termios: change the generic cfsetspeed() to support arbitrary speeds

The generic implementaion of cfsetspeed() had an internal table of
permitted baud rates, which was enforced even on an implementation
supporting arbitrary baud rates. This was to be able to *also* accept
numeric constants as well as Bxxx values.

This fundamentally makes no sense; not only does it go against the
documented behavior of cfsetspeed() which is to take the same input
as cfset[io]speed(), but it means cfsetspeed() is broken with regard
to a platform supporting arbitrary speeds.

With Linux converted to arbitrary baud rates, the only remaining case
of non-arbitrary baud rates appears to be Hurd with USE_OLD_TTY, which
one can presume being a legacy case that few if any people care about,
and so simply strip out this code and make cfsetspeed() rely on
cfsetospeed() to validate acceptable speed constants.

If a new platform is introduced which does not have arbitrary baud
rate support, using non-baud rate Bxxx constants (highly not
recommended; should be abstracted at the glibc level) but such
aliasing is desired, it should be supported by cfset[io]speed() as
well, and belongs in the platform-specific code.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

termios/cfsetspeed.c

@@ -19,143 +19,15 @@
 #include <errno.h>
 #include <stddef.h>
 
-struct speed_struct
-{
-  speed_t value;
-  speed_t internal;
-};
-
-static const struct speed_struct speeds[] =
-  {
-#ifdef B0
-    { 0, B0 },
-#endif
-#ifdef B50
-    { 50, B50 },
-#endif
-#ifdef B75
-    { 75, B75 },
-#endif
-#ifdef B110
-    { 110, B110 },
-#endif
-#ifdef B134
-    { 134, B134 },
-#endif
-#ifdef B150
-    { 150, B150 },
-#endif
-#ifdef B200
-    { 200, B200 },
-#endif
-#ifdef B300
-    { 300, B300 },
-#endif
-#ifdef B600
-    { 600, B600 },
-#endif
-#ifdef B1200
-    { 1200, B1200 },
-#endif
-#ifdef B1200
-    { 1200, B1200 },
-#endif
-#ifdef B1800
-    { 1800, B1800 },
-#endif
-#ifdef B2400
-    { 2400, B2400 },
-#endif
-#ifdef B4800
-    { 4800, B4800 },
-#endif
-#ifdef B9600
-    { 9600, B9600 },
-#endif
-#ifdef B19200
-    { 19200, B19200 },
-#endif
-#ifdef B38400
-    { 38400, B38400 },
-#endif
-#ifdef B57600
-    { 57600, B57600 },
-#endif
-#ifdef B76800
-    { 76800, B76800 },
-#endif
-#ifdef B115200
-    { 115200, B115200 },
-#endif
-#ifdef B153600
-    { 153600, B153600 },
-#endif
-#ifdef B230400
-    { 230400, B230400 },
-#endif
-#ifdef B307200
-    { 307200, B307200 },
-#endif
-#ifdef B460800
-    { 460800, B460800 },
-#endif
-#ifdef B500000
-    { 500000, B500000 },
-#endif
-#ifdef B576000
-    { 576000, B576000 },
-#endif
-#ifdef B921600
-    { 921600, B921600 },
-#endif
-#ifdef B1000000
-    { 1000000, B1000000 },
-#endif
-#ifdef B1152000
-    { 1152000, B1152000 },
-#endif
-#ifdef B1500000
-    { 1500000, B1500000 },
-#endif
-#ifdef B2000000
-    { 2000000, B2000000 },
-#endif
-#ifdef B2500000
-    { 2500000, B2500000 },
-#endif
-#ifdef B3000000
-    { 3000000, B3000000 },
-#endif
-#ifdef B3500000
-    { 3500000, B3500000 },
-#endif
-#ifdef B4000000
-    { 4000000, B4000000 },
-#endif
-  };
-
-
 /* Set both the input and output baud rates stored in *TERMIOS_P to SPEED.  */
 int
 cfsetspeed (struct termios *termios_p, speed_t speed)
 {
-  size_t cnt;
+  int rv;
 
-  for (cnt = 0; cnt < sizeof (speeds) / sizeof (speeds[0]); ++cnt)
-    if (speed == speeds[cnt].internal)
-      {
-	cfsetispeed (termios_p, speed);
-	cfsetospeed (termios_p, speed);
-	return 0;
-      }
-    else if (speed == speeds[cnt].value)
-      {
-	cfsetispeed (termios_p, speeds[cnt].internal);
-	cfsetospeed (termios_p, speeds[cnt].internal);
-	return 0;
-      }
+  rv = cfsetospeed (termios_p, speed);
+  if (rv)
+    return rv;
 
-  __set_errno (EINVAL);
-
-  return -1;
+  return cfsetispeed (termios_p, speed);
 }