11a3aeeae3
init tries to propagate error information up to build context before
logging errors. This is a good thing, however too often init has the
overly verbose paradigm for error handling, below:
bool CalculateResult(const T& input, U* output, std::string* err)
bool CalculateAndUseResult(const T& input, std::string* err) {
U output;
std::string calculate_result_err;
if (!CalculateResult(input, &output, &calculate_result_err)) {
*err = "CalculateResult " + input + " failed: " +
calculate_result_err;
return false;
}
UseResult(output);
return true;
}
Even more common are functions that return only true/false but also
require passing a std::string* err in order to see the error message.
This change introduces a Result<T> that is use to either hold a
successful return value of type T or to hold an error message as a
std::string. If the functional only returns success or a failure with
an error message, Result<Success> may be used. The classes Error and
ErrnoError are used to indicate a failed Result<T>.
A successful Result<T> is constructed implicitly from any type that
can be implicitly converted to T or from the constructor arguments for
T. This allows you to return a type T directly from a function that
returns Result<T>.
Error and ErrnoError are used to construct a Result<T> has
failed. Each of these classes take an ostream as an input and are
implicitly cast to a Result<T> containing that failure. ErrnoError()
additionally appends ": " + strerror(errno) to the end of the failure
string to aid in interacting with C APIs.
The end result is that the above code snippet is turned into the much
clearer example below:
Result<U> CalculateResult(const T& input);
Result<Success> CalculateAndUseResult(const T& input) {
auto output = CalculateResult(input);
if (!output) {
return Error() << "CalculateResult " << input << " failed: "
<< output.error();
}
UseResult(*output);
return Success();
}
This change also makes this conversion for some of the util.cpp
functions that used the old paradigm.
Test: boot bullhead, init unit tests
Merged-In: I1e7d3a8820a79362245041251057fbeed2f7979b
Change-Id: I1e7d3a8820a79362245041251057fbeed2f7979b
70 lines
2.4 KiB
C++
70 lines
2.4 KiB
C++
/*
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* Copyright (C) 2010 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 _INIT_UTIL_H_
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#define _INIT_UTIL_H_
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <chrono>
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#include <functional>
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#include <ostream>
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#include <string>
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#include <android-base/chrono_utils.h>
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#include <selinux/label.h>
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#include "result.h"
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#define COLDBOOT_DONE "/dev/.coldboot_done"
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using android::base::boot_clock;
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using namespace std::chrono_literals;
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namespace android {
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namespace init {
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int CreateSocket(const char* name, int type, bool passcred, mode_t perm, uid_t uid, gid_t gid,
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const char* socketcon);
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Result<std::string> ReadFile(const std::string& path);
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Result<Success> WriteFile(const std::string& path, const std::string& content);
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Result<uid_t> DecodeUid(const std::string& name);
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bool mkdir_recursive(const std::string& pathname, mode_t mode);
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int wait_for_file(const char *filename, std::chrono::nanoseconds timeout);
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void import_kernel_cmdline(bool in_qemu,
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const std::function<void(const std::string&, const std::string&, bool)>&);
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bool make_dir(const std::string& path, mode_t mode);
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std::string bytes_to_hex(const uint8_t *bytes, size_t bytes_len);
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bool is_dir(const char* pathname);
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bool expand_props(const std::string& src, std::string* dst);
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void panic() __attribute__((__noreturn__));
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// Returns the platform's Android DT directory as specified in the kernel cmdline.
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// If the platform does not configure a custom DT path, returns the standard one (based in procfs).
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const std::string& get_android_dt_dir();
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// Reads or compares the content of device tree file under the platform's Android DT directory.
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bool read_android_dt_file(const std::string& sub_path, std::string* dt_content);
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bool is_android_dt_value_expected(const std::string& sub_path, const std::string& expected_content);
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} // namespace init
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} // namespace android
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#endif
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