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systemd/src/basic/terminal-util.c
Zbigniew Jędrzejewski-Szmek 711b5e805d Revert "terminal-util: explicitly reset cursor" 
This reverts commit b177095bfa.

The original issue (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=375275,
https://github.com/systemd/systemd/issues/22168) was about having a block
cursor instead of a box cursor after VM reset, which doesn't seem particularly
urgent. OTOH, the patch causes a minor regression, where the splash screen is
cleared immediately and replaced by a blinking cursor. With the patch, we are
trading one visual issue for another visual issue. The second is probably more
noticeable, since some poeple put in quite a lot of work to have pretty boots
where the firmware splash screen is displayed until the login prompt pops up.
Avoiding a regression is more important than fixing a minor long-standing
issue, so let's revert this.

Fixes https://github.com/systemd/systemd/issues/38752.
2025-09-05 11:18:51 +02:00

2672 lines
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <fcntl.h>
#include <linux/kd.h>
#include <linux/magic.h>
#include <linux/tiocl.h>
#include <linux/vt.h>
#include <poll.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/inotify.h>
#include <sys/ioctl.h>
#include <sys/sysmacros.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>
#include "alloc-util.h"
#include "ansi-color.h"
#include "chase.h"
#include "devnum-util.h"
#include "errno-util.h"
#include "extract-word.h"
#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "hexdecoct.h"
#include "inotify-util.h"
#include "io-util.h"
#include "log.h"
#include "namespace-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "proc-cmdline.h"
#include "process-util.h"
#include "signal-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 "utf8.h"
/* How much to wait for a reply to a terminal sequence */
#define CONSOLE_REPLY_WAIT_USEC (333 * USEC_PER_MSEC)
static volatile unsigned cached_columns = 0;
static volatile unsigned cached_lines = 0;
static volatile int cached_on_tty = -1;
static volatile int cached_on_dev_null = -1;
bool isatty_safe(int fd) {
assert(fd >= 0);
if (isatty(fd))
return true;
/* Linux/glibc returns EIO for hung up TTY on isatty(). Which is wrong, the thing doesn't stop being
* a TTY after all, just because it is temporarily hung up. Let's work around this here, until this
* is fixed in glibc. See: https://sourceware.org/bugzilla/show_bug.cgi?id=32103 */
if (errno == EIO)
return true;
/* Be resilient if we're working on stdio, since they're set up by parent process. */
assert(errno != EBADF || IN_SET(fd, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO));
return false;
}
int chvt(int vt) {
_cleanup_close_ int fd = -EBADF;
/* 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 fd;
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 echo, bool *need_nl) {
_cleanup_free_ char *line = NULL;
struct termios old_termios;
int r, fd;
assert(ret);
if (!f)
f = stdin;
/* 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.) If 'echo' is false we'll also disable ECHO mode so that the pressed key is not made
* visible to the user. */
fd = fileno(f);
if (fd >= 0 && tcgetattr(fd, &old_termios) >= 0) {
struct termios new_termios = old_termios;
new_termios.c_lflag &= ~(ICANON|(echo ? 0 : ECHO));
new_termios.c_cc[VMIN] = 1;
new_termios.c_cc[VTIME] = 0;
if (tcsetattr(fd, TCSANOW, &new_termios) >= 0) {
char c;
if (t != USEC_INFINITY) {
if (fd_wait_for_event(fd, POLLIN, t) <= 0) {
(void) tcsetattr(fd, TCSANOW, &old_termios);
return -ETIMEDOUT;
}
}
r = safe_fgetc(f, &c);
(void) tcsetattr(fd, TCSANOW, &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, /* echo= */ true, &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.");
}
}
typedef enum CompletionResult{
COMPLETION_ALREADY, /* the input string is already complete */
COMPLETION_FULL, /* completed the input string to be complete now */
COMPLETION_PARTIAL, /* completed the input string so that is still incomplete */
COMPLETION_NONE, /* found no matching completion */
_COMPLETION_RESULT_MAX,
_COMPLETION_RESULT_INVALID = -EINVAL,
_COMPLETION_RESULT_ERRNO_MAX = -ERRNO_MAX,
} CompletionResult;
static CompletionResult pick_completion(const char *string, char *const*completions, char **ret) {
_cleanup_free_ char *found = NULL;
bool partial = false;
string = strempty(string);
STRV_FOREACH(c, completions) {
/* Ignore entries that are not actually completions */
if (!startswith(*c, string))
continue;
/* Store first completion that matches */
if (!found) {
found = strdup(*c);
if (!found)
return -ENOMEM;
continue;
}
/* If there's another completion that works truncate the one we already found by common
* prefix */
size_t n = str_common_prefix(found, *c);
if (n == SIZE_MAX)
continue;
found[n] = 0;
partial = true;
}
*ret = TAKE_PTR(found);
if (!*ret)
return COMPLETION_NONE;
if (partial)
return COMPLETION_PARTIAL;
return streq(string, *ret) ? COMPLETION_ALREADY : COMPLETION_FULL;
}
static void clear_by_backspace(size_t n) {
/* Erase the specified number of character cells backwards on the terminal */
for (size_t i = 0; i < n; i++)
fputs("\b \b", stdout);
}
int ask_string_full(
char **ret,
GetCompletionsCallback get_completions,
void *userdata,
const char *text, ...) {
va_list ap;
int r;
assert(ret);
assert(text);
/* Output the prompt */
fputs(ansi_highlight(), stdout);
va_start(ap, text);
vprintf(text, ap);
va_end(ap);
fputs(ansi_normal(), stdout);
fflush(stdout);
_cleanup_free_ char *string = NULL;
size_t n = 0;
/* Do interactive logic only if stdin + stdout are connected to the same place. And yes, we could use
* STDIN_FILENO and STDOUT_FILENO here, but let's be overly correct for once, after all libc allows
* swapping out stdin/stdout. */
int fd_input = fileno(stdin);
int fd_output = fileno(stdout);
if (fd_input < 0 || fd_output < 0 || same_fd(fd_input, fd_output) <= 0)
goto fallback;
/* Try to disable echo, which also tells us if this even is a terminal */
struct termios old_termios;
if (tcgetattr(fd_input, &old_termios) < 0)
goto fallback;
struct termios new_termios = old_termios;
termios_disable_echo(&new_termios);
if (tcsetattr(fd_input, TCSANOW, &new_termios) < 0)
return -errno;
for (;;) {
int c = fgetc(stdin);
/* On EOF or NUL, end the request, don't output anything anymore */
if (IN_SET(c, EOF, 0))
break;
/* On Return also end the request, but make this visible */
if (IN_SET(c, '\n', '\r')) {
fputc('\n', stdout);
break;
}
if (c == '\t') {
/* Tab */
_cleanup_strv_free_ char **completions = NULL;
if (get_completions) {
r = get_completions(string, &completions, userdata);
if (r < 0)
goto fail;
}
_cleanup_free_ char *new_string = NULL;
CompletionResult cr = pick_completion(string, completions, &new_string);
if (cr < 0) {
r = cr;
goto fail;
}
if (IN_SET(cr, COMPLETION_PARTIAL, COMPLETION_FULL)) {
/* Output the new suffix we learned */
fputs(ASSERT_PTR(startswith(new_string, strempty(string))), stdout);
/* And update the whole string */
free_and_replace(string, new_string);
n = strlen(string);
}
if (cr == COMPLETION_NONE)
fputc('\a', stdout); /* BEL */
if (IN_SET(cr, COMPLETION_PARTIAL, COMPLETION_ALREADY)) {
