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init: introduce Result<T> for return values and error handling

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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
Change-Id: I1e7d3a8820a79362245041251057fbeed2f7979b
This commit is contained in:
Tom Cherry 2017-08-03 12:54:07 -07:00
parent b6b9629f02
commit 62ca663475
13 changed files with 528 additions and 206 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
init/Android.bp
View file

@ -159,6 +159,7 @@ cc_test {
"devices_test.cpp",
"init_test.cpp",
"property_service_test.cpp",
"result_test.cpp",
"service_test.cpp",
"ueventd_test.cpp",
"util_test.cpp",

58
init/builtins.cpp
View file

@ -151,9 +151,8 @@ static int do_class_restart(const std::vector<std::string>& args) {
}
static int do_domainname(const std::vector<std::string>& args) {
std::string err;
if (!WriteFile("/proc/sys/kernel/domainname", args[1], &err)) {
LOG(ERROR) << err;
if (auto result = WriteFile("/proc/sys/kernel/domainname", args[1]); !result) {
LOG(ERROR) << "Unable to write to /proc/sys/kernel/domainname: " << result.error();
return -1;
}
return 0;
@ -199,9 +198,8 @@ static int do_export(const std::vector<std::string>& args) {
}
static int do_hostname(const std::vector<std::string>& args) {
std::string err;
if (!WriteFile("/proc/sys/kernel/hostname", args[1], &err)) {
LOG(ERROR) << err;
if (auto result = WriteFile("/proc/sys/kernel/hostname", args[1]); !result) {
LOG(ERROR) << "Unable to write to /proc/sys/kernel/hostname: " << result.error();
return -1;
}
return 0;
@ -244,22 +242,22 @@ static int do_mkdir(const std::vector<std::string>& args) {
}
if (args.size() >= 4) {
uid_t uid;
std::string decode_uid_err;
if (!DecodeUid(args[3], &uid, &decode_uid_err)) {
LOG(ERROR) << "Unable to find UID for '" << args[3] << "': " << decode_uid_err;
auto uid = DecodeUid(args[3]);
if (!uid) {
LOG(ERROR) << "Unable to decode UID for '" << args[3] << "': " << uid.error();
return -1;
}
gid_t gid = -1;
Result<gid_t> gid = -1;
if (args.size() == 5) {
if (!DecodeUid(args[4], &gid, &decode_uid_err)) {
LOG(ERROR) << "Unable to find GID for '" << args[3] << "': " << decode_uid_err;
gid = DecodeUid(args[4]);
if (!gid) {
LOG(ERROR) << "Unable to decode GID for '" << args[3] << "': " << gid.error();
return -1;
}
}
if (lchown(args[1].c_str(), uid, gid) == -1) {
if (lchown(args[1].c_str(), *uid, *gid) == -1) {
return -errno;
}
@ -668,9 +666,8 @@ static int do_verity_update_state(const std::vector<std::string>& args) {
}
static int do_write(const std::vector<std::string>& args) {
std::string err;
if (!WriteFile(args[1], args[2], &err)) {
LOG(ERROR) << err;
if (auto result = WriteFile(args[1], args[2]); !result) {
LOG(ERROR) << "Unable to write to file '" << args[1] << "': " << result.error();
return -1;
}
return 0;
@ -737,39 +734,38 @@ static int do_readahead(const std::vector<std::string>& args) {
}
static int do_copy(const std::vector<std::string>& args) {
std::string data;
std::string err;
if (!ReadFile(args[1], &data, &err)) {
LOG(ERROR) << err;
auto file_contents = ReadFile(args[1]);
if (!file_contents) {
LOG(ERROR) << "Could not read input file '" << args[1] << "': " << file_contents.error();
return -1;
}
if (!WriteFile(args[2], data, &err)) {
LOG(ERROR) << err;
if (auto result = WriteFile(args[2], *file_contents); !result) {
LOG(ERROR) << "Could not write to output file '" << args[2] << "': " << result.error();
return -1;
}
return 0;
}
static int do_chown(const std::vector<std::string>& args) {
uid_t uid;
std::string decode_uid_err;
if (!DecodeUid(args[1], &uid, &decode_uid_err)) {
LOG(ERROR) << "Unable to find UID for '" << args[1] << "': " << decode_uid_err;
auto uid = DecodeUid(args[1]);
if (!uid) {
LOG(ERROR) << "Unable to decode UID for '" << args[1] << "': " << uid.error();
return -1;
}
// GID is optional and pushes the index of path out by one if specified.
const std::string& path = (args.size() == 4) ? args[3] : args[2];
gid_t gid = -1;
Result<gid_t> gid = -1;
if (args.size() == 4) {
if (!DecodeUid(args[2], &gid, &decode_uid_err)) {
LOG(ERROR) << "Unable to find GID for '" << args[2] << "': " << decode_uid_err;
gid = DecodeUid(args[2]);
if (!gid) {
LOG(ERROR) << "Unable to decode GID for '" << args[2] << "': " << gid.error();
return -1;
}
}
if (lchown(path.c_str(), uid, gid) == -1) return -errno;
if (lchown(path.c_str(), *uid, *gid) == -1) return -errno;
return 0;
}

