vatrog-vm-control-io/src/vmctl/qmp_driver.c

/* qmp_driver.c — QMP input driver: serialises an input batch into a single
 * input-send-event command and sends it in one round-trip. No guest driver is
 * required. Switches on vmctl_ev_kind (never on magic numbers). */

#include "driver.h"
#include "keymap.h"

#include <stdlib.h>
#include <stdio.h>

static const char* btn_names[] = {
    "left", "right", "middle", "side", "extra", "forward", "back", "task"
};
#define BTN_NAMES_LEN ((int)(sizeof btn_names / sizeof btn_names[0]))

static int qmp_driver_send(vmctl_t* v, const vmctl_batch* b) {
    char json[8192];
    int  pos = 0;

    pos += snprintf(json + pos, (int)sizeof json - pos,
                    "{\"execute\":\"input-send-event\",\"arguments\":{\"events\":[");

    for (int i = 0; i < b->count; i++) {
        if (i > 0)
            pos += snprintf(json + pos, (int)sizeof json - pos, ",");

        int    code  = b->ev[i].code;
        int    value = b->ev[i].value;
        double scl   = b->ev[i].scroll;

        switch ((vmctl_ev_kind)b->ev[i].kind) {
        case VMCTL_EV_ABS:
            pos += snprintf(json + pos, (int)sizeof json - pos,
                            "{\"type\":\"abs\",\"data\":{\"axis\":\"%s\",\"value\":%d}}",
                            code == VMCTL_AXIS_X ? "x" : "y", value);
            break;
        case VMCTL_EV_REL:
            pos += snprintf(json + pos, (int)sizeof json - pos,
                            "{\"type\":\"rel\",\"data\":{\"axis\":\"%s\",\"value\":%d}}",
                            code == VMCTL_AXIS_X ? "x" : "y", value);
            break;
        case VMCTL_EV_BTN:
            if (code < 0 || code >= BTN_NAMES_LEN) return -1;
            pos += snprintf(json + pos, (int)sizeof json - pos,
                            "{\"type\":\"btn\",\"data\":{\"button\":\"%s\",\"down\":%s}}",
                            btn_names[code], value ? "true" : "false");
            break;
        case VMCTL_EV_KEY: {
            const char* qcode = vmctl_evdev_to_qcode(code);
            if (!qcode) return -1;
            pos += snprintf(json + pos, (int)sizeof json - pos,
                            "{\"type\":\"key\",\"data\":{\"key\":{\"type\":\"qcode\","
                            "\"data\":\"%s\"},\"down\":%s}}",
                            qcode, value ? "true" : "false");
            break;
        }
        case VMCTL_EV_SCROLL:
            pos += snprintf(json + pos, (int)sizeof json - pos,
                            "{\"type\":\"scl\",\"data\":{\"axis\":\"%s\",\"value\":%g}}",
                            code == VMCTL_SCROLL_V ? "vertical" : "horizontal", scl);
            break;
        default:
            return -1;
        }
    }

    pos += snprintf(json + pos, (int)sizeof json - pos, "]}}");

    char resp[4096];
    return qmp_exec(v->qmp, json, resp, sizeof resp);
}

static void qmp_driver_close(vmctl_t* v) {
    qmp_disconnect(v->qmp);
}

vmctl_t* vmctl_open_qmp_driver(const vmctl_config* cfg) {
    qmp_conn* qmp = qmp_connect(cfg->qmp_path);
    if (!qmp) return NULL;

    vmctl_t* v = calloc(1, sizeof *v);
    if (!v) {
        qmp_disconnect(qmp);
        return NULL;
    }
    v->driver     = VMCTL_DRIVER_QMP;
    v->qmp        = qmp;
    v->ui_fd_a    = -1;
    v->ui_fd_b    = -1;
    v->ptr_mode   = 0;
    v->ops.send   = qmp_driver_send;
    v->ops.close  = qmp_driver_close;
    return v;
}