/* If this worked only partially, or if the user hit TAB even though we were
* complete already, then show the remaining options (in the latter case just
* the one). */
fputc('\n', stdout);
_cleanup_strv_free_ char **filtered = strv_filter_prefix(completions, string);
if (!filtered) {
r = -ENOMEM;
goto fail;
}
r = show_menu(filtered,
/* n_columns= */ SIZE_MAX,
/* column_width= */ SIZE_MAX,
/* ellipsize_percentage= */ 0,
/* grey_prefix=*/ string,
/* with_numbers= */ false);
if (r < 0)
goto fail;
/* Show the prompt again */
fputs(ansi_highlight(), stdout);
va_start(ap, text);
vprintf(text, ap);
va_end(ap);
fputs(ansi_normal(), stdout);
fputs(string, stdout);
}
} else if (IN_SET(c, '\b', 127)) {
/* Backspace */
if (n == 0)
fputc('\a', stdout); /* BEL */
else {
size_t m = utf8_last_length(string, n);
char *e = string + n - m;
clear_by_backspace(utf8_console_width(e));
*e = 0;
n -= m;
}
} else if (c == 21) {
/* Ctrl-u → erase all input */
clear_by_backspace(utf8_console_width(string));
if (string)
string[n = 0] = 0;
else
assert(n == 0);
} else if (c == 4) {
/* Ctrl-d → cancel this field input */
r = -ECANCELED;
goto fail;
} else if (char_is_cc(c) || n >= LINE_MAX)
/* refuse control characters and too long strings */
fputc('\a', stdout); /* BEL */
else {
/* Regular char */
if (!GREEDY_REALLOC(string, n+2)) {
r = -ENOMEM;
goto fail;
}
string[n++] = (char) c;
string[n] = 0;
fputc(c, stdout);
}
fflush(stdout);
}
if (tcsetattr(fd_input, TCSANOW, &old_termios) < 0)
return -errno;
if (!string) {
string = strdup("");
if (!string)
return -ENOMEM;
}
*ret = TAKE_PTR(string);
return 0;
fail:
(void) tcsetattr(fd_input, TCSANOW, &old_termios);
return r;
fallback:
/* A simple fallback without TTY magic */
r = read_line(stdin, LONG_LINE_MAX, &string);
if (r < 0)
return r;
if (r == 0)
return -EIO;
*ret = TAKE_PTR(string);
return 0;
}
bool any_key_to_proceed(void) {
/* Insert a new line here as well as to when the user inputs, as this is also used during the boot up
* sequence when status messages may be interleaved with the current program output. This ensures
* that the status messages aren't appended on the same line as this message. */
fputc('\n', stdout);
fputs(ansi_highlight_magenta(), stdout);
fputs("-- Press any key to proceed --", stdout);
fputs(ansi_normal(), stdout);
fputc('\n', stdout);
fflush(stdout);
char key = 0;
(void) read_one_char(stdin, &key, USEC_INFINITY, /* echo= */ false, /* need_nl= */ NULL);
fputc('\n', stdout);
fflush(stdout);
return key != 'q';
}
static size_t widest_list_element(char *const*l) {
size_t w = 0;
/* Returns the largest console width of all elements in 'l' */
STRV_FOREACH(i, l)
w = MAX(w, utf8_console_width(*i));
return w;
}
int show_menu(char **x,
size_t n_columns,
size_t column_width,
unsigned ellipsize_percentage,
const char *grey_prefix,
bool with_numbers) {
assert(n_columns > 0);
if (n_columns == SIZE_MAX)
n_columns = 3;
if (column_width == SIZE_MAX) {
size_t widest = widest_list_element(x);
/* If not specified, derive column width from screen width */
size_t column_max = (columns()-1) / n_columns;
/* Subtract room for numbers */
if (with_numbers && column_max > 6)
column_max -= 6;
/* If columns would get too tight let's make this a linear list instead. */
if (column_max < 10 && widest > 10) {
n_columns = 1;
column_max = columns()-1;
if (with_numbers && column_max > 6)
column_max -= 6;
}
column_width = CLAMP(widest+1, 10U, column_max);
}
size_t n = strv_length(x);
size_t per_column = DIV_ROUND_UP(n, n_columns);
size_t break_lines = lines();
if (break_lines > 2)
break_lines--;
/* The first page gets two extra lines, since we want to show
* a title */
size_t break_modulo = break_lines;
if (break_modulo > 3)
break_modulo -= 3;
for (size_t i = 0; i < per_column; i++) {
for (size_t j = 0; j < n_columns; j++) {
_cleanup_free_ char *e = NULL;
if (j * per_column + i >= n)
break;
e = ellipsize(x[j * per_column + i], column_width, ellipsize_percentage);
if (!e)
return -ENOMEM;
if (with_numbers)
printf("%s%4zu)%s ",
ansi_grey(),
j * per_column + i + 1,
ansi_normal());
if (grey_prefix && startswith(e, grey_prefix)) {
size_t k = MIN(strlen(grey_prefix), column_width);
printf("%s%.*s%s",
ansi_grey(),
(int) k, e,
ansi_normal());
printf("%-*s",
(int) (column_width - k), e+k);
} else
printf("%-*s", (int) column_width, e);
}
putchar('\n');
/* on the first screen we reserve 2 extra lines for the title */
if (i % break_lines == break_modulo)
if (!any_key_to_proceed())
return 0;
}
return 0;
}
int open_terminal(const char *name, int mode) {
_cleanup_close_ int fd = -EBADF;
/*
* 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
*/
assert((mode & (O_CREAT|O_PATH|O_DIRECTORY|O_TMPFILE)) == 0);
for (unsigned c = 0;; c++) {
fd = open(name, mode, 0);
if (fd >= 0)
break;
if (errno != EIO)
return -errno;
/* Max 1s in total */
if (c >= 20)
return -EIO;
(void) usleep_safe(50 * USEC_PER_MSEC);
}
if (!isatty_safe(fd))
return -ENOTTY;
return TAKE_FD(fd);
}
int acquire_terminal(
const char *name,
AcquireTerminalFlags flags,
usec_t timeout) {
_cleanup_close_ int notify = -EBADF, fd = -EBADF;
usec_t ts = USEC_INFINITY;
int r, wd = -1;
assert(name);
AcquireTerminalFlags mode = flags & _ACQUIRE_TERMINAL_MODE_MASK;
assert(IN_SET(mode, ACQUIRE_TERMINAL_TRY, ACQUIRE_TERMINAL_FORCE, ACQUIRE_TERMINAL_WAIT));
assert(mode == ACQUIRE_TERMINAL_WAIT || !FLAGS_SET(flags, ACQUIRE_TERMINAL_WATCH_SIGTERM));
/* 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 (mode == ACQUIRE_TERMINAL_WAIT) {
notify = inotify_init1(IN_CLOEXEC | IN_NONBLOCK);
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);
}
/* If we are called with ACQUIRE_TERMINAL_WATCH_SIGTERM we'll unblock SIGTERM during ppoll() temporarily */
sigset_t poll_ss;
assert_se(sigprocmask(SIG_SETMASK, /* newset= */ NULL, &poll_ss) >= 0);
if (flags & ACQUIRE_TERMINAL_WATCH_SIGTERM) {
assert_se(sigismember(&poll_ss, SIGTERM) > 0);
assert_se(sigdelset(&poll_ss, SIGTERM) >= 0);
}
for (;;) {
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. */
struct sigaction sa_old;
assert_se(sigaction(SIGHUP, &sigaction_ignore, &sa_old) >= 0);
/* First, try to get the tty */
r = RET_NERRNO(ioctl(fd, TIOCSCTTY, mode == 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 (mode != 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 (;;) {
usec_t left;
if (timeout == USEC_INFINITY)
left = USEC_INFINITY;
else {
assert(ts != USEC_INFINITY);
usec_t n = usec_sub_unsigned(now(CLOCK_MONOTONIC), ts);
if (n >= timeout)
return -ETIMEDOUT;
left = timeout - n;
}
r = ppoll_usec_full(
&(struct pollfd) {
.fd = notify,
.events = POLLIN,
},
/* n_fds = */ 1,
left,
&poll_ss);
if (r < 0)
return r;
if (r == 0)
return -ETIMEDOUT;
union inotify_event_buffer buffer;
ssize_t l;
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) {
_cleanup_close_ int fd = -EBADF;
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 */
struct sigaction sa_old;
assert_se(sigaction(SIGHUP, &sigaction_ignore, &sa_old) >= 0);
r = RET_NERRNO(ioctl(fd, TIOCNOTTY));
assert_se(sigaction(SIGHUP, &sa_old, NULL) >= 0);
return r;
}
int terminal_new_session(void) {
/* Make us the new session leader, and set stdin tty to be our controlling terminal.
