//
// VMime library (http://www.vmime.org)
// Copyright (C) 2002 Vincent Richard <vincent@vmime.org>
//
// 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 (at your option) 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, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// Linking this library statically or dynamically with other modules is making
// a combined work based on this library.  Thus, the terms and conditions of
// the GNU General Public License cover the whole combination.
//

#include "vmime/config.hpp"


#if VMIME_PLATFORM_IS_POSIX && VMIME_HAVE_FILESYSTEM_FEATURES


#include "vmime/platforms/posix/posixChildProcess.hpp"
#include "vmime/platforms/posix/posixFile.hpp"

#include "vmime/exception.hpp"

#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/wait.h>


namespace vmime {
namespace platforms {
namespace posix {


// posixChildProcessFactory

shared_ptr <utility::childProcess> posixChildProcessFactory::create(const utility::file::path& path) const {

	return make_shared <posixChildProcess>(path);
}



#ifndef VMIME_BUILDING_DOC


// getPosixSignalMessage
// Returns the name of a POSIX signal.

static const string getPosixSignalMessage(const int num) {

	switch (num) {
		case SIGHUP:  return "SIGHUP";
		case SIGINT:  return "SIGINT";
		case SIGQUIT: return "SIGQUIT";
		case SIGILL:  return "SIGILL";
		case SIGABRT: return "SIGABRT";
		case SIGFPE:  return "SIGFPE";
		case SIGKILL: return "SIGKILL";
		case SIGSEGV: return "SIGSEGV";
		case SIGPIPE: return "SIGPIPE";
		case SIGALRM: return "SIGALRM";
		case SIGTERM: return "SIGTERM";
		case SIGUSR1: return "SIGUSR1";
		case SIGUSR2: return "SIGUSR2";
		case SIGCHLD: return "SIGCHLD";
		case SIGCONT: return "SIGCONT";
		case SIGSTOP: return "SIGSTOP";
		case SIGTSTP: return "SIGTSTP";
		case SIGTTIN: return "SIGTTIN";
		case SIGTTOU: return "SIGTTOU";
	}

	return "(unknown)";
}


// getPosixErrorMessage
// Returns a message corresponding to an error code.

static const string getPosixErrorMessage(const int num) {

#ifdef strerror_r
	char res[256];
	res[0] = '\0';

	strerror_r(num, res, sizeof(res));

	return string(res);
#else
	return string(strerror(num));
#endif

}


// Output stream adapter for POSIX pipe

class outputStreamPosixPipeAdapter : public utility::outputStream {

public:

	outputStreamPosixPipeAdapter(const int desc)
		: m_desc(desc) {

	}

	void flush() {

		::fsync(m_desc);
	}

protected:

	void writeImpl(const byte_t* const data, const size_t count) {

		if (::write(m_desc, data, count) == -1) {
			const string errorMsg = getPosixErrorMessage(errno);
			throw exceptions::system_error(errorMsg);
		}
	}

private:

	const int m_desc;
};


// Input stream adapter for POSIX pipe

class inputStreamPosixPipeAdapter : public utility::inputStream {

public:

	inputStreamPosixPipeAdapter(const int desc)
		: m_desc(desc) {
	}

	bool eof() const {

		return m_eof;
	}

	void reset() {

		// Do nothing: unsupported
	}

	size_t skip(const size_t count) {

		// TODO: not tested
		byte_t buffer[4096];

		ssize_t bytesSkipped = 0;
		ssize_t bytesRead = 0;

		while ((bytesRead = ::read(m_desc, buffer,
			std::min(sizeof(buffer), count - bytesSkipped))) != 0) {

			if (bytesRead == -1) {
				const string errorMsg = getPosixErrorMessage(errno);
				throw exceptions::system_error(errorMsg);
			}

			bytesSkipped += bytesRead;
		}

		return static_cast <size_t>(bytesSkipped);
	}

	size_t read(byte_t* const data, const size_t count) {

		ssize_t bytesRead = 0;

		if ((bytesRead = ::read(m_desc, data, count)) == -1) {
			const string errorMsg = getPosixErrorMessage(errno);
			throw exceptions::system_error(errorMsg);
		}

		m_eof = (bytesRead == 0);

		return static_cast <size_t>(bytesRead);
	}

private:

	const int m_desc;

	bool m_eof;
};


