[1/2] tools/console: Add escape argument to configure escape character

Commit Message

Peter Hoyes June 14, 2023, 7:41 a.m. UTC

From: Peter Hoyes <[e-mail]>

Dom0 may be accessed via telnet, meaning the default escape character
(which is the same as telnet's) cannot be directly used to exit the
console. It would be helpful to make the escape character customizable
in such use cases.

Add --escape argument to console tool for this purpose.

Create parse_escape_character static function to convert a character
string (which may include a '^' modifier) into an ANSI integer.

Add argument to getopt options, parse escape character and pass value
to console_loop.

If --escape is not specified, it falls back to the existing behavior
using DEFAULT_ESCAPE_SEQUENCE.

Issue-Id: SCM-4958
Signed-off-by: Peter Hoyes <[e-mail]>
Change-Id: I3795e654b382e78144d8210f303e3ebccec457ed
---
 tools/console/client/main.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

Comments

Luca Fancellu June 22, 2023, 10:12 a.m. UTC | #1

> On 14 Jun 2023, at 08:41, Peter Hoyes <[e-mail]> wrote:
> 
> From: Peter Hoyes <[e-mail]>
> 
> Dom0 may be accessed via telnet, meaning the default escape character
> (which is the same as telnet's) cannot be directly used to exit the
> console. It would be helpful to make the escape character customizable
> in such use cases.
> 
> Add --escape argument to console tool for this purpose.
> 
> Create parse_escape_character static function to convert a character
> string (which may include a '^' modifier) into an ANSI integer.
> 
> Add argument to getopt options, parse escape character and pass value
> to console_loop.
> 
> If --escape is not specified, it falls back to the existing behavior
> using DEFAULT_ESCAPE_SEQUENCE.
> 
> Issue-Id: SCM-4958
> Signed-off-by: Peter Hoyes <[e-mail]>
> Change-Id: I3795e654b382e78144d8210f303e3ebccec457ed

Hi Peter,

Here in Xen-devel the patches should not have Issue-Id and Change-Id,
they can be stripped on commit if the maintainer is willing to do so,
otherwise you’ll need to send a v2 with the tags removed.

To me the code looks good, still need a maintainer review though.

Reviewed-by: Luca Fancellu <[e-mail]>

Patch

diff --git a/tools/console/client/main.c b/tools/console/client/main.c
index 6775006488..fb7cfb04b5 100644
--- a/tools/console/client/main.c
+++ b/tools/console/client/main.c
@@ -42,7 +42,7 @@ 
 #include <xenstore.h>
 #include "xenctrl.h"
 
-#define ESCAPE_CHARACTER 0x1d
+#define DEFAULT_ESCAPE_CHARACTER 0x1d
 
 static volatile sig_atomic_t received_signal = 0;
 static char lockfile[sizeof (XEN_LOCK_DIR "/xenconsole.") + 8] = { 0 };
@@ -77,6 +77,7 @@  static void usage(const char *program) {
 	       "  -n, --num N      use console number N\n"
 	       "  --type TYPE      console type. must be 'pv', 'serial' or 'vuart'\n"
 	       "  --start-notify-fd N file descriptor used to notify parent\n"
+	       "  --escape E       escape sequence to exit console\n"
 	       , program);
 }
 
@@ -174,7 +175,7 @@  static void restore_term(int fd, struct termios *old)
 }
 
 static int console_loop(int fd, struct xs_handle *xs, char *pty_path,
-		        bool interactive)
+			bool interactive, char escape_character)
 {
 	int ret, xs_fd = xs_fileno(xs), max_fd = -1;
 
@@ -215,7 +216,7 @@  static int console_loop(int fd, struct xs_handle *xs, char *pty_path,
 			char msg[60];
 
 			len = read(STDIN_FILENO, msg, sizeof(msg));
-			if (len == 1 && msg[0] == ESCAPE_CHARACTER) {
+			if (len == 1 && msg[0] == escape_character) {
 				return 0;
 			} 
 
@@ -335,6 +336,7 @@  int main(int argc, char **argv)
 		{ "help",    0, 0, 'h' },
 		{ "start-notify-fd", 1, 0, 's' },
 		{ "interactive", 0, 0, 'i' },
+		{ "escape",  1, 0, 'e' },
 		{ 0 },
 
 	};
@@ -345,6 +347,7 @@  int main(int argc, char **argv)
 	console_type type = CONSOLE_INVAL;
 	bool interactive = 0;
 	const char *console_names = "serial, pv, vuart";
+	char escape_character = DEFAULT_ESCAPE_CHARACTER;
 
 	while((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 		switch(ch) {
@@ -375,6 +378,12 @@  int main(int argc, char **argv)
 		case 'i':
 			interactive = 1;
 			break;
+		case 'e':
+			if (optarg[0] == '^')
+				escape_character = optarg[1] & 0x1f;
+			else
+				escape_character = optarg[0];
+			break;
 		default:
 			fprintf(stderr, "Invalid argument\n");
 			fprintf(stderr, "Try `%s --help' for more information.\n", 
@@ -493,7 +502,7 @@  int main(int argc, char **argv)
 		close(start_notify_fd);
 	}
 
-	console_loop(spty, xs, path, interactive);
+	console_loop(spty, xs, path, interactive, escape_character);
 
 	free(path);
 	free(dom_path);