diff -r 9172bd97ae99 -r 6f15f18d2abf src/SystemProcess.h
--- a/src/SystemProcess.h	Mon Nov 11 14:42:13 2019 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,145 +0,0 @@
-/**
- * Relational pipes
- * Copyright © 2019 František Kučera (Frantovo.cz, GlobalCode.info)
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-#pragma once
-
-#include <vector>
-#include <sstream>
-#include <fcntl.h>
-#include <unistd.h>
-#include <sys/wait.h>
-#include <ext/stdio_filebuf.h>
-
-#include <relpipe/writer/typedefs.h>
-#include <relpipe/cli/RelpipeCLIException.h>
-
-namespace relpipe {
-namespace in {
-namespace filesystem {
-
-/**
- * Simple wrapper for a system process (fork+exec) that captures and returns just the STDOUT.
- */
-class SystemProcess {
-private:
-	/**
-	 * the command + its arguments
-	 */
-	std::vector<std::string> commandLine;
-	std::vector<std::string> environment;
-	int nullFile = -1;
-
-	/**
-	 * TODO: move to a common library (copied from the AWK module) 
-	 * @param args
-	 */
-	void execp(const std::vector<std::string>& args) {
-		const char** a = new const char*[args.size() + 1];
-		for (size_t i = 0; i < args.size(); i++) a[i] = args[i].c_str();
-		a[args.size()] = nullptr;
-
-		execvp(a[0], (char*const*) a);
-
-		delete[] a;
-		throw relpipe::cli::RelpipeCLIException(L"Unable to do execvp().", relpipe::cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exception?
-	}
-
-	/**
-	 * TODO: move to a common library (copied from the AWK module) 
-	 * @param readerFD
-	 * @param writerFD
-	 */
-	void createPipe(int& readerFD, int& writerFD) {
-		int fds[2];
-		int result = pipe(fds);
-		readerFD = fds[0];
-		writerFD = fds[1];
-		if (result < 0) throw relpipe::cli::RelpipeCLIException(L"Unable to create a pipe.", relpipe::cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exception?
-	}
-
-	/**
-	 * TODO: move to a common library (copied from the AWK module) 
-	 */
-	void redirectFD(int oldfd, int newfd) {
-		int result = dup2(oldfd, newfd);
-		if (result < 0) throw relpipe::cli::RelpipeCLIException(L"Unable redirect FD.", relpipe::cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exception?
-	}
-
-	/**
-	 * TODO: move to a common library (copied from the AWK module) 
-	 */
-	void closeOrThrow(int fd) {
-		int error = close(fd);
-		if (error) throw relpipe::cli::RelpipeCLIException(L"Unable to close FD: " + to_wstring(fd) + L" from PID: " + to_wstring(getpid()), relpipe::cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exception?
-	}
-
-public:
-
-	SystemProcess(const std::vector<std::string>& commandLine, const std::vector<std::string>& environment = {}) : commandLine(commandLine), environment(environment) {
-		nullFile = open("/dev/null", O_RDWR);
-	}
-
-	virtual ~SystemProcess() {
-		close(nullFile);
-	}
-
-	std::string execute() {
-
-		std::stringstream result;
-
-		// FIXME: different kinds of exception or return the exit code (now it enters infinite loop if the execp() fails)
-		// TODO: rename (not specific to hash)
-		int hashReaderFD;
-		int hashWriterFD;
-		createPipe(hashReaderFD, hashWriterFD);
-
-		__pid_t hashPid = fork();
-
-		if (hashPid < 0) {
-			throw relpipe::cli::RelpipeCLIException(L"Unable to fork the hash process.", relpipe::cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exception?
-		} else if (hashPid == 0) {
-			// Child process
-			closeOrThrow(hashReaderFD);
-			redirectFD(nullFile, STDIN_FILENO);
-			redirectFD(nullFile, STDERR_FILENO);
-			redirectFD(hashWriterFD, STDOUT_FILENO);
-			for (int i = 0; i < environment.size();) {
-				std::string name = environment[i++];
-				std::string value = environment[i++];
-				setenv(name.c_str(), value.c_str(), true);
-			}
-			execp(commandLine);
-		} else {
-			// Parent process
-			closeOrThrow(hashWriterFD);
-
-			__gnu_cxx::stdio_filebuf<char> hashReaderBuffer(hashReaderFD, std::ios::in);
-			std::istream hashReader(&hashReaderBuffer);
-
-			for (char ch; hashReader.read(&ch, 1).good();) result.put(ch);
-
-			int waitError;
-			__pid_t waitPID = wait(&waitError);
-			if (waitError) throw relpipe::cli::RelpipeCLIException(L"The child process returned an error exit code.", relpipe::cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exception?
-		}
-
-		return result.str();
-	}
-};
-
-}
-}
-}