5
init/init_test.cpp
View file

@ -156,10 +156,9 @@ TEST(init, EventTriggerOrderMultipleFiles) {
"execute 3";
// clang-format on
// WriteFile() ensures the right mode is set
std::string err;
ASSERT_TRUE(WriteFile(std::string(dir.path) + "/a.rc", dir_a_script, &err));
ASSERT_TRUE(WriteFile(std::string(dir.path) + "/a.rc", dir_a_script));
ASSERT_TRUE(WriteFile(std::string(dir.path) + "/b.rc", "on boot\nexecute 5", &err));
ASSERT_TRUE(WriteFile(std::string(dir.path) + "/b.rc", "on boot\nexecute 5"));
// clang-format off
std::string start_script = "import " + std::string(first_import.path) + "\n"

11
init/parser.cpp
View file

@ -102,15 +102,14 @@ void Parser::ParseData(const std::string& filename, const std::string& data) {
bool Parser::ParseConfigFile(const std::string& path) {
LOG(INFO) << "Parsing file " << path << "...";
android::base::Timer t;
std::string data;
std::string err;
if (!ReadFile(path, &data, &err)) {
LOG(ERROR) << err;
auto config_contents = ReadFile(path);
if (!config_contents) {
LOG(ERROR) << "Unable to read config file '" << path << "': " << config_contents.error();
return false;
}
data.push_back('\n'); // TODO: fix parse_config.
ParseData(path, data);
config_contents->push_back('\n'); // TODO: fix parse_config.
ParseData(path, *config_contents);
for (const auto& [section_name, section_parser] : section_parsers_) {
section_parser->EndFile();
}

12
init/property_service.cpp
View file

@ -588,14 +588,14 @@ static void load_properties(char *data, const char *filter)
// "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
static bool load_properties_from_file(const char* filename, const char* filter) {
Timer t;
std::string data;
std::string err;
if (!ReadFile(filename, &data, &err)) {
PLOG(WARNING) << "Couldn't load property file: " << err;
auto file_contents = ReadFile(filename);
if (!file_contents) {
PLOG(WARNING) << "Couldn't load property file '" << filename
<< "': " << file_contents.error();
return false;
}
data.push_back('\n');
load_properties(&data[0], filter);
file_contents->push_back('\n');
load_properties(file_contents->data(), filter);
LOG(VERBOSE) << "(Loading properties from " << filename << " took " << t << ".)";
return true;
}

142
init/result.h Normal file
View file

@ -0,0 +1,142 @@
/*
* 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.
*/
// This file contains classes for returning a successful result along with an optional
// arbitrarily typed return value or for returning a failure result along with an optional string
// indicating why the function failed.
// There are 3 classes that implement this functionality and one additional helper type.
//
// Result<T> either contains a member of type T that can be accessed using similar semantics as
// std::optional<T> or it contains a std::string describing an error, which can be accessed via
// Result<T>::error().
//
// Success is a typedef that aids in creating Result<T> that do not contain a return value.
// Result<Success> is the correct return type for a function that either returns successfully or
// returns an error value. Returning Success() from a function that returns Result<Success> is the
// correct way to indicate that a function without a return type has completed successfully.
//
// 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> that 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.
// An example of how to use these is below:
// Result<U> CalculateResult(const T& input) {
// U output;
// if (!SomeOtherCppFunction(input, &output)) {
// return Error() << "SomeOtherCppFunction(" << input << ") failed";
// }
// if (!c_api_function(output)) {
// return ErrnoError() << "c_api_function(" << output << ") failed";
// }
// return output;
// }
//
// auto output = CalculateResult(input);
// if (!output) return Error() << "CalculateResult failed: " << output.error();
// UseOutput(*output);
#ifndef _INIT_RESULT_H
#define _INIT_RESULT_H
#include <errno.h>
#include <sstream>
#include <string>
#include <variant>
namespace android {
namespace init {
class Error {
public:
Error() : append_errno_(0) {}
template <typename T>
Error&& operator<<(T&& t) {
ss_ << std::forward<T>(t);
return std::move(*this);
}
const std::string str() const {
if (append_errno_) {
return ss_.str() + ": " + strerror(append_errno_);
}
return ss_.str();
}
Error(const Error&) = delete;
Error(Error&&) = delete;
Error& operator=(const Error&) = delete;
Error& operator=(Error&&) = delete;
protected:
Error(int append_errno) : append_errno_(append_errno) {}
private:
std::stringstream ss_;
int append_errno_;
};
class ErrnoError : public Error {
public:
ErrnoError() : Error(errno) {}
};
template <typename T>
class Result {
public:
template <typename... U>
Result(U&&... result) : contents_(std::in_place_index_t<0>(), std::forward<U>(result)...) {}
Result(Error&& fb) : contents_(std::in_place_index_t<1>(), fb.str()) {}
bool has_value() const { return contents_.index() == 0; }
T& value() & { return std::get<0>(contents_); }
const T& value() const & { return std::get<0>(contents_); }
T&& value() && { return std::get<0>(std::move(contents_)); }
const T&& value() const && { return std::get<0>(std::move(contents_)); }
const std::string& error() const & { return std::get<1>(contents_); }
std::string&& error() && { return std::get<1>(std::move(contents_)); }
const std::string&& error() const && { return std::get<1>(std::move(contents_)); }
explicit operator bool() const { return has_value(); }
T& operator*() & { return value(); }
const T& operator*() const & { return value(); }
T&& operator*() && { return std::move(value()); }
const T&& operator*() const && { return std::move(value()); }
T* operator->() { return &value(); }
const T* operator->() const { return &value(); }
private:
std::variant<T, std::string> contents_;
};
using Success = std::monostate;
} // namespace init
} // namespace android
#endif

