C++ xmove_fd函数代码示例

void FAST_FUNC launch_helper(const char **argv)
{
	// setup vanilla unidirectional pipes interchange
	int i;
	int pipes[4];

	xpipe(pipes);
	xpipe(pipes + 2);

	// NB: handler must be installed before vfork
	bb_signals(0
		+ (1 << SIGCHLD)
		+ (1 << SIGALRM)
		, signal_handler);

	G.helper_pid = xvfork();

	i = (!G.helper_pid) * 2; // for parent:0, for child:2
	close(pipes[i + 1]); // 1 or 3 - closing one write end
	close(pipes[2 - i]); // 2 or 0 - closing one read end
	xmove_fd(pipes[i], STDIN_FILENO); // 0 or 2 - using other read end
	xmove_fd(pipes[3 - i], STDOUT_FILENO); // 3 or 1 - other write end

	if (!G.helper_pid) {
		// child: try to execute connection helper
		// NB: SIGCHLD & SIGALRM revert to SIG_DFL on exec
		BB_EXECVP_or_die((char**)argv);
	}

	// parent
	// check whether child is alive
	//redundant:signal_handler(SIGCHLD);
	// child seems OK -> parent goes on
	atexit(kill_helper);
}

int eject_main(int argc UNUSED_PARAM, char **argv)
{
	unsigned flags;
	const char *device;

	opt_complementary = "?1:t--T:T--t";
	flags = getopt32(argv, "tT" IF_FEATURE_EJECT_SCSI("s"));
	device = argv[optind] ? argv[optind] : "/dev/cdrom";

	/* We used to do "umount <device>" here, but it was buggy
	   if something was mounted OVER cdrom and
	   if cdrom is mounted many times.

	   This works equally well (or better):
	   #!/bin/sh
	   umount /dev/cdrom
	   eject /dev/cdrom
	*/

	xmove_fd(xopen_nonblocking(device), dev_fd);

	if (ENABLE_FEATURE_EJECT_SCSI && (flags & FLAG_SCSI))
		eject_scsi(device);
	else
		eject_cdrom(flags, device);

	if (ENABLE_FEATURE_CLEAN_UP)
		close(dev_fd);

	return EXIT_SUCCESS;
}

create_icmp_socket(void)
#define create_icmp_socket(lsa) create_icmp_socket()
#endif
{
	int sock;
#if ENABLE_PING6
	if (lsa->u.sa.sa_family == AF_INET6)
		sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
	else
#endif
		sock = socket(AF_INET, SOCK_RAW, 1); /* 1 == ICMP */
	if (sock < 0) {
		if (errno != EPERM)
			bb_perror_msg_and_die(bb_msg_can_not_create_raw_socket);
#if defined(__linux__) || defined(__APPLE__)
		/* We don't have root privileges.  Try SOCK_DGRAM instead.
		 * Linux needs net.ipv4.ping_group_range for this to work.
		 * MacOSX allows ICMP_ECHO, ICMP_TSTAMP or ICMP_MASKREQ
		 */
#if ENABLE_PING6
		if (lsa->u.sa.sa_family == AF_INET6)
			sock = socket(AF_INET6, SOCK_DGRAM, IPPROTO_ICMPV6);
		else
#endif
			sock = socket(AF_INET, SOCK_DGRAM, 1); /* 1 == ICMP */
		if (sock < 0)
#endif
		bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);
	}

	xmove_fd(sock, pingsock);
}

static void reopen_logfile_to_stderr(void)
{
	if (G.log_filename) {
		int logfd = open_or_warn(G.log_filename, O_WRONLY | O_CREAT | O_APPEND);
		if (logfd >= 0)
			xmove_fd(logfd, STDERR_FILENO);
	}
}

void FAST_FUNC open_transformer(int fd, const char *transform_prog)
#endif
{
	struct fd_pair fd_pipe;
	int pid;

