Add FuseAppLoop to libappfuse.
The class is used at the app side (StorageManager) to parse FUSE
commands.
Bug: 32260320
Test: libappfuse_test
Change-Id: I1ae2904d3290a041f1efbf8fc10ba032eda5449c
diff --git a/libappfuse/FuseAppLoop.cc b/libappfuse/FuseAppLoop.cc
new file mode 100644
index 0000000..a31880e
--- /dev/null
+++ b/libappfuse/FuseAppLoop.cc
@@ -0,0 +1,221 @@
+/*
+ * 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 specic language governing permissions and
+ * limitations under the License.
+ */
+
+#include "libappfuse/FuseAppLoop.h"
+
+#include <sys/stat.h>
+
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+
+namespace android {
+namespace fuse {
+
+namespace {
+
+void HandleLookUp(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+ // AppFuse does not support directory structure now.
+ // It can lookup only files under the mount point.
+ if (buffer->request.header.nodeid != FUSE_ROOT_ID) {
+ LOG(ERROR) << "Nodeid is not FUSE_ROOT_ID.";
+ buffer->response.Reset(0, -ENOENT, buffer->request.header.unique);
+ return;
+ }
+
+ // Ensure that the filename ends with 0.
+ const size_t filename_length =
+ buffer->request.header.len - sizeof(fuse_in_header);
+ if (buffer->request.lookup_name[filename_length - 1] != 0) {
+ LOG(ERROR) << "File name does not end with 0.";
+ buffer->response.Reset(0, -ENOENT, buffer->request.header.unique);
+ return;
+ }
+
+ const uint64_t inode =
+ static_cast<uint64_t>(atol(buffer->request.lookup_name));
+ if (inode == 0 || inode == LONG_MAX) {
+ LOG(ERROR) << "Invalid filename";
+ buffer->response.Reset(0, -ENOENT, buffer->request.header.unique);
+ return;
+ }
+
+ const int64_t size = callback->OnGetSize(inode);
+ if (size < 0) {
+ buffer->response.Reset(0, size, buffer->request.header.unique);
+ return;
+ }
+
+ buffer->response.Reset(sizeof(fuse_entry_out), 0,
+ buffer->request.header.unique);
+ buffer->response.entry_out.nodeid = inode;
+ buffer->response.entry_out.attr_valid = 10;
+ buffer->response.entry_out.entry_valid = 10;
+ buffer->response.entry_out.attr.ino = inode;
+ buffer->response.entry_out.attr.mode = S_IFREG | 0777;
+ buffer->response.entry_out.attr.size = size;
+}
+
+void HandleGetAttr(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+ const uint64_t nodeid = buffer->request.header.nodeid;
+ int64_t size;
+ uint32_t mode;
+ if (nodeid == FUSE_ROOT_ID) {
+ size = 0;
+ mode = S_IFDIR | 0777;
+ } else {
+ size = callback->OnGetSize(buffer->request.header.nodeid);
+ if (size < 0) {
+ buffer->response.Reset(0, size, buffer->request.header.unique);
+ return;
+ }
+ mode = S_IFREG | 0777;
+ }
+
+ buffer->response.Reset(sizeof(fuse_attr_out), 0,
+ buffer->request.header.unique);
+ buffer->response.attr_out.attr_valid = 10;
+ buffer->response.attr_out.attr.ino = nodeid;
+ buffer->response.attr_out.attr.mode = mode;
+ buffer->response.attr_out.attr.size = size;
+}
+
+void HandleOpen(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+ const int32_t file_handle = callback->OnOpen(buffer->request.header.nodeid);
+ if (file_handle < 0) {
+ buffer->response.Reset(0, file_handle, buffer->request.header.unique);
+ return;
+ }
+ buffer->response.Reset(sizeof(fuse_open_out), kFuseSuccess,
+ buffer->request.header.unique);
+ buffer->response.open_out.fh = file_handle;
+}
+
+void HandleFsync(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+ buffer->response.Reset(0, callback->OnFsync(buffer->request.header.nodeid),
+ buffer->request.header.unique);
+}
+
+void HandleRelease(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+ buffer->response.Reset(0, callback->OnRelease(buffer->request.header.nodeid),
+ buffer->request.header.unique);
+}
+
+void HandleRead(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+ const uint64_t unique = buffer->request.header.unique;
+ const uint64_t nodeid = buffer->request.header.nodeid;
+ const uint64_t offset = buffer->request.read_in.offset;
+ const uint32_t size = buffer->request.read_in.size;
+
+ if (size > kFuseMaxRead) {
+ buffer->response.Reset(0, -EINVAL, buffer->request.header.unique);
+ return;
+ }
+
+ const int32_t read_size = callback->OnRead(nodeid, offset, size,
+ buffer->response.read_data);
+ if (read_size < 0) {
+ buffer->response.Reset(0, read_size, buffer->request.header.unique);
+ return;
+ }
+
+ buffer->response.ResetHeader(read_size, kFuseSuccess, unique);
+}
+
+void HandleWrite(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+ const uint64_t unique = buffer->request.header.unique;
+ const uint64_t nodeid = buffer->request.header.nodeid;
+ const uint64_t offset = buffer->request.write_in.offset;
+ const uint32_t size = buffer->request.write_in.size;
+
+ if (size > kFuseMaxWrite) {
+ buffer->response.Reset(0, -EINVAL, buffer->request.header.unique);
+ return;
+ }
+
+ const int32_t write_size = callback->OnWrite(nodeid, offset, size,
+ buffer->request.write_data);
+ if (write_size < 0) {
+ buffer->response.Reset(0, write_size, buffer->request.header.unique);
+ return;
+ }
+
+ buffer->response.Reset(sizeof(fuse_write_out), kFuseSuccess, unique);
+ buffer->response.write_out.size = write_size;
+}
+
+} // namespace
+
+bool StartFuseAppLoop(int raw_fd, FuseAppLoopCallback* callback) {
+ base::unique_fd fd(raw_fd);
+ FuseBuffer buffer;
+
+ LOG(DEBUG) << "Start fuse loop.";
+ while (callback->IsActive()) {
+ if (!buffer.request.Read(fd)) {
+ return false;
+ }
+
+ const uint32_t opcode = buffer.request.header.opcode;
+ LOG(VERBOSE) << "Read a fuse packet, opcode=" << opcode;
+ switch (opcode) {
+ case FUSE_FORGET:
+ // Do not reply to FUSE_FORGET.
+ continue;
+
+ case FUSE_LOOKUP:
+ HandleLookUp(&buffer, callback);
+ break;
+
+ case FUSE_GETATTR:
+ HandleGetAttr(&buffer, callback);
+ break;
+
+ case FUSE_OPEN:
+ HandleOpen(&buffer, callback);
+ break;
+
+ case FUSE_READ:
+ HandleRead(&buffer, callback);
+ break;
+
+ case FUSE_WRITE:
+ HandleWrite(&buffer, callback);
+ break;
+
+ case FUSE_RELEASE:
+ HandleRelease(&buffer, callback);
+ break;
+
+ case FUSE_FSYNC:
+ HandleFsync(&buffer, callback);
+ break;
+
+ default:
+ buffer.HandleNotImpl();
+ break;
+ }
+
+ if (!buffer.response.Write(fd)) {
+ LOG(ERROR) << "Failed to write a response to the device.";
+ return false;
+ }
+ }
+
+ return true;
+}
+
+} // namespace fuse
+} // namespace android