Add a new libc function: cfmakesane(3).

I've noticed various terminal emulators that need to obtain a sane
default termios structure use very complex `hacks'. Even though POSIX
doesn't provide any functionality for this, extend our termios API with
cfmakesane(3), which is similar to the commonly supported cfmakeraw(3),
except that it fills the termios structure with sane defaults.

Change all code in our base system to use this function, instead of
depending on <sys/ttydefaults.h> to provide TTYDEF_*.

bin/stty/key.c

@@ -257,14 +257,15 @@ f_rows(struct info *ip)
 void
 f_sane(struct info *ip)
 {
+	struct termios def;
 
-	ip->t.c_cflag = TTYDEF_CFLAG | (ip->t.c_cflag & CLOCAL);
-	ip->t.c_iflag = TTYDEF_IFLAG;
-	ip->t.c_iflag |= ICRNL;
+	cfmakesane(&def);
+	ip->t.c_cflag = def.c_cflag | (ip->t.c_cflag & CLOCAL);
+	ip->t.c_iflag = def.c_iflag;
 	/* preserve user-preference flags in lflag */
 #define	LKEEP	(ECHOKE|ECHOE|ECHOK|ECHOPRT|ECHOCTL|ALTWERASE|TOSTOP|NOFLSH)
-	ip->t.c_lflag = TTYDEF_LFLAG | (ip->t.c_lflag & LKEEP);
-	ip->t.c_oflag = TTYDEF_OFLAG;
+	ip->t.c_lflag = def.c_lflag | (ip->t.c_lflag & LKEEP);
+	ip->t.c_oflag = def.c_oflag;
 	ip->set = 1;
 }
 

include/termios.h

@@ -88,6 +88,7 @@ pid_t	tcgetsid(int);
 int	tcsetsid(int, pid_t);
 
 void	cfmakeraw(struct termios *);
+void	cfmakesane(struct termios *);
 int	cfsetspeed(struct termios *, speed_t);
 #endif
 __END_DECLS

lib/libc/gen/Makefile.inc

@@ -180,9 +180,9 @@ MLINKS+=syslog.3 closelog.3 syslog.3 openlog.3 syslog.3 setlogmask.3 \
 	syslog.3 vsyslog.3
 MLINKS+=tcsendbreak.3 tcdrain.3 tcsendbreak.3 tcflow.3 tcsendbreak.3 tcflush.3
 MLINKS+=tcsetattr.3 cfgetispeed.3 tcsetattr.3 cfgetospeed.3 \
-	tcsetattr.3 cfmakeraw.3 tcsetattr.3 cfsetispeed.3 \
-	tcsetattr.3 cfsetospeed.3 tcsetattr.3 cfsetspeed.3 \
-	tcsetattr.3 tcgetattr.3
+	tcsetattr.3 cfmakeraw.3 tcsetattr.3 cfmakesane.3 \
+	tcsetattr.3 cfsetispeed.3 tcsetattr.3 cfsetospeed.3 \
+	tcsetattr.3 cfsetspeed.3 tcsetattr.3 tcgetattr.3
 MLINKS+=ttyname.3 isatty.3 ttyname.3 ttyname_r.3
 MLINKS+=tzset.3 tzsetwall.3
 MLINKS+=unvis.3 strunvis.3 unvis.3 strunvisx.3

lib/libc/gen/Symbol.map

@@ -358,6 +358,7 @@ FBSD_1.1 {
 
 FBSD_1.2 {
 	basename_r;
+	cfmakesane;
 	endutxent;
 	getpagesizes;
 	getutxent;