222
init/result_test.cpp Normal file
View file

@ -0,0 +1,222 @@
/*
* 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.
*/
#include "result.h"
#include "errno.h"
#include <string>
#include <gtest/gtest.h>
using namespace std::string_literals;
namespace android {
namespace init {
TEST(result, result_accessors) {
Result<std::string> result = "success";
ASSERT_TRUE(result);
ASSERT_TRUE(result.has_value());
EXPECT_EQ("success", *result);
EXPECT_EQ("success", result.value());
EXPECT_EQ('s', result->data()[0]);
}
TEST(result, result_accessors_rvalue) {
ASSERT_TRUE(Result<std::string>("success"));
ASSERT_TRUE(Result<std::string>("success").has_value());
EXPECT_EQ("success", *Result<std::string>("success"));
EXPECT_EQ("success", Result<std::string>("success").value());
EXPECT_EQ('s', Result<std::string>("success")->data()[0]);
}
TEST(result, result_success) {
Result<Success> result = Success();
ASSERT_TRUE(result);
ASSERT_TRUE(result.has_value());
EXPECT_EQ(Success(), *result);
EXPECT_EQ(Success(), result.value());
}
TEST(result, result_success_rvalue) {
// Success() doesn't actually create a Result<Success> object, but rather an object that can be
// implicitly constructed into a Result<Success> object.
auto MakeRvalueSuccessResult = []() -> Result<Success> { return Success(); };
ASSERT_TRUE(MakeRvalueSuccessResult());
ASSERT_TRUE(MakeRvalueSuccessResult().has_value());
EXPECT_EQ(Success(), *MakeRvalueSuccessResult());
EXPECT_EQ(Success(), MakeRvalueSuccessResult().value());
}
TEST(result, result_error) {
Result<Success> result = Error() << "failure" << 1;
ASSERT_FALSE(result);
ASSERT_FALSE(result.has_value());
EXPECT_EQ("failure1", result.error());
}
TEST(result, result_error_empty) {
Result<Success> result = Error();
ASSERT_FALSE(result);
ASSERT_FALSE(result.has_value());
EXPECT_EQ("", result.error());
}
TEST(result, result_error_rvalue) {
// Error() and ErrnoError() aren't actually used to create a Result<T> object.
// Under the hood, they are an intermediate class that can be implicitly constructed into a
// Result<T>. This is needed both to create the ostream and because Error() itself, by
// definition will not know what the type, T, of the underlying Result<T> object that it would
// create is.
auto MakeRvalueErrorResult = []() -> Result<Success> { return Error() << "failure" << 1; };
ASSERT_FALSE(MakeRvalueErrorResult());
ASSERT_FALSE(MakeRvalueErrorResult().has_value());
EXPECT_EQ("failure1", MakeRvalueErrorResult().error());
}
TEST(result, result_errno_error) {
constexpr int test_errno = 6;
errno = test_errno;
Result<Success> result = ErrnoError() << "failure" << 1;
ASSERT_FALSE(result);
ASSERT_FALSE(result.has_value());
EXPECT_EQ("failure1: "s + strerror(test_errno), result.error());
}
TEST(result, constructor_forwarding) {
auto result = Result<std::string>(5, 'a');
ASSERT_TRUE(result);
ASSERT_TRUE(result.has_value());
EXPECT_EQ("aaaaa", *result);
}
struct ConstructorTracker {
static size_t constructor_called;
static size_t copy_constructor_called;
static size_t move_constructor_called;
static size_t copy_assignment_called;
static size_t move_assignment_called;
template <typename T>
