finit/src/util.c

/* Misc. shared utility functions for initctl, reboot and finit
 *
 * Copyright (c) 2016-2025  Joachim Wiberg <troglobit@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "config.h"		/* Generated by configure script */

#include <ctype.h>		/* isprint() */
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#ifdef HAVE_MNTENT_H
#include <mntent.h>
#endif
#include <regex.h>
#include <string.h>
#include <stdarg.h>
#include <sys/stat.h>
#include <stdlib.h>
#ifdef HAVE_TERMIOS_H
# include <termios.h>
#endif
#include <time.h>
#include <unistd.h>
#include <utmp.h>
#ifdef HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif
#include <sys/resource.h>
#include <ftw.h>		/* rmrf() */
#include <sys/sysinfo.h>	/* sysinfo() */
#include <sys/vfs.h>		/* statfs */
#include <linux/magic.h>
#ifdef _LIBITE_LITE
# include <libite/lite.h>
#else
# include <lite/lite.h>
#endif
#include "util.h"

#ifdef HAVE_TERMIOS_H
/*
 * This flag is used on *BSD when calling tcsetattr() to prevent it
 * from changing speed, duplex, parity.  GNU says we should use the
 * CIGNORE flag to c_cflag, but that doesn't exist so ... we rely on
 * our initial tcgetattr() and prey that nothing changes on the TTY
 * before we exit and restore with tcsetattr()
 */
#ifndef TCSASOFT
#define TCSASOFT 0
#endif

static struct termios ttold;
static struct termios ttnew;
#endif

int   ttrows  = 24;
int   ttcols  = 80;
char *prognm  = NULL;

static char *signames[] = {
	"",
	"HUP",				/* 1 */
	"INT",
	"QUIT",
	"ILL",
	"TRAP",
	"ABRT",
	"BUS",
	"FPE",				/* 8 */
	"KILL",
	"USR1",
	"SEGV",
	"USR2",
	"PIPE",
	"ALRM",
	"TERM",
	"STKFLT",			/* 16 */
	"CHLD",
	"CONT",
	"STOP",
	"TSTP",
	"TTIN",
	"TTOU",
	"URG",
	"XCPU",				/* 24 */
	"XFSZ",
	"VTALRM",
	"PROF",
	"WINCH",
	"IO",
	"PWR",
	"SYS",
};

struct rlimit_name {
	char *name;
	int val;
};

static const struct rlimit_name rlimit_names[] = {
	{ "as",         RLIMIT_AS         },
	{ "core",       RLIMIT_CORE       },
	{ "cpu",        RLIMIT_CPU        },
	{ "data",       RLIMIT_DATA       },
	{ "fsize",      RLIMIT_FSIZE      },
	{ "locks",      RLIMIT_LOCKS      },
	{ "memlock",    RLIMIT_MEMLOCK    },
	{ "msgqueue",   RLIMIT_MSGQUEUE   },
	{ "nice",       RLIMIT_NICE       },
	{ "nofile",     RLIMIT_NOFILE     },
	{ "nproc",      RLIMIT_NPROC      },
	{ "rss",        RLIMIT_RSS        },
	{ "rtprio",     RLIMIT_RTPRIO     },
#ifdef RLIMIT_RTTIME
	{ "rttime",     RLIMIT_RTTIME     },
#endif
	{ "sigpending", RLIMIT_SIGPENDING },
	{ "stack",      RLIMIT_STACK      },

	{ NULL, 0 }
};

