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#include "hotplug.h"
/* C stdlib */
#include <string.h>
/* POSIX */
#include <unistd.h>
#include <sys/socket.h>
/* LINUX */
#include <linux/types.h>
#include <linux/netlink.h>
bool hotplug_event_init(hotplug_event *self) {
memset(self, 0, sizeof(*self));
struct sockaddr_nl nls = {
.nl_family = AF_NETLINK,
.nl_pid = getpid(),
.nl_groups = -1
};
const int fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
if(fd == -1)
return false; /* Not root user */
if(bind(fd, (void*)&nls, sizeof(struct sockaddr_nl))) {
close(fd);
return false;
}
self->fd = fd;
return true;
}
void hotplug_event_deinit(hotplug_event *self) {
if(self->fd > 0) {
close(self->fd);
self->fd = -1;
}
}
int hotplug_event_steal_fd(hotplug_event *self) {
const int fd = self->fd;
self->fd = -1;
return fd;
}
/* TODO: This assumes SUBSYSTEM= is output before DEVNAME=, is that always true? */
static void hotplug_event_parse_netlink_data(hotplug_event *self, const char *line, hotplug_device_added_callback callback, void *userdata) {
const char *at_symbol = strchr(line, '@');
if(at_symbol) {
self->event_is_add = strncmp(line, "add@", 4) == 0;
self->subsystem_is_input = false;
} else if(self->event_is_add) {
if(strcmp(line, "SUBSYSTEM=input") == 0)
self->subsystem_is_input = true;
if(self->subsystem_is_input && strncmp(line, "DEVNAME=", 8) == 0)
callback(line+8, userdata);
}
}
/* Netlink uevent structure is documented here: https://web.archive.org/web/20160127215232/https://www.kernel.org/doc/pending/hotplug.txt */
void hotplug_event_process_event_data(hotplug_event *self, int fd, hotplug_device_added_callback callback, void *userdata) {
const int bytes_read = read(fd, self->event_data, sizeof(self->event_data));
int data_index = 0;
if(bytes_read <= 0)
return;
/* Hotplug data ends with a newline and a null terminator */
while(data_index < bytes_read) {
hotplug_event_parse_netlink_data(self, self->event_data + data_index, callback, userdata);
data_index += strlen(self->event_data + data_index) + 1; /* Skip null terminator as well */
}
}
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