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execute: Add kernel cmdline arguments for tty term, rows and columns

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Let's allow configuring tty term and size using kernel cmdline arguments
so that when running in a VM we can communicate the terminal TERM and size
from the host via SMBIOS extra kernel cmdline arguments.
This commit is contained in:
Daan De Meyer 2023-03-19 11:24:01 +01:00
parent c84d14c525
commit 4d62ee559d
2 changed files with 110 additions and 5 deletions
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12
man/kernel-command-line.xml
View file

@ -571,6 +571,18 @@
is set in <filename>/etc/hostname</filename>. Note that this does not bar later runtime changes to
the hostname, it simply controls the initial hostname set during early boot.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>systemd.tty.term.<replaceable>tty</replaceable>=</varname></term>
<term><varname>systemd.tty.rows.<replaceable>tty</replaceable>=</varname></term>
<term><varname>systemd.tty.columns.<replaceable>tty</replaceable>=</varname></term>
<listitem><para>These arguments allow configuring default values for <varname>$TERM</varname>,
<varname>TTYRows=</varname>, and <varname>TTYColumns=</varname> for tty
<replaceable>tty</replaceable>. The tty name should be specified without the
<filename>/dev/</filename> prefix (e.g. <literal>systemd.tty.rows.ttyS0=80</literal>).
</para></listitem>
</varlistentry>
</variablelist>
</refsect1>

103
src/core/execute.c
View file

@ -80,6 +80,7 @@
#include "namespace.h"
#include "parse-util.h"
#include "path-util.h"
#include "proc-cmdline.h"
#include "process-util.h"
#include "psi-util.h"
#include "random-util.h"
@ -201,6 +202,66 @@ static const char *exec_context_tty_path(const ExecContext *context) {
return "/dev/console";
}
static int exec_context_tty_size(const ExecContext *context, unsigned *ret_rows, unsigned *ret_cols) {
_cleanup_free_ char *rowskey = NULL, *rowsvalue = NULL, *colskey = NULL, *colsvalue = NULL;
unsigned rows, cols;
const char *tty;
int r;
assert(context);
assert(ret_rows);
assert(ret_cols);
rows = context->tty_rows;
cols = context->tty_cols;
tty = exec_context_tty_path(context);
if (!tty || (rows != UINT_MAX && cols != UINT_MAX)) {
*ret_rows = rows;
*ret_cols = cols;
return 0;
}
tty = skip_dev_prefix(tty);
if (!in_charset(tty, ALPHANUMERICAL)) {
log_debug("%s contains non-alphanumeric characters, ignoring", tty);
*ret_rows = rows;
*ret_cols = cols;
return 0;
}
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)
log_debug_errno(r, "Failed to read TTY size of %s from kernel cmdline, ignoring: %m", tty);
if (rows == UINT_MAX && rowsvalue) {
r = safe_atou(rowsvalue, &rows);
if (r < 0)
log_debug_errno(r, "Failed to parse %s=%s, ignoring: %m", rowskey, rowsvalue);
}
if (cols == UINT_MAX && colsvalue) {
r = safe_atou(colsvalue, &cols);
if (r < 0)
log_debug_errno(r, "Failed to parse %s=%s, ignoring: %m", colskey, colsvalue);
}
*ret_rows = rows;
*ret_cols = cols;
return 0;
}
static void exec_context_tty_reset(const ExecContext *context, const ExecParameters *p) {
const char *path;
@ -222,8 +283,12 @@ static void exec_context_tty_reset(const ExecContext *context, const ExecParamet
(void) reset_terminal(path);
}
if (p && p->stdin_fd >= 0)
(void) terminal_set_size_fd(p->stdin_fd, path, context->tty_rows, context->tty_cols);
if (p && p->stdin_fd >= 0) {
unsigned rows = context->tty_rows, cols = context->tty_cols;
(void) exec_context_tty_size(context, &rows, &cols);
(void) terminal_set_size_fd(p->stdin_fd, path, rows, cols);
}
if (context->tty_vt_disallocate && path)
(void) vt_disallocate(path);
@ -481,9 +546,12 @@ static int setup_input(
/* Try to make this the controlling tty, if it is a tty, and reset it */
if (isatty(STDIN_FILENO)) {
unsigned rows = context->tty_rows, cols = context->tty_cols;
(void) exec_context_tty_size(context, &rows, &cols);
(void) ioctl(STDIN_FILENO, TIOCSCTTY, context->std_input == EXEC_INPUT_TTY_FORCE);
(void) reset_terminal_fd(STDIN_FILENO, true);
(void) terminal_set_size_fd(STDIN_FILENO, NULL, context->tty_rows, context->tty_cols);
(void) terminal_set_size_fd(STDIN_FILENO, NULL, rows, cols);
}
return STDIN_FILENO;
@ -499,6 +567,7 @@ static int setup_input(
case EXEC_INPUT_TTY:
case EXEC_INPUT_TTY_FORCE:
case EXEC_INPUT_TTY_FAIL: {
unsigned rows, cols;
int fd;
fd = acquire_terminal(exec_context_tty_path(context),
@ -509,7 +578,11 @@ static int setup_input(
if (fd < 0)
return fd;
r = terminal_set_size_fd(fd, exec_context_tty_path(context), context->tty_rows, context->tty_cols);
r = exec_context_tty_size(context, &rows, &cols);
if (r < 0)
return r;
r = terminal_set_size_fd(fd, exec_context_tty_path(context), rows, cols);
if (r < 0)
return r;
@ -772,6 +845,7 @@ static int setup_confirm_stdio(
int *ret_saved_stdout) {
_cleanup_close_ int fd = -EBADF, saved_stdin = -EBADF, saved_stdout = -EBADF;
unsigned rows, cols;
int r;
assert(ret_saved_stdin);
@ -797,7 +871,11 @@ static int setup_confirm_stdio(
if (r < 0)
return r;
r = terminal_set_size_fd(fd, vc, context->tty_rows, context->tty_cols);
r = exec_context_tty_size(context, &rows, &cols);
if (r < 0)
return r;
r = terminal_set_size_fd(fd, vc, rows, cols);
if (r < 0)
return r;
@ -1837,6 +1915,7 @@ static int build_environment(
_cleanup_strv_free_ char **our_env = NULL;
size_t n_env = 0;
char *x;
int r;
assert(u);
assert(c);
@ -1927,6 +2006,7 @@ static int build_environment(
}
if (exec_context_needs_term(c)) {
_cleanup_free_ char *cmdline = NULL;
const char *tty_path, *term = NULL;
tty_path = exec_context_tty_path(c);
@ -1937,6 +2017,19 @@ static int build_environment(
if (path_equal_ptr(tty_path, "/dev/console") && getppid() == 1)
term = getenv("TERM");
else if (tty_path && in_charset(skip_dev_prefix(tty_path), ALPHANUMERICAL)) {
_cleanup_free_ char *key = NULL;
key = strjoin("systemd.tty.term.", skip_dev_prefix(tty_path));
if (!key)
return -ENOMEM;
r = proc_cmdline_get_key(key, 0, &cmdline);
if (r < 0)
log_debug_errno(r, "Failed to read %s from kernel cmdline, ignoring: %m", key);
else if (r > 0)
term = cmdline;
}
if (!term)
term = default_term_for_tty(tty_path);