qemu/backends/rng-egd.c

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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"
2016-03-14 11:01:28 +03:00
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
#include "qemu/module.h"
#include "qom/object.h"
#define TYPE_RNG_EGD "rng-egd"
OBJECT_DECLARE_SIMPLE_TYPE(RngEgd, RNG_EGD)
struct RngEgd {
RngBackend parent;
CharBackend chr;
char *chr_name;
};
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",
qom: Drop parameter @errp of object_property_add() & friends The only way object_property_add() can fail is when a property with the same name already exists. Since our property names are all hardcoded, failure is a programming error, and the appropriate way to handle it is passing &error_abort. Same for its variants, except for object_property_add_child(), which additionally fails when the child already has a parent. Parentage is also under program control, so this is a programming error, too. We have a bit over 500 callers. Almost half of them pass &error_abort, slightly fewer ignore errors, one test case handles errors, and the remaining few callers pass them to their own callers. The previous few commits demonstrated once again that ignoring programming errors is a bad idea. Of the few ones that pass on errors, several violate the Error API. The Error ** argument must be NULL, &error_abort, &error_fatal, or a pointer to a variable containing NULL. Passing an argument of the latter kind twice without clearing it in between is wrong: if the first call sets an error, it no longer points to NULL for the second call. ich9_pm_add_properties(), sparc32_ledma_realize(), sparc32_dma_realize(), xilinx_axidma_realize(), xilinx_enet_realize() are wrong that way. When the one appropriate choice of argument is &error_abort, letting users pick the argument is a bad idea. Drop parameter @errp and assert the preconditions instead. There's one exception to "duplicate property name is a programming error": the way object_property_add() implements the magic (and undocumented) "automatic arrayification". Don't drop @errp there. Instead, rename object_property_add() to object_property_try_add(), and add the obvious wrapper object_property_add(). Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200505152926.18877-15-armbru@redhat.com> [Two semantic rebase conflicts resolved]
2020-05-05 18:29:22 +03:00
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);