ConstructorTracker(T&& string) : string(string) {
++constructor_called;
}
ConstructorTracker(const ConstructorTracker& ct) {
++copy_constructor_called;
string = ct.string;
}
ConstructorTracker(ConstructorTracker&& ct) noexcept {
++move_constructor_called;
string = std::move(ct.string);
}
ConstructorTracker& operator=(const ConstructorTracker& ct) {
++copy_assignment_called;
string = ct.string;
return *this;
}
ConstructorTracker& operator=(ConstructorTracker&& ct) noexcept {
++move_assignment_called;
string = std::move(ct.string);
return *this;
}
std::string string;
};
size_t ConstructorTracker::constructor_called = 0;
size_t ConstructorTracker::copy_constructor_called = 0;
size_t ConstructorTracker::move_constructor_called = 0;
size_t ConstructorTracker::copy_assignment_called = 0;
size_t ConstructorTracker::move_assignment_called = 0;
Result<ConstructorTracker> ReturnConstructorTracker(const std::string& in) {
if (in.empty()) {
return "literal string";
}
if (in == "test2") {
return ConstructorTracker(in + in + "2");
}
ConstructorTracker result(in + " " + in);
return result;
};
TEST(result, no_copy_on_return) {
// If returning parameters that may be used to implicitly construct the type T of Result<T>,
// then those parameters are forwarded to the construction of Result<T>.
// If returning an prvalue or xvalue, it will be move constructed during the construction of
// Result<T>.
// This check ensures that that is the case, and particularly that no copy constructors
// are called.
auto result1 = ReturnConstructorTracker("");
ASSERT_TRUE(result1);
EXPECT_EQ("literal string", result1->string);
EXPECT_EQ(1U, ConstructorTracker::constructor_called);
EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
EXPECT_EQ(0U, ConstructorTracker::move_constructor_called);
EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
auto result2 = ReturnConstructorTracker("test2");
ASSERT_TRUE(result2);
EXPECT_EQ("test2test22", result2->string);
EXPECT_EQ(2U, ConstructorTracker::constructor_called);
EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
EXPECT_EQ(1U, ConstructorTracker::move_constructor_called);
EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
auto result3 = ReturnConstructorTracker("test3");
ASSERT_TRUE(result3);
EXPECT_EQ("test3 test3", result3->string);
EXPECT_EQ(3U, ConstructorTracker::constructor_called);
EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
EXPECT_EQ(2U, ConstructorTracker::move_constructor_called);
EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
}
TEST(result, die_on_access_failed_result) {
Result<std::string> result = Error();
ASSERT_DEATH(*result, "");
}
TEST(result, die_on_get_error_succesful_result) {
Result<std::string> result = "success";
ASSERT_DEATH(result.error(), "");
}
} // namespace init
} // namespace android

5
init/selinux.cpp
View file

@ -357,9 +357,8 @@ void SelinuxInitialize() {
}
}
std::string err;
if (!WriteFile("/sys/fs/selinux/checkreqprot", "0", &err)) {
LOG(ERROR) << err;
if (auto result = WriteFile("/sys/fs/selinux/checkreqprot", "0"); !result) {
LOG(ERROR) << "Unable to write to /sys/fs/selinux/checkreqprot: " << result.error();
panic();
}

