1 files changed, 81 insertions, 0 deletions
diff --git a/src/Hotplug.cpp b/src/Hotplug.cpp
new file mode 100644
index 0000000..84ed5bb
--- /dev/null
+++ b/src/Hotplug.cpp
@@ -0,0 +1,81 @@
+#include "../include/Hotplug.hpp"
+
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <linux/types.h>
+#include <linux/netlink.h>
+
+namespace gsr {
+    Hotplug::~Hotplug() {
+        if(fd > 0)
+            close(fd);
+    }
+
+    bool Hotplug::start() {
+        if(started)
+            return false;
+
+        struct sockaddr_nl nls = {
+            AF_NETLINK,
+            0,
+            (unsigned int)getpid(),
+            (unsigned int)-1
+        };
+
+        fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
+        if(fd == -1)
+            return false; /* Not root user */
+
+        if(bind(fd, (const struct sockaddr*)&nls, sizeof(struct sockaddr_nl))) {
+            close(fd);
+            fd = -1;
+            return false;
+        }
+
+        started = true;
+        return true;
+    }
+
+    int Hotplug::steal_fd() {
+        const int val = fd;
+        fd = -1;
+        return val;
+    }
+
+    void Hotplug::process_event_data(int fd, const HotplugEventCallback &callback) {
+        const int bytes_read = read(fd, event_data, sizeof(event_data));
+        if(bytes_read <= 0)
+            return;
+
+        /* Hotplug data ends with a newline and a null terminator */
+        int data_index = 0;
+        while(data_index < bytes_read) {
+            parse_netlink_data(event_data + data_index, callback);
+            data_index += strlen(event_data + data_index) + 1; /* Skip null terminator as well */
+        }
+    }
+
+    /* TODO: This assumes SUBSYSTEM= is output before DEVNAME=, is that always true? */
+    void Hotplug::parse_netlink_data(const char *line, const HotplugEventCallback &callback) {
+        const char *at_symbol = strchr(line, '@');
+        if(at_symbol) {
+            event_is_add = strncmp(line, "add@", 4) == 0;
+            event_is_remove = strncmp(line, "remove@", 7) == 0;
+            subsystem_is_input = false;
+        } else if(event_is_add || event_is_remove) {
+            if(strcmp(line, "SUBSYSTEM=input") == 0)
+                subsystem_is_input = true;
+
+            if(subsystem_is_input && strncmp(line, "DEVNAME=", 8) == 0) {
+                if(event_is_add)
+                    callback(HotplugAction::ADD, line+8);
+                else if(event_is_remove)
+                    callback(HotplugAction::REMOVE, line+8);
+
+                event_is_add = false;
+                event_is_remove = false;
+            }
+        }
+    }
+}