// Copyright (C) 2018 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef IORAP_SRC_INODE2FILENAME_SEARCH_DIRECTORIES_H_
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#define IORAP_SRC_INODE2FILENAME_SEARCH_DIRECTORIES_H_
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#include "common/expected.h"
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#include "inode2filename/inode.h"
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#include "inode2filename/system_call.h"
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#include <fruit/fruit.h>
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#include <rxcpp/rx.hpp>
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namespace iorap::inode2filename {
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// Tuple of (Inode -> (Filename|Errno))
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struct InodeResult {
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// We set this error when all root directories have been searched and
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// yet we still could not find a corresponding filename for the inode under search.
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static constexpr int kCouldNotFindFilename = -ENOENT;
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Inode inode;
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// Value: Contains the filename (with a root directory as a prefix).
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// Error: Contains the errno, usually -ENOENT or perhaps a security error.
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iorap::expected<std::string /*filename*/, int /*errno*/> data;
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static InodeResult makeSuccess(Inode inode, std::string filename) {
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return InodeResult{inode, std::move(filename)};
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}
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static InodeResult makeFailure(Inode inode, int err_no) {
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return InodeResult{inode, iorap::unexpected{err_no}};
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}
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constexpr operator bool() const {
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return data.has_value();
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}
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};
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enum class SearchMode {
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// Test modes:
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kInProcessDirect, // Execute the code directly.
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kInProcessIpc, // Execute code via IPC layer using multiple threads.
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// Shipping mode:
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kOutOfProcessIpc, // Execute code via fork+exec with IPC.
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// Note: in-process system-wide stat(2)/readdir/etc is blocked by selinux.
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// Attempting to call the test modes will fail with -EPERM.
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//
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// Use fork+exec mode in shipping configurations, which spawns inode2filename
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// as a separate command.
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};
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struct SearchDirectories {
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// Type-erased subset of rxcpp::connectable_observable<?>
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struct RxAnyConnectable {
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// Connects to the underlying observable.
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//
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// This kicks off the graph, streams begin emitting items.
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// This method will block until all items have been fully emitted
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// and processed by any subscribers.
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virtual void connect() = 0;
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virtual ~RxAnyConnectable(){}
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};
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// Create a cold observable of inode results (a lazy stream) corresponding
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// to the inode search list.
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//
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// A depth-first search is done on each of the root directories (in order),
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// until all inodes have been found (or until all directories have been exhausted).
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//
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// Some internal errors may occur during emission that aren't part of an InodeResult;
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// these will be sent to the error logcat and dropped.
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//
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// Calling this function does not begin the search.
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// The returned observable will begin the search after subscribing to it.
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//
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// The emitted InodeResult stream has these guarantees:
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// - All inodes in inode_list will eventually be emitted exactly once in an InodeResult
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// - When all inodes are found, directory traversal is halted.
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// - The order of emission can be considered arbitrary.
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//
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// Lifetime rules:
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// - The observable must be fully consumed before deleting any of the SearchDirectory's
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// borrowed constructor parameters (e.g. the SystemCall).
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// - SearchDirectory itself can be deleted at any time after creating an observable.
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rxcpp::observable<InodeResult>
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FindFilenamesFromInodes(std::vector<std::string> root_directories,
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std::vector<Inode> inode_list,
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SearchMode mode);
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// Create a cold observable of inode results (a lazy stream) corresponding
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// to the inode search list.
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//
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// A depth-first search is done on each of the root directories (in order),
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// until all inodes have been found (or until all directories have been exhausted).
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//
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// Some internal errors may occur during emission that aren't part of an InodeResult;
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// these will be sent to the error logcat and dropped.
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//
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// Calling this function does not begin the search.
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// The returned observable will begin the search after subscribing to it.
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//
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// The emitted InodeResult stream has these guarantees:
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// - All inodes in inode_list will eventually be emitted exactly once in an InodeResult
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// - When all inodes are found, directory traversal is halted.
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// - The order of emission can be considered arbitrary.
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//
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// Lifetime rules:
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// - The observable must be fully consumed before deleting any of the SearchDirectory's
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// borrowed constructor parameters (e.g. the SystemCall).
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// - SearchDirectory itself can be deleted at any time after creating an observable.
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std::pair<rxcpp::observable<InodeResult>, std::unique_ptr<RxAnyConnectable>>
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FindFilenamesFromInodesPair(std::vector<std::string> root_directories,
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std::vector<Inode> inode_list,
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SearchMode mode);
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// Any borrowed parameters here can also be borrowed by the observables returned by the above
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// member functions.
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//
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// The observables must be fully consumed within the lifetime of the borrowed parameters.
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INJECT(SearchDirectories(borrowed<SystemCall*> system_call))
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: system_call_(system_call) {}
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// TODO: is there a way to get rid of this second RxAnyConnectable parameter?
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private:
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// This gets passed around to lazy lambdas, so we must finish consuming any observables
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// before the injected system call is deleted.
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borrowed<SystemCall*> system_call_;
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};
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} // namespace iorap::inode2filename
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#endif // IORAP_SRC_INODE2FILENAME_SEARCH_DIRECTORIES_H_
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