[RFC PATCH v2 6/8] termios: change the generic cfsetspeed() to support arbitrary speeds

[H. Peter Anvin]

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>
---
 termios/cfsetspeed.c | 138 ++-----------------------------------------
 1 file changed, 5 insertions(+), 133 deletions(-)

diff --git a/termios/cfsetspeed.c b/termios/cfsetspeed.c
index 053e3945ea10..257c6387aaa0 100644
--- a/termios/cfsetspeed.c
+++ b/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;
-
-  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;
-      }
+  int rv;
 
-  __set_errno (EINVAL);
+  rv = cfsetospeed (termios_p, speed);
+  if (rv)
+    return rv;
 
-  return -1;
+  return cfsetispeed (termios_p, speed);
 }
-- 
2.49.0