	xpiped_pair(fd_pipe);
	pid = BB_MMU ? xfork() : xvfork();
	if (pid == 0) {
		/* Child */
		close(fd_pipe.rd); /* we don't want to read from the parent */
		// FIXME: error check?
#if BB_MMU
		{
			transformer_aux_data_t aux;
			init_transformer_aux_data(&aux);
			aux.check_signature = check_signature;
			transformer(&aux, fd, fd_pipe.wr);
			if (ENABLE_FEATURE_CLEAN_UP) {
				close(fd_pipe.wr); /* send EOF */
				close(fd);
			}
			/* must be _exit! bug was actually seen here */
			_exit(EXIT_SUCCESS);
		}
#else
		{
			char *argv[4];
			xmove_fd(fd, 0);
			xmove_fd(fd_pipe.wr, 1);
			argv[0] = (char*)transform_prog;
			argv[1] = (char*)"-cf";
			argv[2] = (char*)"-";
			argv[3] = NULL;
			BB_EXECVP(transform_prog, argv);
			bb_perror_msg_and_die("can't execute '%s'", transform_prog);
		}
#endif
		/* notreached */
	}

	/* parent process */
	close(fd_pipe.wr); /* don't want to write to the child */
	xmove_fd(fd_pipe.rd, fd);
}

/* Callback called by glib main loop when a client connects to ABRT's socket. */
static gboolean server_socket_cb(GIOChannel *source, GIOCondition condition, gpointer ptr_unused)
{
    kill_idle_timeout();
    load_abrt_conf();

    int socket = accept(g_io_channel_unix_get_fd(source), NULL, NULL);
    if (socket == -1)
    {
        perror_msg("accept");
        goto server_socket_finitio;
    }

    log_notice("New client connected");
    fflush(NULL); /* paranoia */

    int pipefd[2];
    xpipe(pipefd);

    pid_t pid = fork();
    if (pid < 0)
    {
        perror_msg("fork");
        close(socket);
        close(pipefd[0]);
        close(pipefd[1]);
        goto server_socket_finitio;
    }
    if (pid == 0) /* child */
    {
        xdup2(socket, STDIN_FILENO);
        xdup2(socket, STDOUT_FILENO);
        close(socket);

        close(pipefd[0]);
        xmove_fd(pipefd[1], STDERR_FILENO);

        char *argv[3];  /* abrt-server [-s] NULL */
        char **pp = argv;
        *pp++ = (char*)"abrt-server";
        if (logmode & LOGMODE_JOURNAL)
            *pp++ = (char*)"-s";
        *pp = NULL;

        execvp(argv[0], argv);
        perror_msg_and_die("Can't execute '%s'", argv[0]);
    }

    /* parent */
    close(socket);
    close(pipefd[1]);
    add_abrt_server_proc(pid, pipefd[0]);

server_socket_finitio:
    start_idle_timeout();
    return TRUE;
}

static
int open_to_or_warn(int to_fd, const char *filename, int flags, int mode)
{
	int fd = open3_or_warn(filename, flags, mode);
	if (fd < 0) {
		return 1;
	}
	xmove_fd(fd, to_fd);
	return 0;
}

int cryptpw_main(int argc UNUSED_PARAM, char **argv)
{
	/* Supports: cryptpw -m sha256 PASS 'rounds=999999999$SALT' */
	char salt[MAX_PW_SALT_LEN + sizeof("rounds=999999999$")];
	char *salt_ptr;
	char *password;
	const char *opt_m, *opt_S;
	int fd;

#if ENABLE_LONG_OPTS
	static const char mkpasswd_longopts[] ALIGN1 =
		"stdin\0"       No_argument       "s"
		"password-fd\0" Required_argument "P"
		"salt\0"        Required_argument "S"
		"method\0"      Required_argument "m"
	;
	applet_long_options = mkpasswd_longopts;
#endif
	fd = STDIN_FILENO;
	opt_m = CONFIG_FEATURE_DEFAULT_PASSWD_ALGO;
	opt_S = NULL;
	/* at most two non-option arguments; -P NUM */
	opt_complementary = "?2";
	getopt32(argv, "sP:+S:m:a:", &fd, &opt_S, &opt_m, &opt_m);
	argv += optind;

