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Date:      Tue, 29 May 2012 13:40:36 +0300
From:      Kustaa Nyholm <Kustaa.Nyholm@planmeca.com>
To:        "freebsd-java@freebsd.org" <freebsd-java@freebsd.org>
Subject:   tcgetattr hangs
Message-ID:  <CBEA8254.385E5%kustaa.nyholm@planmeca.com>
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Hi,

this maybe wrong list but it was suggested I try my luck here.

MY feeling is that this NOT a Java issue per se but here goes.

I'm the developer of PureJavaComm (PJC) , a pure Java serial port access
library that runs on Mac OS X, Linux, Windows and soon I hope on
FreeBSD. I'm co-operating with someone to port the library to
FreeBSD but we have run into mysterious problem that has defeated
all our debugging efforts.

PJC can be found at:

https://github.com/nyholku/purejavacomm

Some background. PJC uses JNA which is a library to access C-code
APIs from Java by writing Java classes that JNA automatically
turns in to standard C calls.

The C functions we are using are very simple and few, here is the complete
list to put you into the picture (btw, this is Java):

int errno();
int fcntl(int fd, int cmd, int arg); int cfgetispeed(Termios termios);
int cfgetospeed(Termios termios);
int setspeed(int fd, int speed);
int cfsetispeed(Termios termios, int speed);
int cfsetospeed(Termios termios, int speed)
int tcflush(int fd, int b);
int tcdrain(int fd);
void cfmakeraw(Termios termios);
int tcgetattr(int fd, Termios termios);
int tcsetattr(int fd, int cmd, Termios termios); int tcsendbreak(int fd,
int duration);
int open(String s, int t); int close(int fd);
int write(int fd, byte[] buffer, int len);
int read(int fd, byte[] buffer, int len);
int ioctl(int fd, int cmd, int[] data);
int select(int n, FDSet read, FDSet write, FDSet error, TimeVal timeout);



So far we have been able to run PJC testsuite in FreeBSD 32 bit Intel with
no problems.

Now however, on FreeBSD 64 bit AMD our test set hangs in a call to
tcgetattr()
in the third test case in our test suite.

The first test opens a port and wiggles some control lines, then closes
the port.
The second test sends and receives a some hundreds of messages using a
background
thread and select(). This is the test that is causing problem further down
the line.
After this test the next test (regardless what it is) hangs in a call to
tcgetattr()
after successfully opening the port.

So how can tcgetattr() hang???

I found one reference to a similar problem but no solution:

http://freebsd.1045724.n5.nabble.com/Re-cups-bugs-tcgetattr-causes-lockup-i
n-USB-backend-on-FreeBSD6-STABLE-td3950285.html

Here is a piece of our debug log that shows the calls from Java to the
native
API showing the end of the successful Test2 and the hang at the beginning
of Test3:

log: > select(9,[8],[],[],jtermios.TimeVal@6f507fb2)
.................................. OK average speed log: <
select(9,[],[],[],jtermios.TimeVal@6f507fb2) =3D> 0
log: > select(9,[8],[],[],jtermios.TimeVal@6f507fb2)
18241 b/sec at baud rate 19200
log: > fcntl(8, 3, 0)
log: < fcntl(8, 3, 0) =3D> 2
log: > fcntl(8, 4, 6)
log: < fcntl(8, 4, 6) =3D> 0
log: > close(8)
log: < close(8) =3D> 0
Test3 - transmit all characters     log: <
select(9,[8],[],[],jtermios.TimeVal@6f507fb2) =3D> -1
log: > open('cuau0',00008006)
log: < open('cuau0',00008006) =3D> 8
log: > close(8)
log: < close(8) =3D> 0
log: > open('cuau0',00008006)
log: < open('cuau0',00008006) =3D> 8
log: > fcntl(8, 3, 0)
log: < fcntl(8, 3, 0) =3D> 6
log: > fcntl(8, 4, 2)
log: < fcntl(8, 4, 2) =3D> 0
log: > tcgetattr(8,jtermios.Termios@5a77a7f9)


All comments welcome.

be Kusti

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