67
init/service.cpp
View file

@ -386,18 +386,20 @@ bool Service::ParseDisabled(const std::vector<std::string>& args, std::string* e
}
bool Service::ParseGroup(const std::vector<std::string>& args, std::string* err) {
std::string decode_uid_err;
if (!DecodeUid(args[1], &gid_, &decode_uid_err)) {
*err = "Unable to find GID for '" + args[1] + "': " + decode_uid_err;
auto gid = DecodeUid(args[1]);
if (!gid) {
*err = "Unable to decode GID for '" + args[1] + "': " + gid.error();
return false;
}
gid_ = *gid;
for (std::size_t n = 2; n < args.size(); n++) {
gid_t gid;
if (!DecodeUid(args[n], &gid, &decode_uid_err)) {
*err = "Unable to find GID for '" + args[n] + "': " + decode_uid_err;
gid = DecodeUid(args[n]);
if (!gid) {
*err = "Unable to decode GID for '" + args[n] + "': " + gid.error();
return false;
}
supp_gids_.emplace_back(gid);
supp_gids_.emplace_back(*gid);
}
return true;
}
@ -527,26 +529,27 @@ bool Service::ParseShutdown(const std::vector<std::string>& args, std::string* e
template <typename T>
bool Service::AddDescriptor(const std::vector<std::string>& args, std::string* err) {
int perm = args.size() > 3 ? std::strtoul(args[3].c_str(), 0, 8) : -1;
uid_t uid = 0;
gid_t gid = 0;
Result<uid_t> uid = 0;
Result<gid_t> gid = 0;
std::string context = args.size() > 6 ? args[6] : "";
std::string decode_uid_err;
if (args.size() > 4) {
if (!DecodeUid(args[4], &uid, &decode_uid_err)) {
*err = "Unable to find UID for '" + args[4] + "': " + decode_uid_err;
uid = DecodeUid(args[4]);
if (!uid) {
*err = "Unable to find UID for '" + args[4] + "': " + uid.error();
return false;
}
}
if (args.size() > 5) {
if (!DecodeUid(args[5], &gid, &decode_uid_err)) {
*err = "Unable to find GID for '" + args[5] + "': " + decode_uid_err;
gid = DecodeUid(args[5]);
if (!gid) {
*err = "Unable to find GID for '" + args[5] + "': " + gid.error();
return false;
}
}
auto descriptor = std::make_unique<T>(args[1], args[2], uid, gid, perm, context);
auto descriptor = std::make_unique<T>(args[1], args[2], *uid, *gid, perm, context);
auto old =
std::find_if(descriptors_.begin(), descriptors_.end(),
@ -585,11 +588,12 @@ bool Service::ParseFile(const std::vector<std::string>& args, std::string* err)
}
bool Service::ParseUser(const std::vector<std::string>& args, std::string* err) {
std::string decode_uid_err;
if (!DecodeUid(args[1], &uid_, &decode_uid_err)) {
*err = "Unable to find UID for '" + args[1] + "': " + decode_uid_err;
auto uid = DecodeUid(args[1]);
if (!uid) {
*err = "Unable to find UID for '" + args[1] + "': " + uid.error();
return false;
}
uid_ = *uid;
return true;
}
@ -979,34 +983,35 @@ std::unique_ptr<Service> Service::MakeTemporaryOneshotService(const std::vector<
if (command_arg > 2 && args[1] != "-") {
seclabel = args[1];
}
uid_t uid = 0;
Result<uid_t> uid = 0;
if (command_arg > 3) {
std::string decode_uid_err;
if (!DecodeUid(args[2], &uid, &decode_uid_err)) {
LOG(ERROR) << "Unable to find UID for '" << args[2] << "': " << decode_uid_err;
uid = DecodeUid(args[2]);
if (!uid) {
LOG(ERROR) << "Unable to decode UID for '" << args[2] << "': " << uid.error();
return nullptr;
}
}
gid_t gid = 0;
Result<gid_t> gid = 0;
std::vector<gid_t> supp_gids;
if (command_arg > 4) {
std::string decode_uid_err;
if (!DecodeUid(args[3], &gid, &decode_uid_err)) {
LOG(ERROR) << "Unable to find GID for '" << args[3] << "': " << decode_uid_err;
gid = DecodeUid(args[3]);
if (!gid) {
LOG(ERROR) << "Unable to decode GID for '" << args[3] << "': " << gid.error();
return nullptr;
}
std::size_t nr_supp_gids = command_arg - 1 /* -- */ - 4 /* exec SECLABEL UID GID */;
for (size_t i = 0; i < nr_supp_gids; ++i) {
gid_t supp_gid;
if (!DecodeUid(args[4 + i], &supp_gid, &decode_uid_err)) {
LOG(ERROR) << "Unable to find UID for '" << args[4 + i] << "': " << decode_uid_err;
auto supp_gid = DecodeUid(args[4 + i]);
if (!supp_gid) {
LOG(ERROR) << "Unable to decode GID for '" << args[4 + i]
<< "': " << supp_gid.error();
return nullptr;
}
supp_gids.push_back(supp_gid);
supp_gids.push_back(*supp_gid);
}
}
return std::make_unique<Service>(name, flags, uid, gid, supp_gids, no_capabilities,
return std::make_unique<Service>(name, flags, *uid, *gid, supp_gids, no_capabilities,
namespace_flags, seclabel, str_args);
}

