2 * QEMU Random Number Generator Backend
4 * Copyright IBM, Corp. 2012
7 * Anthony Liguori <aliguori@us.ibm.com>
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
13 #include "sysemu/rng.h"
14 #include "sysemu/char.h"
15 #include "qapi/qmp/qerror.h"
16 #include "hw/qdev.h" /* just for DEFINE_PROP_CHR */
18 #define TYPE_RNG_EGD "rng-egd"
19 #define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD)
31 typedef struct RngRequest
33 EntropyReceiveFunc *receive_entropy;
40 static void rng_egd_request_entropy(RngBackend *b, size_t size,
41 EntropyReceiveFunc *receive_entropy,
44 RngEgd *s = RNG_EGD(b);
47 req = g_malloc(sizeof(*req));
51 req->receive_entropy = receive_entropy;
53 req->data = g_malloc(req->size);
57 uint8_t len = MIN(size, 255);
59 /* synchronous entropy request */
63 qemu_chr_fe_write(s->chr, header, sizeof(header));
68 s->requests = g_slist_append(s->requests, req);
71 static void rng_egd_free_request(RngRequest *req)
77 static int rng_egd_chr_can_read(void *opaque)
79 RngEgd *s = RNG_EGD(opaque);
83 for (i = s->requests; i; i = i->next) {
84 RngRequest *req = i->data;
85 size += req->size - req->offset;
91 static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size)
93 RngEgd *s = RNG_EGD(opaque);
94 size_t buf_offset = 0;
96 while (size > 0 && s->requests) {
97 RngRequest *req = s->requests->data;
98 int len = MIN(size, req->size - req->offset);
100 memcpy(req->data + req->offset, buf + buf_offset, len);
105 if (req->offset == req->size) {
106 s->requests = g_slist_remove_link(s->requests, s->requests);
108 req->receive_entropy(req->opaque, req->data, req->size);
110 rng_egd_free_request(req);
115 static void rng_egd_free_requests(RngEgd *s)
119 for (i = s->requests; i; i = i->next) {
120 rng_egd_free_request(i->data);
123 g_slist_free(s->requests);
127 static void rng_egd_cancel_requests(RngBackend *b)
129 RngEgd *s = RNG_EGD(b);
131 /* We simply delete the list of pending requests. If there is data in the
132 * queue waiting to be read, this is okay, because there will always be
133 * more data than we requested originally
135 rng_egd_free_requests(s);
138 static void rng_egd_opened(RngBackend *b, Error **errp)
140 RngEgd *s = RNG_EGD(b);
142 if (s->chr_name == NULL) {
143 error_set(errp, QERR_INVALID_PARAMETER_VALUE,
144 "chardev", "a valid character device");
148 s->chr = qemu_chr_find(s->chr_name);
149 if (s->chr == NULL) {
150 error_set(errp, QERR_DEVICE_NOT_FOUND, s->chr_name);
154 if (qemu_chr_fe_claim(s->chr) != 0) {
155 error_set(errp, QERR_DEVICE_IN_USE, s->chr_name);
159 /* FIXME we should resubmit pending requests when the CDS reconnects. */
160 qemu_chr_add_handlers(s->chr, rng_egd_chr_can_read, rng_egd_chr_read,
164 static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp)
166 RngBackend *b = RNG_BACKEND(obj);
167 RngEgd *s = RNG_EGD(b);
170 error_set(errp, QERR_PERMISSION_DENIED);
172 s->chr_name = g_strdup(value);
176 static char *rng_egd_get_chardev(Object *obj, Error **errp)
178 RngEgd *s = RNG_EGD(obj);
180 if (s->chr && s->chr->label) {
181 return g_strdup(s->chr->label);
187 static void rng_egd_init(Object *obj)
189 object_property_add_str(obj, "chardev",
190 rng_egd_get_chardev, rng_egd_set_chardev,
194 static void rng_egd_finalize(Object *obj)
196 RngEgd *s = RNG_EGD(obj);
199 qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL);
200 qemu_chr_fe_release(s->chr);
205 rng_egd_free_requests(s);
208 static void rng_egd_class_init(ObjectClass *klass, void *data)
210 RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
212 rbc->request_entropy = rng_egd_request_entropy;
213 rbc->cancel_requests = rng_egd_cancel_requests;
214 rbc->opened = rng_egd_opened;
217 static const TypeInfo rng_egd_info = {
218 .name = TYPE_RNG_EGD,
219 .parent = TYPE_RNG_BACKEND,
220 .instance_size = sizeof(RngEgd),
221 .class_init = rng_egd_class_init,
222 .instance_init = rng_egd_init,
223 .instance_finalize = rng_egd_finalize,
226 static void register_types(void)
228 type_register_static(&rng_egd_info);
231 type_init(register_types);