Adding upstream version 252.22.upstream/252.22

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1463 insertions, 0 deletions

diff --git a/src/basic/terminal-util.c b/src/basic/terminal-util.c
new file mode 100644
index 0000000..b9d1ff8
--- /dev/null
+++ b/src/basic/terminal-util.c
@@ -0,0 +1,1463 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <linux/kd.h>
+#include <linux/tiocl.h>
+#include <linux/vt.h>
+#include <poll.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <sys/inotify.h>
+#include <sys/ioctl.h>
+#include <sys/sysmacros.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/utsname.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "def.h"
+#include "devnum-util.h"
+#include "env-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "inotify-util.h"
+#include "io-util.h"
+#include "log.h"
+#include "macro.h"
+#include "namespace-util.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "proc-cmdline.h"
+#include "process-util.h"
+#include "socket-util.h"
+#include "stat-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "terminal-util.h"
+#include "time-util.h"
+#include "user-util.h"
+#include "util.h"
+
+static volatile unsigned cached_columns = 0;
+static volatile unsigned cached_lines = 0;
+
+static volatile int cached_on_tty = -1;
+static volatile int cached_color_mode = _COLOR_INVALID;
+static volatile int cached_underline_enabled = -1;
+
+int chvt(int vt) {
+        _cleanup_close_ int fd = -1;
+
+        /* Switch to the specified vt number. If the VT is specified <= 0 switch to the VT the kernel log messages go,
+         * if that's configured. */
+
+        fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
+        if (fd < 0)
+                return -errno;
+
+        if (vt <= 0) {
+                int tiocl[2] = {
+                        TIOCL_GETKMSGREDIRECT,
+                        0
+                };
+
+                if (ioctl(fd, TIOCLINUX, tiocl) < 0)
+                        return -errno;
+
+                vt = tiocl[0] <= 0 ? 1 : tiocl[0];
+        }
+
+        return RET_NERRNO(ioctl(fd, VT_ACTIVATE, vt));
+}
+
+int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
+        _cleanup_free_ char *line = NULL;
+        struct termios old_termios;
+        int r, fd;
+
+        assert(f);
+        assert(ret);
+
+        /* If this is a terminal, then switch canonical mode off, so that we can read a single
+         * character. (Note that fmemopen() streams do not have an fd associated with them, let's handle that
+         * nicely.) */
+        fd = fileno(f);
+        if (fd >= 0 && tcgetattr(fd, &old_termios) >= 0) {
+                struct termios new_termios = old_termios;
+
+                new_termios.c_lflag &= ~ICANON;
+                new_termios.c_cc[VMIN] = 1;
+                new_termios.c_cc[VTIME] = 0;
+
+                if (tcsetattr(fd, TCSADRAIN, &new_termios) >= 0) {
+                        char c;
+
+                        if (t != USEC_INFINITY) {
+                                if (fd_wait_for_event(fd, POLLIN, t) <= 0) {
+                                        (void) tcsetattr(fd, TCSADRAIN, &old_termios);
+                                        return -ETIMEDOUT;
+                                }
+                        }
+
+                        r = safe_fgetc(f, &c);
+                        (void) tcsetattr(fd, TCSADRAIN, &old_termios);
+                        if (r < 0)
+                                return r;
+                        if (r == 0)
+                                return -EIO;
+
+                        if (need_nl)
+                                *need_nl = c != '\n';
+
+                        *ret = c;
+                        return 0;
+                }
+        }
+
+        if (t != USEC_INFINITY && fd > 0) {
+                /* Let's wait the specified amount of time for input. When we have no fd we skip this, under
+                 * the assumption that this is an fmemopen() stream or so where waiting doesn't make sense
+                 * anyway, as the data is either already in the stream or cannot possible be placed there
+                 * while we access the stream */
+
+                if (fd_wait_for_event(fd, POLLIN, t) <= 0)
+                        return -ETIMEDOUT;
+        }
+
+        /* If this is not a terminal, then read a full line instead */
+
+        r = read_line(f, 16, &line); /* longer than necessary, to eat up UTF-8 chars/vt100 key sequences */
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EIO;
+
+        if (strlen(line) != 1)
+                return -EBADMSG;
+
+        if (need_nl)
+                *need_nl = false;
+
+        *ret = line[0];
+        return 0;
+}
+
+#define DEFAULT_ASK_REFRESH_USEC (2*USEC_PER_SEC)
+
+int ask_char(char *ret, const char *replies, const char *fmt, ...) {
+        int r;
+
+        assert(ret);
+        assert(replies);
+        assert(fmt);
+
+        for (;;) {
+                va_list ap;
+                char c;
+                bool need_nl = true;
+
+                fputs(ansi_highlight(), stdout);
+
+                putchar('\r');
+
+                va_start(ap, fmt);
+                vprintf(fmt, ap);
+                va_end(ap);
+
+                fputs(ansi_normal(), stdout);
+
+                fflush(stdout);
+
+                r = read_one_char(stdin, &c, DEFAULT_ASK_REFRESH_USEC, &need_nl);
+                if (r < 0) {
+
+                        if (r == -ETIMEDOUT)
+                                continue;
+
+                        if (r == -EBADMSG) {
+                                puts("Bad input, please try again.");