28
init/service_test.cpp
View file

@ -132,29 +132,29 @@ static void Test_make_temporary_oneshot_service(bool dash_dash, bool seclabel, b
ASSERT_EQ("", svc->seclabel());
}
if (uid) {
uid_t decoded_uid;
std::string err;
ASSERT_TRUE(DecodeUid("log", &decoded_uid, &err));
ASSERT_EQ(decoded_uid, svc->uid());
auto decoded_uid = DecodeUid("log");
ASSERT_TRUE(decoded_uid);
ASSERT_EQ(*decoded_uid, svc->uid());
} else {
ASSERT_EQ(0U, svc->uid());
}
if (gid) {
uid_t decoded_uid;
std::string err;
ASSERT_TRUE(DecodeUid("shell", &decoded_uid, &err));
ASSERT_EQ(decoded_uid, svc->gid());
auto decoded_uid = DecodeUid("shell");
ASSERT_TRUE(decoded_uid);
ASSERT_EQ(*decoded_uid, svc->gid());
} else {
ASSERT_EQ(0U, svc->gid());
}
if (supplementary_gids) {
ASSERT_EQ(2U, svc->supp_gids().size());
uid_t decoded_uid;
std::string err;
ASSERT_TRUE(DecodeUid("system", &decoded_uid, &err));
ASSERT_EQ(decoded_uid, svc->supp_gids()[0]);
ASSERT_TRUE(DecodeUid("adb", &decoded_uid, &err));
ASSERT_EQ(decoded_uid, svc->supp_gids()[1]);
auto decoded_uid = DecodeUid("system");
ASSERT_TRUE(decoded_uid);
ASSERT_EQ(*decoded_uid, svc->supp_gids()[0]);
decoded_uid = DecodeUid("adb");
ASSERT_TRUE(decoded_uid);
ASSERT_EQ(*decoded_uid, svc->supp_gids()[1]);
} else {
ASSERT_EQ(0U, svc->supp_gids().size());
}

60
init/util.cpp
View file

@ -57,30 +57,20 @@ namespace init {
const std::string kDefaultAndroidDtDir("/proc/device-tree/firmware/android/");
// DecodeUid() - decodes and returns the given string, which can be either the
// numeric or name representation, into the integer uid or gid. Returns
// UINT_MAX on error.
bool DecodeUid(const std::string& name, uid_t* uid, std::string* err) {
*uid = UINT_MAX;
*err = "";
// numeric or name representation, into the integer uid or gid.
Result<uid_t> DecodeUid(const std::string& name) {
if (isalpha(name[0])) {
passwd* pwd = getpwnam(name.c_str());
if (!pwd) {
*err = "getpwnam failed: "s + strerror(errno);
return false;
}
*uid = pwd->pw_uid;
return true;
if (!pwd) return ErrnoError() << "getpwnam failed";
return pwd->pw_uid;
}
errno = 0;
uid_t result = static_cast<uid_t>(strtoul(name.c_str(), 0, 0));
if (errno) {
*err = "strtoul failed: "s + strerror(errno);
return false;
}
*uid = result;
return true;
if (errno) return ErrnoError() << "strtoul failed";
return result;
}
/*
@ -164,50 +154,40 @@ out_unlink:
return -1;
}
bool ReadFile(const std::string& path, std::string* content, std::string* err) {
content->clear();
*err = "";
Result<std::string> ReadFile(const std::string& path) {
android::base::unique_fd fd(
TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC)));
if (fd == -1) {
*err = "Unable to open '" + path + "': " + strerror(errno);
return false;
return ErrnoError() << "open() failed";
}
// For security reasons, disallow world-writable
// or group-writable files.
struct stat sb;
if (fstat(fd, &sb) == -1) {
*err = "fstat failed for '" + path + "': " + strerror(errno);
return false;
return ErrnoError() << "fstat failed()";
}
if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
*err = "Skipping insecure file '" + path + "'";
return false;
return Error() << "Skipping insecure file";
}
if (!android::base::ReadFdToString(fd, content)) {
*err = "Unable to read '" + path + "': " + strerror(errno);
return false;
std::string content;
if (!android::base::ReadFdToString(fd, &content)) {
return ErrnoError() << "Unable to read file contents";
}
return true;
return content;
}
bool WriteFile(const std::string& path, const std::string& content, std::string* err) {
*err = "";
Result<Success> WriteFile(const std::string& path, const std::string& content) {
android::base::unique_fd fd(TEMP_FAILURE_RETRY(
open(path.c_str(), O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0600)));
if (fd == -1) {
*err = "Unable to open '" + path + "': " + strerror(errno);
return false;
return ErrnoError() << "open() failed";
}
if (!android::base::WriteStringToFd(content, fd)) {
*err = "Unable to write to '" + path + "': " + strerror(errno);
return false;
return ErrnoError() << "Unable to write file contents";
}
return true;
return Success();
}
bool mkdir_recursive(const std::string& path, mode_t mode) {