#endif // VMIME_BUILDING_DOC



// posixChildProcess

posixChildProcess::posixChildProcess(const utility::file::path& path)
	: m_processPath(path),
	  m_started(false),
	  m_stdIn(null),
	  m_stdOut(null),
	  m_pid(0),
	  m_argArray(NULL) {

	m_pipe[0] = 0;
	m_pipe[1] = 0;

	sigemptyset(&m_oldProcMask);
}


posixChildProcess::~posixChildProcess() {

	if (m_started) {
		sigprocmask(SIG_SETMASK, &m_oldProcMask, NULL);
	}

	if (m_pipe[0] != 0) {
		close(m_pipe[0]);
	}

	if (m_pipe[1] != 0) {
		close(m_pipe[1]);
	}

	delete [] m_argArray;
}


// The following code is highly inspired and adapted from the 'sendmail'
// provider module in Evolution data server code.
//
// Original authors: Dan Winship <danw@ximian.com>
// Copyright 2000 Ximian, Inc. (www.ximian.com)

void posixChildProcess::start(const std::vector <string>& args, const int flags) {

	if (m_started) {
		return;
	}

	// Construct C-style argument array
	const char** argv = new const char*[args.size() + 2];

	m_argVector = args;  // for c_str() pointer to remain valid
	m_argArray = argv;   // to free later

	argv[0] = m_processPath.getLastComponent().getBuffer().c_str();
	argv[args.size() + 1] = NULL;

	for (unsigned int i = 0 ; i < m_argVector.size() ; ++i) {
		argv[i + 1] = m_argVector[i].c_str();
	}

	// Create a pipe to communicate with the child process
	int fd[2];

	if (pipe(fd) == -1) {
		throw exceptions::system_error(getPosixErrorMessage(errno));
	}

	m_pipe[0] = fd[0];
	m_pipe[1] = fd[1];

	// Block SIGCHLD so the calling application doesn't notice
	// process exiting before we do
	sigset_t mask;

	sigemptyset(&mask);
	sigaddset(&mask, SIGCHLD);
	sigprocmask(SIG_BLOCK, &mask, &m_oldProcMask);

	// Spawn process
	const pid_t pid = fork();

	if (pid == -1) {  // error

		const string errorMsg = getPosixErrorMessage(errno);

		sigprocmask(SIG_SETMASK, &m_oldProcMask, NULL);

		close(fd[0]);
		close(fd[1]);

		throw exceptions::system_error(errorMsg);

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

		if (flags & FLAG_REDIRECT_STDIN) {
			dup2(fd[0], STDIN_FILENO);
		} else {
			close(fd[0]);
		}

		if (flags & FLAG_REDIRECT_STDOUT) {
			dup2(fd[1], STDOUT_FILENO);
		} else {
			close(fd[1]);
		}

		posixFileSystemFactory* pfsf = new posixFileSystemFactory();

		const string path = pfsf->pathToString(m_processPath);

		delete pfsf;

		execv(path.c_str(), const_cast <char**>(argv));
		_exit(255);
	}

	if (flags & FLAG_REDIRECT_STDIN) {

		m_stdIn = make_shared <outputStreamPosixPipeAdapter>(m_pipe[1]);

	} else {

		close(m_pipe[1]);
		m_pipe[1] = 0;
	}

	if (flags & FLAG_REDIRECT_STDOUT) {

		m_stdOut = make_shared <inputStreamPosixPipeAdapter>(m_pipe[0]);

	} else {

		close(m_pipe[0]);
		m_pipe[0] = 0;
	}

	m_pid = pid;
	m_started = true;
}


shared_ptr <utility::outputStream> posixChildProcess::getStdIn() {

	return m_stdIn;
}


shared_ptr <utility::inputStream> posixChildProcess::getStdOut() {

	return m_stdOut;
}


void posixChildProcess::waitForFinish() {

	// Close stdin pipe
	if (m_pipe[1] != 0) {
		close(m_pipe[1]);
		m_pipe[1] = 0;
	}

	int wstat;

	while (waitpid(m_pid, &wstat, 0) == -1 && errno == EINTR) {
		;
	}

	if (!WIFEXITED(wstat)) {

		throw exceptions::system_error("Process exited with signal "
			+ getPosixSignalMessage(WTERMSIG(wstat)));

	} else if (WEXITSTATUS(wstat) != 0) {

		if (WEXITSTATUS(wstat) == 255) {

			scoped_ptr <posixFileSystemFactory> pfsf(new posixFileSystemFactory());

			throw exceptions::system_error("Could not execute '"
				+ pfsf->pathToString(m_processPath) + "'");

		} else {

			std::ostringstream oss;
			oss.imbue(std::locale::classic());

			oss << "Process exited with status " << WEXITSTATUS(wstat);

			throw exceptions::system_error(oss.str());
		}
	}
}


} // posix
} // platforms
} // vmime


#endif // VMIME_PLATFORM_IS_POSIX && VMIME_HAVE_FILESYSTEM_FEATURES