WIP::: dump_systemstate: Rewritesandbox/klewandowski/dump-systemstate-rewrite

This change brings following changes:

 - support for parallel command execution

   All commands are started concurrently with their
   stdout and stderr is connected to private pipe(s).

 - timeout removal

   Utility will not set any arbitrary timeouts to
   executed commands - it's now dump_systemstate
   caller responsibility.

 - rewrite to c++

   C++ brings non-trivial data structures and allows
   to make code more readable.  It's also lighter than
   eg. glib.

Change-Id: Ia7f8996e2687451b13d11ec9d15c41ba0f3381ed

6 files changed, 423 insertions, 248 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d16b0ea..9947009 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
-PROJECT(crash-worker C)
+PROJECT(crash-worker C CXX)
 
 SET(PREFIX ${CMAKE_INSTALL_PREFIX})
 
diff --git a/src/dump_systemstate/CMakeLists.txt b/src/dump_systemstate/CMakeLists.txt
index 60737cb..296d85c 100755
--- a/src/dump_systemstate/CMakeLists.txt
+++ b/src/dump_systemstate/CMakeLists.txt
@@ -1,24 +1,24 @@
 CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
-PROJECT(dump_systemstate C)
+PROJECT(dump_systemstate C CXX)
 
 INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/src)
 SET(SRCS
-	dump_systemstate.c
+	dump_systemstate.cc
+	${CMAKE_SOURCE_DIR}/src/shared/command.cc
 	${CMAKE_SOURCE_DIR}/src/shared/util.c
 	${CMAKE_SOURCE_DIR}/src/shared/spawn.c
-   )
+)
 
 INCLUDE(FindPkgConfig)
 pkg_check_modules(dump_systemstate_pkgs REQUIRED dlog libunwind)
 
 FOREACH(flag ${dump_systemstate_pkgs_CFLAGS})
 	SET(EXTRA_CFLAGS "${EXTRA_CFLAGS} ${flag}")
+	SET(EXTRA_CXXFLAGS "${EXTRA_CXXFLAGS} ${flag}")
 ENDFOREACH(flag)
 
-SET(EXTRA_CFLAGS "${EXTRA_CFLAGS} -g -fno-omit-frame-pointer -finstrument-functions")
-
-SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_CFLAGS} -fPIE")
-MESSAGE("FLAGS: ${CMAKE_C_FLAGS}")
+SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_CFLAGS} -D_GNU_SOURCE=1 -fPIE")
+SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_CXXFLAGS} -D_GNU_SOURCE=1 -fPIE")
 
