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_*.

4 files changed, 37 insertions, 6 deletions

diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc
index 32888dd..d55bc46 100644
--- a/lib/libc/gen/Makefile.inc
+++ b/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
diff --git a/lib/libc/gen/Symbol.map b/lib/libc/gen/Symbol.map
index dd375b0..f9abab5 100644
--- a/lib/libc/gen/Symbol.map
+++ b/lib/libc/gen/Symbol.map
@@ -358,6 +358,7 @@ FBSD_1.1 {
 
 FBSD_1.2 {
 	basename_r;
+	cfmakesane;
 	endutxent;
 	getpagesizes;
 	getutxent;
diff --git a/lib/libc/gen/tcsetattr.3 b/lib/libc/gen/tcsetattr.3
index 01628d3..9be012e 100644
--- a/lib/libc/gen/tcsetattr.3
+++ b/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,
diff --git a/lib/libc/gen/termios.c b/lib/libc/gen/termios.c
index fc21757..7e9f169 100644
--- a/lib/libc/gen/termios.c
+++ b/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)
 {