	/* have no idea how to handle -s... */

	if (argv[0] && !opt_S)
		opt_S = argv[1];

	salt_ptr = crypt_make_pw_salt(salt, opt_m);
	if (opt_S)
		/* put user's data after the "$N$" prefix */
		safe_strncpy(salt_ptr, opt_S, sizeof(salt) - (sizeof("$N$")-1));

	xmove_fd(fd, STDIN_FILENO);

	password = argv[0];
	if (!password) {
		/* Only mkpasswd, and only from tty, prompts.
		 * Otherwise it is a plain read. */
		password = (ENABLE_MKPASSWD && isatty(STDIN_FILENO) && applet_name[0] == 'm')
			? bb_ask_stdin("Password: ")
			: xmalloc_fgetline(stdin)
		;
		/* may still be NULL on EOF/error */
	}

	if (password)
		puts(pw_encrypt(password, salt, 1));

	return EXIT_SUCCESS;
}

static void start_logging(void)
{
    /* Open stdin to /dev/null */
    xmove_fd(xopen("/dev/null", O_RDWR), STDIN_FILENO);
    /* We must not leave fds 0,1,2 closed.
     * Otherwise fprintf(stderr) dumps messages into random fds, etc. */
    xdup2(STDIN_FILENO, STDOUT_FILENO);
    xdup2(STDIN_FILENO, STDERR_FILENO);
    logmode = LOGMODE_JOURNAL;
    putenv((char*)"ABRT_SYSLOG=1");
}

void FAST_FUNC launch_helper(const char **argv)
{
	// setup vanilla unidirectional pipes interchange
	int i;
	int pipes[4];

	xpipe(pipes);
	xpipe(pipes + 2);

	// NB: handler must be installed before vfork
	bb_signals(0
		+ (1 << SIGCHLD)
		+ (1 << SIGALRM)
		, signal_handler);

	G.helper_pid = xvfork();

	i = (!G.helper_pid) * 2; // for parent:0, for child:2
	close(pipes[i + 1]);     // 1 or 3 - closing one write end
	close(pipes[2 - i]);     // 2 or 0 - closing one read end
	xmove_fd(pipes[i], STDIN_FILENO);      // 0 or 2 - using other read end
	xmove_fd(pipes[3 - i], STDOUT_FILENO); // 3 or 1 - using other write end
	// End result:
	// parent stdout [3] -> child stdin [2]
	// child stdout [1] -> parent stdin [0]

	if (!G.helper_pid) {
		// child
		// if parent dies, get SIGTERM
		prctl(PR_SET_PDEATHSIG, SIGTERM, 0, 0, 0);
		// try to execute connection helper
		// NB: SIGCHLD & SIGALRM revert to SIG_DFL on exec
		BB_EXECVP_or_die((char**)argv);
	}

	// parent goes on
}

static void open_file_and_read_lines(void)
{
	if (filename) {
		xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO);
	} else {
		/* "less" with no arguments in argv[] */
		/* For status line only */
		filename = xstrdup(bb_msg_standard_input);
	}
	readpos = 0;
	readeof = 0;
	last_line_pos = 0;
	terminated = 1;
	read_lines();
}

int cryptpw_main(int argc UNUSED_PARAM, char **argv)
{
	char salt[MAX_PW_SALT_LEN];
	char *salt_ptr;
	const char *opt_m, *opt_S;
	int fd;

#if ENABLE_LONG_OPTS
	static const char mkpasswd_longopts[] ALIGN1 =
		"stdin\0"       No_argument       "s"
		"password-fd\0" Required_argument "P"
		"salt\0"        Required_argument "S"
		"method\0"      Required_argument "m"
	;
	applet_long_options = mkpasswd_longopts;
#endif
	fd = STDIN_FILENO;
	opt_m = "d";
	opt_S = NULL;
	/* at most two non-option arguments; -P NUM */
	opt_complementary = "?2:P+";
	getopt32(argv, "sP:S:m:a:", &fd, &opt_S, &opt_m, &opt_m);
	argv += optind;

