Re: [ECOS] Termios and waiting for character input

[Gary Thomas <gary at mlbassoc dot com>]

Andre-John Mas wrote:
> Hi,
>
> I have the code below. I want to be able to block until something
> is inputted and then continue. The only problem is am finding that
> it continues even without anything being inputed. What should I be
> doing differently:

It looks like a bug :-(  It seems when ICANON is turned off, the
channel becomes non-blocking and will return EOF (or the equivalent)
when read.  I tried the attached program - on Linux it works as
expected, but on eCos, it gets EOF.

Jonathan - you worked the termios code originally - any ideas?

--
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <errno.h>

int
main(int argc, char *argv[])
{
  struct termios term;
  struct termios termsave;
  int c;  
  int    fd = STDIN_FILENO;      

  // INFO: make sure this is a tty
  if (!isatty(fd)) {
	fprintf(stderr,"isatty: STDIN_FILENO not a tty\n");
	exit(1);
  }

  // INFO: get term i/o flags for this tty
  if (tcgetattr(fd, &termsave) < 0) {
	perror("tcgetattr");
	exit(1);
  }

  term = termsave;            /* termsave contains old termios */
  term.c_lflag &= ~ECHO;      /* turn off echo if it's set */
  term.c_lflag &= ~ECHOE;     /* turn off echoe if it's set */
  term.c_lflag &= ~ICANON;    /* turn off echoe if it's set */

  // INFO: propagate changes
  if (tcsetattr(fd, TCSAFLUSH, &term) < 0) {
	perror("tcsetattr");
	exit(1);
  }

  if ((c = fgetc(stdin)) == EOF) {
      fprintf(stderr, "\nCan't read: %s\n", strerror(errno));
  } else {
      fprintf(stderr, "\nYou typed 0x%02x\n", (int)c);
  }

  // INFO: restore old state
  if (tcsetattr(fd, TCSAFLUSH, &termsave) < 0) {
	perror("tcsetattr");
   exit(1);
  }    
}

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