92 lines
2.0 KiB
C
92 lines
2.0 KiB
C
/* Copyright (c) 1994 by Olin Shivers.
|
|
** Copyright (c) 1994-1995 by Brian D. Carlstrom.
|
|
**
|
|
** This file implements the char-ready? procedure for file descriptors
|
|
** and Scsh's fdports. It is not Posix, so it must be implemented for
|
|
** each OS to which scsh is ported.
|
|
**
|
|
** This version assumes two things:
|
|
** - the existence of select to tell if there is data
|
|
** available for the file descriptor.
|
|
** - the existence of the _cnt field in the stdio FILE struct, telling
|
|
** if there is any buffered input in the struct.
|
|
**
|
|
** Most Unixes have these things, so this file should work for them.
|
|
** However, Your Mileage May Vary.
|
|
**
|
|
** You could also replace the select() with a iotctl(FIONREAD) call, if you
|
|
** had one but not the other.
|
|
** -Olin&Brian
|
|
*/
|
|
|
|
#include <sys/types.h>
|
|
#include <sys/time.h>
|
|
#include <stdio.h>
|
|
#include <unistd.h>
|
|
#include "libcig.h"
|
|
#include <errno.h>
|
|
|
|
#include "stdio_dep.h" /* Make sure the .h interface agrees with the code. */
|
|
|
|
/* These two procs return #t if data ready, #f data not ready,
|
|
** and errno if error.
|
|
*/
|
|
|
|
s48_value char_ready_fdes(int fd)
|
|
{
|
|
fd_set readfds;
|
|
struct timeval timeout;
|
|
int result;
|
|
|
|
FD_ZERO(&readfds);
|
|
FD_SET(fd,&readfds);
|
|
|
|
timeout.tv_sec=0;
|
|
timeout.tv_usec=0;
|
|
|
|
result=select(fd+1, &readfds, NULL, NULL, &timeout);
|
|
|
|
if(result == -1 )
|
|
return(s48_enter_fixnum(errno));
|
|
if(result)
|
|
return(S48_TRUE);
|
|
return(S48_FALSE);
|
|
}
|
|
|
|
s48_value stream_char_readyp(FILE *f)
|
|
{
|
|
int fd = fileno(f);
|
|
return f->_cnt > 0 ? S48_TRUE : char_ready_fdes(fd);
|
|
}
|
|
|
|
void setfileno(FILE *fs, int fd)
|
|
{
|
|
fileno(fs) = fd;
|
|
}
|
|
|
|
int fbufcount(FILE* fs)
|
|
{
|
|
return fs->_cnt;
|
|
}
|
|
|
|
|
|
/* Returns true if there is no buffered data in stream FS
|
|
** (or there is no buffering, period.)
|
|
*/
|
|
|
|
int ibuf_empty(FILE *fs)
|
|
{
|
|
return fs->_cnt <= 0;
|
|
}
|
|
|
|
|
|
/* Returns true if the buffer in stream FS is full
|
|
** (or there is no buffering, period).
|
|
*/
|
|
|
|
int obuf_full(FILE *fs)
|
|
{
|
|
return (fs->_flag & _IOLBF) ? (- fs->_cnt >= fs->_bufsiz-1)
|
|
: (fs->_cnt <= 0);
|
|
}
|