static int
lx_ptm_read(dev_t dev, struct uio *uiop, cred_t *credp)
{
int pktio = lx_ptm_lh_pktio_get(DEVT_TO_INDEX(dev));
int err, loop;
struct uio uio;
struct iovec iovp;
ASSERT(uiop->uio_iovcnt > 0);
/*
* If packet mode has been enabled (via TIOCPKT) we need to pad
* all read requests with a leading byte that indicates any
* relevant control status information.
*/
if (pktio != 0) {
/*
* We'd like to write the control information into
* the current buffer but we can't yet. We don't
* want to modify userspace memory here only to have
* the read operation fail later. So instead
* what we'll do here is read one character from the
* beginning of the memory pointed to by the uio
* structure. This will advance the output pointer
* by one. Then when the read completes successfully
* we can update the byte that we passed over. Before
* we do the read make a copy of the current uiop and
* iovec structs so we can write to them later.
*/
uio = *uiop;
iovp = *uiop->uio_iov;
uio.uio_iov = &iovp;
if (uwritec(uiop) == -1)
return (EFAULT);
}
do {
/*
* Before we actually attempt a read operation we need
* to make sure there's some buffer space to actually
* read in some data. We do this because if we're in
* pktio mode and the caller only requested one byte,
* then we've already used up that one byte and we
* don't want to pass this read request. Doing a 0
* byte read (unless there is a problem with the stream
* head) always returns succcess. Normally when a streams
* read returns 0 bytes we interpret that as an EOF on
* the stream (ie, the slave side has been opened and
* closed) and we ignore it and re-try the read operation.
* So if we pass on a 0 byte read here lx_ptm_read_loop()
* will tell us to loop around and we'll end up in an
* infinite loop.
*/
if (uiop->uio_resid == 0)
break;
/*
* Serialize all reads. We need to do this so that we can
* properly emulate the behavior of master terminals on Linux.
* In reality this serializaion should not pose any kind of
* performance problem since it would be very strange to have
* multiple threads trying to read from the same master
* terminal device concurrently.
*/
if (lx_ptm_read_start(dev) != 0)
return (EINTR);
err = lx_ptm_read_loop(dev, uiop, credp, &loop);
lx_ptm_read_end(dev);
if (err != 0)
return (err);
} while (loop != 0);
if (pktio != 0) {
uint8_t pktio_data = TIOCPKT_DATA;
/*
* Note that the control status information we
* pass back is faked up in the sense that we
* don't actually report any events, we always
* report a status of 0.
*/
if (uiomove(&pktio_data, 1, UIO_READ, &uio) != 0)
return (EFAULT);
}
return (0);
}
lowinit()
{
#if !defined(GPROF)
caddr_t cp;
#endif
extern int dumpmag;
extern int rthashsize;
extern int arptab_size;
extern int dk_ndrive;
extern struct domain unixdomain;
#ifdef INET
extern struct domain inetdomain;
#endif
#include "imp.h"
#if NIMP > 0
extern struct domain impdomain;
#endif
#ifdef NS
extern struct domain nsdomain;
#endif
/* cpp messes these up for lint so put them here */
unixdomain.dom_next = domains;
domains = &unixdomain;
#ifdef INET
inetdomain.dom_next = domains;
domains = &inetdomain;
#endif
#if NIMP > 0
impdomain.dom_next = domains;
domains = &impdomain;
#endif
#ifdef NS
nsdomain.dom_next = domains;
domains = &nsdomain;
#endif
dumpmag = 0; /* used only by savecore */
rthashsize = rthashsize; /* used by netstat, etc. */
arptab_size = arptab_size; /* used by arp command */
dk_ndrive = dk_ndrive; /* used by vmstat, iostat, etc. */
/*
* Pseudo-uses of globals.
*/
lowinit();
intstack[0] = intstack[1];
maxmem = physmem = freemem = 0;
u = u;
fixctlrmask();
main(0);
Xustray();
/*
* Routines called from interrupt vectors.
*/
panic("Machine check");
printf("Write timeout");
consdin();
consdout();
hardclock((caddr_t)0, 0);
softclock((caddr_t)0, 0);
trap((unsigned)0, (unsigned)0, (unsigned)0, (unsigned)0);
memerr();
/*
* Miscellaneous routines called from configurable
* drivers.
*/
disksort((struct buf *)0, (struct buf *)0);
(void) uwritec((struct uio *)0);
(void) todr();
if (vmemall((struct pte *)0, 0, (struct proc *)0, 0))
return; /* use value */
boothowto = 0;
dumpflag = 0; dumpflag = dumpflag;
#ifdef KADB
bootesym = 0; bootesym = bootesym;
#endif
#if !defined(GPROF)
cp = (caddr_t)&etext;
cp = cp;
#endif
}
