popen: added iostream-based bidirectional popen()

common/include/villas/popen.hpp

@@ -0,0 +1,84 @@
+/** Bi-directional popen
+ *
+ * @file
+ * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
+ * @copyright 2014-2019, Institute for Automation of Complex Power Systems, EONERC
+ * @license GNU General Public License (version 3)
+ *
+ * VILLAScommon
+ *
+ * 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, either version 3 of the License, or
+ * any later version.
+ *
+ * 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 <signal.h>
+
+#include <ext/stdio_filebuf.h>
+
+#include <string>
+#include <istream>
+#include <ostream>
+#include <memory>
+
+namespace villas {
+namespace utils {
+
+class Popen {
+
+public:
+	using char_type = char;
+	using stdio_buf = __gnu_cxx::stdio_filebuf<char_type>;
+
+	Popen(const std::string &command);
+	~Popen();
+
+	void open();
+	int close();
+	void kill(int signal = SIGINT);
+
+	std::istream &in()
+	{
+		return *(input.stream);
+	}
+
+	std::ostream &out()
+	{
+		return *(output.stream);
+	}
+
+protected:
+	std::string command;
+	pid_t pid;
+
+	struct {
+		std::unique_ptr<std::istream> stream;
+		std::unique_ptr<stdio_buf> buffer;
+	} input;
+
+	struct {
+		std::unique_ptr<std::ostream> stream;
+		std::unique_ptr<stdio_buf> buffer;
+	} output;
+
+};
+
+} /* namespace utils */
+} /* namespace villas */
+
+template<typename T>
+std::istream& operator>>(villas::utils::Popen& po, T& value)
+{
+	return *(po.input.stream) >> value;
+}

common/lib/CMakeLists.txt

@@ -46,6 +46,7 @@ add_library(villas-common SHARED
 	common.cpp
 	tool.cpp
 	base64.cpp
+	popen.cpp
 )
 
 execute_process( 

common/lib/popen.cpp

@@ -0,0 +1,145 @@
+/** Bi-directional popen
+ *
+ * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
+ * @copyright 2014-2019, Institute for Automation of Complex Power Systems, EONERC
+ * @license GNU General Public License (version 3)
+ *
+ * VILLAScommon
+ *
+ * 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, either version 3 of the License, or
+ * any later version.
+ *
+ * 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/>.
+ *********************************************************************************/
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <paths.h>
+#include <dirent.h>
+
+#include <villas/exceptions.hpp>
+#include <villas/popen.hpp>
+
+namespace villas {
+namespace utils {
+
+Popen::Popen(const std::string &cmd) :
+	command(cmd)
+{
+	open();
+}
+
+Popen::~Popen()
+{
+	close();
+}
+
+void Popen::kill(int signal)
+{
+	::kill(pid, signal);
+}
+
+void Popen::open()
+{
+	const int READ = 0;
+	const int WRITE = 1;
+
+	int ret;
+	int inpipe[2];
+	int outpipe[2];
+	char *argv[4];
+
+	ret = pipe(inpipe);
+	if (ret)
+		goto error_out;
+
+	ret = pipe(outpipe);
+	if (ret)
+		goto clean_inpipe_out;
+
+	input.buffer = std::make_unique<stdio_buf>(outpipe[READ], std::ios_base::in);
+	output.buffer = std::make_unique<stdio_buf>(inpipe[WRITE], std::ios_base::out);
+
+	input.stream  = std::make_unique<std::istream>(input.buffer.get());
+	output.stream = std::make_unique<std::ostream>(output.buffer.get());
+
+	pid = fork();
+	if (pid == -1)
+		goto clean_outpipe_out;
+
+	if (pid == 0) {
+		::close(outpipe[READ]);
+		::close(inpipe[WRITE]);
+
+		if (inpipe[READ] != STDIN_FILENO) {
+			dup2(inpipe[READ], STDIN_FILENO);
+			::close(inpipe[READ]);
+		}
+
+		if (outpipe[WRITE] != STDOUT_FILENO) {
+			dup2(outpipe[WRITE], STDOUT_FILENO);
+			::close(outpipe[WRITE]);
+		}
+
+		argv[0] = (char *) "sh";
+		argv[1] = (char *) "-c";
+		argv[2] = (char *) command.c_str();
+		argv[3] = nullptr;
+
+		execv(_PATH_BSHELL, (char * const *) argv);
+		exit(127);
+	}
+
+	::close(outpipe[WRITE]);
+	::close(inpipe[READ]);
+
+	return;
+
+clean_outpipe_out:
+	::close(outpipe[READ]);
+	::close(outpipe[WRITE]);
+
+clean_inpipe_out:
+	::close(inpipe[READ]);
+	::close(inpipe[WRITE]);
+
+error_out:
+	throw SystemError("Failed to start subprocess");
+}
+
+int Popen::close()
+{
+	int pstat;
+
+	if (pid != -1) {
+		do {
+			pid = waitpid(pid, &pstat, 0);
+		} while (pid == -1 && errno == EINTR);
+	}
+
+	input.stream.reset();
+	output.stream.reset();
+
+	input.buffer.reset();
+	output.buffer.reset();
+
+	return pid == -1 ? -1 : pstat;
+}
+
+} /* namespace utils */
+} /* namespace villas */

common/tests/unit/CMakeLists.txt

@@ -31,6 +31,7 @@ add_executable(unit-tests-common
 	timing.cpp
 	utils.cpp
 	base64.cpp
+	popen.cpp
 )
 
 if(ARCH STREQUAL "x86_64")

common/tests/unit/popen.cpp

@@ -0,0 +1,48 @@
+/** Unit tests for bi-directional popen
+ *
+ * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
+ * @copyright 2014-2019, Institute for Automation of Complex Power Systems, EONERC
+ * @license GNU General Public License (version 3)
+ *
+ * VILLAScommon
+ *
+ * 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, either version 3 of the License, or
+ * any later version.
+ *
+ * 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/>.
+ *********************************************************************************/
+
+#include <iostream>
+#include <criterion/criterion.h>
+
+#include <villas/popen.hpp>
+
+using namespace villas::utils;
+
+TestSuite(popen, .description = "Bi-directional popen");
+
+Test(popen, cat)
+{
+	Popen proc("cat");
+
+	proc.out() << "Hello World" << std::endl;
+	proc.out().flush();
+
+	std::string str, str2;
+
+	proc.in() >> str >> str2;
+
+	cr_assert_eq(str, "Hello");
+	cr_assert_eq(str2, "World");
+
+	proc.kill();
+	proc.close();
+}