8
init/util.h
View file

@ -28,6 +28,8 @@
#include <android-base/chrono_utils.h>
#include <selinux/label.h>
#include "result.h"
#define COLDBOOT_DONE "/dev/.coldboot_done"
using android::base::boot_clock;
@ -39,10 +41,10 @@ namespace init {
int CreateSocket(const char* name, int type, bool passcred, mode_t perm, uid_t uid, gid_t gid,
const char* socketcon);
bool ReadFile(const std::string& path, std::string* content, std::string* err);
bool WriteFile(const std::string& path, const std::string& content, std::string* err);
Result<std::string> ReadFile(const std::string& path);
Result<Success> WriteFile(const std::string& path, const std::string& content);
bool DecodeUid(const std::string& name, uid_t* uid, std::string* err);
Result<uid_t> DecodeUid(const std::string& name);
bool mkdir_recursive(const std::string& pathname, mode_t mode);
int wait_for_file(const char *filename, std::chrono::nanoseconds timeout);

115
init/util_test.cpp
View file

@ -30,61 +30,51 @@ namespace android {
namespace init {
TEST(util, ReadFile_ENOENT) {
std::string s("hello");
std::string err;
errno = 0;
EXPECT_FALSE(ReadFile("/proc/does-not-exist", &s, &err));
EXPECT_EQ("Unable to open '/proc/does-not-exist': No such file or directory", err);
auto file_contents = ReadFile("/proc/does-not-exist");
EXPECT_EQ(ENOENT, errno);
EXPECT_EQ("", s); // s was cleared.
ASSERT_FALSE(file_contents);
EXPECT_EQ("open() failed: No such file or directory", file_contents.error());
}
TEST(util, ReadFileGroupWriteable) {
std::string s("hello");
TemporaryFile tf;
std::string err;
ASSERT_TRUE(tf.fd != -1);
EXPECT_TRUE(WriteFile(tf.path, s, &err)) << strerror(errno);
EXPECT_EQ("", err);
EXPECT_TRUE(WriteFile(tf.path, s)) << strerror(errno);
EXPECT_NE(-1, fchmodat(AT_FDCWD, tf.path, 0620, AT_SYMLINK_NOFOLLOW)) << strerror(errno);
EXPECT_FALSE(ReadFile(tf.path, &s, &err)) << strerror(errno);
EXPECT_EQ("Skipping insecure file '"s + tf.path + "'", err);
EXPECT_EQ("", s); // s was cleared.
auto file_contents = ReadFile(tf.path);
ASSERT_FALSE(file_contents) << strerror(errno);
EXPECT_EQ("Skipping insecure file", file_contents.error());
}
TEST(util, ReadFileWorldWiteable) {
std::string s("hello");
TemporaryFile tf;
std::string err;
ASSERT_TRUE(tf.fd != -1);
EXPECT_TRUE(WriteFile(tf.path, s, &err)) << strerror(errno);
EXPECT_EQ("", err);
EXPECT_TRUE(WriteFile(tf.path, s)) << strerror(errno);
EXPECT_NE(-1, fchmodat(AT_FDCWD, tf.path, 0602, AT_SYMLINK_NOFOLLOW)) << strerror(errno);
EXPECT_FALSE(ReadFile(tf.path, &s, &err)) << strerror(errno);
EXPECT_EQ("Skipping insecure file '"s + tf.path + "'", err);
EXPECT_EQ("", s); // s was cleared.
auto file_contents = ReadFile(tf.path);
ASSERT_FALSE(file_contents) << strerror(errno);
EXPECT_EQ("Skipping insecure file", file_contents.error());
}
TEST(util, ReadFileSymbolicLink) {
std::string s("hello");
errno = 0;
// lrwxrwxrwx 1 root root 13 1970-01-01 00:00 charger -> /sbin/healthd
std::string err;
EXPECT_FALSE(ReadFile("/charger", &s, &err));
EXPECT_EQ("Unable to open '/charger': Too many symbolic links encountered", err);
auto file_contents = ReadFile("/charger");
EXPECT_EQ(ELOOP, errno);
EXPECT_EQ("", s); // s was cleared.
ASSERT_FALSE(file_contents);
EXPECT_EQ("open() failed: Too many symbolic links encountered", file_contents.error());
}
TEST(util, ReadFileSuccess) {
std::string s("hello");
