// -*- c++ -*-
// Distributed under the BSD 2-Clause License.
// See accompanying file LICENSE for details.
#include "execute.h"

#include <unistd.h>
#include <cstring>
#include <sys/types.h>
#include <sys/wait.h>
#include <spawn.h>
#include <iostream>

/*
https://blog.famzah.net/2009/11/20/a-much-faster-popen-and-system-implementation-for-linux/
https://github.com/famzah/popen-noshell/commit/1f9eaf4eeef348d1efe0f3c7fe8ab670653cfbb1
https://blog.famzah.net/2018/12/19/posix_spawn-performance-benchmarks-and-usage-examples/
https://stackoverflow.com/questions/4259629/what-is-the-difference-between-fork-and-vfork/5207945#5207945
 */


namespace
{
int parent_waitpid(pid_t pid)
{
	int status;

	if(waitpid(pid, &status, 0) != pid)
	{
		return 1;
	}

	return WEXITSTATUS(status);
}
} // namespace ::

int execute(const std::string& command,
            const std::vector<std::string>& args,
            bool verbose)
{
	std::vector<const char*> argv;
	argv.push_back(command.data());
	for(const auto& arg : args)
	{
		argv.push_back(arg.data());
	}
	argv.push_back(nullptr);

	if(verbose)
	{
		std::string cmd;
		for(const auto& arg : argv)
		{
			if(arg == nullptr)
			{
				break;
			}
			if(!cmd.empty())
			{
				cmd += " ";
			}
			cmd += arg;
		}

		std::cout << cmd << "\n";
	}

#if 1
	auto pid = vfork();
	if(pid == 0)
	{
		execv(command.data(), (char**)argv.data());
		std::cout << "Could not execute " << command << ": " <<
			strerror(errno) << "\n";
		_exit(1); // execv only returns if an error occurred
	}
	auto ret = parent_waitpid(pid);
#elif 0
	pid_t pid;
	if(posix_spawn(&pid, command.data(), nullptr, nullptr,
	               (char**)argv.data(), nullptr))
	{
		return 1;
	}
	auto ret = parent_waitpid(pid);
#else
	auto ret = system(cmd.data());
#endif

	return ret;
}