#define __STDC_WANT_LIB_EXT1__ 1

#include <matplot/util/popen.h>

#include <array>

#include <system_error>

#include <cstring> // strerror

#ifdef _WIN32

#include <io.h>

int common_pipe::open(const std::string& cmd, char mode)

{

if (opened())

close(); // prevent resource leak

HANDLE hChildStdinRd, hChildStdinWr, hStdin, hStdout;

SECURITY_ATTRIBUTES saAttr{};

// Set up security attributes for inheritable handles

saAttr.nLength = sizeof(SECURITY_ATTRIBUTES);

saAttr.bInheritHandle = TRUE;

saAttr.lpSecurityDescriptor = NULL;

// Create a pipe for the child process's input

if (!CreatePipe(&hChildStdinRd, &hChildStdinWr, &saAttr, 0))

return report(GetLastError(), "CreatePipe");

// Ensure the write handle to the pipe is not inherited by child

// processes

if (!SetHandleInformation(hChildStdinWr, HANDLE_FLAG_INHERIT, 0)) {

auto err = GetLastError();

CloseHandle(hChildStdinRd);

return report(err, "SetHandleInformation(hChildStdinWr)");

}

// Create a pipe for the child process's output

if (!CreatePipe(&hStdin, &hStdout, &saAttr, 0)) {

auto err = GetLastError();

CloseHandle(hChildStdinRd);

CloseHandle(hChildStdinWr);

return report(err, "CreatePipe");

}

// Ensure the read handle to the output pipe is not inherited by child

// processes

if (!SetHandleInformation(hStdout, HANDLE_FLAG_INHERIT, 0)) {

auto err = GetLastError();

CloseHandle(hChildStdinRd);

CloseHandle(hChildStdinWr);

CloseHandle(hStdin);

return report(err, "SetHandleInformation(hStdout)");

}

// Configure STARTUPINFO structure for the new process

STARTUPINFO si{};

ZeroMemory(&si, sizeof(STARTUPINFO));

si.cb = sizeof(STARTUPINFO);

si.hStdError = hStdout;

si.hStdOutput = hStdout;

si.hStdInput = hChildStdinRd;

si.dwFlags |= STARTF_USESTDHANDLES;

PROCESS_INFORMATION pi;

// Create the child process, while hiding the window

if (!CreateProcess(NULL, const_cast<char *>(cmd.c_str()), NULL, NULL, TRUE,

CREATE_NO_WINDOW, NULL, NULL, &si, &pi)) {

auto err = GetLastError();

CloseHandle(hChildStdinRd);

CloseHandle(hChildStdinWr);

CloseHandle(hStdin);

CloseHandle(hStdout);

return report(err, "CreateProcess");

}

hProcess = pi.hProcess;

hThread = pi.hThread;

// Close unnecessary handles

CloseHandle(hChildStdinRd);

CloseHandle(hStdout);

// Create a FILE pointer from the write handle to the child process's

// input

if (mode == 'r')

file_ = _fdopen(_open_osfhandle((intptr_t)hChildStdinWr, 0), "r");

else

file_ = _fdopen(_open_osfhandle((intptr_t)hChildStdinWr, 0), "w");

if (file_ == nullptr) {

auto err = GetLastError();

CloseHandle(hChildStdinWr);

CloseHandle(hStdin);

CloseHandle(pi.hProcess);

CloseHandle(pi.hThread);

return report(err, "_fdopen(_open_osfhandle)");

}

return 0;

}

int common_pipe::close(int *exit_code)

{

if (!opened())

return 0; // nothing to do

// Close the pipe to process:

fclose(file_);

file_ = nullptr;

// Wait for the process to finish

if (auto r = WaitForSingleObject(hProcess, INFINITE); r != WAIT_OBJECT_0) {

CloseHandle(hThread);

CloseHandle(hProcess);

return ECHILD;

}

// Retrieve the exit code

if (exit_code != nullptr) {

if (BOOL r = GetExitCodeProcess(hProcess, (LPDWORD)exit_code); !r) {

auto err = GetLastError();

CloseHandle(hThread);

CloseHandle(hProcess);

return err;

}

}

CloseHandle(hThread);

CloseHandle(hProcess);

return 0;

}

#endif // _WIN32 implementtion

#if defined(__linux) || defined(__APPLE__)