std::string err;
EXPECT_TRUE(ReadFile("/proc/version", &s, &err));
EXPECT_EQ("", err);
EXPECT_GT(s.length(), 6U);
EXPECT_EQ('\n', s[s.length() - 1]);
s[5] = 0;
EXPECT_STREQ("Linux", s.c_str());
auto file_contents = ReadFile("/proc/version");
ASSERT_TRUE(file_contents);
EXPECT_GT(file_contents->length(), 6U);
EXPECT_EQ('\n', file_contents->at(file_contents->length() - 1));
(*file_contents)[5] = 0;
EXPECT_STREQ("Linux", file_contents->c_str());
}
TEST(util, WriteFileBinary) {
@ -95,29 +85,23 @@ TEST(util, WriteFileBinary) {
ASSERT_EQ(10u, contents.size());
TemporaryFile tf;
std::string err;
ASSERT_TRUE(tf.fd != -1);
EXPECT_TRUE(WriteFile(tf.path, contents, &err)) << strerror(errno);
EXPECT_EQ("", err);
EXPECT_TRUE(WriteFile(tf.path, contents)) << strerror(errno);
std::string read_back_contents;
EXPECT_TRUE(ReadFile(tf.path, &read_back_contents, &err)) << strerror(errno);
EXPECT_EQ("", err);
EXPECT_EQ(contents, read_back_contents);
EXPECT_EQ(10u, read_back_contents.size());
auto read_back_contents = ReadFile(tf.path);
ASSERT_TRUE(read_back_contents) << strerror(errno);
EXPECT_EQ(contents, *read_back_contents);
EXPECT_EQ(10u, read_back_contents->size());
}
TEST(util, WriteFileNotExist) {
std::string s("hello");
std::string s2("hello");
TemporaryDir test_dir;
std::string path = android::base::StringPrintf("%s/does-not-exist", test_dir.path);
std::string err;
EXPECT_TRUE(WriteFile(path, s, &err));
EXPECT_EQ("", err);
EXPECT_TRUE(ReadFile(path, &s2, &err));
EXPECT_EQ("", err);
EXPECT_EQ(s, s2);
EXPECT_TRUE(WriteFile(path, s));
auto file_contents = ReadFile(path);
ASSERT_TRUE(file_contents);
EXPECT_EQ(s, *file_contents);
struct stat sb;
int fd = open(path.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
EXPECT_NE(-1, fd);
@ -127,37 +111,30 @@ TEST(util, WriteFileNotExist) {
}
TEST(util, WriteFileExist) {
std::string s2("");
TemporaryFile tf;
ASSERT_TRUE(tf.fd != -1);
std::string err;
EXPECT_TRUE(WriteFile(tf.path, "1hello1", &err)) << strerror(errno);
EXPECT_EQ("", err);
EXPECT_TRUE(ReadFile(tf.path, &s2, &err));
EXPECT_EQ("", err);
EXPECT_STREQ("1hello1", s2.c_str());
EXPECT_TRUE(WriteFile(tf.path, "2ll2", &err));
EXPECT_EQ("", err);
EXPECT_TRUE(ReadFile(tf.path, &s2, &err));
EXPECT_EQ("", err);
EXPECT_STREQ("2ll2", s2.c_str());
EXPECT_TRUE(WriteFile(tf.path, "1hello1")) << strerror(errno);
auto file_contents = ReadFile(tf.path);
ASSERT_TRUE(file_contents);
EXPECT_EQ("1hello1", *file_contents);
EXPECT_TRUE(WriteFile(tf.path, "2ll2"));
file_contents = ReadFile(tf.path);
ASSERT_TRUE(file_contents);
EXPECT_EQ("2ll2", *file_contents);
}
TEST(util, DecodeUid) {
uid_t decoded_uid;
std::string err;
auto decoded_uid = DecodeUid("root");
EXPECT_TRUE(decoded_uid);
EXPECT_EQ(0U, *decoded_uid);
EXPECT_TRUE(DecodeUid("root", &decoded_uid, &err));
EXPECT_EQ("", err);
EXPECT_EQ(0U, decoded_uid);
decoded_uid = DecodeUid("toot");
EXPECT_FALSE(decoded_uid);
EXPECT_EQ("getpwnam failed: No such file or directory", decoded_uid.error());
EXPECT_FALSE(DecodeUid("toot", &decoded_uid, &err));
EXPECT_EQ("getpwnam failed: No such file or directory", err);
EXPECT_EQ(UINT_MAX, decoded_uid);
EXPECT_TRUE(DecodeUid("123", &decoded_uid, &err));
EXPECT_EQ("", err);
EXPECT_EQ(123U, decoded_uid);
decoded_uid = DecodeUid("123");
EXPECT_TRUE(decoded_uid);
EXPECT_EQ(123U, *decoded_uid);
}
TEST(util, is_dir) {