/* https://freedesktop.org/software/systemd/man/systemd.exec.html#id-1.20.8 */
static char *exitcodes[] = {
	"SUCCESS",			/* 0: Std C exit OK   */
	"FAILURE",			/* 1: Std C exit FAIL */
	/* 2-7: LSB init scripts (usually) */
	"INVALIDARGUMENT",		/* 2: Invalid or excess args */
	"NOTIMPLEMENTED",		/* 3: Unimplemented feature, e.g. 'reload' */
	"NOPERMISSION",			/* 4: Insufficient privilege */
	"NOTINSTALLED",			/* 5: Program is not installed */
	"NOTCONFIGURED",		/* 6: Program is not configured */
	"NOTRUNNING",			/* 7: Program is not running */
	"", "", "", "", "", "", "", "",	/* 8-63: Not standardized */
	"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", /* 16-31 */
	"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", /* 32-47 */
	"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", /* 48-63 */
	/* 64-78: BSD, from sysexit.h */
	"USAGE",			/* 64: Command line usage error */
	"DATAERR",			/* 65: data format error */
	"NOINPUT",			/* 66: cannot open input */
	"NOUSER",			/* 67: addressee unknown */
	"NOHOST",			/* 68: host name unknown */
	"UNAVAILABLE",			/* 69: service unavailable */
	"SOFTWARE",			/* 70: internal software error */
	"OSERR",			/* 71: system error (e.g., can't fork) */
	"OSFILE",			/* 72: critical OS file missing */
	"CANTCREAT",			/* 73: can't create (user) output file */
	"IOERR",			/* 74: input/output error */
	"TEMPFAIL",			/* 75: temp failure; user is invited to retry */
	"PROTOCOL",			/* 76: remote error in protocol */
	"NOPERM",			/* 77: permission denied */
	"CONFIG",			/* 78: configuration error */
	/* 79-199: Not standardized, typically 127 == -1 */
	/* >= 200: reserved (LSB), used by systemd */
};


char *progname(char *arg0)
{
       prognm = strrchr(arg0, '/');
       if (prognm)
	       prognm++;
       else
	       prognm = arg0;

       return prognm;
}

/* basename(3) replacement that does not modify its argument */
const char *basenm(const char *path)
{
	const char *basename;

	basename = rindex(path, '/');
	if (!basename)
		return path;

	basename++;
	return basename;
}

char *str(char *fmt, ...)
{
	static char buf[32];
	va_list ap;

	va_start(ap, fmt);
	vsnprintf(buf, sizeof(buf), fmt, ap);
	va_end(ap);

	return buf;
}

/*
 * Return UID for the given user, with fallback to 'root' if user is unset.
 * Fails with -1 only if user (incl. fallback) does not exist.
 */
int getuser(const char *username, char **home)
{
#ifdef ENABLE_STATIC
	if (!username || !username[0])
		username = "root";

	if (home)
		*home = "/";	/* XXX: Fixme */
	return fgetint("/etc/passwd", "x:\n", username);
#else
	const struct passwd *usr;

	if (!username || !username[0]) {
		usr = getpwuid(0);
		if (!usr)
			return -1;

		if (home)
			*home = usr->pw_dir;
		return usr->pw_uid;
	}

	usr = getpwnam(username);
	if (!usr)
		return -1;

	if (home)
		*home = usr->pw_dir;
	return  usr->pw_uid;
#endif
}

/*
 * Return GID for the given group, with fallback to 'root' if group is unset.
 * Fails with -1 only if user (incl. fallback) does not exist.
 */
int getgroup(const char *group)
{
#ifdef ENABLE_STATIC
	if (!group || !group[0])
		group = "root";

	return fgetint("/etc/group", "x:\n", group);
#else
	const struct group *grp;

	if (!group || !group[0]) {
		grp = getgrgid(0);
		if (!grp)
			return -1;

		return grp->gr_gid;
	}

	grp = getgrnam(group);
	if (!grp)
		return -1;

	return grp->gr_gid;
#endif
}

/* get current user */
int getcuser(char *buf, size_t len)
{
	char *ptr = "root";

#ifndef ENABLE_STATIC
	struct passwd *pw = getpwuid(getuid());

	if (pw)
		ptr = pw->pw_name;
#endif
	if (strlcpy(buf, ptr, len) > len)
		return -1;

	return 0;
}

/* get current group */
int getcgroup(char *buf, size_t len)
{
	char *ptr = "root";