+                                continue;
+                        }
+
+                        putchar('\n');
+                        return r;
+                }
+
+                if (need_nl)
+                        putchar('\n');
+
+                if (strchr(replies, c)) {
+                        *ret = c;
+                        return 0;
+                }
+
+                puts("Read unexpected character, please try again.");
+        }
+}
+
+int ask_string(char **ret, const char *text, ...) {
+        _cleanup_free_ char *line = NULL;
+        va_list ap;
+        int r;
+
+        assert(ret);
+        assert(text);
+
+        fputs(ansi_highlight(), stdout);
+
+        va_start(ap, text);
+        vprintf(text, ap);
+        va_end(ap);
+
+        fputs(ansi_normal(), stdout);
+
+        fflush(stdout);
+
+        r = read_line(stdin, LONG_LINE_MAX, &line);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EIO;
+
+        *ret = TAKE_PTR(line);
+        return 0;
+}
+
+int reset_terminal_fd(int fd, bool switch_to_text) {
+        struct termios termios;
+        int r = 0;
+
+        /* Set terminal to some sane defaults */
+
+        assert(fd >= 0);
+
+        if (isatty(fd) < 1)
+                return log_debug_errno(errno, "Asked to reset a terminal that actually isn't a terminal: %m");
+
+        /* We leave locked terminal attributes untouched, so that Plymouth may set whatever it wants to set,
+         * and we don't interfere with that. */
+
+        /* Disable exclusive mode, just in case */
+        if (ioctl(fd, TIOCNXCL) < 0)
+                log_debug_errno(errno, "TIOCNXCL ioctl failed on TTY, ignoring: %m");
+
+        /* Switch to text mode */
+        if (switch_to_text)
+                if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
+                        log_debug_errno(errno, "KDSETMODE ioctl for switching to text mode failed on TTY, ignoring: %m");
+
+
+        /* Set default keyboard mode */
+        (void) vt_reset_keyboard(fd);
+
+        if (tcgetattr(fd, &termios) < 0) {
+                r = log_debug_errno(errno, "Failed to get terminal parameters: %m");
+                goto finish;
+        }
+
+        /* We only reset the stuff that matters to the software. How
+         * hardware is set up we don't touch assuming that somebody
+         * else will do that for us */
+
+        termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
+        termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
+        termios.c_oflag |= ONLCR | OPOST;
+        termios.c_cflag |= CREAD;
+        termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE;
+
+        termios.c_cc[VINTR]    =   03;  /* ^C */
+        termios.c_cc[VQUIT]    =  034;  /* ^\ */
+        termios.c_cc[VERASE]   = 0177;
+        termios.c_cc[VKILL]    =  025;  /* ^X */
+        termios.c_cc[VEOF]     =   04;  /* ^D */
+        termios.c_cc[VSTART]   =  021;  /* ^Q */
+        termios.c_cc[VSTOP]    =  023;  /* ^S */
+        termios.c_cc[VSUSP]    =  032;  /* ^Z */
+        termios.c_cc[VLNEXT]   =  026;  /* ^V */
+        termios.c_cc[VWERASE]  =  027;  /* ^W */
+        termios.c_cc[VREPRINT] =  022;  /* ^R */
+        termios.c_cc[VEOL]     =    0;
+        termios.c_cc[VEOL2]    =    0;
+
+        termios.c_cc[VTIME]  = 0;
+        termios.c_cc[VMIN]   = 1;
+
+        if (tcsetattr(fd, TCSANOW, &termios) < 0)
+                r = -errno;
+
+finish:
+        /* Just in case, flush all crap out */
+        (void) tcflush(fd, TCIOFLUSH);
+
+        return r;
+}
+
+int reset_terminal(const char *name) {
+        _cleanup_close_ int fd = -1;
+
+        /* We open the terminal with O_NONBLOCK here, to ensure we
+         * don't block on carrier if this is a terminal with carrier
+         * configured. */
+
+        fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
+        if (fd < 0)
+                return fd;
+
+        return reset_terminal_fd(fd, true);
+}
+
+int open_terminal(const char *name, int mode) {
+        _cleanup_close_ int fd = -1;
+        unsigned c = 0;
+
+        /*
+         * If a TTY is in the process of being closed opening it might cause EIO. This is horribly awful, but
+         * unlikely to be changed in the kernel. Hence we work around this problem by retrying a couple of
+         * times.
+         *
+         * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
+         */
+
+        if (mode & O_CREAT)
+                return -EINVAL;
+
+        for (;;) {
+                fd = open(name, mode, 0);
+                if (fd >= 0)
+                        break;
+
+                if (errno != EIO)
+                        return -errno;
+
+                /* Max 1s in total */
+                if (c >= 20)
+                        return -errno;
+
+                (void) usleep(50 * USEC_PER_MSEC);
+                c++;
+        }
+
+        if (isatty(fd) < 1)
+                return negative_errno();
+
+        return TAKE_FD(fd);
+}
+
+int acquire_terminal(
+                const char *name,
+                AcquireTerminalFlags flags,
+                usec_t timeout) {
+
+        _cleanup_close_ int notify = -1, fd = -1;
+        usec_t ts = USEC_INFINITY;
+        int r, wd = -1;
+
+        assert(name);
+        assert(IN_SET(flags & ~ACQUIRE_TERMINAL_PERMISSIVE, ACQUIRE_TERMINAL_TRY, ACQUIRE_TERMINAL_FORCE, ACQUIRE_TERMINAL_WAIT));
+
+        /* We use inotify to be notified when the tty is closed. We create the watch before checking if we can actually
+         * acquire it, so that we don't lose any event.