#include <cerrno>

#include <sys/wait.h> // waitpid

int common_pipe::open(const std::string &cmd, char mode)

{

if (opened())

close(); // prevent resource leak

constexpr auto READ = 0u;

constexpr auto WRITE = 1u;

int fd[2];

if (::pipe(fd) == -1)

return report(errno, "pipe");

if ((pid = ::fork()) == -1)

return report(errno, "fork");

if (pid == 0) { // child process

if (mode == 'r') {

::close(fd[READ]); // Close the READ end of the pipe

::dup2(fd[WRITE], 1); // Redirect stdout to pipe

} else { // (mode == 'w')

::close(fd[WRITE]); // Close the WRITE end of the pipe

dup2(fd[READ], 0); // Redirect stdin to pipe

}

::setpgid(pid, pid); // Needed so negative PIDs can kill children of /bin/sh

::execl("/bin/sh", "/bin/sh", "-c", cmd.c_str(), nullptr);

// execl returns only upon error

std::exit(EXIT_FAILURE);

} else {

if (mode == 'r') {

::close(fd[WRITE]); // Close the WRITE end of the pipe since parent's

// fd is read-only

} else { // (mode == 'w')

::close(fd[READ]); // Close the READ end of the pipe since parent's fd

// is write-only

}

}

if (mode == 'r')

file_ = ::fdopen(fd[READ], "r");

else

file_ = ::fdopen(fd[WRITE], "w");

if (file_ == nullptr)

return report(errno, "fdopen");

return 0;

}

/// Closes the pipe opened by popen2 and waits for termination

int common_pipe::close(int *exit_code)

{

if (!opened())

return 0; // nothing to do

::fclose(file_);

file_ = nullptr;

while (::waitpid(pid, exit_code, 0) == -1) {

if (errno != EINTR) {

if (exit_code != nullptr)

*exit_code = -1;

break;

}

}

return 0;

}

#endif // POSIX implementation

inline int common_pipe::report(int code, const std::string& what)

{

#if defined(__STDC_LIB_EXT1__) || defined(_MSC_VER)

char buffer[128]{}; // MSVC has no strerrorlen_s

strerror_s(buffer, 128, code); // MSVC rejects strerror

error_ = what + ": " + buffer;

#else

error_ = what + ": " + std::strerror(code); // GCC fixed strerror and has no strerror_s

#endif // __STDC_LIB_EXT1__ or MSVC

if (exceptions_)

throw std::system_error{code, std::generic_category(), what};

return code;

}

ipipe::ipipe() = default; // starting with C++20 could be in-class

opipe::opipe() = default; // starting with C++20 could be in-class

int opipe::write(std::string_view data)

{

constexpr auto CSIZE = sizeof(std::string_view::value_type);

if (!opened())

return report(EINVAL, "opipe::write");

if (auto sz = std::fwrite(data.data(), CSIZE, data.length(), file_);

sz != data.size()) {

if (auto err = std::ferror(file_); err != 0)

return report(EIO, "fwrite error");

if (auto err = std::feof(file_); err != 0)

return report(EIO, "fwrite eof");

}

return 0;

}

int opipe::flush(std::string_view data)

{

if (!opened())

return report(EINVAL, "opipe::flush");

if (!data.empty())

if (auto err = write(data); err != 0)

return report(err, "opipe::write");

if (auto res = std::fflush(file_); res != 0)

return report(errno, "fflush");

return 0;

}

int ipipe::read(std::string &data)

{

if (!opened())

return report(EINVAL, "ipipe::read");

data.clear();

auto buffer = std::array<char, 128>{};

while (!std::feof(file_) && !std::ferror(file_)) {

auto count =

std::fread(buffer.data(), sizeof(char), buffer.size(), file_);

if (count > 0)

data.append(buffer.data(), count);

}

if (std::ferror(file_))

return report(EIO, "fread");

return 0;

}

int shell_write(const std::string &cmd, std::string &data)

{

auto pipe = opipe{};

if (auto err = pipe.open(cmd); err != 0)

return err;

return pipe.write(data);

}

int shell_read(const std::string &cmd, std::string &data)

{

auto pipe = ipipe{};

if (auto err = pipe.open(cmd); err != 0)

return err;

return pipe.read(data);

}