#ifndef ENABLE_STATIC
	struct group *gr = getgrgid(getgid());

	if (gr)
		ptr = gr->gr_name;
#endif
	if (strlcpy(buf, ptr, len) > len)
		return -1;

	return 0;
}

static int rmrf_cb(const char *fpath, const struct stat *sb, int tflag, struct FTW *ftw)
{
	(void)sb;
	(void)tflag;

	if (ftw->level == 0)
		return 0;

	if (remove(fpath) && errno != EBUSY)
		warn("Failed removing %s", fpath);

	return 0;
}

/* nftw() cannot pass user data, see also tmpfiles.c do_clean() */
static uid_t chownr_uid;
static gid_t chownr_gid;

static int chownr_cb(const char *fpath, const struct stat *sb, int tflag, struct FTW *ftw)
{
	(void)tflag;
	(void)ftw;

	if (sb->st_uid == chownr_uid && sb->st_gid == chownr_gid)
		return 0;

	if (lchown(fpath, chownr_uid, chownr_gid))
		warn("Failed chown(%s, %d, %d)", fpath, (int)chownr_uid, (int)chownr_gid);

	return 0;
}

/* chown -R */
int chownr(const char *path, uid_t uid, gid_t gid)
{
	chownr_uid = uid;
	chownr_gid = gid;

	return nftw(path, chownr_cb, 20, FTW_PHYS);
}

/* empty a directory but keep it, silently ignores a missing path */
int rmcontents(const char *path)
{
	if (!fisdir(path))
		return 0;

	return nftw(path, rmrf_cb, 20, FTW_DEPTH | FTW_PHYS);
}

/* rm -rf, silently ignores a missing path */
int rmrf(const char *path)
{
	if (!fisdir(path))
		return 0;

	nftw(path, rmrf_cb, 20, FTW_DEPTH | FTW_PHYS);
	if (remove(path) && errno != ENOENT)
		warn("Failed removing path %s", path);

	return 0;
}

/*
 * Like mksubsys() but with the ids already resolved, uid -1 skips the
 * chown.  Parents are created 0755, only the leaf gets @mode.
 */
int mksubsysd(const char *dir, mode_t mode, uid_t uid, gid_t gid)
{
	mode_t omask;
	int rc;

	omask = umask(0);

	rc = mkpath(dir, 0755);
	if (!rc) {
		rc = chmod(dir, mode);
		if (!rc && uid != (uid_t)-1 && chown(dir, uid, gid))
			err(1, "Failed chown(%s, %d, %d)", dir, (int)uid, (int)gid);
	}

	umask(omask);

	return rc;
}

int mksubsys(const char *dir, mode_t mode, char *user, char *group)
{
	int uid, gid;

	uid = getuser(user, NULL);
	gid = getgroup(group);
	if (gid < 0)
		gid = 0;
	if (uid < 0)
		warnx("Cannot find user %s, %s is owned by root", user, dir);

	return mksubsysd(dir, mode, uid < 0 ? (uid_t)-1 : (uid_t)uid, (gid_t)gid);
}

/*
 * Read an open stream to EOF into a malloc()'ed, NUL terminated buffer.
 *
 * st_size is only a hint here, and zero on procfs, so the read loop
 * runs until EOF rather than trusting it.  Sizing from the already
 * open fd also leaves no window for the file to change between the
 * look and the read.
 */
static char *slurp(FILE *fp, size_t *lenp)
{
	size_t len = 0, size = BUFSIZ;
	struct stat st;
	char *buf;

	if (!fstat(fileno(fp), &st) && st.st_size > 0 && (size_t)st.st_size > size)
		size = (size_t)st.st_size;

	buf = malloc(size + 1);
	if (!buf)
		return NULL;

	while (1) {
		char *ptr;

		len += fread(&buf[len], 1, size - len, fp);
		if (len < size)
			break;		/* EOF, or error caught below */

		ptr = realloc(buf, size * 2 + 1);
		if (!ptr) {
			free(buf);
			return NULL;
		}
		buf = ptr;
		size *= 2;
	}

	if (ferror(fp)) {
		free(buf);
		return NULL;
	}

	buf[len] = 0;
	if (lenp)
		*lenp = len;