+         *
+         * Note: strictly speaking this actually watches for the device being closed, it does *not* really watch
+         * whether a tty loses its controlling process. However, unless some rogue process uses TIOCNOTTY on /dev/tty
+         * *after* closing its tty otherwise this will not become a problem. As long as the administrator makes sure to
+         * not configure any service on the same tty as an untrusted user this should not be a problem. (Which they
+         * probably should not do anyway.) */
+
+        if ((flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_WAIT) {
+                notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
+                if (notify < 0)
+                        return -errno;
+
+                wd = inotify_add_watch(notify, name, IN_CLOSE);
+                if (wd < 0)
+                        return -errno;
+
+                if (timeout != USEC_INFINITY)
+                        ts = now(CLOCK_MONOTONIC);
+        }
+
+        for (;;) {
+                struct sigaction sa_old, sa_new = {
+                        .sa_handler = SIG_IGN,
+                        .sa_flags = SA_RESTART,
+                };
+
+                if (notify >= 0) {
+                        r = flush_fd(notify);
+                        if (r < 0)
+                                return r;
+                }
+
+                /* We pass here O_NOCTTY only so that we can check the return value TIOCSCTTY and have a reliable way
+                 * to figure out if we successfully became the controlling process of the tty */
+                fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
+                if (fd < 0)
+                        return fd;
+
+                /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed if we already own the tty. */
+                assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
+
+                /* First, try to get the tty */
+                r = RET_NERRNO(ioctl(fd, TIOCSCTTY, (flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_FORCE));
+
+                /* Reset signal handler to old value */
+                assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
+
+                /* Success? Exit the loop now! */
+                if (r >= 0)
+                        break;
+
+                /* Any failure besides -EPERM? Fail, regardless of the mode. */
+                if (r != -EPERM)
+                        return r;
+
+                if (flags & ACQUIRE_TERMINAL_PERMISSIVE) /* If we are in permissive mode, then EPERM is fine, turn this
+                                                          * into a success. Note that EPERM is also returned if we
+                                                          * already are the owner of the TTY. */
+                        break;
+
+                if (flags != ACQUIRE_TERMINAL_WAIT) /* If we are in TRY or FORCE mode, then propagate EPERM as EPERM */
+                        return r;
+
+                assert(notify >= 0);
+                assert(wd >= 0);
+
+                for (;;) {
+                        union inotify_event_buffer buffer;
+                        ssize_t l;
+
+                        if (timeout != USEC_INFINITY) {
+                                usec_t n;
+
+                                assert(ts != USEC_INFINITY);
+
+                                n = usec_sub_unsigned(now(CLOCK_MONOTONIC), ts);
+                                if (n >= timeout)
+                                        return -ETIMEDOUT;
+
+                                r = fd_wait_for_event(notify, POLLIN, usec_sub_unsigned(timeout, n));
+                                if (r < 0)
+                                        return r;
+                                if (r == 0)
+                                        return -ETIMEDOUT;
+                        }
+
+                        l = read(notify, &buffer, sizeof(buffer));
+                        if (l < 0) {
+                                if (ERRNO_IS_TRANSIENT(errno))
+                                        continue;
+
+                                return -errno;
+                        }
+
+                        FOREACH_INOTIFY_EVENT(e, buffer, l) {
+                                if (e->mask & IN_Q_OVERFLOW) /* If we hit an inotify queue overflow, simply check if the terminal is up for grabs now. */
+                                        break;
+
+                                if (e->wd != wd || !(e->mask & IN_CLOSE)) /* Safety checks */
+                                        return -EIO;
+                        }
+
+                        break;
+                }
+
+                /* We close the tty fd here since if the old session ended our handle will be dead. It's important that
+                 * we do this after sleeping, so that we don't enter an endless loop. */
+                fd = safe_close(fd);
+        }
+
+        return TAKE_FD(fd);
+}
+
+int release_terminal(void) {
+        static const struct sigaction sa_new = {
+                .sa_handler = SIG_IGN,
+                .sa_flags = SA_RESTART,
+        };
+
+        _cleanup_close_ int fd = -1;
+        struct sigaction sa_old;
+        int r;
+
+        fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
+        if (fd < 0)
+                return -errno;
+
+        /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
+         * by our own TIOCNOTTY */
+        assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
+
+        r = RET_NERRNO(ioctl(fd, TIOCNOTTY));
+
