From: "Dave Yeo" <gnuports@2rosenthals.com>
Subject: getting a single keypress
To: GNU Ports for eCS Mailing List <gnuports@2rosenthals.com>
Message-ID: <a6d31b03-40eb-29d4-8307-e9fb7ba682e5@gmail.com>
Date: Sun, 15 May 2022 21:07:25 -0700
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Trying to fix mpg123's key reading while playing a mp3, things like 
pause etc.
Example program that almost works from the developer, here it hangs and 
sometimes hangs the system.

-----------8<--------------

#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/select.h>
#include <unistd.h>
#include <termios.h>

int term_fd = -1;

int get_key(int do_delay, char *val)
{
	fd_set r;
	struct timeval t;
	t.tv_sec=0;
	t.tv_usec=(do_delay) ? 1000 : 0;
	FD_ZERO(&r);
	FD_SET(term_fd,&r);
	int n = select(term_fd+1,&r,NULL,NULL,&t);
	if(n > 0 && FD_ISSET(term_fd,&r) && read(term_fd,val,1) == 1)
		return 1;
	return 0;
}


int main(int argc, char **argv)
{
	if(argc >= 2)
		term_fd = open("/dev/tty", O_RDONLY);
	else
		term_fd = STDIN_FILENO;
	if(term_fd < 0)
	{
		perror("failure opening terminal input");
		return 1;
	}
	fprintf(stderr, "terminal fd: %d\n", term_fd);

	struct termios old_tio;
	int termsetup = 0;
	if(!tcgetattr(term_fd, &old_tio))
	{
		fprintf(stderr, "proper terminal setup\n");
		struct termios tio = old_tio;
		tio.c_lflag &= ~(ICANON|ECHO);
		tio.c_cc[VMIN] = 1;
		tio.c_cc[VTIME] = 0;
		tcsetattr(term_fd,TCSANOW,&tio);
		termsetup = 1;
	}

	char val = 0;
	while(val != 'q')
	{
		if(get_key(1, &val))
			fprintf(stderr, "got key: %c\n", val);
	}

	if(termsetup)
		tcsetattr(term_fd,TCSAFLUSH,&old_tio);
	if(term_fd > 0)
		close(term_fd);
	return 0;
}

------------>8--------------

Ideas or fixes?
Dave