1 files changed, 153 insertions, 0 deletions
diff --git a/backends/rng-random.c b/backends/rng-random.c
new file mode 100644
index 000000000..7add272ed
--- /dev/null
+++ b/backends/rng-random.c
@@ -0,0 +1,153 @@
+/*
+ * 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-random.h"
+#include "sysemu/rng.h"
+#include "qapi/error.h"
+#include "qapi/qmp/qerror.h"
+#include "qemu/main-loop.h"
+#include "qemu/module.h"
+
+struct RngRandom
+{
+    RngBackend parent;
+
+    int fd;
+    char *filename;
+};
+
+/**
+ * A simple and incomplete backend to request entropy from /dev/random.
+ *
+ * This backend exposes an additional "filename" property that can be used to
+ * set the filename to use to open the backend.
+ */
+
+static void entropy_available(void *opaque)
+{
+    RngRandom *s = RNG_RANDOM(opaque);
+
+    while (!QSIMPLEQ_EMPTY(&s->parent.requests)) {
+        RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests);
+        ssize_t len;
+
+        len = read(s->fd, req->data, req->size);
+        if (len < 0 && errno == EAGAIN) {
+            return;
+        }
+        g_assert(len != -1);
+
+        req->receive_entropy(req->opaque, req->data, len);
+
+        rng_backend_finalize_request(&s->parent, req);
+    }
+
+    /* We've drained all requests, the fd handler can be reset. */
+    qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
+}
+
+static void rng_random_request_entropy(RngBackend *b, RngRequest *req)
+{
+    RngRandom *s = RNG_RANDOM(b);
+
+    if (QSIMPLEQ_EMPTY(&s->parent.requests)) {
+        /* If there are no pending requests yet, we need to
+         * install our fd handler. */
+        qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
+    }
+}
+
+static void rng_random_opened(RngBackend *b, Error **errp)
+{
+    RngRandom *s = RNG_RANDOM(b);
+
+    if (s->filename == NULL) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
+                   "filename", "a valid filename");
+    } else {
+        s->fd = qemu_open_old(s->filename, O_RDONLY | O_NONBLOCK);
+        if (s->fd == -1) {
+            error_setg_file_open(errp, errno, s->filename);
+        }
+    }
+}
+
+static char *rng_random_get_filename(Object *obj, Error **errp)
+{
+    RngRandom *s = RNG_RANDOM(obj);
+
+    return g_strdup(s->filename);
+}
+
+static void rng_random_set_filename(Object *obj, const char *filename,
+                                 Error **errp)
+{
+    RngBackend *b = RNG_BACKEND(obj);
+    RngRandom *s = RNG_RANDOM(obj);
+
+    if (b->opened) {
+        error_setg(errp, QERR_PERMISSION_DENIED);
+        return;
+    }
+
+    g_free(s->filename);
+    s->filename = g_strdup(filename);
+}
+
+static void rng_random_init(Object *obj)
+{
+    RngRandom *s = RNG_RANDOM(obj);
+
+    s->filename = g_strdup("/dev/urandom");
+    s->fd = -1;
+}
+
+static void rng_random_finalize(Object *obj)
+{
+    RngRandom *s = RNG_RANDOM(obj);
+
+    if (s->fd != -1) {
+        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
+        qemu_close(s->fd);
+    }
+
+    g_free(s->filename);
+}
+
+static void rng_random_class_init(ObjectClass *klass, void *data)
+{
+    RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
+
+    rbc->request_entropy = rng_random_request_entropy;
+    rbc->opened = rng_random_opened;
+    object_class_property_add_str(klass, "filename",
+                                  rng_random_get_filename,
+                                  rng_random_set_filename);
+
+}
+
+static const TypeInfo rng_random_info = {
+    .name = TYPE_RNG_RANDOM,
+    .parent = TYPE_RNG_BACKEND,
+    .instance_size = sizeof(RngRandom),
+    .class_init = rng_random_class_init,
+    .instance_init = rng_random_init,
+    .instance_finalize = rng_random_finalize,
+};
+
+static void register_types(void)
+{
+    type_register_static(&rng_random_info);
+}
+
+type_init(register_types);