+        assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
+
+        return r;
+}
+
+int terminal_vhangup_fd(int fd) {
+        assert(fd >= 0);
+        return RET_NERRNO(ioctl(fd, TIOCVHANGUP));
+}
+
+int terminal_vhangup(const char *name) {
+        _cleanup_close_ int fd = -1;
+
+        fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
+        if (fd < 0)
+                return fd;
+
+        return terminal_vhangup_fd(fd);
+}
+
+int vt_disallocate(const char *name) {
+        const char *e;
+        int r;
+
+        /* Deallocate the VT if possible. If not possible
+         * (i.e. because it is the active one), at least clear it
+         * entirely (including the scrollback buffer). */
+
+        e = path_startswith(name, "/dev/");
+        if (!e)
+                return -EINVAL;
+
+        if (tty_is_vc(name)) {
+                _cleanup_close_ int fd = -1;
+                unsigned u;
+                const char *n;
+
+                n = startswith(e, "tty");
+                if (!n)
+                        return -EINVAL;
+
+                r = safe_atou(n, &u);
+                if (r < 0)
+                        return r;
+
+                if (u <= 0)
+                        return -EINVAL;
+
+                /* Try to deallocate */
+                fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
+                if (fd < 0)
+                        return fd;
+
+                r = ioctl(fd, VT_DISALLOCATE, u);
+                if (r >= 0)
+                        return 0;
+                if (errno != EBUSY)
+                        return -errno;
+        }
+
+        /* So this is not a VT (in which case we cannot deallocate it),
+         * or we failed to deallocate. Let's at least clear the screen. */
+
+        _cleanup_close_ int fd2 = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (fd2 < 0)
+                return fd2;
+
+        (void) loop_write(fd2,
+                          "\033[r"   /* clear scrolling region */
+                          "\033[H"   /* move home */
+                          "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
+                          10, false);
+        return 0;
+}
+
+int make_console_stdio(void) {
+        int fd, r;
+
+        /* Make /dev/console the controlling terminal and stdin/stdout/stderr, if we can. If we can't use
+         * /dev/null instead. This is particularly useful if /dev/console is turned off, e.g. if console=null
+         * is specified on the kernel command line. */
+
+        fd = acquire_terminal("/dev/console", ACQUIRE_TERMINAL_FORCE|ACQUIRE_TERMINAL_PERMISSIVE, USEC_INFINITY);
+        if (fd < 0) {
+                log_warning_errno(fd, "Failed to acquire terminal, using /dev/null stdin/stdout/stderr instead: %m");
+
+                r = make_null_stdio();
+                if (r < 0)
+                        return log_error_errno(r, "Failed to make /dev/null stdin/stdout/stderr: %m");
+
+        } else {
+                r = reset_terminal_fd(fd, true);
+                if (r < 0)
+                        log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
+
+                r = rearrange_stdio(fd, fd, fd); /* This invalidates 'fd' both on success and on failure. */
+                if (r < 0)
+                        return log_error_errno(r, "Failed to make terminal stdin/stdout/stderr: %m");
+        }
+
+        reset_terminal_feature_caches();
+        return 0;
+}
+
+bool tty_is_vc(const char *tty) {
+        assert(tty);
+
+        return vtnr_from_tty(tty) >= 0;
+}
+
+bool tty_is_console(const char *tty) {
+        assert(tty);
+
+        return streq(skip_dev_prefix(tty), "console");
+}
+
+int vtnr_from_tty(const char *tty) {
+        int i, r;
+
+        assert(tty);
+
+        tty = skip_dev_prefix(tty);
+
+        if (!startswith(tty, "tty") )
+                return -EINVAL;
+
+        if (!ascii_isdigit(tty[3]))
+                return -EINVAL;
+
+        r = safe_atoi(tty+3, &i);
+        if (r < 0)
+                return r;
+
+        if (i < 0 || i > 63)
+                return -EINVAL;
+
+        return i;
+}
+
+ int resolve_dev_console(char **ret) {
+        _cleanup_free_ char *active = NULL;
+        char *tty;
+        int r;
+
+        assert(ret);
+
+        /* Resolve where /dev/console is pointing to, if /sys is actually ours (i.e. not read-only-mounted which is a
+         * sign for container setups) */
+
+        if (path_is_read_only_fs("/sys") > 0)
+                return -ENOMEDIUM;
+
+        r = read_one_line_file("/sys/class/tty/console/active", &active);
+        if (r < 0)
+                return r;
+
+        /* If multiple log outputs are configured the last one is what /dev/console points to */
+        tty = strrchr(active, ' ');
+        if (tty)
+                tty++;
+        else
+                tty = active;
+
+        if (streq(tty, "tty0")) {
+                active = mfree(active);
+
+                /* Get the active VC (e.g. tty1) */
+                r = read_one_line_file("/sys/class/tty/tty0/active", &active);
+                if (r < 0)
+                        return r;
+
+                tty = active;
+        }
+
+        if (tty == active)
+                *ret = TAKE_PTR(active);
+        else {
+                char *tmp;
+
+                tmp = strdup(tty);
+                if (!tmp)
+                        return -ENOMEM;
+
+                *ret = tmp;
+        }
+
+        return 0;
+}
+
+int get_kernel_consoles(char ***ret) {
+        _cleanup_strv_free_ char **l = NULL;
+        _cleanup_free_ char *line = NULL;