*
* Why stdin? Well, the ctty logic is relevant for signal delivery mostly, i.e. if people hit C-c
* or the line is hung up. Such events are basically just a form of input, via a side channel
* (that side channel being signal delivery, i.e. SIGINT, SIGHUP et al). Hence we focus on input,
* not output here. */
if (!isatty_safe(STDIN_FILENO))
return -ENXIO;
(void) setsid();
return RET_NERRNO(ioctl(STDIN_FILENO, TIOCSCTTY, 0));
}
void terminal_detach_session(void) {
(void) setsid();
(void) release_terminal();
}
int terminal_vhangup_fd(int fd) {
assert(fd >= 0);
return RET_NERRNO(ioctl(fd, TIOCVHANGUP));
}
int terminal_vhangup(const char *tty) {
_cleanup_close_ int fd = -EBADF;
assert(tty);
fd = open_terminal(tty, O_RDWR|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return fd;
return terminal_vhangup_fd(fd);
}
int vt_disallocate(const char *tty_path) {
assert(tty_path);
/* 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). */
int ttynr = vtnr_from_tty(tty_path);
if (ttynr > 0) {
_cleanup_close_ int fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
if (fd < 0)
return fd;
/* Try to deallocate */
if (ioctl(fd, VT_DISALLOCATE, ttynr) >= 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(tty_path, O_WRONLY|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
if (fd2 < 0)
return fd2;
return loop_write_full(fd2,
"\033[r" /* clear scrolling region */
"\033[H" /* move home */
"\033[3J" /* clear screen including scrollback, requires Linux 2.6.40 */
"\033c", /* reset to initial state */
SIZE_MAX,
100 * USEC_PER_MSEC);
}
static 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);
}
static int vt_reset_keyboard(int fd) {
int r, kb;
assert(fd >= 0);
/* If we can't read the default, then default to Unicode. It's 2024 after all. */
r = vt_default_utf8();
if (r < 0)
log_debug_errno(r, "Failed to determine kernel VT UTF-8 mode, assuming enabled: %m");
kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
return RET_NERRNO(ioctl(fd, KDSKBMODE, kb));
}
static int terminal_reset_ioctl(int fd, bool switch_to_text) {
struct termios termios;
int r;
/* Set terminal to some sane defaults */
assert(fd >= 0);
/* 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 */
r = vt_reset_keyboard(fd);
if (r < 0)
log_debug_errno(r, "Failed to reset VT keyboard, ignoring: %m");
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;
r = RET_NERRNO(tcsetattr(fd, TCSANOW, &termios));
if (r < 0)
log_debug_errno(r, "Failed to set terminal parameters: %m");
finish:
/* Just in case, flush all crap out */
(void) tcflush(fd, TCIOFLUSH);
return r;
}
static int terminal_reset_ansi_seq(int fd) {
int r, k;
assert(fd >= 0);
if (getenv_terminal_is_dumb())
return 0;
r = fd_nonblock(fd, true);
if (r < 0)
return log_debug_errno(r, "Failed to set terminal to non-blocking mode: %m");
k = loop_write_full(fd,
"\033[!p" /* soft terminal reset */
"\033]104\007" /* reset colors */
"\033[?7h" /* enable line-wrapping */
"\033[1G" /* place cursor at beginning of current line */
"\033[0J", /* erase till end of screen */
SIZE_MAX,
100 * USEC_PER_MSEC);
if (k < 0)
log_debug_errno(k, "Failed to reset terminal through ANSI sequences: %m");
if (r > 0) {
r = fd_nonblock(fd, false);
if (r < 0)
log_debug_errno(r, "Failed to set terminal back to blocking mode: %m");
}
return k < 0 ? k : r;
}
void reset_dev_console_fd(int fd, bool switch_to_text) {
int r;
assert(fd >= 0);
_cleanup_close_ int lock_fd = lock_dev_console();
if (lock_fd < 0)
log_debug_errno(lock_fd, "Failed to lock /dev/console, ignoring: %m");
r = terminal_reset_ioctl(fd, switch_to_text);
if (r < 0)
log_warning_errno(r, "Failed to reset /dev/console, ignoring: %m");
unsigned rows, cols;
r = proc_cmdline_tty_size("/dev/console", &rows, &cols);
if (r < 0)
log_warning_errno(r, "Failed to get /dev/console size, ignoring: %m");
else if (r > 0) {
r = terminal_set_size_fd(fd, NULL, rows, cols);
if (r < 0)
log_warning_errno(r, "Failed to set configured terminal size on /dev/console, ignoring: %m");
} else
(void) terminal_fix_size(fd, fd);
r = terminal_reset_ansi_seq(fd);
if (r < 0)
log_warning_errno(r, "Failed to reset /dev/console using ANSI sequences, ignoring: %m");
}
int lock_dev_console(void) {
_cleanup_close_ int fd = -EBADF;
int r;
/* NB: We do not use O_NOFOLLOW here, because some container managers might place a symlink to some
* pty in /dev/console, in which case it should be fine to lock the target TTY. */
fd = open_terminal("/dev/console", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0)
return fd;
r = lock_generic(fd, LOCK_BSD, LOCK_EX);
if (r < 0)
return r;
return TAKE_FD(fd);
}
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 {
reset_dev_console_fd(fd, /* switch_to_text= */ true);
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;
}
static int vtnr_from_tty_raw(const char *tty, unsigned *ret) {
assert(tty);
tty = skip_dev_prefix(tty);
const char *e = startswith(tty, "tty");
if (!e)
return -EINVAL;
return safe_atou(e, ret);
}
int vtnr_from_tty(const char *tty) {
unsigned u;
int r;
assert(tty);
r = vtnr_from_tty_raw(tty, &u);
if (r < 0)
return r;
if (!vtnr_is_valid(u))
return -ERANGE;
return (int) u;
}
bool tty_is_vc(const char *tty) {
assert(tty);
/* NB: for >= 0 values no range check is conducted here, on the assumption that the caller will
* either extract vtnr through vtnr_from_tty() later where ERANGE would be reported, or doesn't care
* about whether it's strictly valid, but only asking "does this fall into the vt category?", for which
* "yes" seems to be a better answer. */
return vtnr_from_tty_raw(tty, /* ret = */ NULL) >= 0;
}
bool tty_is_console(const char *tty) {
assert(tty);
return streq(skip_dev_prefix(tty), "console");
}
int resolve_dev_console(char **ret) {
int r;
assert(ret);
/* Resolve where /dev/console is pointing to. If /dev/console is a symlink (like in container
* managers), we'll just resolve the symlink. If it's a real device node, we'll use if
