tty: add cli options

It is now possible to set via the --tty switch options on the inner pty
termios, including control characters.

enter.c

@@ -346,7 +346,7 @@ int enter(struct entry_settings *opts)
 		if (parentSock >= 0) {
 			/* tty_parent_setup handles SIGWINCH to resize the pty */
 			sigdelset(&mask, SIGWINCH);
-			tty_parent_setup(epollfd, parentSock);
+			tty_parent_setup(&opts->ttyopts, epollfd, parentSock);
 		}
 		sig_setup(epollfd, &mask, outer_helper.pid, sig_handler);
 
@@ -672,9 +672,9 @@ int enter(struct entry_settings *opts)
 	}
 
 	if (childSock >= 0) {
-		tty_child(childSock);
+		tty_child(&opts->ttyopts, childSock);
 	}
-	
+
 	if (opts->init != NULL && opts->init[0] != '\0') {
 
 		if (!pid_unshare && prctl(PR_SET_CHILD_SUBREAPER, 1) == -1) {

enter.h

@@ -19,6 +19,7 @@
 # include "ns.h"
 # include "timens.h"
 # include "userns.h"
+# include "tty.h"
 
 struct limit {
 	bool present;
@@ -84,6 +85,7 @@ struct entry_settings {
 	const char *pidfile;
 
 	bool tty;
+	struct tty_opts ttyopts;
 
 	int no_copy_hard_limits;
 	int no_fake_devtmpfs;

kvlist.c

@@ -9,6 +9,11 @@
 
 void kvlist_parse(char *in, struct kvlist *out, size_t len, char **rest)
 {
+	memset(out, 0, sizeof (out) * len);
+	if (in == NULL) {
+		return;
+	}
+
 	char *end = in + strlen(in);
 	char *save = NULL;
 	char *tok = strtok_r(in, ",", &save);

main.c

@@ -285,7 +285,7 @@ int main(int argc, char *argv[], char *envp[])
 		{ "pidfile",            required_argument, NULL, OPTION_PIDFILE         },
 		{ "ip",                 required_argument, NULL, OPTION_IP              },
 		{ "route",              required_argument, NULL, OPTION_ROUTE           },
-		{ "tty",                no_argument,       NULL, OPTION_TTY             },
+		{ "tty",                optional_argument, NULL, OPTION_TTY             },
 
 		/* Opt-out feature flags */
 		{ "no-copy-hard-limits", no_argument, NULL, OPTION_NO_COPY_HARD_LIMITS  },
@@ -665,8 +665,20 @@ int main(int argc, char *argv[], char *envp[])
 				break;
 
 			case OPTION_TTY:
-			  opts.tty = 1;
-			  break;
+			{
+				opts.tty = 1;
+				opts.ttyopts.ptmx = tty_default_ptmx;
+
+				/* 128 is enough to support everything */
+				struct kvlist kvlist[128];
+				size_t nopts = sizeof (kvlist) / sizeof (*kvlist);
+				kvlist_parse(optarg, kvlist, nopts, NULL);
+
+				for (size_t i = 0; i < nopts && kvlist[i].key != NULL; ++i) {
+					tty_opt_parse(&opts.ttyopts, kvlist[i].key, kvlist[i].value);
+				}
+				break;
+			}
 
 			case 'r':
 				opts.root = optarg;

man/bst.1.scd

@@ -284,6 +284,40 @@ _VAR=value_ before the executable to run.
 	To avoid lock races with other processes sharing a common pidfile path, the
 	file is never removed.
 
+\--tty[=<options>]
+	Allocate a pty for the process.
+
+	_--tty_ optionally takes a list of flags or key=value pairs to set specific
+	termios options and control characters for the newly allocated pty.
+
+	Options take no value and can be negated by prepending _'-'_ to the option
+	name (e.g. _-echo_). Supported options are: *brkint*, *clocal*, *cmspar*,
+	*cr0*, *cr1*, *cr2*, *cr3*, *cread*, *crtscts*, *cstopb*, *echo*, *echoctl*,
+	*echoe*, *echok*, *echoke*, *echonl*, *echoprt*, *extproc*, *ff0*, *ff1*,
+	*flusho*, *hupcl*, *icanon*, *icrnl*, *iexten*, *ignbrk*, *igncr*, *ignpar*,
+	*inlcr*, *inpck*, *isig*, *istrip*, *iuclc*, *iutf8*, *ixany*, *ixoff*,
+	*ixon*, *nl0*, *nl1*, *noflsh*, *ocrnl*, *ofill*, *olcuc*, *onlcr*, *onlret*,
+	*onocr*, *opost*, *parenb*, *parmrk*, *parodd*, *tab0*, *tab1*, *tab2*,
+	*tab3*, *tostop*, *vt0*, and *vt1*.
+
+	Control characters are specified as a key-value pair, _<cc>=<val>_. Values
+	can be specified using the caret notation, or a backslash-escaped octal
+	(\\nnn) or hexadecimal (\\xnn) value. Supported control characters are: *veof*,
+	*veol*, *veol2*, *verase*, *vintr*, *vkill*, *vlnext*, *vquit*, *vreprint*,
+	*vstart*, *vstop*, *vsusp*, and *vwerase*.
+
+	A comprehensive description of what these options and control characters do
+	can be found in the *termios*(3) manual.
+
+	Other bst-specific options are:
+
+	- *ptmx*=<path>: use the specified ptmx device (relative to the target root)
+	  to allocated the pty.
+
+	By default bst inherits the parent's terminal device (or lack thereof).  Use
+	the --tty option to allocate a new pty for the child process.
+
+
 \--no-copy-hard-limits
 	Do not copy hard limit values to soft limits for all resources mentioned above.
 