+        const char *p;
+        int r;
+
+        assert(ret);
+
+        /* If /sys is mounted read-only this means we are running in some kind of container environment. In that
+         * case /sys would reflect the host system, not us, hence ignore the data we can read from it. */
+        if (path_is_read_only_fs("/sys") > 0)
+                goto fallback;
+
+        r = read_one_line_file("/sys/class/tty/console/active", &line);
+        if (r < 0)
+                return r;
+
+        p = line;
+        for (;;) {
+                _cleanup_free_ char *tty = NULL, *path = NULL;
+
+                r = extract_first_word(&p, &tty, NULL, 0);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        break;
+
+                if (streq(tty, "tty0")) {
+                        tty = mfree(tty);
+                        r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
+                        if (r < 0)
+                                return r;
+                }
+
+                path = path_join("/dev", tty);
+                if (!path)
+                        return -ENOMEM;
+
+                if (access(path, F_OK) < 0) {
+                        log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
+                        continue;
+                }
+
+                r = strv_consume(&l, TAKE_PTR(path));
+                if (r < 0)
+                        return r;
+        }
+
+        if (strv_isempty(l)) {
+                log_debug("No devices found for system console");
+                goto fallback;
+        }
+
+        *ret = TAKE_PTR(l);
+
+        return 0;
+
+fallback:
+        r = strv_extend(&l, "/dev/console");
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(l);
+
+        return 0;
+}
+
+bool tty_is_vc_resolve(const char *tty) {
+        _cleanup_free_ char *resolved = NULL;
+
+        assert(tty);
+
+        tty = skip_dev_prefix(tty);
+
+        if (streq(tty, "console")) {
+                if (resolve_dev_console(&resolved) < 0)
+                        return false;
+
+                tty = resolved;
+        }
+
+        return tty_is_vc(tty);
+}
+
+const char *default_term_for_tty(const char *tty) {
+        return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
+}
+
+int fd_columns(int fd) {
+        struct winsize ws = {};
+
+        if (fd < 0)
+                return -EBADF;
+
+        if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
+                return -errno;
+
+        if (ws.ws_col <= 0)
+                return -EIO;
+
+        return ws.ws_col;
+}
+
+unsigned columns(void) {
+        const char *e;
+        int c;
+
+        if (cached_columns > 0)
+                return cached_columns;
+
+        c = 0;
+        e = getenv("COLUMNS");
+        if (e)
+                (void) safe_atoi(e, &c);
+
+        if (c <= 0 || c > USHRT_MAX) {
+                c = fd_columns(STDOUT_FILENO);
+                if (c <= 0)
+                        c = 80;
+        }
+
+        cached_columns = c;
+        return cached_columns;
+}
+
+int fd_lines(int fd) {
+        struct winsize ws = {};
+
+        if (fd < 0)
+                return -EBADF;
+
+        if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
+                return -errno;
+
+        if (ws.ws_row <= 0)
+                return -EIO;
+
+        return ws.ws_row;
+}
+
+unsigned lines(void) {
+        const char *e;
+        int l;
+
+        if (cached_lines > 0)
+                return cached_lines;
+
+        l = 0;
+        e = getenv("LINES");
+        if (e)
+                (void) safe_atoi(e, &l);
+
+        if (l <= 0 || l > USHRT_MAX) {
+                l = fd_lines(STDOUT_FILENO);
+                if (l <= 0)
+                        l = 24;
+        }
+
+        cached_lines = l;
+        return cached_lines;
+}
+
+int terminal_set_size_fd(int fd, const char *ident, unsigned rows, unsigned cols) {
+        struct winsize ws;
+
+        if (rows == UINT_MAX && cols == UINT_MAX)
+                return 0;
+
+        if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
+                return log_debug_errno(errno,
+                                       "TIOCGWINSZ ioctl for getting %s size failed, not setting terminal size: %m",
+                                       ident ?: "TTY");
+
+        if (rows == UINT_MAX)
+                rows = ws.ws_row;
+        else if (rows > USHRT_MAX)
+                rows = USHRT_MAX;
+
+        if (cols == UINT_MAX)
+                cols = ws.ws_col;
+        else if (cols > USHRT_MAX)
+                cols = USHRT_MAX;
+
+        if (rows == ws.ws_row && cols == ws.ws_col)
+                return 0;
+
+        ws.ws_row = rows;
+        ws.ws_col = cols;
+
+        if (ioctl(fd, TIOCSWINSZ, &ws) < 0)
+                return log_debug_errno(errno, "TIOCSWINSZ ioctl for setting %s size failed: %m", ident ?: "TTY");
+
+        return 0;
+}
+
+/* intended to be used as a SIGWINCH sighandler */
+void columns_lines_cache_reset(int signum) {
+        cached_columns = 0;
+        cached_lines = 0;
+}
+
+void reset_terminal_feature_caches(void) {
+        cached_columns = 0;
+        cached_lines = 0;
+
+        cached_color_mode = _COLOR_INVALID;
+        cached_underline_enabled = -1;
+        cached_on_tty = -1;
+}
+
+bool on_tty(void) {
+
+        /* We check both stdout and stderr, so that situations where pipes on the shell are used are reliably
+         * recognized, regardless if only the output or the errors are piped to some place. Since on_tty() is generally
+         * used to default to a safer, non-interactive, non-color mode of operation it's probably good to be defensive
