Detect touchpad

1 files changed, 65 insertions, 17 deletions

diff --git a/Touchpad.cpp b/Touchpad.cpp
index 3989df7..9d3fe22 100644
--- a/Touchpad.cpp
+++ b/Touchpad.cpp
@@ -1,34 +1,82 @@
 #include "Touchpad.h"
 
+#include <filesystem>
 #include <fmt/format.h>
 #include <sys/poll.h>
 #include <fcntl.h>
 
 #include "log.h"
 
-Touchpad::Touchpad(): m_valid{}, m_ev{}
-{
-  m_fd = open("/dev/input/event0", O_RDONLY | O_NONBLOCK);
-  int rc = libevdev_new_from_fd(m_fd, &m_dev);
-  if (rc < 0) {
-    log_cout << fmt::format("Failed to init libevdev ({})\n", strerror(-rc));
-    return;
+namespace fs = std::filesystem;
+
+namespace {
+  fs::path eventfile_from_index(int i)
+  {
+    fs::path result{"/dev/input/event"};
+    result += fs::path{std::to_string(i)};
+    return result;
+  }
+
+  libevdev* get_evdev(int& result_fd)
+  {
+    for (int i = 0; ; ++i) {
+      fs::path filename = eventfile_from_index(i);
+      if (!fs::exists(filename)) {
+        log_cout << "Warning: No suitable evdev device found.\n";
+        return nullptr;
+      }
+
+      int fd = open(filename.string().c_str(), O_RDONLY | O_NONBLOCK);
+      if (fd < 0) {
+        log_cout << fmt::format("Warning: evdev open() failed for {}", filename.string()) << std::endl;
+        continue;
+      }
+      libevdev* result{};
+      int rc = libevdev_new_from_fd(fd, &result);
+      if (rc < 0) {
+        log_cout << fmt::format("Warning: Failed to init libevdev ({})\n", strerror(-rc));
+        continue;
+      }
+
+      if (!libevdev_has_event_type(result, EV_REL) ||
+        !libevdev_has_event_code(result, EV_KEY, BTN_LEFT) ||
+        !libevdev_has_event_code(result, EV_KEY, BTN_RIGHT))
+      {
+        // Not the correct device
+        continue;
+      }
+      log_cout << fmt::format("evdev using: Input device name: \"{}\"\n", libevdev_get_name(result));
+      log_cout << fmt::format("evdev using: Input device ID: bus {:x} vendor {:x} product {:x}\n",
+        libevdev_get_id_bustype(result),
+        libevdev_get_id_vendor(result),
+        libevdev_get_id_product(result));
+      result_fd = fd;
+      return result;
+    }
   }
 
-  log_cout << fmt::format("Input device name: \"{}\"\n", libevdev_get_name(m_dev));
-  log_cout << fmt::format("Input device ID: bus {:x} vendor {:x} product {:x}\n",
-       libevdev_get_id_bustype(m_dev),
-       libevdev_get_id_vendor(m_dev),
-       libevdev_get_id_product(m_dev));
-  if (!libevdev_has_event_type(m_dev, EV_REL) ||
-      !libevdev_has_event_code(m_dev, EV_KEY, BTN_LEFT) ||
-      !libevdev_has_event_code(m_dev, EV_KEY, BTN_RIGHT)) {
-    log_cout << fmt::format("Not the correct device, ignoring.\n");
-  } else {
+  void free_evdev(libevdev* evdev, int fd)
+  {
+    if (evdev) {
+      libevdev_free(evdev);
+      close(fd);
+    }
+  }
+}
+
+Touchpad::Touchpad(): m_fd{}, m_dev{}, m_valid{}, m_ev{}
+{
+  m_dev = get_evdev(m_fd);
+  if (m_dev != nullptr) {
     m_valid = true;
   }
 }
 
+Touchpad::~Touchpad()
+{
+  free_evdev(m_dev, m_fd);
+}
+
 bool Touchpad::is_valid()
 {
   return m_valid;