* /sys/class/tty/tty0/active, but only if /sys/ is actually ours (i.e. not read-only-mounted which
* is a sign for container setups). */
_cleanup_free_ char *chased = NULL;
r = chase("/dev/console", /* root= */ NULL, /* flags= */ 0, &chased, /* ret_fd= */ NULL);
if (r < 0)
return r;
if (!path_equal(chased, "/dev/console")) {
*ret = TAKE_PTR(chased);
return 0;
}
r = path_is_read_only_fs("/sys");
if (r < 0)
return r;
if (r > 0)
return -ENOMEDIUM;
_cleanup_free_ char *active = NULL;
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 */
const char *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;
}
_cleanup_free_ char *path = NULL;
path = path_join("/dev", tty);
if (!path)
return -ENOMEM;
*ret = TAKE_PTR(path);
return 0;
}
int get_kernel_consoles(char ***ret) {
_cleanup_strv_free_ char **l = NULL;
_cleanup_free_ char *line = NULL;
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;
for (const char *p = line;;) {
_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 strv_length(*ret);
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);
if (streq(skip_dev_prefix(tty), "console")) {
if (resolve_dev_console(&resolved) < 0)
return false;
tty = resolved;
}
return tty_is_vc(tty);
}
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 -ENODATA; /* some tty types come up with invalid row/column initially, return a recognizable error for that */
return ws.ws_col;
}
int getenv_columns(void) {
int r;
const char *e = getenv("COLUMNS");
if (!e)
return -ENXIO;
unsigned c;
r = safe_atou_bounded(e, 1, USHRT_MAX, &c);
if (r < 0)
return r;
return (int) c;
}
unsigned columns(void) {
if (cached_columns > 0)
return cached_columns;
int c = getenv_columns();
if (c < 0) {
c = fd_columns(STDOUT_FILENO);
if (c < 0)
c = 80;
}
assert(c > 0);
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 -ENODATA; /* some tty types come up with invalid row/column initially, return a recognizable error for that */
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;
assert(fd >= 0);
if (!ident)
ident = "TTY";
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);
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);
return 0;
}
int proc_cmdline_tty_size(const char *tty, unsigned *ret_rows, unsigned *ret_cols) {
_cleanup_free_ char *rowskey = NULL, *rowsvalue = NULL, *colskey = NULL, *colsvalue = NULL;
unsigned rows = UINT_MAX, cols = UINT_MAX;
int r;
assert(tty);
if (!ret_rows && !ret_cols)
return 0;
tty = skip_dev_prefix(tty);
if (path_startswith(tty, "pts/"))
return -EMEDIUMTYPE;
if (!in_charset(tty, ALPHANUMERICAL))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
"TTY name '%s' contains non-alphanumeric characters, not searching kernel cmdline for size.", tty);
rowskey = strjoin("systemd.tty.rows.", tty);
if (!rowskey)
return -ENOMEM;
colskey = strjoin("systemd.tty.columns.", tty);
if (!colskey)
return -ENOMEM;
r = proc_cmdline_get_key_many(/* flags = */ 0,
rowskey, &rowsvalue,
colskey, &colsvalue);
if (r < 0)
return log_debug_errno(r, "Failed to read TTY size of %s from kernel cmdline: %m", tty);
if (rowsvalue) {
r = safe_atou(rowsvalue, &rows);
if (r < 0)
return log_debug_errno(r, "Failed to parse %s=%s: %m", rowskey, rowsvalue);
}
if (colsvalue) {
r = safe_atou(colsvalue, &cols);
if (r < 0)
return log_debug_errno(r, "Failed to parse %s=%s: %m", colskey, colsvalue);
}
if (ret_rows)
*ret_rows = rows;
if (ret_cols)
*ret_cols = cols;
return rows != UINT_MAX || cols != UINT_MAX;
}
/* 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_on_tty = -1;
cached_on_dev_null = -1;
reset_ansi_feature_caches();
}
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_safe(STDOUT_FILENO) &&
isatty_safe(STDERR_FILENO);
return cached_on_tty;
}
int getttyname_malloc(int fd, char **ret) {
char path[PATH_MAX]; /* 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;
return strdup_to(ret, skip_dev_prefix(path));
}
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 *ret) {
_cleanup_free_ char *line = NULL;
unsigned long ttynr;
const char *p;
int r;
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 (devnum_is_zero(ttynr))
return -ENXIO;
if (ret)
*ret = (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) {
r = strdup_to(ret, w);
if (r < 0)
return r;
}
if (ret_devnr)
*ret_devnr = devnr;
return 0;
}
int ptsname_malloc(int fd, char **ret) {
assert(fd >= 0);
assert(ret);
for (size_t l = 50;;) {
_cleanup_free_ char *c = NULL;
c = new(char, l);
if (!c)
return -ENOMEM;
if (ptsname_r(fd, c, l) >= 0) {
*ret = TAKE_PTR(c);
return 0;
}
if (errno != ERANGE)
return -errno;
if (!MUL_ASSIGN_SAFE(&l, 2))
return -ENOMEM;
}
}
int openpt_allocate(int flags, char **ret_peer_path) {
_cleanup_close_ int fd = -EBADF;
int r;
fd = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return -errno;
_cleanup_free_ char *p = NULL;
if (ret_peer_path) {
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_peer_path)
*ret_peer_path = TAKE_PTR(p);
return TAKE_FD(fd);
}
static int ptsname_namespace(int pty, char **ret) {
int no = -1;
assert(pty >= 0);
assert(ret);
/* Like ptsname(), but doesn't assume that the path is
* accessible in the local namespace. */
if (ioctl(pty, TIOCGPTN, &no) < 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(
const PidRef *pidref,
int flags,
char **ret_peer_path) {
_cleanup_close_ int pidnsfd = -EBADF, mntnsfd = -EBADF, usernsfd = -EBADF, rootfd = -EBADF, fd = -EBADF;
_cleanup_close_pair_ int pair[2] = EBADF_PAIR;
int r;
r = pidref_namespace_open(pidref, &pidnsfd, &mntnsfd, /* ret_netns_fd = */ NULL, &usernsfd, &rootfd);
if (r < 0)
return r;
if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0, pair) < 0)
return -errno;
r = namespace_fork(
"(sd-openptns)",
"(sd-openpt)",
/* except_fds= */ NULL,
/* n_except_fds= */ 0,
FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGKILL|FORK_WAIT,
pidnsfd,
mntnsfd,
/* netns_fd= */ -EBADF,
usernsfd,
rootfd,
/* ret_pid= */ NULL);
if (r < 0)
return r;
if (r == 0) {
pair[0] = safe_close(pair[0]);
