On 15.07.2014 14:40, Stef Walter wrote:
> On 15.07.2014 11:19, Karel Zak wrote:
>> Maybe the best would be to implement all within agetty, I mean add
>> a special command
>>
>> agetty --reload [<tty>]
>>
>> to reload another already running agetty process(es). So rather than
>> "killall agetty" you have to use "agetty --reload".
>>
>> Then all the implementation will be a private thing and only the "--reload"
>> command line option will be a public API.
>
> Okay. I'll work on this and keep you posted.
Attached is the updated patch.
The current patch implements --reload. We use inotify on a path in /run
to signal the process. We don't create the file initially until does a
--reload.
Note that I didn't implement the [<tty>] option. It seems like it would
need inotify track multiple files, and as such be prone to races, when
trying to signal all agetty processes.
What do you think?
Stef
>From 33583bff1b4dfb3dcff582d1dec9f4005e8bdafd Mon Sep 17 00:00:00 2001
From: Stef Walter <stefw@xxxxxxxxxx>
Date: Thu, 3 Jul 2014 17:44:41 +0200
Subject: [PATCH] agetty: Reprompt and reprint /etc/issue when asked
Add an 'agetty --reload' command which asks all running agetty
commands to display their prompts again.
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.
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 after that point.
Signed-off-by: Stef Walter <stefw@xxxxxxxxxx>
---
term-utils/agetty.8 | 5 +++
term-utils/agetty.c | 126 +++++++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 119 insertions(+), 12 deletions(-)
diff --git a/term-utils/agetty.8 b/term-utils/agetty.8
index 27a0d1b..c997129 100644
--- a/term-utils/agetty.8
+++ b/term-utils/agetty.8
@@ -252,6 +252,11 @@ Sleep seconds before open tty.
\-\-nice \fInumber\fP
Run login with this priority.
.TP
+\-\-reload
+Ask all running agetty instances to reload and update their displayed prompts,
+if the user has not yet commenced logging in. After doing so the command will
+exit.
+.TP
\-\-version
Display version information and exit.
.TP
diff --git a/term-utils/agetty.c b/term-utils/agetty.c
index 2b5932d..d92da80 100644
--- a/term-utils/agetty.c
+++ b/term-utils/agetty.c
@@ -18,6 +18,7 @@
#include <signal.h>
#include <errno.h>
#include <sys/ioctl.h>
+#include <sys/inotify.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
@@ -112,6 +113,9 @@
#define LOGIN "login: "
#define LOGIN_ARGV_MAX 16 /* Numbers of args for login */
+/* Reload trigger file */
+#define GETTY_RELOAD_TRIGGER "/run/agetty.reload"
+
/*
* When multiple baud rates are specified on the command line, the first one
* we will try is the first one specified.