+         * here, and check for both. Note that we don't check for STDIN_FILENO, because it should fine to use fancy
+         * terminal functionality when outputting stuff, even if the input is piped to us. */
+
+        if (cached_on_tty < 0)
+                cached_on_tty =
+                        isatty(STDOUT_FILENO) > 0 &&
+                        isatty(STDERR_FILENO) > 0;
+
+        return cached_on_tty;
+}
+
+int getttyname_malloc(int fd, char **ret) {
+        char path[PATH_MAX], *c; /* PATH_MAX is counted *with* the trailing NUL byte */
+        int r;
+
+        assert(fd >= 0);
+        assert(ret);
+
+        r = ttyname_r(fd, path, sizeof path); /* positive error */
+        assert(r >= 0);
+        if (r == ERANGE)
+                return -ENAMETOOLONG;
+        if (r > 0)
+                return -r;
+
+        c = strdup(skip_dev_prefix(path));
+        if (!c)
+                return -ENOMEM;
+
+        *ret = c;
+        return 0;
+}
+
+int getttyname_harder(int fd, char **ret) {
+        _cleanup_free_ char *s = NULL;
+        int r;
+
+        r = getttyname_malloc(fd, &s);
+        if (r < 0)
+                return r;
+
+        if (streq(s, "tty"))
+                return get_ctty(0, NULL, ret);
+
+        *ret = TAKE_PTR(s);
+        return 0;
+}
+
+int get_ctty_devnr(pid_t pid, dev_t *d) {
+        int r;
+        _cleanup_free_ char *line = NULL;
+        const char *p;
+        unsigned long ttynr;
+
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "stat");
+        r = read_one_line_file(p, &line);
+        if (r < 0)
+                return r;
+
+        p = strrchr(line, ')');
+        if (!p)
+                return -EIO;
+
+        p++;
+
+        if (sscanf(p, " "
+                   "%*c "  /* state */
+                   "%*d "  /* ppid */
+                   "%*d "  /* pgrp */
+                   "%*d "  /* session */
+                   "%lu ", /* ttynr */
+                   &ttynr) != 1)
+                return -EIO;
+
+        if (major(ttynr) == 0 && minor(ttynr) == 0)
+                return -ENXIO;
+
+        if (d)
+                *d = (dev_t) ttynr;
+
+        return 0;
+}
+
+int get_ctty(pid_t pid, dev_t *ret_devnr, char **ret) {
+        char pty[STRLEN("/dev/pts/") + DECIMAL_STR_MAX(dev_t) + 1];
+        _cleanup_free_ char *buf = NULL;
+        const char *fn = NULL, *w;
+        dev_t devnr;
+        int r;
+
+        r = get_ctty_devnr(pid, &devnr);
+        if (r < 0)
+                return r;
+
+        r = device_path_make_canonical(S_IFCHR, devnr, &buf);
+        if (r < 0) {
+                struct stat st;
+
+                if (r != -ENOENT) /* No symlink for this in /dev/char/? */
+                        return r;
+
+                /* Maybe this is PTY? PTY devices are not listed in /dev/char/, as they don't follow the
+                 * Linux device model and hence device_path_make_canonical() doesn't work for them. Let's
+                 * assume this is a PTY for a moment, and check if the device node this would then map to in
+                 * /dev/pts/ matches the one we are looking for. This way we don't have to hardcode the major
+                 * number (which is 136 btw), but we still rely on the fact that PTY numbers map directly to
+                 * the minor number of the pty. */
+                xsprintf(pty, "/dev/pts/%u", minor(devnr));
+
+                if (stat(pty, &st) < 0) {
+                        if (errno != ENOENT)
+                                return -errno;
+
+                } else if (S_ISCHR(st.st_mode) && devnr == st.st_rdev) /* Bingo! */
+                        fn = pty;
+
+                if (!fn) {
+                        /* Doesn't exist, or not a PTY? Probably something similar to the PTYs which have no
+                         * symlink in /dev/char/. Let's return something vaguely useful. */
+                        r = device_path_make_major_minor(S_IFCHR, devnr, &buf);
+                        if (r < 0)
+                                return r;
+
+                        fn = buf;
+                }
+        } else
+                fn = buf;
+
+        w = path_startswith(fn, "/dev/");
+        if (!w)
+                return -EINVAL;
+
+        if (ret) {
+                _cleanup_free_ char *b = NULL;
+
+                b = strdup(w);
+                if (!b)
+                        return -ENOMEM;
+
+                *ret = TAKE_PTR(b);
+        }
+
+        if (ret_devnr)
+                *ret_devnr = devnr;
+
+        return 0;
+}
+
+int ptsname_malloc(int fd, char **ret) {
+        size_t l = 100;
+
+        assert(fd >= 0);
+        assert(ret);
+
+        for (;;) {
+                char *c;
+
+                c = new(char, l);
+                if (!c)
+                        return -ENOMEM;
+
+                if (ptsname_r(fd, c, l) == 0) {
+                        *ret = c;
+                        return 0;
+                }
+                if (errno != ERANGE) {
+                        free(c);
+                        return -errno;
+                }
+
+                free(c);
+
+                if (l > SIZE_MAX / 2)
+                        return -ENOMEM;
+
+                l *= 2;
+        }
+}
+
+int openpt_allocate(int flags, char **ret_slave) {
+        _cleanup_close_ int fd = -1;
+        _cleanup_free_ char *p = NULL;
+        int r;
+
+        fd = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        if (ret_slave) {
+                r = ptsname_malloc(fd, &p);
+                if (r < 0)
+                        return r;