@@ -328,12 +362,6 @@ _VAR=value_ before the executable to run.
 	the spacetime process. This can cause issues for environment variables like
 	PATH if the rootfs layout is different than the host.
 
-\--tty
-	Allocate a pty for the process.
-
-	By default bst inherits the parent's terminal device (or lack thereof).  Use
-	the --tty option to allocate a new pty for the child process.
-
 # PRIVILEGE MODEL
 
 *bst* strives to be runnable by unprivileged users.  However, some code paths

test/tty.t

@@ -1,23 +1,56 @@
 #!/usr/bin/env cram.sh
 
 Allocate a PTY for the spacetime
-	$ bst --tty --mount devpts,/dev/pts,devpts,mode=620,ptmxmode=666 tty
-	/dev/pts/0
+
+	$ bst --tty --mount devpts,/dev/pts,devpts,mode=620,ptmxmode=666 tty | cat -e
+	/dev/pts/0^M$
+
+	$ bst --tty=ptmx=/dev/pts/ptmx --mount devpts,/dev/pts,devpts,mode=620,ptmxmode=666 tty | cat -e
+	/dev/pts/0^M$
+
+	$ </dev/null bst --tty stty -a | cat -e
+	speed 38400 baud; rows 0; columns 0; line = 0;^M$
+	intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;^M$
+	eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R;^M$
+	werase = ^W; lnext = ^V; discard = ^O; min = 1; time = 0;^M$
+	-parenb -parodd -cmspar cs8 -hupcl -cstopb cread -clocal -crtscts^M$
+	-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff^M$
+	-iuclc -ixany -imaxbel -iutf8^M$
+	opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0^M$
+	isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt^M$
+	echoctl echoke -flusho -extproc^M$
 
 Check that redirections still work
 
-	$ echo hello | bst --tty cat
-	hello
-	hello
+	$ echo hello | bst --tty=-echo,-onlcr cat
+	hello
+
+	$ bst --tty=-onlcr echo bonjour | cat
+	bonjour
+
+Change flags and control characters
 
-	$ bst --tty echo hello | cat
-	hello
+	$ bst --tty='-echo,-onlcr,-icanon,veof=^B,vintr=\4,vquit=\x10' stty
+	speed 38400 baud; line = 0;
+	intr = ^D; quit = ^P; eof = ^B; min = 1; time = 0;
+	-brkint -imaxbel
+	-onlcr
+	-icanon -echo
 
 Ensure we send the correct VEOF control character
 
-	$ yes '' | head -c 32768 | timeout 1 bst --tty sh -c 'stty eof ^B && cat' >/dev/null
+	$ yes '' | head -c 32768 | timeout 1 bst --tty=veof=^B cat >/dev/null
+
+	$ yes '' | head -c 32768 | timeout 1 bst --tty sh -c 'head -c 1 && stty eof ^B && cat' >/dev/null
 
 Ensure that we send VEOF twice in case there is pending input in the pty buffer
 
-	$ echo -n hello | bst --tty cat
-	hellohello
+	$ echo -n hola | bst --tty=-echo,-onlcr cat
+	hola
+
+Inner PTYs should inherit their parent termios:
+
+	$ bst --tty sh -c '[ "$(stty -a)" = "$(bst --tty stty -a | tr -d "\r")" ]'
+
+	$ raw=-ignbrk,-brkint,-ignpar,-parmrk,-inpck,-istrip,-inlcr,-igncr,-icrnl,-ixon,-ixoff,-icanon,-opost,-isig,-iuclc,-ixany
+	> [ "$(bst --tty=$raw stty -a)" = "$(bst --tty=$raw bst --tty stty -a)" ]