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bsod: add new option --tty= to specify TTY to output on

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If specified we'll not try to find a free V, but instead just output
directly to the specified TTY. This is particularly useful for
debugging, as it means "systemd-bsod --tty=/dev/tty" just works.
This commit is contained in:
Lennart Poettering 2024-02-20 15:41:16 +01:00
parent 1d9fb8c12d
commit 9655cd3c95
2 changed files with 54 additions and 23 deletions
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11
man/systemd-bsod.service.xml
View file

@ -55,6 +55,17 @@
<xi:include href="version-info.xml" xpointer="v255"/></listitem>
</varlistentry>
<varlistentry>
<term><option>--tty=</option><replaceable></replaceable></term>
<listitem><para>Specify the TTY to output to. By default <command>systemd-bsod</command> will
automatically find a free VT to display the message on. If this option is specified a TTY may be
selected explicitly. Use <option>--tty=/dev/tty</option> to direct output to the terminal the command
is invoked on.</para>
<xi:include href="version-info.xml" xpointer="v256"/></listitem>
</varlistentry>
</variablelist>
</refsect1>

66
src/journal/bsod.c
View file

@ -17,6 +17,7 @@
#include "log.h"
#include "logs-show.h"
#include "main-func.h"
#include "parse-argument.h"
#include "pretty-print.h"
#include "qrcode-util.h"
#include "sigbus.h"
@ -25,6 +26,9 @@
#include "terminal-util.h"
static bool arg_continuous = false;
static char *arg_tty = NULL;
STATIC_DESTRUCTOR_REGISTER(arg_tty, freep);
static int help(void) {
_cleanup_free_ char *link = NULL;
@ -42,6 +46,7 @@ static int help(void) {
" --version Show package version\n"
" -c --continuous Make systemd-bsod wait continuously\n"
" for changes in the journal\n"
" --tty=TTY Specify path to TTY to use\n"
"\nSee the %2$s for details.\n",
program_invocation_short_name,
link,
@ -135,9 +140,9 @@ static int find_next_free_vt(int fd, int *ret_free_vt, int *ret_original_vt) {
}
static int display_emergency_message_fullscreen(const char *message) {
int r, ret = 0, free_vt = 0, original_vt = 0;
int r, ret = 0, free_vt = -1, original_vt = 0;
unsigned qr_code_start_row = 1, qr_code_start_column = 1;
char tty[STRLEN("/dev/tty") + DECIMAL_STR_MAX(int) + 1];
char ttybuf[STRLEN("/dev/tty") + DECIMAL_STR_MAX(int) + 1];
_cleanup_close_ int fd = -EBADF;
_cleanup_fclose_ FILE *stream = NULL;
char read_character_buffer = '\0';
@ -145,30 +150,36 @@ static int display_emergency_message_fullscreen(const char *message) {
.ws_col = 80,
.ws_row = 25,
};
const char *tty;
assert(message);
fd = open_terminal("/dev/tty1", O_RDWR|O_NOCTTY|O_CLOEXEC);
if (arg_tty)
tty = arg_tty;
else {
fd = open_terminal("/dev/tty1", O_RDWR|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return log_error_errno(fd, "Failed to open /dev/tty1: %m");
r = find_next_free_vt(fd, &free_vt, &original_vt);
if (r < 0)
return log_error_errno(r, "Failed to find a free VT: %m");
xsprintf(ttybuf, "/dev/tty%d", free_vt + 1);
tty = ttybuf;
fd = safe_close(fd);
}
fd = open_terminal(tty, O_RDWR|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return log_error_errno(fd, "Failed to open tty1: %m");
r = find_next_free_vt(fd, &free_vt, &original_vt);
if (r < 0)
return log_error_errno(r, "Failed to find a free VT: %m");
xsprintf(tty, "/dev/tty%d", free_vt + 1);
r = open_terminal(tty, O_RDWR|O_NOCTTY|O_CLOEXEC);
if (r < 0)
return log_error_errno(fd, "Failed to open tty: %m");
close_and_replace(fd, r);
return log_error_errno(fd, "Failed to open %s: %m", tty);
if (ioctl(fd, TIOCGWINSZ, &w) < 0)
log_warning_errno(errno, "Failed to fetch tty size, ignoring: %m");
if (ioctl(fd, VT_ACTIVATE, free_vt + 1) < 0)
return log_error_errno(errno, "Failed to activate tty: %m");
if (free_vt >= 0 && ioctl(fd, VT_ACTIVATE, free_vt + 1) < 0)
return log_error_errno(errno, "Failed to activate tty, ignoring: %m");
r = loop_write(fd, ANSI_BACKGROUND_BLUE ANSI_HOME_CLEAR, SIZE_MAX);
if (r < 0)
@ -221,7 +232,7 @@ static int display_emergency_message_fullscreen(const char *message) {
ret = log_error_errno(r, "Failed to read character: %m");
cleanup:
if (ioctl(fd, VT_ACTIVATE, original_vt) < 0)
if (original_vt > 0 && ioctl(fd, VT_ACTIVATE, original_vt) < 0)
return log_error_errno(errno, "Failed to switch back to original VT: %m");
return ret;
@ -231,16 +242,18 @@ static int parse_argv(int argc, char * argv[]) {
enum {
ARG_VERSION = 0x100,
ARG_TTY,
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, ARG_VERSION },
{ "continuous", no_argument, NULL, 'c' },
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, ARG_VERSION },
{ "continuous", no_argument, NULL, 'c' },
{ "tty", required_argument, NULL, ARG_TTY },
{}
};
int c;
int c, r;
assert(argc >= 0);
assert(argv);
@ -259,6 +272,13 @@ static int parse_argv(int argc, char * argv[]) {
arg_continuous = true;
break;
case ARG_TTY:
r = parse_path_argument(optarg, /* suppress_root= */ false, &arg_tty);
if (r < 0)
return r;
break;
case '?':
return -EINVAL;