 ADD_EXECUTABLE(${PROJECT_NAME} ${SRCS})
 TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${dump_systemstate_pkgs_LDFLAGS} -pie)
diff --git a/src/dump_systemstate/dump_systemstate.c b/src/dump_systemstate/dump_systemstate.c
deleted file mode 100644
index c226203..0000000
--- a/src/dump_systemstate/dump_systemstate.c
+++ /dev/null
@@ -1,240 +0,0 @@
-/*
- * dump_systemstate
- *
- * Copyright (c) 2012 - 2013 Samsung Electronics Co., Ltd.
- *
- * 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.
- */
-
-/**
- * @file    dump_systemstate.c
- * @brief   dump system states.
- */
-
-#include <stdbool.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <time.h>
-#include <limits.h>
-#include <getopt.h>
-#include <sys/stat.h>
-#include <sys/vfs.h>
-
-#include "shared/util.h"
-#include "shared/log.h"
-#include "shared/spawn.h"
-
-#define FILE_PERM (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH)
-
-#define TIMEOUT_DEFAULT_MS 60*1000 /* 60sec */
-
-static struct dump_item {
-	const char *title;
-	const char *path;
-} dump_item[] = {
-	{"==== Binary version "            , "/etc/info.ini"},
-	{"==== Tizen version "             , "/etc/tizen-release"},
-	{"==== Kernel version "            , "/proc/version"},
-	{"==== Boot arguments "            , "/proc/cmdline"},
-	{"==== CPU & system architecture " , "/proc/cpuinfo"},
-	{"==== System uptime "             , "/proc/uptime"},
-	{"==== System statistics "         , "/proc/stat"},
-	{"==== System memory usage "       , "/proc/meminfo"},
-	{"==== Device major numbers "      , "/proc/devices"},
-	{"==== System disk I/O satistics " , "/proc/diskstats"},
-};
-
-static void usage()
-{
-	fprintf(stderr, "usage: dump_systemstate [-k] [-d] [-f file]\n"
-			"  -f: write to file (instead of stdout)\n"
-			"  -k: dump kernel messages (only root)\n"
-			"  -d: dump dlog messages\n"
-			"  -j: dump journal log messages\n"
-	   );
-}
-
-/* get disk used percentage */
-static int get_disk_used_percent(const char *path)
-{
-	struct statfs lstatfs;
-	int percent;
-
-	if (!path)
-		return -1;
-
-	if (statfs(path, &lstatfs) < 0)
-		return -1;
-	percent = (((lstatfs.f_blocks - lstatfs.f_bfree) * 1000) / (lstatfs.f_blocks)) + 9;
-	percent = percent/10;
-	return percent;
-}
-
-int main(int argc, char *argv[])
-{
-	int c, ret, i, is_root, dpercent;
-	const char *arg_file = NULL;
-	int out_fd = -1;
-	bool arg_dlog = false;
-	bool arg_dmesg = false;
-	bool arg_journal = false;
-	char timestr[80];
-	time_t cur_time;
-	struct tm gm_tm;
-	struct tm loc_tm;
-
-	while ((c = getopt(argc, argv, "hf:kdj")) != -1) {
-		switch (c) {
-		case 'd':
-			arg_dlog = true;
-			break;
-		case 'k':
-			arg_dmesg = true;
-			break;
-		case 'j':
-			arg_journal = true;
-			break;
-		case 'f':
-			arg_file = optarg;
-			break;
-		case '?':
-		case 'h':
-			printf("\n");
-			usage();
-			ret = 0;
-			goto exit;
-		}
-	}
-	ret = 0;
-	cur_time = time(NULL);
-	gmtime_r(&cur_time, &gm_tm);
-	localtime_r(&cur_time, &loc_tm);
-	is_root = !(geteuid());
-
-	/* open output file */
-	if (arg_file == NULL) {
-		out_fd = STDOUT_FILENO;
-	} else {
-		out_fd = open(arg_file, O_WRONLY | O_TRUNC | O_CREAT, FILE_PERM);
-		if (out_fd < 0) {
-			perror("couldn't open output file");
-			ret = out_fd;
-			goto exit;
-		}
-	}
-	/* print timestamp */
-	strftime(timestr, sizeof(timestr),
-					"%Y-%m-%d %H:%M:%S%z", &loc_tm);
-	fprintf_fd(out_fd, "dump_systemstate: %s\n", timestr);
-
-	for (i = 0; i < ARRAY_SIZE(dump_item); i++) {
-		fsync(out_fd);
-		fprintf_fd(out_fd, "\n%s(%s)\n",
-						dump_item[i].title, dump_item[i].path);
-		ret = dump_file_write_fd((char *)dump_item[i].path, out_fd);
-		if (ret < 0)
-			goto exit_close;
-	}
-	fprintf_fd(out_fd, "\n");
-
-	fprintf_fd(out_fd, "\n==== System disk space usage (/bin/df -h)\n");
-	char *df_args[] = {"/bin/df", "-h", NULL};
-	ret = spawn_wait(df_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-	if (ret != 0)
-		goto exit_close;
-
-	dpercent = get_disk_used_percent("/opt");
