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core: Limit terminal reset using ANSI sequences to /dev/console

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Doing this in reset_terminal_fd() is a bit too invasive, see
https://github.com/systemd/systemd/pull/32406#issuecomment-2070923583.

Let's only do this for /dev/console so that we work around weird firmwares
disabling line-wrapping, but avoid messing too much with other things.

While we're at it, let's handle more than just line wrapping, and do a
more general reset of stuff to get the terminal into a sane state.
This commit is contained in:
Daan De Meyer 2024-04-22 22:58:49 +02:00 committed by Zbigniew Jędrzejewski-Szmek
parent 1b47cfab7f
commit 00bc83a275
3 changed files with 39 additions and 23 deletions
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53
src/basic/terminal-util.c
View File

@ -306,29 +306,9 @@ int reset_terminal_fd(int fd, bool switch_to_text) {
termios.c_cc[VMIN] = 1;
r = RET_NERRNO(tcsetattr(fd, TCSANOW, &termios));
if (r < 0) {
if (r < 0)
log_debug_errno(r, "Failed to set terminal parameters: %m");
goto finish;
}
if (!terminal_is_dumb()) {
r = fd_nonblock(fd, true);
if (r < 0) {
log_debug_errno(r, "Failed to set terminal to non-blocking mode: %m");
goto finish;
}
/* Enable line wrapping. */
(void) loop_write_full(fd, "\033[?7h", SIZE_MAX, 50 * USEC_PER_MSEC);
if (r > 0) {
r = fd_nonblock(fd, false);
if (r < 0) {
log_debug_errno(r, "Failed to set terminal back to blocking mode: %m");
goto finish;
}
}
}
finish:
/* Just in case, flush all crap out */
(void) tcflush(fd, TCIOFLUSH);
@ -1565,6 +1545,37 @@ int set_terminal_cursor_position(int fd, unsigned int row, unsigned int column)
return 0;
}
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,
"\033c" /* reset to initial state */
"\033[!p" /* soft terminal reset */
"\033]104\007" /* reset colors */
"\033[?7h", /* enable line-wrapping */
SIZE_MAX,
50 * USEC_PER_MSEC);
if (k < 0)
log_debug_errno(k, "Failed to write to terminal: %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 termios_disable_echo(struct termios *termios) {
assert(termios);

1
src/basic/terminal-util.h
View File

@ -98,6 +98,7 @@ bool isatty_safe(int fd);
int reset_terminal_fd(int fd, bool switch_to_text);
int reset_terminal(const char *name);
int set_terminal_cursor_position(int fd, unsigned int row, unsigned int column);
int terminal_reset_ansi_seq(int fd);
int open_terminal(const char *name, int mode);

8
src/core/main.c
View File

@ -208,13 +208,17 @@ static int console_setup(void) {
r = proc_cmdline_tty_size("/dev/console", &rows, &cols);
if (r < 0)
log_warning_errno(r, "Failed to get terminal size, ignoring: %m");
log_warning_errno(r, "Failed to get /dev/console size, ignoring: %m");
else {
r = terminal_set_size_fd(tty_fd, NULL, rows, cols);
if (r < 0)
log_warning_errno(r, "Failed to set terminal size, ignoring: %m");
log_warning_errno(r, "Failed to set /dev/console size, ignoring: %m");
}
r = terminal_reset_ansi_seq(tty_fd);
if (r < 0)
log_warning_errno(r, "Failed to reset /dev/console using ANSI sequences, ignoring: %m");
return 0;
}