv;
+	}
+
+	for (i = 0; i < count; i++) {
+		if (template[i].ulValueLen == (CK_ULONG)-1 ||
+		    template[i].ulValueLen == 0) {
+			free (original[i].pValue);
+
+		} else if (original[i].pValue != NULL &&
+		           template[i].ulValueLen == original[i].ulValueLen) {
+			template[i].pValue = original[i].pValue;
+
+		} else {
+			template[i].pValue = realloc (original[i].pValue, template[i].ulValueLen);
+			return_val_if_fail (template[i].pValue != NULL, 0);
+		}
+	}
+
+	free (original);
+
+	rv = (iter->module->C_GetAttributeValue) (iter->session, iter->object, template, count);
+
+	switch (rv) {
+	case CKR_OK:
+	case CKR_ATTRIBUTE_TYPE_INVALID:
+	case CKR_ATTRIBUTE_SENSITIVE:
+		rv = CKR_OK;
+		break;
+	default:
+		return_val_if_fail (rv != CKR_BUFFER_TOO_SMALL, rv);
+		return rv;
+	}
+
+	for (i = 0; i < count; i++) {
+		if (template[i].ulValueLen == (CK_ULONG)-1 ||
+		    template[i].ulValueLen == 0) {
+			free (template[i].pValue);
+			template[i].pValue = NULL;
+		}
+	}
+
+	return rv;
+}
+
+/**
+ * p11_kit_iter_keep_session:
+ * @iter: the iterator
+ *
+ * After calling this function the session open for iterating
+ * the current object will not be automatically closed by
+ * the iterator after later calls to p11_kit_iter_next() or
+ * p11_kit_iter_free().
+ *
+ * It is the callers responsibility to close this session,
+ * after the iterator has been freed. The session may still be
+ * used by the iterator if further iterations are performed.
+ *
+ * This can only be called after p11_kit_iter_next() succeeds.
+ *
+ * Returns: the current session
+ */
+CK_SESSION_HANDLE
+p11_kit_iter_keep_session (P11KitIter *iter)
+{
+	return_val_if_fail (iter != NULL, 0);
+	return_val_if_fail (iter->iterating, 0);
+	return_val_if_fail (iter->session != 0, 0);
+
+	iter->keep_session = 1;
+	return iter->session;
+}
+
+/**
+ * p11_kit_iter_free:
+ * @iter: the iterator
+ *
+ * Frees the iterator and all resources, such as sessions
+ * or callbacks held by the iterator.
+ */
+void
+p11_kit_iter_free (P11KitIter *iter)
+{
+	Callback *cb, *next;
+
+	if (iter == NULL)
+		return;
+
+	finish_iterating (iter, CKR_OK);
+	p11_array_free (iter->modules);
+	p11_attrs_free (iter->match_attrs);
+
+	for (cb = iter->callbacks; cb != NULL; cb = next) {
+		next = cb->next;
+		if (cb->destroyer)
+			(cb->destroyer) (cb->callback_data);
+		free (cb);
+	}
+}