fd = openpt_allocate(flags, /* ret_peer_path= */ 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]);
fd = receive_one_fd(pair[0], 0);
if (fd < 0)
return fd;
if (ret_peer_path) {
r = ptsname_namespace(fd, ret_peer_path);
if (r < 0)
return r;
}
return TAKE_FD(fd);
}
static bool on_dev_null(void) {
struct stat dst, ost, est;
if (cached_on_dev_null >= 0)
return cached_on_dev_null;
if (stat("/dev/null", &dst) < 0 || fstat(STDOUT_FILENO, &ost) < 0 || fstat(STDERR_FILENO, &est) < 0)
cached_on_dev_null = false;
else
cached_on_dev_null = stat_inode_same(&dst, &ost) && stat_inode_same(&dst, &est);
return cached_on_dev_null;
}
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() && !on_dev_null())
return true;
return getenv_terminal_is_dumb();
}
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");
}
int vt_restore(int fd) {
static const struct vt_mode mode = {
.mode = VT_AUTO,
};
int r, ret = 0;
assert(fd >= 0);
if (!isatty_safe(fd))
return log_debug_errno(SYNTHETIC_ERRNO(ENOTTY), "Asked to restore the VT for an fd that does not refer to a terminal.");
if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
RET_GATHER(ret, log_debug_errno(errno, "Failed to set VT to text mode, ignoring: %m"));
r = vt_reset_keyboard(fd);
if (r < 0)
RET_GATHER(ret, log_debug_errno(r, "Failed to reset keyboard mode, ignoring: %m"));
if (ioctl(fd, VT_SETMODE, &mode) < 0)
RET_GATHER(ret, log_debug_errno(errno, "Failed to set VT_AUTO mode, ignoring: %m"));
r = fchmod_and_chown(fd, TTY_MODE, 0, GID_INVALID);
if (r < 0)
RET_GATHER(ret, log_debug_errno(r, "Failed to chmod()/chown() VT, ignoring: %m"));
return ret;
}
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_safe(fd))
return log_debug_errno(SYNTHETIC_ERRNO(ENOTTY), "Asked to release the VT for an fd that does not refer to a terminal.");
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();
}
}
int terminal_set_cursor_position(int fd, unsigned row, unsigned column) {
assert(fd >= 0);
char cursor_position[STRLEN("\x1B[" ";" "H") + DECIMAL_STR_MAX(unsigned) * 2 + 1];
xsprintf(cursor_position, "\x1B[%u;%uH", row, column);
return loop_write(fd, cursor_position, SIZE_MAX);
}
int terminal_reset_defensive(int fd, TerminalResetFlags flags) {
int r = 0;
assert(fd >= 0);
assert(!FLAGS_SET(flags, TERMINAL_RESET_AVOID_ANSI_SEQ|TERMINAL_RESET_FORCE_ANSI_SEQ));
/* Resets the terminal comprehensively, i.e. via both ioctl()s and via ANSI sequences, but do so only
* if $TERM is unset or set to "dumb" */
if (!isatty_safe(fd))
return -ENOTTY;
RET_GATHER(r, terminal_reset_ioctl(fd, FLAGS_SET(flags, TERMINAL_RESET_SWITCH_TO_TEXT)));
if (!FLAGS_SET(flags, TERMINAL_RESET_AVOID_ANSI_SEQ) &&
(FLAGS_SET(flags, TERMINAL_RESET_FORCE_ANSI_SEQ) || !getenv_terminal_is_dumb()))
RET_GATHER(r, terminal_reset_ansi_seq(fd));
return r;
}
int terminal_reset_defensive_locked(int fd, TerminalResetFlags flags) {
assert(fd >= 0);
_cleanup_close_ int lock_fd = lock_dev_console();
if (lock_fd < 0)
log_debug_errno(lock_fd, "Failed to acquire lock for /dev/console, ignoring: %m");
return terminal_reset_defensive(fd, flags);
}
void termios_disable_echo(struct termios *termios) {
assert(termios);
termios->c_lflag &= ~(ICANON|ECHO);
termios->c_cc[VMIN] = 1;
termios->c_cc[VTIME] = 0;
}
static int terminal_verify_same(int input_fd, int output_fd) {
assert(input_fd >= 0);
assert(output_fd >= 0);
/* Validates that the specified fds reference the same TTY */
if (input_fd != output_fd) {
struct stat sti;
if (fstat(input_fd, &sti) < 0)
return -errno;
if (!S_ISCHR(sti.st_mode)) /* TTYs are character devices */
return -ENOTTY;
struct stat sto;
if (fstat(output_fd, &sto) < 0)
return -errno;
if (!S_ISCHR(sto.st_mode))
return -ENOTTY;
if (sti.st_rdev != sto.st_rdev)
return -ENOLINK;
}
if (!isatty_safe(input_fd)) /* The check above was just for char device, but now let's ensure it's actually a tty */
return -ENOTTY;
return 0;
}
typedef enum BackgroundColorState {
BACKGROUND_TEXT,
BACKGROUND_ESCAPE,
BACKGROUND_BRACKET,
BACKGROUND_FIRST_ONE,
BACKGROUND_SECOND_ONE,
BACKGROUND_SEMICOLON,
BACKGROUND_R,
BACKGROUND_G,
BACKGROUND_B,
BACKGROUND_RED,
BACKGROUND_GREEN,
BACKGROUND_BLUE,
BACKGROUND_STRING_TERMINATOR,
} BackgroundColorState;
typedef struct BackgroundColorContext {
BackgroundColorState state;
uint32_t red, green, blue;
unsigned red_bits, green_bits, blue_bits;
} BackgroundColorContext;
static int scan_background_color_response(
BackgroundColorContext *context,
const char *buf,
size_t size,
size_t *ret_processed) {
assert(context);
assert(buf);
assert(ret_processed);
for (size_t i = 0; i < size; i++) {
char c = buf[i];
switch (context->state) {
case BACKGROUND_TEXT:
context->state = c == '\x1B' ? BACKGROUND_ESCAPE : BACKGROUND_TEXT;
break;
case BACKGROUND_ESCAPE:
context->state = c == ']' ? BACKGROUND_BRACKET : BACKGROUND_TEXT;
break;
case BACKGROUND_BRACKET:
context->state = c == '1' ? BACKGROUND_FIRST_ONE : BACKGROUND_TEXT;
break;
case BACKGROUND_FIRST_ONE:
context->state = c == '1' ? BACKGROUND_SECOND_ONE : BACKGROUND_TEXT;
break;
case BACKGROUND_SECOND_ONE:
context->state = c == ';' ? BACKGROUND_SEMICOLON : BACKGROUND_TEXT;
break;
case BACKGROUND_SEMICOLON:
context->state = c == 'r' ? BACKGROUND_R : BACKGROUND_TEXT;
break;
case BACKGROUND_R:
context->state = c == 'g' ? BACKGROUND_G : BACKGROUND_TEXT;
break;
case BACKGROUND_G:
context->state = c == 'b' ? BACKGROUND_B : BACKGROUND_TEXT;
break;
case BACKGROUND_B:
context->state = c == ':' ? BACKGROUND_RED : BACKGROUND_TEXT;
break;
case BACKGROUND_RED:
if (c == '/')
context->state = context->red_bits > 0 ? BACKGROUND_GREEN : BACKGROUND_TEXT;
else {
int d = unhexchar(c);
if (d < 0 || context->red_bits >= sizeof(context->red)*8)
context->state = BACKGROUND_TEXT;
else {
context->red = (context->red << 4) | d;
context->red_bits += 4;
}
}
break;
case BACKGROUND_GREEN:
if (c == '/')
context->state = context->green_bits > 0 ? BACKGROUND_BLUE : BACKGROUND_TEXT;
else {
int d = unhexchar(c);
if (d < 0 || context->green_bits >= sizeof(context->green)*8)