@@ -281,10 +285,14 @@ static ssize_t append(char *dest, size_t len, const char *sep, const char *src)
static void check_username (const char* nm);
static void login_options_to_argv(char *argv[], int *argc, char *str, char *username);
static int plymouth_command(const char* arg);
+static void reload_agettys(void);
/* 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 inotify_fd = -1;
+
#ifdef DEBUGGING
# include "closestream.h"
# ifndef DEBUG_OUTPUT
@@ -334,6 +342,10 @@ int main(int argc, char **argv)
debug("\n");
#endif /* DEBUGGING */
+ inotify_fd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
+ if (inotify_fd > 0)
+ inotify_add_watch (inotify_fd, GETTY_RELOAD_TRIGGER, IN_ATTRIB | IN_MODIFY);
+
/* Parse command-line arguments. */
parse_args(argc, argv, &options);
@@ -587,6 +599,7 @@ static void parse_args(int argc, char **argv, struct options *op)
HELP_OPTION,
ERASE_CHARS_OPTION,
KILL_CHARS_OPTION,
+ RELOAD_OPTION,
};
const struct option longopts[] = {
{ "8bits", no_argument, 0, '8' },
@@ -618,6 +631,7 @@ static void parse_args(int argc, char **argv, struct options *op)
{ "nohints", no_argument, 0, NOHINTS_OPTION },
{ "nohostname", no_argument, 0, NOHOSTNAME_OPTION },
{ "long-hostname", no_argument, 0, LONGHOSTNAME_OPTION },
+ { "reload", no_argument, 0, RELOAD_OPTION },
{ "version", no_argument, 0, VERSION_OPTION },
{ "help", no_argument, 0, HELP_OPTION },
{ "erase-chars", required_argument, 0, ERASE_CHARS_OPTION },
@@ -736,6 +750,9 @@ static void parse_args(int argc, char **argv, struct options *op)
case KILL_CHARS_OPTION:
op->killchars = optarg;
break;
+ case RELOAD_OPTION:
+ reload_agettys();
+ exit(EXIT_SUCCESS);
case VERSION_OPTION:
printf(_("%s from %s\n"), program_invocation_short_name,
PACKAGE_STRING);
@@ -1114,6 +1131,21 @@ 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 +1198,8 @@ 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 +1615,60 @@ static void next_speed(struct options *op, struct termios *tp)
tcsetattr(STDIN_FILENO, TCSANOW, tp);
}
+static int wait_for_term_input(int fd)
+{
+ char buffer[sizeof(struct inotify_event) + NAME_MAX + 1];
+ struct termios orig, nonc;
+ fd_set rfds;
+ 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;
+
+ FD_ZERO(&rfds);
+ FD_SET(fd, &rfds);
+ if (inotify_fd >= 0)
+ FD_SET(inotify_fd, &rfds);
+
+ /* If waiting fails, just fall through, presumably reading input will fail */
+ if (select (MAX(fd, inotify_fd) + 1, &rfds, NULL, NULL, NULL) < 0)
+ return 1;
+
+ if (FD_ISSET(fd, &rfds)) {
+ count = read(fd, buffer, sizeof (buffer));
+
+ tcsetattr(fd, TCSANOW, &orig);
+
+ /* Reinject the bytes we read back into the buffer, usually just one byte */
+ for (i = 0; i < count; i++)
+ ioctl(fd, TIOCSTI, buffer + i);
+
+ /* Have terminal input */
+ return 1;
+
+ } else {
+ tcsetattr(fd, TCSANOW, &orig);
+
+ /* Just drain the inotify buffer */
+ while (read(inotify_fd, buffer, sizeof (buffer)) > 0);
+
+ /* Need to reprompt */
+ return 0;
+ }
+}
+
/* Get user name, establish parity, speed, erase, kill & eol. */
static char *get_logname(struct options *op, struct termios *tp, struct chardata *cp)
{
@@ -1628,6 +1704,13 @@ static char *get_logname(struct options *op, struct termios *tp, struct chardata
/* 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)) {
+ if (op->flags & F_VCONSOLE)
+ termio_clear(STDOUT_FILENO);
+ continue;
+ }
+
cp->eol = '\0';
/* Read name, watch for break and end-of-line. */
@@ -2364,3 +2447,22 @@ static int plymouth_command(const char* arg)
}
return 1;
}
+
+static void reload_agettys(void)
+{
+ struct timeval tv[2];
+ int fd;
+
+ if (gettimeofday (tv, NULL) < 0)
+ err (1, "couldn't get current time");
+ memcpy (tv, tv + 1, sizeof (struct timeval));
+
+ fd = open(GETTY_RELOAD_TRIGGER, O_CREAT|O_CLOEXEC|O_WRONLY, 0700);
+ if (fd < 0)
+ err (1, "couldn't open: %s", GETTY_RELOAD_TRIGGER);
+
+ if (futimes (fd, tv) < 0 || close (fd) < 0)
+ err (1, "couldn't touch file: %s", GETTY_RELOAD_TRIGGER);
+
+ close (fd);
+}
--
1.9.3
