Several of the /etc/issue escape codes such as \4 and \S depend on
variable data which can change after the agetty prompt is displayed.
This can cause stale data to be displayed when a user looks at a VT,
especially in cases of DHCP racing with system start up.
This commit allows agetty to react a SIGUSR1 signal by reprinting
its prompt including the reprocessing of /etc/issue.
We never want this to occur once the user has started typing a
user name. So we detect when the user starts typing, after which
no further reprompting occurs even if SIGUSR1 is received.
Signed-off-by: Stef Walter <stefw@xxxxxxxxxx>
---
term-utils/agetty.8 | 9 +++++-
term-utils/agetty.c | 86 +++++++++++++++++++++++++++++++++++++++++++++--------
2 files changed, 81 insertions(+), 14 deletions(-)
diff --git a/term-utils/agetty.8 b/term-utils/agetty.8
index 27a0d1b..b11dd4b 100644
--- a/term-utils/agetty.8
+++ b/term-utils/agetty.8
@@ -385,7 +385,14 @@ displays as:
This is thingol.orcan.dk (Linux i386 1.1.9) 18:29:30
.fi
.RE
-
+.SH SIGNALS
+Upon receiving
+.BR SIGUSR1
+.BR agetty
+will reprint the
+.B /etc/issue
+(if so configured) and login prompt. It will do this unless the
+user has started typing a login name.
.SH FILES
.na
.TP
diff --git a/term-utils/agetty.c b/term-utils/agetty.c
index 2b5932d..3e38107 100644
--- a/term-utils/agetty.c
+++ b/term-utils/agetty.c
@@ -270,6 +270,7 @@ static char *get_logname(struct options *op,
struct termios *tp, struct chardata *cp);
static void termio_final(struct options *op,
struct termios *tp, struct chardata *cp);
+static void sig_usr1_handler(int sig);
static int caps_lock(char *s);
static speed_t bcode(char *s);
static void usage(FILE * out) __attribute__((__noreturn__));
@@ -285,6 +286,9 @@ static int plymouth_command(const char* arg);
/* Fake hostname for ut_host specified on command line. */
static char *fakehost;
+/* Indicates whether we've been asked (via a signal) to reprompt */
+static int reprompt_flag;
+
#ifdef DEBUGGING
# include "closestream.h"
# ifndef DEBUG_OUTPUT
@@ -309,7 +313,7 @@ int main(int argc, char **argv)
};
char *login_argv[LOGIN_ARGV_MAX + 1];
int login_argc = 0;
- struct sigaction sa, sa_hup, sa_quit, sa_int;
+ struct sigaction sa, sa_hup, sa_quit, sa_int, sa_usr1;
sigset_t set;
setlocale(LC_ALL, "");
@@ -324,6 +328,12 @@ int main(int argc, char **argv)
sigaction(SIGQUIT, &sa, &sa_quit);
sigaction(SIGINT, &sa, &sa_int);
+ /* Signal to restart prompting */
+ memset(&sa_usr1, 0, sizeof (sa_usr1));
+ sa_usr1.sa_handler = sig_usr1_handler;
+ sigemptyset (&sa_usr1.sa_mask);
+ sigaction(SIGUSR1, &sa_usr1, NULL);
+
#ifdef DEBUGGING
dbf = fopen(DEBUG_OUTPUT, "w");
for (int i = 1; i < argc; i++) {
@@ -824,6 +834,11 @@ static void parse_args(int argc, char **argv, struct options *op)
debug("exiting parseargs\n");
}
+static void sig_usr1_handler(int sig)
+{
+ reprompt_flag = sig;
+}
+
/* Parse alternate baud rates. */
static void parse_speeds(struct options *op, char *arg)
{
@@ -1114,6 +1129,21 @@ static void open_tty(char *tty, struct termios *tp, struct options *op)
}
/* Initialize termios settings. */
+static void termio_clear(int fd)
+{
+ /*
+ * Do not write a full reset (ESC c) because this destroys
+ * the unicode mode again if the terminal was in unicode
+ * mode. Also it clears the CONSOLE_MAGIC features which
+ * are required for some languages/console-fonts.
+ * Just put the cursor to the home position (ESC [ H),
+ * erase everything below the cursor (ESC [ J), and set the
+ * scrolling region to the full window (ESC [ r)
+ */
+ write_all(fd, "\033[r\033[H\033[J", 9);
+}
+
+/* Initialize termios settings. */
static void termio_init(struct options *op, struct termios *tp)
{
speed_t ispeed, ospeed;
@@ -1166,18 +1196,8 @@ static void termio_init(struct options *op, struct termios *tp)
if ((tp->c_cflag & (CS8|PARODD|PARENB)) == CS8)
op->flags |= F_EIGHTBITS;
- if ((op->flags & F_NOCLEAR) == 0) {
- /*
- * Do not write a full reset (ESC c) because this destroys
- * the unicode mode again if the terminal was in unicode
- * mode. Also it clears the CONSOLE_MAGIC features which
- * are required for some languages/console-fonts.
- * Just put the cursor to the home position (ESC [ H),
- * erase everything below the cursor (ESC [ J), and set the
- * scrolling region to the full window (ESC [ r)
- */
- write_all(STDOUT_FILENO, "\033[r\033[H\033[J", 9);
- }
+ if ((op->flags & F_NOCLEAR) == 0)
+ termio_clear(STDOUT_FILENO);
return;
}
@@ -1593,6 +1613,37 @@ static void next_speed(struct options *op, struct termios *tp)
tcsetattr(STDIN_FILENO, TCSANOW, tp);
}
+static int wait_for_term_input(int fd)
+{
+ struct termios orig, nonc;
+ char input[32];
+ int count;
+ int i;
+
+ /* Our aim here is to fall through if something fails
+ * and not be stuck waiting. On failure assume we have input */
+
+ if (tcgetattr(fd, &orig) != 0)
+ return 1;
+
+ memcpy(&nonc, &orig, sizeof (nonc));
+ nonc.c_lflag &= ~(ICANON | ECHO | ECHOE | ECHOK | ECHOKE);
+ nonc.c_cc[VMIN] = 1;
+ nonc.c_cc[VTIME] = 0;
+
+ if (tcsetattr(fd, TCSANOW, &nonc) != 0)
+ return 1;
+
+ count = read(fd, input, sizeof (input));
+ tcsetattr(fd, TCSANOW, &orig);
+
+ /* Reinject the bytes we read back into the buffer */
+ for (i = 0; i < count; i++)
+ ioctl(fd, TIOCSTI, input + i);
+
+ return count > 0;
+}
+
/* Get user name, establish parity, speed, erase, kill & eol. */
static char *get_logname(struct options *op, struct termios *tp, struct chardata *cp)
{
@@ -1625,9 +1676,18 @@ static char *get_logname(struct options *op, struct termios *tp, struct chardata
while (*logname == '\0') {
+ reprompt_flag = 0;
+
/* Write issue file and prompt */
do_prompt(op, tp);
+ /* If asked to reprompt *before* terminal input arrives, then do so */
+ if (!wait_for_term_input(STDIN_FILENO) && reprompt_flag != 0) {
+ if (op->flags & F_VCONSOLE)
+ termio_clear(STDOUT_FILENO);
+ continue;
+ }
+
cp->eol = '\0';
/* Read name, watch for break and end-of-line. */
--
1.9.3
--
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