On Tue, 8 Jan 2019 17:00:14 +0200
Slavomir Kaslev <kaslevs@xxxxxxxxxx> wrote:
> Add TRACE_REQ and TRACE_RESP messages which are used for initiating guest VM
> tracing.
>
> + /*
> + * NOTE: On success, the returned `argv` should be freed with:
> + * free(argv[0]);
> + * free(argv);
> + */
> +int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
> + int *argc, char ***argv)
> +{
> + struct tracecmd_msg msg;
> + char *p, *buf_end;
> + size_t buf_len;
> + int i, ret;
> +
> + ret = tracecmd_msg_recv(msg_handle->fd, &msg);
> + if (ret < 0)
> + return ret;
> +
> + if (ntohl(msg.hdr.cmd) != MSG_TRACE_REQ)
> + goto out;
> +
> + if (ntohl(msg.trace_req.argc) < 0)
> + goto out;
> +
> + buf_len = ntohl(msg.hdr.size) - MSG_HDR_LEN - ntohl(msg.hdr.cmd_size);
> + buf_end = (char *)msg.buf + buf_len;
> + p = msg.buf;
> + *argc = ntohl(msg.trace_req.argc);
> + *argv = calloc(*argc, sizeof(**argv));
Need to test for failed calloc().
> + for (i = 0; i < *argc; i++) {
> + if (p >= buf_end) {
> + ret = -1;
> + free(*argv);
> + goto out;
> + }
> +
> + (*argv)[i] = p;
> + p = strchr(p, '\0');
> + p++;
> + }
> +
> + ret = 0;
Should add a comment here saying that we are passing msg.buf as
argv[0], and we don't want to have msg_free() free it.
> + msg.buf = NULL;
> +
> +out:
Need to free argv and argv[0] as the description only says that the
caller has to free it on success. Make sure to set those pointers to
zero (NULL) afterward.
> + msg_free(&msg);
> + return ret;
> +}
> +
> +static int make_trace_resp(struct tracecmd_msg *msg,
> + int page_size, int nr_cpus, int *ports)
> +{
> + int ports_size = nr_cpus * sizeof(*msg->port_array);
> + int i;
> +
> + msg->hdr.size = htonl(ntohl(msg->hdr.size) + ports_size);
> + msg->trace_resp.cpus = htonl(nr_cpus);
> + msg->trace_resp.page_size = htonl(page_size);
> +
> + msg->port_array = malloc(ports_size);
> + if (!msg->port_array)
> + return -ENOMEM;
> +
> + for (i = 0; i < nr_cpus; i++)
> + msg->port_array[i] = htonl(ports[i]);
> +
> + return 0;
> +}
> +
> +int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
> + int nr_cpus, int page_size, int *ports)
> +{
> + struct tracecmd_msg msg;
> + int ret;
> +
> + tracecmd_msg_init(MSG_TRACE_RESP, &msg);
> + ret = make_trace_resp(&msg, page_size, nr_cpus, ports);
> + if (ret < 0)
> + return ret;
> +
> + return tracecmd_msg_send(msg_handle->fd, &msg);
> +}
> +
> +int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
> + int *nr_cpus, int *page_size, int **ports)
> +{
> + struct tracecmd_msg msg;
> + size_t buf_len;
> + int i, ret;
> +
> + ret = tracecmd_msg_recv(msg_handle->fd, &msg);
> + if (ret < 0)
> + return ret;
> +
> + if (ntohl(msg.hdr.cmd) != MSG_TRACE_RESP) {
> + ret = -1;
> + goto out;
> + }
> +
> + buf_len = ntohl(msg.hdr.size) - MSG_HDR_LEN - ntohl(msg.hdr.cmd_size);
> + if (buf_len <= 0 ||
> + buf_len != sizeof(*msg.port_array) * ntohl(msg.trace_resp.cpus)) {
> + ret = -1;
> + goto out;
> + }
> +
> + *nr_cpus = ntohl(msg.trace_resp.cpus);
> + *page_size = ntohl(msg.trace_resp.page_size);
> + *ports = calloc(*nr_cpus, sizeof(**ports));
Again, this needs to test the result of calloc().
-- Steve
> + for (i = 0; i < *nr_cpus; i++)
> + (*ports)[i] = ntohl(msg.port_array[i]);
> +
> + ret = 0;
> +
> +out:
> + msg_free(&msg);
> + return ret;
> +}
> +
> +int tracecmd_msg_wait_close(struct tracecmd_msg_handle *msg_handle)
> +{
> + char buf[BUFSIZ];
> + int ret;
> +
> + for (;;) {
> + ret = read(msg_handle->fd, buf, sizeof(buf));
> + if (ret <= 0)
> + return ret;
> + }
> +
> + return -1;
> +}
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