context->state = BACKGROUND_TEXT;
else {
context->green = (context->green << 4) | d;
context->green_bits += 4;
}
}
break;
case BACKGROUND_BLUE:
if (c == '\x07') {
if (context->blue_bits > 0) {
*ret_processed = i + 1;
return 1; /* success! */
}
context->state = BACKGROUND_TEXT;
} else if (c == '\x1b')
context->state = context->blue_bits > 0 ? BACKGROUND_STRING_TERMINATOR : BACKGROUND_TEXT;
else {
int d = unhexchar(c);
if (d < 0 || context->blue_bits >= sizeof(context->blue)*8)
context->state = BACKGROUND_TEXT;
else {
context->blue = (context->blue << 4) | d;
context->blue_bits += 4;
}
}
break;
case BACKGROUND_STRING_TERMINATOR:
if (c == '\\') {
*ret_processed = i + 1;
return 1; /* success! */
}
context->state = c == ']' ? BACKGROUND_ESCAPE : BACKGROUND_TEXT;
break;
}
/* Reset any colors we might have picked up */
if (IN_SET(context->state, BACKGROUND_TEXT, BACKGROUND_ESCAPE)) {
/* reset color */
context->red = context->green = context->blue = 0;
context->red_bits = context->green_bits = context->blue_bits = 0;
}
}
*ret_processed = size;
return 0; /* all good, but not enough data yet */
}
int get_default_background_color(double *ret_red, double *ret_green, double *ret_blue) {
_cleanup_close_ int nonblock_input_fd = -EBADF;
int r;
assert(ret_red);
assert(ret_green);
assert(ret_blue);
if (!colors_enabled())
return -EOPNOTSUPP;
r = terminal_verify_same(STDIN_FILENO, STDOUT_FILENO);
if (r < 0)
return r;
if (streq_ptr(getenv("TERM"), "linux")) {
/* Linux console is black */
*ret_red = *ret_green = *ret_blue = 0.0;
return 0;
}
struct termios old_termios;
if (tcgetattr(STDIN_FILENO, &old_termios) < 0)
return -errno;
struct termios new_termios = old_termios;
termios_disable_echo(&new_termios);
if (tcsetattr(STDIN_FILENO, TCSANOW, &new_termios) < 0)
return -errno;
r = loop_write(STDOUT_FILENO, ANSI_OSC "11;?" ANSI_ST, SIZE_MAX);
if (r < 0)
goto finish;
/* Open a 2nd input fd, in non-blocking mode, so that we won't ever hang in read() should someone
* else process the POLLIN. */
nonblock_input_fd = r = fd_reopen(STDIN_FILENO, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (r < 0)
goto finish;
usec_t end = usec_add(now(CLOCK_MONOTONIC), CONSOLE_REPLY_WAIT_USEC);
char buf[STRLEN(ANSI_OSC "11;rgb:0/0/0" ANSI_ST)]; /* shortest possible reply */
size_t buf_full = 0;
BackgroundColorContext context = {};
for (bool first = true;; first = false) {
if (buf_full == 0) {
usec_t n = now(CLOCK_MONOTONIC);
if (n >= end) {
r = -EOPNOTSUPP;
goto finish;
}
r = fd_wait_for_event(nonblock_input_fd, POLLIN, usec_sub_unsigned(end, n));
if (r < 0)
goto finish;
if (r == 0) {
r = -EOPNOTSUPP;
goto finish;
}
/* On the first try, read multiple characters, i.e. the shortest valid
* reply. Afterwards read byte-wise, since we don't want to read too much, and
* unnecessarily drop too many characters from the input queue. */
ssize_t l = read(nonblock_input_fd, buf, first ? sizeof(buf) : 1);
if (l < 0) {
if (errno == EAGAIN)
continue;
r = -errno;
goto finish;
}
assert((size_t) l <= sizeof(buf));
buf_full = l;
}
size_t processed;
r = scan_background_color_response(&context, buf, buf_full, &processed);
if (r < 0)
goto finish;
assert(processed <= buf_full);
buf_full -= processed;
memmove(buf, buf + processed, buf_full);
if (r > 0) {
assert(context.red_bits > 0);
*ret_red = (double) context.red / ((UINT64_C(1) << context.red_bits) - 1);
assert(context.green_bits > 0);
*ret_green = (double) context.green / ((UINT64_C(1) << context.green_bits) - 1);
assert(context.blue_bits > 0);
*ret_blue = (double) context.blue / ((UINT64_C(1) << context.blue_bits) - 1);
r = 0;
goto finish;
}
}
finish:
RET_GATHER(r, RET_NERRNO(tcsetattr(STDIN_FILENO, TCSANOW, &old_termios)));
return r;
}
typedef enum CursorPositionState {
CURSOR_TEXT,
CURSOR_ESCAPE,
CURSOR_ROW,
CURSOR_COLUMN,
} CursorPositionState;
typedef struct CursorPositionContext {
CursorPositionState state;
unsigned row, column;
} CursorPositionContext;
static int scan_cursor_position_response(
CursorPositionContext *context,
const char *buf,
size_t size,
size_t *ret_processed) {
assert(context);
assert(buf);
assert(ret_processed);
for (size_t i = 0; i < size; i++) {
char c = buf[i];
switch (context->state) {
case CURSOR_TEXT:
context->state = c == '\x1B' ? CURSOR_ESCAPE : CURSOR_TEXT;
break;
case CURSOR_ESCAPE:
context->state = c == '[' ? CURSOR_ROW : CURSOR_TEXT;
break;
case CURSOR_ROW:
if (c == ';')
context->state = context->row > 0 ? CURSOR_COLUMN : CURSOR_TEXT;
else {
int d = undecchar(c);
/* We read a decimal character, let's suffix it to the number we so far read,
* but let's do an overflow check first. */
if (d < 0 || context->row > (UINT_MAX-d)/10)
context->state = CURSOR_TEXT;
else
context->row = context->row * 10 + d;
}
break;
case CURSOR_COLUMN:
if (c == 'R') {
if (context->column > 0) {
*ret_processed = i + 1;
return 1; /* success! */
}
context->state = CURSOR_TEXT;
} else {
int d = undecchar(c);
/* As above, add the decimal character to our column number */
if (d < 0 || context->column > (UINT_MAX-d)/10)
context->state = CURSOR_TEXT;
else
context->column = context->column * 10 + d;
}
break;
}
/* Reset any positions we might have picked up */
if (IN_SET(context->state, CURSOR_TEXT, CURSOR_ESCAPE))
context->row = context->column = 0;
}
*ret_processed = size;
return 0; /* all good, but not enough data yet */
}
int terminal_get_size_by_dsr(
int input_fd,
int output_fd,
unsigned *ret_rows,
unsigned *ret_columns) {
_cleanup_close_ int nonblock_input_fd = -EBADF;
int r;
assert(input_fd >= 0);
assert(output_fd >= 0);
/* Tries to determine the terminal dimension by means of ANSI sequences rather than TIOCGWINSZ
* ioctl(). Why bother with this? The ioctl() information is often incorrect on serial terminals
* (since there's no handshake or protocol to determine the right dimensions in RS232), but since the
* ANSI sequences are interpreted by the final terminal instead of an intermediary tty driver they
* should be more accurate.
