Add input pipeline handling to streamer

1 files changed, 143 insertions, 0 deletions

diff --git a/input.c b/input.c
new file mode 100644
index 0000000..6add38d
--- /dev/null
+++ b/input.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2023 Mikhail Burakov. This file is part of streamer.
+ *
+ * streamer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * streamer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with streamer.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "input.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/uhid.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "toolbox/buffer.h"
+#include "toolbox/utils.h"
+
+struct InputHandler {
+  struct Buffer buffer;
+  int uhid_fd;
+};
+
+struct InputHandler* InputHandlerCreate(void) {
+  struct InputHandler* input_handler = malloc(sizeof(struct InputHandler));
+  if (!input_handler) {
+    LOG("Failed to allocate input handler (%s)", strerror(errno));
+    return NULL;
+  }
+  *input_handler = (struct InputHandler){
+      .uhid_fd = -1,
+  };
+
+  BufferCreate(&input_handler->buffer);
+  input_handler->uhid_fd = open("/dev/uhid", O_RDWR);
+  if (input_handler->uhid_fd == -1) {
+    LOG("Failed to open uhid device (%s)", strerror(errno));
+    goto rollback_input_handler;
+  }
+  return input_handler;
+
+rollback_input_handler:
+  free(input_handler);
+  return NULL;
+}
+
+int InputHandlerGetEventsFd(struct InputHandler* input_handler) {
+  return input_handler->uhid_fd;
+}
+
+bool InputHandlerProcessEvents(struct InputHandler* input_handler) {
+  struct uhid_event uhid_event;
+  if (read(input_handler->uhid_fd, &uhid_event, sizeof(uhid_event)) < 0) {
+    LOG("Failed to process uhid events (%s)", strerror(errno));
+    return false;
+  }
+  // TODO(mburakov): Add logging?
+  return true;
+}
+
+bool InputHandlerHandle(struct InputHandler* input_handler, int fd) {
+  switch (BufferAppendFrom(&input_handler->buffer, fd)) {
+    case -1:
+      LOG("Failed to append input data to buffer (%s)", strerror(errno));
+      return false;
+    case 0:
+      LOG("Client closed connection");
+      return false;
+    default:
+      break;
+  }
+
+  for (;;) {
+    struct uhid_event* event = input_handler->buffer.data;
+    if (input_handler->buffer.size < sizeof(event->type)) {
+      // mburakov: Packet type is not yet available.
+      return true;
+    }
+
+    size_t size;
+    switch (event->type) {
+      case UHID_CREATE2:
+        if (input_handler->buffer.size <
+            offsetof(struct uhid_event, u.create2.rd_size) +
+                sizeof(event->u.create2.rd_size)) {
+          // mburakov: Report descriptor size is not yet available.
+          return true;
+        }
+        size = offsetof(struct uhid_event, u.create2.rd_data) +
+               event->u.create2.rd_size;
+        if (input_handler->buffer.size < size) {
+          // mburakov: Report descriptor data is not yet available.
+          return true;
+        }
+        break;
+      case UHID_INPUT2:
+        if (input_handler->buffer.size <
+            offsetof(struct uhid_event, u.input2.size) +
+                sizeof(event->u.input2.size)) {
+          // mburakov: Report size is not yet available.
+          return true;
+        }
+        size =
+            offsetof(struct uhid_event, u.input2.data) + event->u.input2.size;
+        if (input_handler->buffer.size < size) {
+          // mburakov: Report data is not yet available.
+          return true;
+        }
+        break;
+      case UHID_DESTROY:
+        size = sizeof(event->type);
+        break;
+      default:
+        __builtin_unreachable();
+    }
+
+    // mburakov: This write has to be atomic.
+    if (write(input_handler->uhid_fd, event, size) != (ssize_t)size) {
+      LOG("Failed to write uhid event (%s)", strerror(errno));
+      return false;
+    }
+    BufferDiscard(&input_handler->buffer, size);
+  }
+}
+
+void InputHandlerDestroy(struct InputHandler* input_handler) {
+  close(input_handler->uhid_fd);
+  BufferDestroy(&input_handler->buffer);
+  free(input_handler);
+}