-	if (90 < dpercent) {
-		fprintf_fd(out_fd, "\n==== System disk space usage detail - %d%% (/bin/du -ah /opt)\n", dpercent);
-		char *du_args[] = {"/bin/du", "-ah", "/opt", "--exclude=/opt/usr", NULL};
-		ret = spawn_wait(du_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-		if (ret != 0)
-			goto exit_close;
-	}
-	fprintf_fd(out_fd, "\n==== System timezone (ls -al /opt/etc/localtime)\n");
-	char *ls_args[] = {"/bin/ls", "-al", "/opt/etc/localtime", NULL};
-	ret = spawn_wait(ls_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-	if (ret != 0)
-		goto exit_close;
-
-	fprintf_fd(out_fd, "\n==== System summary (/usr/bin/top -bcH -n 1)\n");
-	char *top_args[] = {"/bin/top", "-bcH", "-n", "1", NULL};
-	char *top_env[] = {"COLUMNS=200", NULL};
-	ret = spawn_wait(top_args, top_env, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-	if (ret != 0)
-		goto exit_close;
-
-	fprintf_fd(out_fd, "\n==== Current processes (/bin/ps auxfw)\n");
-	char *ps_args[] = {"/bin/ps", "auxfw", NULL};
-	ret = spawn_wait(ps_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-	if (ret != 0)
-		goto exit_close;
-
-	fprintf_fd(out_fd, "\n==== System memory statistics (/usr/bin/memps -v)\n");
-	char *memps_args[] = {"/bin/memps", "-v", NULL};
-	ret = spawn_wait(memps_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-	if (ret != 0)
-		goto exit_close;
-
-	if (is_root) {
-		fprintf_fd(out_fd, "\n==== System configuration (/usr/bin/vconftool get memory, db, file)\n");
-		char *get_mem_args[] = {"/bin/vconftool", "get", "memory/", "-r", NULL};
-		ret = spawn_wait(get_mem_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-		if (ret != 0)
-			goto exit_close;
-
-		char *get_db_args[] = {"/bin/vconftool", "get", "db/", "-r", NULL};
-		ret = spawn_wait(get_db_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-		if (ret != 0)
-			goto exit_close;
-
-		char *get_file_args[] = {"/bin/vconftool", "get", "file/", "-r", NULL};
-		ret = spawn_wait(get_file_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-		if (ret != 0)
-			goto exit_close;
-	}
-
-	if (arg_dmesg && is_root) {
-		fprintf_fd(out_fd, "\n==== Kernel messages (TZ=UTC /bin/dmesg -T)\n");
-		char *dmesg_args[] = {"/bin/dmesg", "-T", NULL};
-		char *dmesg_env[] = {"TZ=UTC", NULL};
-		ret = spawn_wait(dmesg_args, dmesg_env, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-		if (ret != 0)
-			goto exit_close;
-	}
-
-	if (arg_dlog) {
-		fprintf_fd(out_fd, "\n==== Log messages\n");
-		char *dlogutil_args[] = {"/bin/dlogutil", "-d", "-v", "threadtime", "-u", "16384", NULL};
-		ret = spawn_wait(dlogutil_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-		if (ret != 0)
-			goto exit_close;
-	}
-
-	if (arg_journal) {
-		fprintf_fd(out_fd, "\n==== Journal messages\n");
-		char *journalctl_args[] = {"/bin/journalctl", "-b", "-n", "1024", NULL};
-		ret = spawn_wait(journalctl_args, NULL, spawn_setstdout, (void *)out_fd, TIMEOUT_DEFAULT_MS);
-		if (ret != 0)
-			goto exit_close;
-	}
-
-exit_close:
-	if (arg_file)
-		close(out_fd);
-exit:
-	return ret;
-}
diff --git a/src/dump_systemstate/dump_systemstate.cc b/src/dump_systemstate/dump_systemstate.cc
new file mode 100644
index 0000000..50f43fd
--- /dev/null
+++ b/src/dump_systemstate/dump_systemstate.cc
@@ -0,0 +1,237 @@
+/*
+ * dump_systemstate
+ *
+ * Copyright (c) 2012 - 2013, 2018 Samsung Electronics Co., Ltd.
+ *
+ * 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.
+ */
+
+/**
+ * @file    dump_systemstate.cc
+ * @brief   dump system states.
+ */
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <time.h>
+#include <limits.h>
+#include <getopt.h>
+#include <sys/stat.h>
+#include <sys/vfs.h>
+
+#include <vector>
+#include <list>
+
+#define LOG_TAG "DUMP_SYSTEMSTATE"
+#include "shared/log.h"
+#include "shared/util.h"
+#include "shared/command.hh"
+
+#define FILE_PERM (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH)
+
+static struct dump_path {
+	const char *title;
+	const char *path;
+} dump_path[] = {
