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137 lines
4.6 KiB
137 lines
4.6 KiB
/*
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* Copyright (C) 2017 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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*/
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#ifndef NETUTILS_STATUS_H
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#define NETUTILS_STATUS_H
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#include <cassert>
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#include <limits>
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#include <ostream>
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#include <android-base/result.h>
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namespace android {
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namespace netdutils {
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// Simple status implementation suitable for use on the stack in low
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// or moderate performance code. This can definitely be improved but
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// for now short string optimization is expected to keep the common
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// success case fast.
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//
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// Status is implicitly movable via the default noexcept move constructor
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// and noexcept move-assignment operator.
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class [[nodiscard]] Status {
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public:
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Status() = default;
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explicit Status(int code) : mCode(code) {}
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// Constructs an error Status, |code| must be non-zero.
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Status(int code, std::string msg) : mCode(code), mMsg(std::move(msg)) { assert(!ok()); }
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Status(android::base::Result<void> result)
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: mCode(result.ok() ? 0 : result.error().code()),
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mMsg(result.ok() ? "" : result.error().message()) {}
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int code() const { return mCode; }
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bool ok() const { return code() == 0; }
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const std::string& msg() const { return mMsg; }
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// Explicitly ignores the Status without triggering [[nodiscard]] errors.
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void ignoreError() const {}
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bool operator==(const Status& other) const { return code() == other.code(); }
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bool operator!=(const Status& other) const { return !(*this == other); }
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private:
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int mCode = 0;
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std::string mMsg;
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};
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namespace status {
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const Status ok{0};
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// EOF is not part of errno space, we'll place it far above the
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// highest existing value.
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const Status eof{0x10001, "end of file"};
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const Status undefined{std::numeric_limits<int>::max(), "undefined"};
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} // namespace status
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// Return true if status is "OK". This is sometimes preferable to
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// status.ok() when we want to check the state of Status-like objects
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// that implicitly cast to Status.
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inline bool isOk(const Status& status) {
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return status.ok();
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}
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// For use only in tests. Used for both Status and Status-like objects. See also isOk().
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#define EXPECT_OK(status) EXPECT_TRUE(isOk(status))
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#define ASSERT_OK(status) ASSERT_TRUE(isOk(status))
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// Documents that status is expected to be ok. This function may log
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// (or assert when running in debug mode) if status has an unexpected value.
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inline void expectOk(const Status& /*status*/) {
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// TODO: put something here, for now this function serves solely as documentation.
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}
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// Convert POSIX errno to a Status object.
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// If Status is extended to have more features, this mapping may
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// become more complex.
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Status statusFromErrno(int err, const std::string& msg);
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// Helper that checks Status-like object (notably StatusOr) against a
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// value in the errno space.
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bool equalToErrno(const Status& status, int err);
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// Helper that converts Status-like object (notably StatusOr) to a
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// message.
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std::string toString(const Status& status);
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std::ostream& operator<<(std::ostream& os, const Status& s);
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// Evaluate 'stmt' to a Status object and if it results in an error, return that
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// error. Use 'tmp' as a variable name to avoid shadowing any variables named
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// tmp.
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#define RETURN_IF_NOT_OK_IMPL(tmp, stmt) \
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do { \
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::android::netdutils::Status tmp = (stmt); \
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if (!isOk(tmp)) { \
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return tmp; \
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} \
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} while (false)
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// Create a unique variable name to avoid shadowing local variables.
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#define RETURN_IF_NOT_OK_CONCAT(line, stmt) RETURN_IF_NOT_OK_IMPL(__CONCAT(_status_, line), stmt)
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// Macro to allow exception-like handling of error return values.
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//
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// If the evaluation of stmt results in an error, return that error
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// from current function.
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//
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// Example usage:
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// Status bar() { ... }
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//
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// RETURN_IF_NOT_OK(status);
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// RETURN_IF_NOT_OK(bar());
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#define RETURN_IF_NOT_OK(stmt) RETURN_IF_NOT_OK_CONCAT(__LINE__, stmt)
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} // namespace netdutils
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} // namespace android
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#endif /* NETUTILS_STATUS_H */
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