boxberry/lib/sys.cc

#include "sys.h"

#include <libgen.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdexcept>
#include <system_error>
#include <unordered_set>
#include <atomic>

#include "logger.h"
#include "globals.h"

namespace sys {

static thread_local std::unordered_set<std::string> mkdirp_set;

static std::atomic<int> signalCounter(0);

struct SigCtx {
	SigCtx(bool enabled): enabled(enabled) {
		if (enabled && signalCounter++ == 0) {
			signal(SIGINT, SIG_IGN);
		}
	}

	~SigCtx() {
		if (enabled && --signalCounter == 0) {
			signal(SIGINT, SIG_DFL);
		}
	}

	bool enabled;
};

std::string sanitizePath(const std::string &path) {
	std::string npath;
	size_t idx = 0;
	while (idx < path.size()) {
		if (idx >= path.size() - 2) {
			npath += path[idx++];
		} else if (path[idx] == '.' && path[idx + 1] == '.' && path[idx + 2] == '/') {
			npath += "__parent__/";
			idx += 3;
		} else {
			npath += path[idx++];
		}
	}

	if (npath[npath.size() - 1] == '.' && npath[npath.size() - 2] == '.') {
		npath.replace(npath.size() - 2, 2, "__parent__");
	}

	return npath;
}

FileInfo fileInfo(const std::string &path) {
	FileInfo finfo;

	struct stat st;
	if (stat(path.c_str(), &st) < 0) {
		throw std::runtime_error("stat '" + path + "': " + strerror(errno));
	}

	finfo.mTimeSec = st.st_mtim.tv_sec;
	finfo.mTimeNsec = st.st_mtim.tv_nsec;
	finfo.isDir = S_ISDIR(st.st_mode);
	return finfo;
}

bool fileExists(const std::string &path) {
	struct stat st;
	if (stat(path.c_str(), &st) < 0) {
		if (errno == ENOENT) {
			return false;
		} else {
			throw std::runtime_error("stat '" + path + "': " + strerror(errno));
		}
	}

	return true;
}

void mkdirp(const std::string &path) {
	auto res = mkdirp_set.emplace(path);
	if (!res.second)
		return;

	// TODO: Implement this in C++ instead
	std::vector<std::string> argv;
	argv.push_back("mkdir");
	argv.push_back("-p");
	argv.push_back("--");
	argv.push_back(path);
	ProcConf conf;
	conf.print = global::verbose >= 2;
	execute(argv, conf);
}

void rmrf(const std::string &path) {
	mkdirp_set.erase(path);
	// TODO: Implement this in C++ instead
	std::vector<std::string> argv;
	argv.push_back("rm");
	argv.push_back("-rf");
	argv.push_back("--");
	argv.push_back(path);
	ProcConf conf;
	conf.print = global::verbose >= 2;
	execute(argv, conf);
}

void execute(const std::vector<std::string> &args, const ProcConf &conf) {
	if (conf.print) {
		std::string str;
		for (size_t i = 0; i < args.size(); ++i) {
			if (i != 0) {
				str += " ";
			}
			str += args[i];
		}
		logger::log(str);
	}

	// argv[0] should be interpreted as a shell command, because being able to run
	// CC='gcc --sysroot=/blah' is used by some systems.
	std::string command = std::string(args[0]) + " \"$@\"";
	static thread_local std::vector<const char *> argv;
	argv.clear();
	argv.push_back("/bin/sh"); // TODO: Use $SHELL?
	argv.push_back("-c");
	argv.push_back(command.c_str());
	argv.push_back("--");
	for (size_t i = 1; i < args.size(); ++i) {
		argv.push_back(args[i].c_str());
	}
	argv.push_back(nullptr);

	int stdoutPipe[2];
	if (conf.output == nullptr) {
		stdoutPipe[1] = STDOUT_FILENO;
	} else {
		if (pipe(stdoutPipe) < 0) {
			throw std::runtime_error(std::string("pipe: ") + strerror(errno));
		}
	}

	SigCtx sigCtx(conf.forwardSignals);
	pid_t child = fork();
	if (child == 0) {
		signal(SIGINT, SIG_DFL);
		if (conf.output != nullptr) {
			close(stdoutPipe[0]);
			dup2(stdoutPipe[1], 1);
		}

		// So, from what I've read, execvp should never modify its argv; so this should be fine?
		if (execvp(argv[0], (char *const *)argv.data()) < 0) {
			perror(argv[0]);
			abort();
		}

		// This shouldn't happen
		abort();
	} else if (child < 0) {
		throw std::runtime_error(std::string("fork: ") + strerror(errno));
	}

	if (conf.output != nullptr) {
		close(stdoutPipe[1]);
		char buf[1025];
		while (true) {
			ssize_t num = read(stdoutPipe[0], buf, sizeof(buf) - 1);
			if (num < 0 && errno != EAGAIN) {
				close(stdoutPipe[0]);
				throw std::runtime_error(
					std::string("read: ") + strerror(errno) +
					" (fd: " + std::to_string(stdoutPipe[0]) + ")");
			} else if (num < 0) {
				continue;
			}

			if (num == 0) {
				close(stdoutPipe[0]);
				break;
			}

			buf[num] = '\0';
			*conf.output += buf;
		}
	}

	int wstatus;
	waitpid(child, &wstatus, 0);
	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0) {
		throw std::runtime_error(std::string(args[0]) +
				" exited with code " + std::to_string(WEXITSTATUS(wstatus)));
	}

	if (WTERMSIG(wstatus)) {
		throw std::runtime_error(std::string(args[0]) +
				" terminated due to " + strsignal(WTERMSIG(wstatus)));
	}

	if (conf.output != nullptr && conf.output->back() == '\n') {
		conf.output->pop_back();
	}
}

void readDir(const std::string &path, std::vector<std::string> &files) {
	DIR *d = opendir(path.c_str());
	if (d == NULL) {
		throw std::runtime_error("opendir '" + path + "': " + strerror(errno));
	}

	struct dirent *ent;
	while ((ent = readdir(d)) != NULL) {
		if (ent->d_name[0] == '.')
			continue;
		files.emplace_back(ent->d_name);
	}

	closedir(d);
}

void chdir(const std::string &path) {
	if (::chdir(path.c_str()) < 0) {
		throw std::runtime_error("chdir '" + path + "': " + strerror(errno));
	}
}

std::string cwd() {
	std::vector<char> buf;
	buf.reserve(128);
	while (1) {
		char *res = getcwd(buf.data(), buf.capacity());
		if (res == NULL) {
			if (errno == ERANGE) {
				buf.reserve(buf.capacity() * 2);
			} else {
				throw std::system_error(EFAULT, std::generic_category());
			}
		} else {
			std::string str(buf.data());
			return str;
		}
	}
}

void symlink(const std::string &from, const std::string &to) {
	// TODO: Implement this in C++ instead
	std::vector<std::string> argv;
	argv.push_back("ln");
	argv.push_back("-s");
	argv.push_back("-f");
	argv.push_back("--");
	argv.push_back(from);
	argv.push_back(to);
	sys::execute(argv, ProcConf{});
}

std::string dirname(const std::string &path) {
	std::vector<char> buf(path.begin(), path.end());
	buf.push_back('\0');
	char *dir = ::dirname(buf.data());
	return std::string(dir);
}

}