#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <termios.h>

#include "cbi.h"

/* All the apparently redundant sigemptyset() calls are because sigsetops(3)
   says that it (or sigfillset()) must be called before anything else is
   done with a sigset_t...including, by implication, fetching one via calls
   like sigprocmask() or sigaction(). */

static int ifd;
static int ttyp;
static struct termios tio;
static struct termios tio2;
static unsigned int initflags;
static struct sigaction tstpsa;
static struct sigaction oldtstp;

static void cbi_tstp(int sig __attribute__((__unused__)))
{
 sigset_t m;

 sigaction(SIGTSTP,&oldtstp,0);
 tcgetattr(ifd,&tio);
 kill(getpid(),SIGTSTP);
 sigemptyset(&m);
 sigprocmask(SIG_BLOCK,0,&m);
 sigdelset(&m,SIGTSTP);
 sigsuspend(&m);
 tcsetattr(ifd,TCSADRAIN|TCSASOFT,&tio);
 sigaction(SIGTSTP,&tstpsa,&oldtstp);
}

void cbi_init(int fd, unsigned int flags)
{
 ifd = fd;
 initflags = flags;
 ttyp = (tcgetattr(ifd,&tio) == 0);
 if (ttyp)
  { tio2 = tio;
    tio2.c_lflag &= ~(ICANON|ECHO|ECHOKE|ECHOE|ECHONL);
    tio2.c_cc[VMIN] = 1;
    tio2.c_cc[VTIME] = 0;
    tcsetattr(ifd,TCSADRAIN|TCSASOFT,&tio2);
    if (! (initflags & CBI_NO_TSTP))
     { tstpsa.sa_handler = cbi_tstp;
       sigemptyset(&tstpsa.sa_mask);
       tstpsa.sa_flags = 0;
       sigemptyset(&oldtstp.sa_mask);
       sigaction(SIGTSTP,&tstpsa,&oldtstp);
       if (oldtstp.sa_handler == SIG_IGN)
	{ sigaction(SIGTSTP,&oldtstp,0);
	  initflags |= CBI_NO_TSTP;
	}
     }
  }
}

int cbi_getc(void)
{
 unsigned char c;
 int n;

 n = read(ifd,&c,1);
 return((n<=0)?EOF:c);
}

void cbi_end(void)
{
 sigset_t m1;
 sigset_t m2;

 sigemptyset(&m1);
 sigemptyset(&m2);
 sigaddset(&m2,SIGTSTP);
 sigprocmask(SIG_BLOCK,&m2,&m1);
 if (ttyp) tcsetattr(ifd,TCSADRAIN|TCSASOFT,&tio);
 if (! (initflags & CBI_NO_TSTP)) sigaction(SIGTSTP,&oldtstp,0);
 sigprocmask(SIG_SETMASK,&m1,0);
}