+	{"==== Binary version "            , "/etc/info.ini"},
+	{"==== Tizen version "             , "/etc/tizen-release"},
+	{"==== Kernel version "            , "/proc/version"},
+	{"==== Boot arguments "            , "/proc/cmdline"},
+	{"==== CPU & system architecture " , "/proc/cpuinfo"},
+	{"==== System uptime "             , "/proc/uptime"},
+	{"==== System statistics "         , "/proc/stat"},
+	{"==== System memory usage "       , "/proc/meminfo"},
+	{"==== Device major numbers "      , "/proc/devices"},
+	{"==== System disk I/O satistics " , "/proc/diskstats"},
+};
+
+static void usage()
+{
+	fprintf(stderr, "usage: dump_systemstate [-k] [-d] [-j] [-f file]\n"
+			"  -f: write to file (instead of stdout)\n"
+			"  -k: dump kernel messages (only root)\n"
+			"  -d: dump dlog messages\n"
+			"  -j: dump journal log messages\n");
+}
+
+static int dump_paths(int out_fd)
+{
+	for (unsigned u = 0; u < ARRAY_SIZE(dump_path); u++) {
+		dprintf(out_fd, "\n%s(%s)\n", dump_path[u].title, dump_path[u].path);
+		int ret = dump_file_write_fd((char *)dump_path[u].path, out_fd);
+		if (ret < 0)
+			return ret;
+	}
+	dprintf(out_fd, "\n");
+	return 0;
+}
+
+static int get_disk_used_percent(const char *path)
+{
+	struct statfs lstatfs;
+	int percent;
+
+	if (!path || statfs(path, &lstatfs) < 0)
+		return -1;
+	percent = (((lstatfs.f_blocks - lstatfs.f_bfree) * 1000) / (lstatfs.f_blocks)) + 9;
+	percent = percent/10;
+	return percent;
+}
+
+static std::list<Command *> prepare_commands(bool dump_dmesg, bool dump_dlog, bool dump_journal)
+{
+	std::list<Command *> cmd;
+
+	cmd.push_back(new Command("System disk space usage", {"/bin/df", "-h"}));
+
+	int dpercent = get_disk_used_percent("/opt");
+	if (90 < dpercent) {
+		char *dtitle = NULL;
+		int r = asprintf(&dtitle, "System disk space usage detail - %d%%", dpercent);
+		if (!dtitle || r < 0) {
+			_W("Skipping 'System disk space usage detail' due to error: %m");
+		} else {
+			cmd.push_back(new Command(dtitle, {"/bin/du", "-ah", "/opt", "--exclude=/opt/usr"}));
+			free(dtitle);
+		}
+	}
+
+	cmd.push_back(new Command("System timezone",
+				  {"/bin/ls", "-al", "/opt/etc/localtime"}));
+	cmd.push_back(new Command("System summary",
+				  { "/bin/top", "-bcH", "-n", "1"}, {"COLUMNS=200"}));
+	cmd.push_back(new Command("Current processes",
+				  {"/bin/ps", "auxfw"}));
+	cmd.push_back(new Command("System memory statistics",
+				  {"/bin/memps", "-v"}));
+
+	bool is_root = geteuid() == 0;
+	if (is_root) {
+		cmd.push_back(new Command("System configuration (memory, db, file)",
+					  {"/bin/vconftool", "get", "memory/", "-r"}));
+		cmd.push_back(new Command(NULL,
+					  {"/bin/vconftool", "get", "db/", "-r"}));
+		cmd.push_back(new Command(NULL,
+					  {"/bin/vconftool", "get", "file/", "-r"}));
+
+		if (dump_dmesg)
+			cmd.push_back(new Command("Kernel messages",
+						  {"/bin/dmesg", "-T"}, {"TZ=UTC"}));
+	}
+
+	if (dump_dlog)
+		cmd.push_back(new Command("Log messages",
+					  {"/bin/dlogutil", "-d", "-v", "threadtime", "-u", "16384"}));
+
+	if (dump_journal)
+		cmd.push_back(new Command("Journal messages",
+					  {"/bin/journalctl", "-b", "-n", "1024"}));
+
+	return cmd;
+}
+
+static void process_commands(std::list<Command *> &cmd, int out_fd)
+{
+	for (auto c : cmd)
+		c->run();
+
+	for (auto c : cmd)
+		c->dump(out_fd);
+}
+
+static void cleanup_commands(std::list<Command *> &cmd)
+{
+	for (auto c : cmd)
+		delete(c);
+}
+
+void dump_header(int out_fd)
+{
+	char timestr[80];
+	time_t cur_time;
+	struct tm gm_tm;
+	struct tm loc_tm;
+
+	cur_time = time(NULL);
+	gmtime_r(&cur_time, &gm_tm);
+	localtime_r(&cur_time, &loc_tm);
+
+	strftime(timestr, sizeof(timestr), "%Y-%m-%d %H:%M:%S%z", &loc_tm);
+	dprintf(out_fd, "dump_systemstate: %s\n", timestr);
+}
+
+struct FdHelper {
+	FdHelper(const char *path) {
+		if (path)
+			fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, FILE_PERM);
+		else
+			fd = STDOUT_FILENO;
+	}
+	~FdHelper() {
+		if (fd > 0)
+			fdatasync(fd);