+
+                if (!path_startswith(p, "/dev/pts/"))
+                        return -EINVAL;
+        }
+
+        if (unlockpt(fd) < 0)
+                return -errno;
+
+        if (ret_slave)
+                *ret_slave = TAKE_PTR(p);
+
+        return TAKE_FD(fd);
+}
+
+static int ptsname_namespace(int pty, char **ret) {
+        int no = -1, r;
+
+        /* Like ptsname(), but doesn't assume that the path is
+         * accessible in the local namespace. */
+
+        r = ioctl(pty, TIOCGPTN, &no);
+        if (r < 0)
+                return -errno;
+
+        if (no < 0)
+                return -EIO;
+
+        if (asprintf(ret, "/dev/pts/%i", no) < 0)
+                return -ENOMEM;
+
+        return 0;
+}
+
+int openpt_allocate_in_namespace(pid_t pid, int flags, char **ret_slave) {
+        _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1, fd = -1;
+        _cleanup_close_pair_ int pair[2] = { -1, -1 };
+        pid_t child;
+        int r;
+
+        assert(pid > 0);
+
+        r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
+        if (r < 0)
+                return r;
+
+        if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
+                return -errno;
+
+        r = namespace_fork("(sd-openptns)", "(sd-openpt)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
+                           pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                pair[0] = safe_close(pair[0]);
+
+                fd = openpt_allocate(flags, NULL);
+                if (fd < 0)
+                        _exit(EXIT_FAILURE);
+
+                if (send_one_fd(pair[1], fd, 0) < 0)
+                        _exit(EXIT_FAILURE);
+
+                _exit(EXIT_SUCCESS);
+        }
+
+        pair[1] = safe_close(pair[1]);
+
+        r = wait_for_terminate_and_check("(sd-openptns)", child, 0);
+        if (r < 0)
+                return r;
+        if (r != EXIT_SUCCESS)
+                return -EIO;
+
+        fd = receive_one_fd(pair[0], 0);
+        if (fd < 0)
+                return fd;
+
+        if (ret_slave) {
+                r = ptsname_namespace(fd, ret_slave);
+                if (r < 0)
+                        return r;
+        }
+
+        return TAKE_FD(fd);
+}
+
+int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
+        _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
+        _cleanup_close_pair_ int pair[2] = { -1, -1 };
+        pid_t child;
+        int r;
+
+        r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
+        if (r < 0)
+                return r;
+
+        if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
+                return -errno;
+
+        r = namespace_fork("(sd-terminalns)", "(sd-terminal)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
+                           pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                int master;
+
+                pair[0] = safe_close(pair[0]);
+
+                master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
+                if (master < 0)
+                        _exit(EXIT_FAILURE);
+
+                if (send_one_fd(pair[1], master, 0) < 0)
+                        _exit(EXIT_FAILURE);
+
+                _exit(EXIT_SUCCESS);
+        }
+
+        pair[1] = safe_close(pair[1]);
+
+        r = wait_for_terminate_and_check("(sd-terminalns)", child, 0);
+        if (r < 0)
+                return r;
+        if (r != EXIT_SUCCESS)
+                return -EIO;
+
+        return receive_one_fd(pair[0], 0);
+}
+
+static bool getenv_terminal_is_dumb(void) {
+        const char *e;
+
+        e = getenv("TERM");
+        if (!e)
+                return true;
+
+        return streq(e, "dumb");
+}
+
+bool terminal_is_dumb(void) {
+        if (!on_tty())
+                return true;
+
+        return getenv_terminal_is_dumb();
+}
+
+static ColorMode parse_systemd_colors(void) {
+        const char *e;
+        int r;
+
+        e = getenv("SYSTEMD_COLORS");
+        if (!e)
+                return _COLOR_INVALID;
+        if (streq(e, "16"))
+                return COLOR_16;
+        if (streq(e, "256"))
+                return COLOR_256;
+        r = parse_boolean(e);
+        if (r >= 0)
+                return r > 0 ? COLOR_ON : COLOR_OFF;
+        return _COLOR_INVALID;
+}
+
+ColorMode get_color_mode(void) {
+
+        /* Returns the mode used to choose output colors. The possible modes are COLOR_OFF for no colors,
+         * COLOR_16 for only the base 16 ANSI colors, COLOR_256 for more colors and COLOR_ON for unrestricted
+         * color output. For that we check $SYSTEMD_COLORS first (which is the explicit way to
+         * change the mode). If that didn't work we turn colors off unless we are on a TTY. And if we are on a TTY
+         * we turn it off if $TERM is set to "dumb". There's one special tweak though: if we are PID 1 then we do not
+         * check whether we are connected to a TTY, because we don't keep /dev/console open continuously due to fear
+         * of SAK, and hence things are a bit weird. */
+        ColorMode m;
+
+        if (cached_color_mode < 0) {
+                m = parse_systemd_colors();
+                if (m >= 0)
+                        cached_color_mode = m;
+                else if (getenv("NO_COLOR"))
+                        /* We only check for the presence of the variable; value is ignored. */
+                        cached_color_mode = COLOR_OFF;
+
+                else if (getpid_cached() == 1) {
+                        /* PID1 outputs to the console without holding it open all the time.