*
* Unfortunately there's no direct ANSI sequence to query terminal dimensions. But we can hack around
* it: we position the cursor briefly at an absolute location very far down and very far to the
* right, and then read back where we actually ended up. Because cursor locations are capped at the
* terminal width/height we should then see the right values. In order to not risk integer overflows
* in terminal applications we'll use INT16_MAX-1 as location to jump to — hopefully a value that is
* large enough for any real-life terminals, but small enough to not overflow anything or be
* recognized as a "niche" value. (Note that the dimension fields in "struct winsize" are 16bit only,
* too). */
if (terminal_is_dumb())
return -EOPNOTSUPP;
r = terminal_verify_same(input_fd, output_fd);
if (r < 0)
return log_debug_errno(r, "Called with distinct input/output fds: %m");
struct termios old_termios;
if (tcgetattr(input_fd, &old_termios) < 0)
return log_debug_errno(errno, "Failed to get terminal settings: %m");
struct termios new_termios = old_termios;
termios_disable_echo(&new_termios);
if (tcsetattr(input_fd, TCSANOW, &new_termios) < 0)
return log_debug_errno(errno, "Failed to set new terminal settings: %m");
unsigned saved_row = 0, saved_column = 0;
r = loop_write(output_fd,
"\x1B[6n" /* Request cursor position (DSR/CPR) */
"\x1B[32766;32766H" /* Position cursor really far to the right and to the bottom, but let's stay within the 16bit signed range */
"\x1B[6n", /* Request cursor position again */
SIZE_MAX);
if (r < 0)
goto finish;
/* Open a 2nd input fd, in non-blocking mode, so that we won't ever hang in read() should someone
* else process the POLLIN. */
nonblock_input_fd = r = fd_reopen(input_fd, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (r < 0)
goto finish;
usec_t end = usec_add(now(CLOCK_MONOTONIC), CONSOLE_REPLY_WAIT_USEC);
char buf[STRLEN("\x1B[1;1R")]; /* The shortest valid reply possible */
size_t buf_full = 0;
CursorPositionContext context = {};
for (bool first = true;; first = false) {
if (buf_full == 0) {
usec_t n = now(CLOCK_MONOTONIC);
if (n >= end) {
r = -EOPNOTSUPP;
goto finish;
}
r = fd_wait_for_event(nonblock_input_fd, POLLIN, usec_sub_unsigned(end, n));
if (r < 0)
goto finish;
if (r == 0) {
r = -EOPNOTSUPP;
goto finish;
}
/* On the first try, read multiple characters, i.e. the shortest valid
* reply. Afterwards read byte-wise, since we don't want to read too much, and
* unnecessarily drop too many characters from the input queue. */
ssize_t l = read(nonblock_input_fd, buf, first ? sizeof(buf) : 1);
if (l < 0) {
if (errno == EAGAIN)
continue;
r = -errno;
goto finish;
}
assert((size_t) l <= sizeof(buf));
buf_full = l;
}
size_t processed;
r = scan_cursor_position_response(&context, buf, buf_full, &processed);
if (r < 0)
goto finish;
assert(processed <= buf_full);
buf_full -= processed;
memmove(buf, buf + processed, buf_full);
if (r > 0) {
if (saved_row == 0) {
assert(saved_column == 0);
/* First sequence, this is the cursor position before we set it somewhere
* into the void at the bottom right. Let's save where we are so that we can
* return later. */
/* Superficial validity checks */
if (context.row <= 0 || context.column <= 0 || context.row >= 32766 || context.column >= 32766) {
r = -ENODATA;
goto finish;
}
saved_row = context.row;
saved_column = context.column;
/* Reset state */
context = (CursorPositionContext) {};
} else {
/* Second sequence, this is the cursor position after we set it somewhere
* into the void at the bottom right. */
/* Superficial validity checks (no particular reason to check for < 4, it's
* just a way to look for unreasonably small values) */
if (context.row < 4 || context.column < 4 || context.row >= 32766 || context.column >= 32766) {
r = -ENODATA;
goto finish;
}
if (ret_rows)
*ret_rows = context.row;
if (ret_columns)
*ret_columns = context.column;
r = 0;
goto finish;
}
}
}
finish:
/* Restore cursor position */
if (saved_row > 0 && saved_column > 0)
RET_GATHER(r, terminal_set_cursor_position(output_fd, saved_row, saved_column));
RET_GATHER(r, RET_NERRNO(tcsetattr(input_fd, TCSANOW, &old_termios)));
return r;
}
int terminal_fix_size(int input_fd, int output_fd) {
unsigned rows, columns;
int r;
/* Tries to update the current terminal dimensions to the ones reported via ANSI sequences */
r = terminal_verify_same(input_fd, output_fd);
if (r < 0)
return r;
struct winsize ws = {};
if (ioctl(output_fd, TIOCGWINSZ, &ws) < 0)
return log_debug_errno(errno, "Failed to query terminal dimensions, ignoring: %m");
r = terminal_get_size_by_dsr(input_fd, output_fd, &rows, &columns);
if (r < 0)
return log_debug_errno(r, "Failed to acquire terminal dimensions via ANSI sequences, not adjusting terminal dimensions: %m");
if (ws.ws_row == rows && ws.ws_col == columns) {
log_debug("Terminal dimensions reported via ANSI sequences match currently set terminal dimensions, not changing.");
return 0;
}
ws.ws_col = columns;
ws.ws_row = rows;
if (ioctl(output_fd, TIOCSWINSZ, &ws) < 0)
return log_debug_errno(errno, "Failed to update terminal dimensions, ignoring: %m");
log_debug("Fixed terminal dimensions to %ux%u based on ANSI sequence information.", columns, rows);
return 1;
}
#define MAX_TERMINFO_LENGTH 64
/* python -c 'print("".join(hex(ord(i))[2:] for i in "name").upper())' */
#define DCS_TERMINFO_Q ANSI_DCS "+q" "6E616D65" ANSI_ST
/* The answer is either 0+r… (invalid) or 1+r… (OK). */
#define DCS_TERMINFO_R0 ANSI_DCS "0+r" ANSI_ST