	return buf;
}

/*
 * Read a whole file into a malloc()'ed, NUL terminated buffer, which
 * the caller frees.  @lenp, when given, returns the number of bytes
 * read; the content may itself contain NUL, e.g. /proc/PID/cmdline.
 */
char *vfslurp(size_t *lenp, const char *fmt, va_list ap)
{
	char *buf;
	FILE *fp;

	fp = vfopenf("r", fmt, ap);
	if (!fp)
		return NULL;

	buf = slurp(fp, lenp);
	fclose(fp);

	return buf;
}

char *fslurp(size_t *lenp, const char *fmt, ...)
{
	va_list ap;
	char *buf;

	va_start(ap, fmt);
	buf = vfslurp(lenp, fmt, ap);
	va_end(ap);

	return buf;
}

int fnread(char *buf, size_t len, char *fmt, ...)
{
	size_t dlen;
	va_list ap;
	char *data;

	va_start(ap, fmt);
	data = vfslurp(&dlen, fmt, ap);
	va_end(ap);

	if (!data)
		return -1;

	if (buf && len) {
		if (dlen > len - 1)
			dlen = len - 1;
		memcpy(buf, data, dlen);
		buf[dlen] = 0;
	}
	free(data);

	return (int)dlen;
}

int fnwrite(char *value, char *fmt, ...)
{
	char path[256];
	va_list ap;
	FILE *fp;
	int rc;

	if (!value) {
		errno = EINVAL;
		return -1;
	}

	va_start(ap, fmt);
	vsnprintf(path, sizeof(path), fmt, ap);
	va_end(ap);

	fp = fopen(path, "w");
	if (!fp)
		return -1;

	/* echo(1) always adds a newline */
	if (fputs(value, fp) == EOF || fputs("\n", fp) == EOF)
		rc = -1;
	if (fclose(fp) == EOF)
		rc = -1;
	else
		rc = 0;

	return rc;
}

int fngetint(char *path, int *val)
{
	char buf[64];

	if (fnread(buf, sizeof(buf), "%s", path) <= 0)
		return -1;

	errno = 0;
	*val = strtoul(chomp(buf), NULL, 0);
	if (errno)
		return -1;

	return 0;
}

/*
 * This is a replacement for the non-working reboot(RB_SW_SUSPEND).  It
 * checks for suspend to RAM support, assuming `mem_sleep` has a sane
 * default, e.g. 'deep' or 's2idle'.  The latter should be possible to
 * select from finit.conf, but for now we go with the kernel default.
 * For more information on kernel sleep states, see:
 * https://www.kernel.org/doc/html/latest/admin-guide/pm/sleep-states.html
 */
int suspend(void)
{
	char buf[80];
	char *ptr;

	if (fnread(buf, sizeof(buf), "/sys/power/state") <= 0) {
	opnotsup:
		errno = EINVAL;
		return 1;
	}

	chomp(buf);

	ptr = strtok(buf, " ");
	while (ptr) {
		if (!strcmp(ptr, "mem"))
			break;

		ptr = strtok(NULL, " ");
	}
	if (!ptr)
		goto opnotsup;

	return fnwrite("mem", "/sys/power/state");
}

int strtobytes(char *arg)
{
	int mod = 0, bytes;
	size_t pos;

	if (!arg)
		return -1;

	pos = strspn(arg, "0123456789");
	if (arg[pos] != 0) {
		if (arg[pos] == 'G')
			mod = 3;
		else if (arg[pos] == 'M')
			mod = 2;
		else if (arg[pos] == 'k')
			mod = 1;
		else
			return -1;

		arg[pos] = 0;
	}

	bytes = atoi(arg);
	while (mod--)
		bytes *= 1000;

	return bytes;
}

char *sig2str(int signo)
{
	if (signo < 1 || signo >= (int)NELEMS(signames))
		return "";

