kernel/Documentation/input/uinput.rst
Introduction
uinput 是一个内核模块，能够从用户空间模仿输出设施。通过写入 /dev/uinput（或 /dev/input/uinport）设施，过程能够创立具备特定性能的虚构输出设施。一旦创立了这个虚构设施，过程就能够通过它发送事件，这些事件将传递给用户空间和内核中事件消费者。
Interface
linux/uinput.huinpu t 头定义 ioctl 来创立、设置和销毁虚构设施。
libevdev
libevdev 是 evdev 设施的包装库，它提供了创立 uinput 设施和发送事件的接口。libevdev 比间接拜访 uinput 更不容易出错，新软件应该思考应用此形式。
无关 libevdev 的示例和更多信息：https://www.freedesktop.org/s…
Examples
Keyboard events
第一个示例演示了如何创立新的虚构设施，以及如何发送要害事件。为了简略起见，删除了所有默认导入和谬误处理程序。
#include <linux/uinput.h>
void emit(int fd, int type, int code, int val)
{
struct input_event ie;
ie.type = type;
ie.code = code;
ie.value = val;
/* timestamp values below are ignored */
ie.time.tv_sec = 0;
ie.time.tv_usec = 0;
write(fd, &ie, sizeof(ie));
}
int main(void)
{
struct uinput_setup usetup;
int fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
/*
* The ioctls below will enable the device that is about to be
* created, to pass key events, in this case the space key.
*/
ioctl(fd, UI_SET_EVBIT, EV_KEY);
ioctl(fd, UI_SET_KEYBIT, KEY_SPACE);
memset(&usetup, 0, sizeof(usetup));
usetup.id.bustype = BUS_USB;
usetup.id.vendor = 0x1234; /* sample vendor */
usetup.id.product = 0x5678; /* sample product */
strcpy(usetup.name, "Example device");
ioctl(fd, UI_DEV_SETUP, &usetup);
ioctl(fd, UI_DEV_CREATE);
/*
* On UI_DEV_CREATE the kernel will create the device node for this
* device. We are inserting a pause here so that userspace has time
* to detect, initialize the new device, and can start listening to
* the event, otherwise it will not notice the event we are about
* to send. This pause is only needed in our example code!
*/
sleep(1);
/* Key press, report the event, send key release, and report again */
emit(fd, EV_KEY, KEY_SPACE, 1);
emit(fd, EV_SYN, SYN_REPORT, 0);
emit(fd, EV_KEY, KEY_SPACE, 0);
emit(fd, EV_SYN, SYN_REPORT, 0);
/*
* Give userspace some time to read the events before we destroy the
* device with UI_DEV_DESTROY.
*/
sleep(1);
ioctl(fd, UI_DEV_DESTROY);
close(fd);
return 0;
} Mouse movements
这个例子展现了如何创立一个行为相似于物理鼠标的虚构设施。
#include <linux/uinput.h>
/* emit function is identical to of the first example */
int main(void)
{
struct uinput_setup usetup;
int i = 50;
int fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
/* enable mouse button left and relative events */
ioctl(fd, UI_SET_EVBIT, EV_KEY);
ioctl(fd, UI_SET_KEYBIT, BTN_LEFT);
ioctl(fd, UI_SET_EVBIT, EV_REL);
ioctl(fd, UI_SET_RELBIT, REL_X);
ioctl(fd, UI_SET_RELBIT, REL_Y);
memset(&usetup, 0, sizeof(usetup));
usetup.id.bustype = BUS_USB;
usetup.id.vendor = 0x1234; /* sample vendor */
usetup.id.product = 0x5678; /* sample product */
strcpy(usetup.name, "Example device");
ioctl(fd, UI_DEV_SETUP, &usetup);
ioctl(fd, UI_DEV_CREATE);
/*
* On UI_DEV_CREATE the kernel will create the device node for this
* device. We are inserting a pause here so that userspace has time
* to detect, initialize the new device, and can start listening to
* the event, otherwise it will not notice the event we are about
* to send. This pause is only needed in our example code!
*/
sleep(1);
/* Move the mouse diagonally, 5 units per axis */
while (i--) {emit(fd, EV_REL, REL_X, 5);
emit(fd, EV_REL, REL_Y, 5);
emit(fd, EV_SYN, SYN_REPORT, 0);
usleep(15000);
}
/*
* Give userspace some time to read the events before we destroy the
* device with UI_DEV_DESTROY.
*/
sleep(1);
ioctl(fd, UI_DEV_DESTROY);
close(fd);
return 0;
} uinput old interface
在 uinput 版本 5 之前，没有专门的 ioctl 来设置虚构设施。较旧版本的 uinput 接口须要填充 uinput_user_dev 构造，并将其写入 uinput 文件描述符以配置新的 uinport 设施。新代码不应该应用旧接口，而是通过 ioctl 调用与 uinput 交互，或者应用 libevdev。
#include <linux/uinput.h>
/* emit function is identical to of the first example */
int main(void)
{
struct uinput_user_dev uud;
int version, rc, fd;
fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
rc = ioctl(fd, UI_GET_VERSION, &version);
if (rc == 0 && version >= 5) {
/* use UI_DEV_SETUP */
return 0;
}
/*
* The ioctls below will enable the device that is about to be
* created, to pass key events, in this case the space key.
*/
ioctl(fd, UI_SET_EVBIT, EV_KEY);
ioctl(fd, UI_SET_KEYBIT, KEY_SPACE);
memset(&uud, 0, sizeof(uud));
snprintf(uud.name, UINPUT_MAX_NAME_SIZE, "uinput old interface");
write(fd, &uud, sizeof(uud));
ioctl(fd, UI_DEV_CREATE);
/*
* On UI_DEV_CREATE the kernel will create the device node for this
* device. We are inserting a pause here so that userspace has time
* to detect, initialize the new device, and can start listening to
* the event, otherwise it will not notice the event we are about
* to send. This pause is only needed in our example code!
*/
sleep(1);
/* Key press, report the event, send key release, and report again */
emit(fd, EV_KEY, KEY_SPACE, 1);
emit(fd, EV_SYN, SYN_REPORT, 0);
emit(fd, EV_KEY, KEY_SPACE, 0);
emit(fd, EV_SYN, SYN_REPORT, 0);
/*
* Give userspace some time to read the events before we destroy the
* device with UI_DEV_DESTROY.
*/
sleep(1);
ioctl(fd, UI_DEV_DESTROY);
close(fd);
return 0;
}