+		if (fd != STDOUT_FILENO)
+			close(fd);
+	}
+	int fd;
+};
+
+int main(int argc, char *argv[])
+{
+	const char *arg_file = NULL;
+	bool arg_dlog = false;
+	bool arg_dmesg = false;
+	bool arg_journal = false;
+
+	for (int c; (c = getopt(argc, argv, "hf:kdj")) != -1; ) {
+		switch (c) {
+		case 'd':
+			arg_dlog = true;
+			break;
+		case 'k':
+			arg_dmesg = true;
+			break;
+		case 'j':
+			arg_journal = true;
+			break;
+		case 'f':
+			arg_file = optarg;
+			break;
+		case '?':
+		case 'h':
+			printf("\n");
+			usage();
+			return 0;
+		}
+	}
+
+	FdHelper fh(arg_file);
+	if (fh.fd < 0)
+		return 1;
+
+	dump_header(fh.fd);
+
+	if (dump_paths(fh.fd) < 0)
+		return 2;
+
+	auto cmd = prepare_commands(arg_dmesg, arg_dlog, arg_journal);
+	process_commands(cmd, fh.fd);
+	cleanup_commands(cmd);
+
+	return 0;
+}
diff --git a/src/shared/command.cc b/src/shared/command.cc
new file mode 100644
index 0000000..b3f66ef
--- /dev/null
+++ b/src/shared/command.cc
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2018 Samsung Electronics Co., Ltd.
+ *
+ * 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 <vector>
+#include <cstdio>
+#include <cstdlib>
+#include <string>
+#include <sstream>
+#include <limits.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "command.hh"
+#include "spawn.h"
+#include "util.h"
+#include "log.h"
+
+static constexpr int pipe_buf_size (1024*1024);
+
+Command::Command(const char *_title,
+		 std::vector<const char *> _av,
+		 std::vector<const char *> _ev)
+	: av(_av),
+	  ev(_ev),
+	  childpid(-1),
+	  child_waitfd(-1),
+	  child_datafd(-1)
+{
+	if (_title)
+		title.assign(_title);
+
+	av.push_back(NULL);
+	ev.push_back(NULL);
+}
+
+Command::~Command()
+{
+	if (child_waitfd != -1)
+		close(child_waitfd);
+	if (child_datafd != -1)
+		close(child_datafd);
+}
+
+void Command::wait()
+{
+	if (childpid != -1)
+		wait_for_pid(childpid);
+	childpid = -1;
+}
+
+void Command::run()
+{
+	int pipefd[2];
+	if (pipe(pipefd) < 0) {
+		_E("pipe: %m");
+		return;
+	}
+	fcntl(pipefd[1], F_SETPIPE_SZ, pipe_buf_size);
+
+	auto args = av;
+	args.push_back(NULL);
+	auto envs = ev;
+	envs.push_back(NULL);
+	int r = spawn((char *const *)args.data(), (char *const *)envs.data(),
+		      spawn_setstdouterr, (void*)pipefd[1],
+		      &childpid, &child_waitfd);
+
+	close(pipefd[1]);
+
+	if (r != 0)
+		close(pipefd[0]);
+
+	child_datafd = pipefd[0];
+}
+
+/*
+static bool appendvec2string(const std::vector<const char *> &vec, std::stringstream &ss)
+{
+	if (vec.size() == 0)
+		return false;
+
+	for (auto elem : vec) {
+		ss << elem;
+//		if (it != vec.cend())
+//			ss << " ";
+	}
+
+	return true;
+}
+*/
+
+static bool appendvec2string(const std::vector<const char *> &vec, std::string &s)
+{
+	if (vec.size() == 0)
+		return false;
+
+	for (auto elem : vec) {
+		s.append(elem);
+//		if (it != vec.cend())
+//			ss << " ";
+	}
+
+	return true;
+}
+
+void Command::dump(int out_fd)
+{
+	if (title.length() > 0) {
+		std::string header = "\n==== ";
+		header.append(title);
+		header.append(" (");
+		if (appendvec2string(ev, header))
+			header.append(" ");
+		appendvec2string(av, header);
+		header.append(")\n");
+		_D("ss is %s", header.c_str());
+		dprintf(out_fd, header.c_str());
+	}
+	copy_bytes(child_datafd, out_fd);
+}
diff --git a/src/shared/command.hh b/src/shared/command.hh
new file mode 100644
index 0000000..3a6e9b1
--- /dev/null
+++ b/src/shared/command.hh
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2018 Samsung Electronics Co., Ltd.
+ *
+ * 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 COMMAND_HH
+#define COMMAND_HH
+
+#include <string>
+#include <vector>
+
+class Command {
+public:
+	Command(const char *_title,
+		std::vector<const char *> _av,
+		std::vector<const char *> _ev = {});
+
+	~Command();
+
+	void run();
+
+	void dump(int out_fd);
+
+	void wait();
+
+private:
+	std::string title;
+	std::vector<const char *> av, ev;
+
+	pid_t childpid;
+	int child_waitfd;
+	int child_datafd;
+
+};
+
+#endif