	return signames[signo];
}

/**
 * str2sig - Translate signal name to the corresponding signal number.
 * @sig: The name of the signal
 *
 * A signal can be a complete signal name such as "SIGHUP", or
 * it can be the shortest unique name, such as "HUP" (no SIG prefix).
 */
int str2sig(char *sig)
{
	size_t i;

	if (!strncasecmp(sig, "SIG", 3))
		sig += 3;

	for (i = 1; i < NELEMS(signames); ++i) {
		if (strcasecmp(sig, signames[i]) == 0)
			return i;
	}

	return -1;
}

char *code2str(int code)
{
	if (code < 0 || code >= (int)NELEMS(exitcodes))
		return "";

	return exitcodes[code];
}

int str2rlim(char *str)
{
	const struct rlimit_name *rn;

	for (rn = rlimit_names; rn->name; rn++) {
		if (!strcmp(str, rn->name))
			return rn->val;
	}

	return -1;
}

char *rlim2str(int rlim)
{
	const struct rlimit_name *rn;

	for (rn = rlimit_names; rn->name; rn++) {
		if (rn->val == rlim)
			return rn->name;
	}

	return "unknown";
}

char *lim2str(struct rlimit *rlim)
{
	char tmp[25];
	static char buf[42];

	buf[0] = 0;
	if (RLIM_INFINITY == rlim->rlim_cur)
		snprintf(tmp, sizeof(tmp), "unlimited, ");
	else
		snprintf(tmp, sizeof(tmp), "%llu, ", (unsigned long long)rlim->rlim_cur);
	strlcat(buf, tmp, sizeof(buf));

	if (RLIM_INFINITY == rlim->rlim_max)
		snprintf(tmp, sizeof(tmp), "unlimited, ");
	else
		snprintf(tmp, sizeof(tmp), "%llu, ", (unsigned long long)rlim->rlim_max);
	strlcat(buf, tmp, sizeof(buf));

	return buf;
}

void do_sleep(unsigned int sec)
{
	struct timespec requested_sleep = {
		.tv_sec = sec,
		.tv_nsec = 0,
	};
	while (nanosleep(&requested_sleep, &requested_sleep))
		;
}

void do_usleep(unsigned int usec)
{
	struct timespec deadline;

	clock_gettime(CLOCK_MONOTONIC, &deadline);

	deadline.tv_nsec += usec * 1000;
	deadline.tv_sec += deadline.tv_nsec / 1000000000;
	deadline.tv_nsec = deadline.tv_nsec % 1000000000;

	while (clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &deadline, NULL) != 0 && errno == EINTR)
		;
}

/* Seconds since boot, from sysinfo() */
long jiffies(void)
{
	struct sysinfo si;

	if (!sysinfo(&si))
		return si.uptime;

	return 0;
}

char *uptime(long secs, char *buf, size_t len)
{
	long mins, hours, days, years;
	char y[20] = "", d[20] = "", h[20] = "", m[20] = "", s[20] = "";

	if (!buf) {
		errno = EINVAL;
		return NULL;
	}

	years = secs / 31556926;
	secs  = secs % 31556926;
	days  = secs / 86400;
	secs  = secs % 86400;
	hours = secs / 3600;
	secs  = secs % 3600;
	mins  = secs / 60;
	secs  = secs % 60;

	if (years)
		snprintf(y, sizeof(y), "%ld year", years);
	if (days)
		snprintf(d, sizeof(d), "%ld day", days);
	if (hours)
		snprintf(h, sizeof(h), "%ld hour", hours);
	if (mins)
		snprintf(m, sizeof(m), "%ld min", mins);
	if (secs)
		snprintf(s, sizeof(s), "%ld sec", secs);

	snprintf(buf, len, "%s%s%s%s%s%s%s%s%s",
		 y, years ? " " : "",
		 d, days  ? " " : "",
		 h, hours ? " " : "",
		 m, mins  ? " " : "",
		 s);

	return buf;
}

char *memsz(uint64_t sz, char *buf, size_t len)
{
        int gb, mb, kb, b;