	/* have no idea how to handle -s... */

	if (argv[0] && !opt_S)
		opt_S = argv[1];

	salt_ptr = crypt_make_pw_salt(salt, opt_m);
	if (opt_S)
		safe_strncpy(salt_ptr, opt_S, sizeof(salt) - (sizeof("$N$")-1));

	xmove_fd(fd, STDIN_FILENO);

	puts(pw_encrypt(
		argv[0] ? argv[0] : (
			/* Only mkpasswd, and only from tty, prompts.
			 * Otherwise it is a plain read. */
			(isatty(STDIN_FILENO) && applet_name[0] == 'm')
			? bb_ask_stdin("Password: ")
			: xmalloc_fgetline(stdin)
		),
		salt, 1));

	return EXIT_SUCCESS;
}

int watchdog_main(int argc, char **argv)
{
	unsigned opts;
	unsigned timer_duration = 30000; /* Userspace timer duration, in milliseconds */
	char *t_arg;

	opt_complementary = "=1"; /* must have 1 argument */
	opts = getopt32(argv, "Ft:", &t_arg);

	if (opts & OPT_TIMER) {
		static const struct suffix_mult suffixes[] = {
			{ "ms", 1 },
			{ "", 1000 },
			{ }
		};
		timer_duration = xatou_sfx(t_arg, suffixes);
	}

	if (!(opts & OPT_FOREGROUND)) {
		bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
	}

	bb_signals(BB_FATAL_SIGS, watchdog_shutdown);

	/* Use known fd # - avoid needing global 'int fd' */
	xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3);

// TODO?
//	if (!(opts & OPT_TIMER)) {
//		if (ioctl(fd, WDIOC_GETTIMEOUT, &timer_duration) == 0)
//			timer_duration *= 500;
//		else
//			timer_duration = 30000;
//	}

	while (1) {
		/*
		 * Make sure we clear the counter before sleeping, as the counter value
		 * is undefined at this point -- PFM
		 */
		write(3, "", 1); /* write zero byte */
		usleep(timer_duration * 1000L);
	}
	return EXIT_SUCCESS; /* - not reached, but gcc 4.2.1 is too dumb! */
}

int rpm2cpio_main(int argc UNUSED_PARAM, char **argv)
{
	struct rpm_lead lead;
	unsigned pos;

	if (argv[1]) {
		xmove_fd(xopen(argv[1], O_RDONLY), rpm_fd);
	}
	xread(rpm_fd, &lead, sizeof(lead));

	/* Just check the magic, the rest is irrelevant */
	if (lead.magic != htonl(RPM_LEAD_MAGIC)) {
		bb_error_msg_and_die("invalid RPM magic");
	}

	/* Skip the signature header, align to 8 bytes */
	pos = skip_header();
	seek_by_jump(rpm_fd, (-(int)pos) & 7);

	/* Skip the main header */
	skip_header();

	//if (SEAMLESS_COMPRESSION)
	//	/* We need to know whether child (gzip/bzip/etc) exits abnormally */
	//	signal(SIGCHLD, check_errors_in_children);

	/* This works, but doesn't report uncompress errors (they happen in child) */
	setup_unzip_on_fd(rpm_fd, /*fail_if_not_compressed:*/ 1);
	if (bb_copyfd_eof(rpm_fd, STDOUT_FILENO) < 0)
		bb_error_msg_and_die("error unpacking");

	if (ENABLE_FEATURE_CLEAN_UP) {
		close(rpm_fd);
	}

	if (SEAMLESS_COMPRESSION) {
		check_errors_in_children(0);
		return bb_got_signal;
	}
	return EXIT_SUCCESS;
}

static void crondlog(const char *ctl, ...)
{
	va_list va;
	int level = (ctl[0] & 0x1f);

	va_start(va, ctl);
	if (level >= (int)LogLevel) {
		/* Debug mode: all to (non-redirected) stderr, */
		/* Syslog mode: all to syslog (logmode = LOGMODE_SYSLOG), */
		if (!DebugOpt && LogFile) {
			/* Otherwise (log to file): we reopen log file at every write: */
			int logfd = open3_or_warn(LogFile, O_WRONLY | O_CREAT | O_APPEND, 0600);
			if (logfd >= 0)
				xmove_fd(logfd, STDERR_FILENO);
		}
// TODO: ERR -> error, WARN -> warning, LVL -> info
		bb_verror_msg(ctl + 1, va, /* strerr: */ NULL);
	}
	va_end(va);
	if (ctl[0] & 0x80)
		exit(20);
}