#define DCS_TERMINFO_R1 ANSI_DCS "1+r" "6E616D65" "=" /* This is followed by Pt ST. */
assert_cc(STRLEN(DCS_TERMINFO_R0) <= STRLEN(DCS_TERMINFO_R1 ANSI_ST));
static int scan_terminfo_response(
const char *buf,
size_t size,
char **ret_name) {
int r;
assert(buf);
assert(ret_name);
/* Check if we have enough space for the shortest possible answer. */
if (size < STRLEN(DCS_TERMINFO_R0))
return -EAGAIN;
/* Check if the terminating sequence is present */
if (memcmp(buf + size - STRLEN(ANSI_ST), ANSI_ST, STRLEN(ANSI_ST)) != 0)
return -EAGAIN;
if (size <= STRLEN(DCS_TERMINFO_R1 ANSI_ST))
return -EINVAL; /* The answer is invalid or empty */
if (memcmp(buf, DCS_TERMINFO_R1, STRLEN(DCS_TERMINFO_R1)) != 0)
return -EINVAL; /* The answer is not valid */
_cleanup_free_ void *dec = NULL;
size_t dec_size;
r = unhexmem_full(buf + STRLEN(DCS_TERMINFO_R1), size - STRLEN(DCS_TERMINFO_R1 ANSI_ST),
/* secure= */ false,
&dec, &dec_size);
if (r < 0)
return r;
assert(((const char *) dec)[dec_size] == '\0'); /* unhexmem appends NUL for our convenience */
if (memchr(dec, '\0', dec_size) || string_has_cc(dec, NULL) || !filename_is_valid(dec))
return -EUCLEAN;
*ret_name = TAKE_PTR(dec);
return 0;
}
int terminal_get_terminfo_by_dcs(int fd, char **ret_name) {
int r;
assert(fd >= 0);
assert(ret_name);
/* Note: fd must be in non-blocking read-write mode! */
struct termios old_termios;
if (tcgetattr(fd, &old_termios) < 0)
return -errno;
struct termios new_termios = old_termios;
termios_disable_echo(&new_termios);
if (tcsetattr(fd, TCSANOW, &new_termios) < 0)
return -errno;
r = loop_write(fd, DCS_TERMINFO_Q, SIZE_MAX);
if (r < 0)
goto finish;
usec_t end = usec_add(now(CLOCK_MONOTONIC), CONSOLE_REPLY_WAIT_USEC);
char buf[STRLEN(DCS_TERMINFO_R1) + MAX_TERMINFO_LENGTH + STRLEN(ANSI_ST)];
size_t bytes = 0;
for (;;) {
usec_t n = now(CLOCK_MONOTONIC);
if (n >= end) {
r = -EOPNOTSUPP;
break;
}
r = fd_wait_for_event(fd, POLLIN, usec_sub_unsigned(end, n));
if (r < 0)
break;
if (r == 0) {
r = -EOPNOTSUPP;
break;
}
/* On the first read, read multiple characters, i.e. the shortest valid reply. Afterwards
* read byte by byte, since we don't want to read too much and drop characters from the input
* queue. */
ssize_t l = read(fd, buf + bytes, bytes == 0 ? STRLEN(DCS_TERMINFO_R0) : 1);
if (l < 0) {
if (errno == EAGAIN)
continue;
r = -errno;
break;
}
assert((size_t) l <= sizeof(buf) - bytes);
bytes += l;
r = scan_terminfo_response(buf, bytes, ret_name);
if (r != -EAGAIN)
break;
if (bytes == sizeof(buf)) {
r = -EOPNOTSUPP; /* The response has the right prefix, but we didn't find a valid
* answer with a terminator in the allotted space. Something is
* wrong, possibly some unrelated bytes got injected into the
* answer. */
break;
}
}
finish:
/* We ignore failure here. We already got a reply and if cleanup fails, we can't help that. */
(void) tcsetattr(fd, TCSANOW, &old_termios);
return r;
}
int have_terminfo_file(const char *name) {
/* This is a heuristic check if we have the file, using the directory layout used on
* current Linux systems. Checks for other layouts can be added later if appropriate. */
int r;
assert(filename_is_valid(name));
_cleanup_free_ char *p = path_join("/usr/share/terminfo", CHAR_TO_STR(name[0]), name);
if (!p)
return log_oom_debug();
r = RET_NERRNO(access(p, F_OK));
if (r == -ENOENT)
return false;
if (r < 0)
return r;
return true;
}
int query_term_for_tty(const char *tty, char **ret_term) {
_cleanup_free_ char *dcs_term = NULL;
int r;
assert(tty);
assert(ret_term);
if (tty_is_vc_resolve(tty))
return strdup_to(ret_term, "linux");
/* Try to query the terminal implementation that we're on. This will not work in all
* cases, which is fine, since this is intended to be used as a fallback. */
_cleanup_close_ int tty_fd = open_terminal(tty, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
if (tty_fd < 0)
return log_debug_errno(tty_fd, "Failed to open %s to query terminfo: %m", tty);
r = terminal_get_terminfo_by_dcs(tty_fd, &dcs_term);
if (r < 0)
return log_debug_errno(r, "Failed to query %s for terminfo: %m", tty);
r = have_terminfo_file(dcs_term);
if (r < 0)
return log_debug_errno(r, "Failed to look for terminfo %s: %m", dcs_term);
if (r == 0)
return log_info_errno(SYNTHETIC_ERRNO(ENODATA),
"Terminfo %s not found for %s.", dcs_term, tty);
*ret_term = TAKE_PTR(dcs_term);
return 0;
}
int terminal_is_pty_fd(int fd) {
int r;
assert(fd >= 0);
/* Returns true if we are looking at a pty, i.e. if it's backed by the /dev/pts/ file system */
if (!isatty_safe(fd))
return false;
r = is_fs_type_at(fd, NULL, DEVPTS_SUPER_MAGIC);
if (r != 0)
return r;
/* The ptmx device is weird, it exists twice, once inside and once outside devpts. To detect the
* latter case, let's fire off an ioctl() that only works on ptmx devices. */
int v;
if (ioctl(fd, TIOCGPKT, &v) < 0) {
if (ERRNO_IS_NOT_SUPPORTED(errno))
return false;
return -errno;
}
return true;
}
int pty_open_peer(int fd, int mode) {
assert(fd >= 0);
/* Opens the peer PTY using the new race-free TIOCGPTPEER ioctl() (kernel 4.13).
*
* This is safe to be called on TTYs from other namespaces. */
assert((mode & (O_CREAT|O_PATH|O_DIRECTORY|O_TMPFILE)) == 0);
/* This replicates the EIO retry logic of open_terminal() in a modified way. */
for (unsigned c = 0;; c++) {
int peer_fd = ioctl(fd, TIOCGPTPEER, mode);
if (peer_fd >= 0)
return peer_fd;
if (errno != EIO)
return -errno;
/* Max 1s in total */
if (c >= 20)
return -EIO;
(void) usleep_safe(50 * USEC_PER_MSEC);
}
}
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