	if (!sz) {
		strlcpy(buf, "--.--", len);
		return buf;
	}

        gb = sz / (1024 * 1024 * 1024);
        sz = sz % (1024 * 1024 * 1024);
        mb = sz / (1024 * 1024);
        sz = sz % (1024 * 1024);
        kb = sz / (1024);
        b  = sz % (1024);

        if (gb)
                snprintf(buf, len, "%d.%dG", gb, mb / 102);
        else if (mb)
                snprintf(buf, len, "%d.%dM", mb, kb / 102);
        else
                snprintf(buf, len, "%d.%dk", kb, b / 102);

        return buf;
}

/*
 * Verify string argument is NUL terminated
 * Verify string is a JOB[:ID], JOB and ID
 * can both be string or number, or combo.
 */
char *sanitize(char *arg, size_t len)
{
	const char *regex = "[a-z0-9_]+[:]?[a-z0-9_]*";
	regex_t preg;
	int rc;

	if (!memchr(arg, 0, len))
		return NULL;

	if (regcomp(&preg, regex, REG_ICASE | REG_EXTENDED))
		return NULL;

	rc = regexec(&preg, arg, 0, NULL, 0);
	regfree(&preg);
	if (rc)
		return NULL;

	return arg;
}

void de_dotdot(char *file)
{
        char *cp, *cp2;
        int l;

        /* Remove leading ./ and any /./ sequences. */
        while (strncmp(file, "./", 2) == 0)
                memmove(file, file + 2, strlen(file) - 1);
        while ((cp = strstr(file, "/./")))
                memmove(cp, cp + 2, strlen(cp) - 1);

        /* Alternate between removing leading ../ and removing xxx/../ */
        for (;;) {
                while (strncmp(file, "../", 3) == 0)
                        memmove(file, file + 3, strlen(file) - 2);
                cp = strstr(file, "/../");
                if (!cp)
                        break;

                for (cp2 = cp - 1; cp2 >= file && *cp2 != '/'; --cp2)
                        continue;

                memmove(cp2 + 1, cp + 4, strlen(cp + 3));
        }

        /* Also elide any xxx/.. at the end. */
        while ((l = strlen(file)) > 3 && strcmp((cp = file + l - 3), "/..") == 0) {
                for (cp2 = cp - 1; cp2 >= file && *cp2 != '/'; --cp2)
                        continue;
                if (cp2 < file)
                        break;
                *cp2 = '\0';
        }

        /* Collapse any multiple / sequences. */
        while ((cp = strstr(file, "//"))) {
                cp2 = cp + 1;
                memmove(cp, cp2, strlen(cp2) + 1);
        }
}

static int hasopt(char *opts, char *opt)
{
	char buf[strlen(opts) + 1];
	char *ptr;

	memcpy(buf, opts, sizeof(buf));
	ptr = strtok(buf, ",");
	while (ptr) {
		if (!strcmp(ptr, opt))
			return 1;

		ptr = strtok(NULL, ",");
	}

	return 0;
}

int ismnt(char *file, char *dir, char *mode)
{
	struct mntent mount;
	struct mntent *mnt;
	char buf[256];
	int found = 0;
	FILE *fp;

	fp = setmntent(file, "r");
	if (!fp)
		return 0;	/* Dunno, maybe not */

	while ((mnt = getmntent_r(fp, &mount, buf, sizeof(buf)))) {
		if (!strcmp(mnt->mnt_dir, dir)) {
			if (mode) {
				if (hasopt(mnt->mnt_opts, mode))
					found = 1;
			} else
				found = 1;

			break;
		}
	}
	endmntent(fp);

	return found;
}

/* Requires /proc to be mounted */
int fismnt(char *dir)
{
	return ismnt("/proc/mounts", dir, NULL);
}

