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// Copyright 2018 Google LLC
//
// 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.
#ifndef GVISOR_TEST_UTIL_MULTIPROCESS_UTIL_H_
#define GVISOR_TEST_UTIL_MULTIPROCESS_UTIL_H_
#include <unistd.h>
#include <algorithm>
#include <string>
#include <utility>
#include <vector>
#include "absl/strings/string_view.h"
#include "test/util/cleanup.h"
#include "test/util/posix_error.h"
namespace gvisor {
namespace testing {
// Immutable holder for a dynamically-sized array of pointers to mutable char,
// terminated by a null pointer, as required for the argv and envp arguments to
// execve(2).
class ExecveArray {
public:
// Constructs an empty ExecveArray.
ExecveArray() = default;
// Constructs an ExecveArray by copying strings from the given range. T must
// be a range over ranges of char.
template <typename T>
explicit ExecveArray(T const& strs) : ExecveArray(strs.begin(), strs.end()) {}
// Constructs an ExecveArray by copying strings from [first, last). InputIt
// must be an input iterator over a range over char.
template <typename InputIt>
ExecveArray(InputIt first, InputIt last) {
std::vector<size_t> offsets;
auto output_it = std::back_inserter(str_);
for (InputIt it = first; it != last; ++it) {
offsets.push_back(str_.size());
auto const& s = *it;
std::copy(s.begin(), s.end(), output_it);
str_.push_back('\0');
}
ptrs_.reserve(offsets.size() + 1);
for (auto offset : offsets) {
ptrs_.push_back(str_.data() + offset);
}
ptrs_.push_back(nullptr);
}
// Constructs an ExecveArray by copying strings from list. This overload must
// exist independently of the single-argument template constructor because
// std::initializer_list does not participate in template argument deduction
// (i.e. cannot be type-inferred in an invocation of the templated
// constructor).
/* implicit */ ExecveArray(std::initializer_list<absl::string_view> list)
: ExecveArray(list.begin(), list.end()) {}
// Disable move construction and assignment since ptrs_ points into str_.
ExecveArray(ExecveArray&&) = delete;
ExecveArray& operator=(ExecveArray&&) = delete;
char* const* get() const { return ptrs_.data(); }
size_t get_size() { return str_.size(); }
private:
std::vector<char> str_;
std::vector<char*> ptrs_;
};
// Simplified version of SubProcess. Returns OK and a cleanup function to kill
// the child if it made it to execve.
//
// fn is run between fork and exec. If it needs to fail, it should exit the
// process.
//
// The child pid is returned via child, if provided.
// execve's error code is returned via execve_errno, if provided.
PosixErrorOr<Cleanup> ForkAndExec(const std::string& filename,
const ExecveArray& argv,
const ExecveArray& envv,
const std::function<void()>& fn, pid_t* child,
int* execve_errno);
inline PosixErrorOr<Cleanup> ForkAndExec(const std::string& filename,
const ExecveArray& argv,
const ExecveArray& envv, pid_t* child,
int* execve_errno) {
return ForkAndExec(filename, argv, envv, [] {}, child, execve_errno);
}
// Calls fn in a forked subprocess and returns the exit status of the
// subprocess.
//
// fn must be async-signal-safe.
PosixErrorOr<int> InForkedProcess(const std::function<void()>& fn);
} // namespace testing
} // namespace gvisor
#endif // GVISOR_TEST_UTIL_MULTIPROCESS_UTIL_H_
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