lib/libc/gen/tcsetattr.3

@@ -38,6 +38,7 @@
 .Nm cfsetospeed ,
 .Nm cfsetspeed ,
 .Nm cfmakeraw ,
+.Nm cfmakesane ,
 .Nm tcgetattr ,
 .Nm tcsetattr
 .Nd manipulating the termios structure
@@ -57,6 +58,8 @@
 .Fn cfsetspeed "struct termios *t" "speed_t speed"
 .Ft void
 .Fn cfmakeraw "struct termios *t"
+.Ft void
+.Fn cfmakesane "struct termios *t"
 .Ft int
 .Fn tcgetattr "int fd" "struct termios *t"
 .Ft int
@@ -64,6 +67,7 @@
 .Sh DESCRIPTION
 The
 .Fn cfmakeraw ,
+.Fn cfmakesane ,
 .Fn tcgetattr
 and
 .Fn tcsetattr
@@ -180,14 +184,20 @@ The
 .Fn cfmakeraw
 function sets the flags stored in the termios structure to a state disabling
 all input and output processing, giving a
-.Dq raw I/O path .
+.Dq raw I/O path ,
+while the
+.Fn cfmakesane
+function sets them to a state similar to those of a newly created
+terminal device.
 It should be noted that there is no function to reverse this effect.
 This is because there are a variety of processing options that could be
 re-enabled and the correct method is for an application to snapshot the
 current terminal state using the function
 .Fn tcgetattr ,
-setting raw mode with
+setting raw or sane mode with
 .Fn cfmakeraw
+or
+.Fn cfmakesane
 and the subsequent
 .Fn tcsetattr ,
 and then using another
@@ -316,7 +326,8 @@ functions are expected to be compliant with the
 .St -p1003.1-88
 specification.
 The
-.Fn cfmakeraw
+.Fn cfmakeraw ,
+.Fn cfmakesane
 and
 .Fn cfsetspeed
 functions,

lib/libc/gen/termios.c

@@ -40,6 +40,8 @@ __FBSDID("$FreeBSD$");
 #include <sys/time.h>
 
 #include <errno.h>
+#include <string.h>
+#define	TTYDEFCHARS
 #include <termios.h>
 #include <unistd.h>
 #include "un-namespace.h"
@@ -173,6 +175,23 @@ cfmakeraw(struct termios *t)
 	t->c_cc[VTIME] = 0;
 }
 
+/*
+ * Obtain a termios structure which is similar to the one provided by
+ * the kernel.
+ */
+void
+cfmakesane(struct termios *t)
+{
+
+	t->c_cflag = TTYDEF_CFLAG;
+	t->c_iflag = TTYDEF_IFLAG;
+	t->c_lflag = TTYDEF_LFLAG;
+	t->c_oflag = TTYDEF_OFLAG;
+	t->c_ispeed = TTYDEF_SPEED;
+	t->c_ospeed = TTYDEF_SPEED;
+	memcpy(&t->c_cc, ttydefchars, sizeof ttydefchars);
+}
+
 int
 tcsendbreak(int fd, int len __unused)
 {

libexec/getty/main.c

@@ -454,8 +454,9 @@ opentty(const char *tty, int flags)
 }
 
 static void
-defttymode()
+defttymode(void)
 {
+	struct termios def;
 
 	/* Start with default tty settings. */
 	if (tcgetattr(STDIN_FILENO, &tmode) < 0) {
@@ -471,10 +472,11 @@ defttymode()
 	 * to leave their idea of the preferred VERASE key value
 	 * there.
 	 */
-	tmode.c_iflag = TTYDEF_IFLAG;
-	tmode.c_oflag = TTYDEF_OFLAG;
-	tmode.c_lflag = TTYDEF_LFLAG;
-	tmode.c_cflag = TTYDEF_CFLAG;
+	cfmakesane(&def);
+	tmode.c_iflag = def.c_iflag;
+	tmode.c_oflag = def.c_oflag;
+	tmode.c_lflag = def.c_lflag;
+	tmode.c_cflag = def.c_cflag;
 	if (NC)
 		tmode.c_cflag |= CLOCAL;
 	omode = tmode;

libexec/rlogind/rlogind.c

@@ -545,7 +545,7 @@ setup_term(int fd)
 {
 	char *cp = index(term+ENVSIZE, '/');
 	char *speed;
-	struct termios tt;
+	struct termios tt, def;
 
 #ifndef notyet
 	tcgetattr(fd, &tt);
@@ -558,9 +558,10 @@ setup_term(int fd)
 		cfsetspeed(&tt, atoi(speed));
 	}
 
-	tt.c_iflag = TTYDEF_IFLAG;
-	tt.c_oflag = TTYDEF_OFLAG;
-	tt.c_lflag = TTYDEF_LFLAG;
+	cfmakesane(&def);
+	tt.c_iflag = def.c_iflag;
+	tt.c_oflag = def.c_oflag;
+	tt.c_lflag = def.c_lflag;
 	tcsetattr(fd, TCSAFLUSH, &tt);
 #else
 	if (cp) {