/* Return 1 if dir is a backed by tmpfs or overlayfs */
int fistmpfs(char *dir)
{
	struct statfs info = {0};

	if (statfs(dir, &info))
		return 0;

	if (info.f_type == TMPFS_MAGIC || info.f_type == OVERLAYFS_SUPER_MAGIC)
		return 1;

	return 0;
}

#ifdef HAVE_TERMIOS_H
/*
 * Called by initctl, and by finit at boot and shutdown, to
 * (re)initialize the screen size for print() et al.
 */
int ttinit(int probe_size)
{
	struct pollfd fd = { STDIN_FILENO, POLLIN, 0 };
	struct winsize ws = { 0 };
	struct termios tc, saved;
	int cached = 0;

	/*
	 * Basic TTY init, CLOCaL is important or TIOCWINSZ will block
	 * until DCD is asserted, and we won't ever get it.
	 */
	if (!tcgetattr(STDERR_FILENO, &tc)) {
		saved = tc;
		cached = 1;

		tc.c_cflag |= (CLOCAL | CREAD);
		tc.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
		tcsetattr(STDERR_FILENO, TCSANOW, &tc);
	}

	if (probe_size)
		goto fallback;

	/* 1. Try TIOCWINSZ to query window size from kernel */
	if (!ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws)) {
		ttrows = ws.ws_row;
		ttcols = ws.ws_col;

		/* Likely doesn't work in PID 1 after kernel starts us ... */
		if (!ws.ws_row && !ws.ws_col)
			goto fallback;
	} else if (!isatty(STDOUT_FILENO)) {
		/* 2. We may be running under watch(1) */
		ttcols = atonum(getenv("COLUMNS"));
		ttrows = atonum(getenv("LINES"));
	} else {
	fallback:
		/* 3. ANSI goto + query cursor position trick as fallback */
		fprintf(stderr, "\e7\e[r\e[999;999H\e[6n");

		if (poll(&fd, 1, 300) > 0) {
			int row, col;

			if (scanf("\e[%d;%dR", &row, &col) == 2) {
				ttcols = col;
				ttrows = row;
			}
		}

		/* Jump back to where we started (\e7) */
		fprintf(stderr, "\e8");
	}

	if (cached)
		tcsetattr(STDERR_FILENO, TCSANOW, &saved);

	/* Sanity check */
	if (ttcols <= 0)
		ttcols = 80;
	if (ttrows <= 0)
		ttrows = 24;

	return ttcols;
}

/*
 * This function sets the terminal to RAW mode, as defined for the current
 * shell.  This is called both by ttopen() above and by spawncli() to
 * get the current terminal settings and then change them to what
 * mg expects.	Thus, tty changes done while spawncli() is in effect
 * will be reflected in mg.
 */
int ttraw(void)
{
	if (tcgetattr(0, &ttold) == -1) {
		fprintf(stderr, "%s: failed querying tty attrs: %s\n",
			prognm, strerror(errno));
		return 1;
	}

	(void)memcpy(&ttnew, &ttold, sizeof(ttnew));
	/* Set terminal to 'raw' mode and ignore a 'break' */
	ttnew.c_cc[VMIN] = 1;
	ttnew.c_cc[VTIME] = 0;
	ttnew.c_iflag |= IGNBRK;
	ttnew.c_iflag &= ~(BRKINT | PARMRK | INLCR | IGNCR | ICRNL | IXON);
	ttnew.c_oflag &= ~OPOST;
	ttnew.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);

	if (tcsetattr(0, TCSASOFT | TCSADRAIN, &ttnew) == -1) {
		fprintf(stderr, "%s: failed setting tty in raw mode: %s\n",
			prognm, strerror(errno));
		return 1;
	}

	return 0;
}

/*
 * This function restores all terminal settings to their default values,
 * in anticipation of exiting or suspending the editor.
 */
int ttcooked(void)
{
	if (tcsetattr(0, TCSASOFT | TCSADRAIN, &ttold) == -1) {
		fprintf(stderr, "%s: failed restoring tty to cooked mode: %s\n",
			prognm, strerror(errno));
		return 1;
	}

	return 0;
}
#endif /* HAVE_TERMIOS_H */

/**
 * Local Variables:
 *  indent-tabs-mode: t
 *  c-file-style: "linux"
 * End:
 */