Hi,
I am polling a NetLib socket like this:
chhar buf[1];
while (readit(fd, buf, 1) >= 0) {
/* do something else or sleep */
}
The socket is connected to a remote host, which writes some data to the
socket and closes it immidiately. I am expecting my code to read all
the data from the socket and then quit the while loop. I am reading
one byte at a time.
However, after all the data has been read, NetLibSelect doesn't return
any error. It just returns 0 to indicate that no more data is available.
So my loop just hangs.
Then, after about 10 seconds, NetLibSelect finally returns 1 (data is
available). When I read it using NetLibReceive, it returns zero bytes.
The strange part is at this point, err is still zero, not
netErrSocketClosedByRemote as I expected.
The doc says exceptFDs does nothing, so I don't use it. Should I use
it to check for netErrSocketClosedByRemote??
What am I doing wrong here? I am using OS 3.5.
Thanks for your help!
- Ioi
/*=========================================================================
* FUNCTION: readit()
* RETURN: number of bytes read, or <0 if error, or 0 if the caller
* needs to call this function again.
*=======================================================================*/
int
readit(int fd, char *p, int len)
{
int res;
Err err;
NetFDSetType readFDs, writeFDs, exceptFDs;
Int16 numFDs;
UInt16 width;
Int32 timeout;
netFDZero(&readFDs);
netFDZero(&writeFDs);
netFDZero(&exceptFDs);
netFDSet(fd, &readFDs);
width = fd;
if (width < 1) {
width = 1;
}
numFDs = NetLibSelect(AppNetRefnum, width+1, &readFDs, &writeFDs,
&exceptFDs, 0, &err);
if (numFDs <= 0) {
/*
* Socket not ready for reading. The caller should call
* this function later.
*/
return 0;
}
if (err) {
return -1;
}
if (len == 1) {
timeout = -1;
} else {
timeout = 0;
}
res = NetLibReceive(AppNetRefnum, fd, p, len, 0, NULL, NULL, timeout,&err);
if (res == 0) {
/*
* NetLibSelect() told us data is available. If we read 0
* bytes now, it means remote host has closed connection.
*/
res = -1;
}
return res;
}
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