adb: Use kernel aio for functionfs.

This method works around the downsides of
ENDPOINT_ALLOC, namely that it is not affected
by memory fragmentation and it uses an upstream
interface.

Also add libasyncio to provide the necessary syscalls
to both adb and mtp.

Add some small optimizations to file_sync.

Bug: 37916658
Test: run adb push/pull
Change-Id: If3b3be02b5e2d4f9cffec1b8ddc02a5768a51a1f

3 files changed, 141 insertions, 0 deletions

diff --git a/libasyncio/Android.bp b/libasyncio/Android.bp
new file mode 100644
index 000000000..9a637acb7
--- /dev/null
+++ b/libasyncio/Android.bp
@@ -0,0 +1,44 @@
+//
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+libasyncio_cppflags = [
+    "-Wall",
+    "-Wextra",
+    "-Werror",
+]
+
+cc_library {
+    name: "libasyncio",
+    vendor_available: true,
+    host_supported: true,
+    srcs: [
+        "AsyncIO.cpp",
+    ],
+    cppflags: libasyncio_cppflags,
+
+    export_include_dirs: ["include"],
+    target: {
+        darwin: {
+            enabled: false,
+        },
+        linux_bionic: {
+            enabled: true,
+        },
+        windows: {
+            enabled: false,
+        },
+    },
+}
diff --git a/libasyncio/AsyncIO.cpp b/libasyncio/AsyncIO.cpp
new file mode 100644
index 000000000..7430bc81e
--- /dev/null
+++ b/libasyncio/AsyncIO.cpp
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <asyncio/AsyncIO.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+int io_setup(unsigned nr, aio_context_t* ctxp) {
+    memset(ctxp, 0, sizeof(*ctxp));
+    return syscall(__NR_io_setup, nr, ctxp);
+}
+
+int io_destroy(aio_context_t ctx) {
+    return syscall(__NR_io_destroy, ctx);
+}
+
+int io_submit(aio_context_t ctx, long nr, iocb** iocbpp) {
+    return syscall(__NR_io_submit, ctx, nr, iocbpp);
+}
+
+int io_getevents(aio_context_t ctx, long min_nr, long max_nr, io_event* events, timespec* timeout) {
+    return syscall(__NR_io_getevents, ctx, min_nr, max_nr, events, timeout);
+}
+
+int io_cancel(aio_context_t ctx, iocb* iocbp, io_event* result) {
+    return syscall(__NR_io_cancel, ctx, iocbp, result);
+}
+
+void io_prep(iocb* iocb, int fd, const void* buf, uint64_t count, int64_t offset, bool read) {
+    memset(iocb, 0, sizeof(*iocb));
+    iocb->aio_fildes = fd;
+    iocb->aio_lio_opcode = read ? IOCB_CMD_PREAD : IOCB_CMD_PWRITE;
+    iocb->aio_reqprio = 0;
+    iocb->aio_buf = reinterpret_cast<uint64_t>(buf);
+    iocb->aio_nbytes = count;
+    iocb->aio_offset = offset;
+}
diff --git a/libasyncio/include/asyncio/AsyncIO.h b/libasyncio/include/asyncio/AsyncIO.h
new file mode 100644
index 000000000..e3fb93a4d
--- /dev/null
+++ b/libasyncio/include/asyncio/AsyncIO.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _ASYNCIO_H
+#define _ASYNCIO_H
+
+#include <cstring>
+#include <cstdint>
+#include <linux/aio_abi.h>
+#include <sys/cdefs.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Provides kernel aio operations.
+ */
+
+int io_setup(unsigned nr, aio_context_t* ctxp);
+int io_destroy(aio_context_t ctx);
+int io_submit(aio_context_t ctx, long nr, iocb** iocbpp);
+int io_getevents(aio_context_t ctx, long min_nr, long max_nr, io_event* events, timespec* timeout);
+int io_cancel(aio_context_t ctx, iocb*, io_event* result);
+void io_prep(iocb* iocb, int fd, const void* buf, uint64_t count, int64_t offset, bool read);
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif  // ASYNCIO_H