+                         *
+                         * Note that the Linux console can only display 16 colors. We still enable 256 color
+                         * mode even for PID1 output though (which typically goes to the Linux console),
+                         * since the Linux console is able to parse the 256 color sequences and automatically
+                         * map them to the closest color in the 16 color palette (since kernel 3.16). Doing
+                         * 256 colors is nice for people who invoke systemd in a container or via a serial
+                         * link or such, and use a true 256 color terminal to do so. */
+                        if (getenv_terminal_is_dumb())
+                                cached_color_mode = COLOR_OFF;
+                } else {
+                        if (terminal_is_dumb())
+                                cached_color_mode = COLOR_OFF;
+                }
+
+                if (cached_color_mode < 0) {
+                        /* We failed to figure out any reason to *disable* colors.
+                         * Let's see how many colors we shall use. */
+                        if (STRPTR_IN_SET(getenv("COLORTERM"),
+                                          "truecolor",
+                                          "24bit"))
+                                cached_color_mode = COLOR_24BIT;
+                        else
+                                cached_color_mode = COLOR_256;
+                }
+        }
+
+        return cached_color_mode;
+}
+
+bool dev_console_colors_enabled(void) {
+        _cleanup_free_ char *s = NULL;
+        ColorMode m;
+
+        /* Returns true if we assume that color is supported on /dev/console.
+         *
+         * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
+         * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
+         * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
+         * colors_enabled() operates. */
+
+        m = parse_systemd_colors();
+        if (m >= 0)
+                return m;
+
+        if (getenv("NO_COLOR"))
+                return false;
+
+        if (getenv_for_pid(1, "TERM", &s) <= 0)
+                (void) proc_cmdline_get_key("TERM", 0, &s);
+
+        return !streq_ptr(s, "dumb");
+}
+
+bool underline_enabled(void) {
+
+        if (cached_underline_enabled < 0) {
+
+                /* The Linux console doesn't support underlining, turn it off, but only there. */
+
+                if (colors_enabled())
+                        cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
+                else
+                        cached_underline_enabled = false;
+        }
+
+        return cached_underline_enabled;
+}
+
+int vt_default_utf8(void) {
+        _cleanup_free_ char *b = NULL;
+        int r;
+
+        /* Read the default VT UTF8 setting from the kernel */
+
+        r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
+        if (r < 0)
+                return r;
+
+        return parse_boolean(b);
+}
+
+int vt_reset_keyboard(int fd) {
+        int kb;
+
+        /* If we can't read the default, then default to unicode. It's 2017 after all. */
+        kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
+
+        return RET_NERRNO(ioctl(fd, KDSKBMODE, kb));
+}
+
+int vt_restore(int fd) {
+        static const struct vt_mode mode = {
+                .mode = VT_AUTO,
+        };
+        int r, q = 0;
+
+        if (isatty(fd) < 1)
+                return log_debug_errno(errno, "Asked to restore the VT for an fd that does not refer to a terminal: %m");
+
+        if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
+                q = log_debug_errno(errno, "Failed to set VT in text mode, ignoring: %m");
+
+        r = vt_reset_keyboard(fd);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to reset keyboard mode, ignoring: %m");
+                if (q >= 0)
+                        q = r;
+        }
+
+        if (ioctl(fd, VT_SETMODE, &mode) < 0) {
+                log_debug_errno(errno, "Failed to set VT_AUTO mode, ignoring: %m");
+                if (q >= 0)
+                        q = -errno;
+        }
+
+        r = fchmod_and_chown(fd, TTY_MODE, 0, GID_INVALID);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to chmod()/chown() VT, ignoring: %m");
+                if (q >= 0)
+                        q = r;
+        }
+
+        return q;
+}
+
+int vt_release(int fd, bool restore) {
+        assert(fd >= 0);
+
+        /* This function releases the VT by acknowledging the VT-switch signal
+         * sent by the kernel and optionally reset the VT in text and auto
+         * VT-switching modes. */
+
+        if (isatty(fd) < 1)
+                return log_debug_errno(errno, "Asked to release the VT for an fd that does not refer to a terminal: %m");
+
+        if (ioctl(fd, VT_RELDISP, 1) < 0)
+                return -errno;
+
+        if (restore)
+                return vt_restore(fd);
+
+        return 0;
+}
+
+void get_log_colors(int priority, const char **on, const char **off, const char **highlight) {
+        /* Note that this will initialize output variables only when there's something to output.
+         * The caller must pre-initialize to "" or NULL as appropriate. */
+
+        if (priority <= LOG_ERR) {
+                if (on)
+                        *on = ansi_highlight_red();
+                if (off)
+                        *off = ansi_normal();
+                if (highlight)
+                        *highlight = ansi_highlight();
+
+        } else if (priority <= LOG_WARNING) {
+                if (on)
+                        *on = ansi_highlight_yellow();
+                if (off)
+                        *off = ansi_normal();
+                if (highlight)
+                        *highlight = ansi_highlight();
+
+        } else if (priority <= LOG_NOTICE) {
+                if (on)
+                        *on = ansi_highlight();
+                if (off)
+                        *off = ansi_normal();
+                if (highlight)
+                        *highlight = ansi_highlight_red();
+
+        } else if (priority >= LOG_DEBUG) {
+                if (on)
+                        *on = ansi_grey();
+                if (off)
+                        *off = ansi_normal();
+                if (highlight)
+                        *highlight = ansi_highlight_red();
+        }
+}