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/*
* QEMU Random Number Generator Backend
*
* Copyright IBM, Corp. 2012
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "sysemu/rng.h"
#include "chardev/char-fe.h"
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
#include "qemu/module.h"
#define TYPE_RNG_EGD "rng-egd"
#define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD)
typedef struct RngEgd
{
RngBackend parent;
CharBackend chr;
char *chr_name;
} RngEgd;
static void rng_egd_request_entropy(RngBackend *b, RngRequest *req)
{
RngEgd *s = RNG_EGD(b);
size_t size = req->size;
while (size > 0) {
uint8_t header[2];
uint8_t len = MIN(size, 255);
/* synchronous entropy request */
header[0] = 0x02;
header[1] = len;
/* XXX this blocks entire thread. Rewrite to use
* qemu_chr_fe_write and background I/O callbacks */
qemu_chr_fe_write_all(&s->chr, header, sizeof(header));
size -= len;
}
}
static int rng_egd_chr_can_read(void *opaque)
{
RngEgd *s = RNG_EGD(opaque);
RngRequest *req;
int size = 0;
QSIMPLEQ_FOREACH(req, &s->parent.requests, next) {
size += req->size - req->offset;
}
return size;
}
static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size)
{
RngEgd *s = RNG_EGD(opaque);
size_t buf_offset = 0;
while (size > 0 && !QSIMPLEQ_EMPTY(&s->parent.requests)) {
RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests);
int len = MIN(size, req->size - req->offset);
memcpy(req->data + req->offset, buf + buf_offset, len);
buf_offset += len;
req->offset += len;
size -= len;
if (req->offset == req->size) {
req->receive_entropy(req->opaque, req->data, req->size);
rng_backend_finalize_request(&s->parent, req);
}
}
}
static void rng_egd_opened(RngBackend *b, Error **errp)
{
RngEgd *s = RNG_EGD(b);
Chardev *chr;
if (s->chr_name == NULL) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
"chardev", "a valid character device");
return;
}
chr = qemu_chr_find(s->chr_name);
if (chr == NULL) {
error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
"Device '%s' not found", s->chr_name);
return;
}
if (!qemu_chr_fe_init(&s->chr, chr, errp)) {
return;
}
/* FIXME we should resubmit pending requests when the CDS reconnects. */
qemu_chr_fe_set_handlers(&s->chr, rng_egd_chr_can_read,
rng_egd_chr_read, NULL, NULL, s, NULL, true);
}
static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp)
{
RngBackend *b = RNG_BACKEND(obj);
RngEgd *s = RNG_EGD(b);
if (b->opened) {
error_setg(errp, QERR_PERMISSION_DENIED);
} else {
g_free(s->chr_name);
s->chr_name = g_strdup(value);
}
}
static char *rng_egd_get_chardev(Object *obj, Error **errp)
{
RngEgd *s = RNG_EGD(obj);
Chardev *chr = qemu_chr_fe_get_driver(&s->chr);
if (chr && chr->label) {
return g_strdup(chr->label);
}
return NULL;
}
static void rng_egd_init(Object *obj)
{
object_property_add_str(obj, "chardev",
rng_egd_get_chardev, rng_egd_set_chardev);
}
static void rng_egd_finalize(Object *obj)
{
RngEgd *s = RNG_EGD(obj);
qemu_chr_fe_deinit(&s->chr, false);
g_free(s->chr_name);
}
static void rng_egd_class_init(ObjectClass *klass, void *data)
{
RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
rbc->request_entropy = rng_egd_request_entropy;
rbc->opened = rng_egd_opened;
}
static const TypeInfo rng_egd_info = {
.name = TYPE_RNG_EGD,
.parent = TYPE_RNG_BACKEND,
.instance_size = sizeof(RngEgd),
.class_init = rng_egd_class_init,
.instance_init = rng_egd_init,
.instance_finalize = rng_egd_finalize,
};
static void register_types(void)
{
type_register_static(&rng_egd_info);
}
type_init(register_types);
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