Restore tty attributes if interactive child is terminated by signal

Some programs like su(1) do not restore tty attributes like ECHO when they are
terminated by receiving SIGINT. Other shells (bash, mksh, zsh) save tty
attributes before executing an external command and restore them if the child
exited due to the receipt of a signal. rc now does the same if it is
interactive.

1 files changed, 13 insertions, 1 deletions

diff --git a/walk.c b/walk.c
index 314484b..4f06fcf 100644
--- a/walk.c
+++ b/walk.c
@@ -4,6 +4,8 @@
 
 #include <signal.h>
 #include <setjmp.h>
+#include <termios.h>
+#include <unistd.h>
 
 #include "jbwrap.h"
 
@@ -322,11 +324,16 @@ static bool isallpre(Node *n) {
 
 static bool dofork(bool parent) {
 	int pid, sp;
+	struct termios t;
 
+	if (interactive)
+		tcgetattr(0, &t);
 	if (!parent || (pid = rc_fork()) == 0)
 		return TRUE;
 	redirq = NULL; /* clear out the pre-redirection queue in the parent */
 	rc_wait4(pid, &sp, TRUE);
+	if (interactive && WIFSIGNALED(sp))
+		tcsetattr(0, TCSANOW, &t);
 	setstatus(-1, sp);
 	sigchk();
 	return FALSE;
@@ -336,7 +343,10 @@ static void dopipe(Node *n) {
 	int i, j, sp, pid, fd_prev, fd_out, pids[512], stats[512], p[2];
 	bool intr;
 	Node *r;
+	struct termios t;
 
+	if (interactive)
+		tcgetattr(0, &t);
 	fd_prev = fd_out = 1;
 	for (r = n, i = 0; r != NULL && r->type == nPipe; r = r->u[2].p, i++) {
 		if (i > 500) /* the only hard-wired limit in rc? */
@@ -379,8 +389,10 @@ static void dopipe(Node *n) {
 	for (j = 0; j < i; j++) {
 		rc_wait4(pids[j], &sp, TRUE);
 		stats[j] = sp;
-		intr |= (sp == SIGINT);
+		intr |= WIFSIGNALED(sp);
 	}
+	if (interactive && intr)
+		tcsetattr(0, TCSANOW, &t);
 	setpipestatus(stats, i);
 	sigchk();
 }