Re: Socket Connection

[Larry Morley <lmorley albany net>]

Tom,

What are you doing when you get SIGPIPE?  Are you sure that you're
getting SIGPIPE and not EACCCES (the values for the two are the same;
13; at least with Solaris 7 & gcc 2.8.1).  The return value should
be < 0 from whatever socket function call (socket(), bind() etc.)
you're using, and "errno" will be set to the actual error code (see
sys/errno.h).  If your app is compiled as reentrant, errno() (func-
tion call) is used in place of errno (extern int variable).  See
man socket, man bind, etc.

To get SIGPIPE, you would have to have called signal() to establish
a signal handler for it.  I've never seen SIGPIPE raised for a
socket; that one's a signal that's raised by the OS when you're att-
empting to write to a pipe which can't be read by anything; when the
readable end of the pipe is inaccessable to other process, thread,
etc.  EACCES is pretty common though; especially for ports in the
privileged socket range when the app-in-question is running as a
normal user.  Try running the app as root and see if the error goes
away; if it does, this is probably the case.  Try using a higher port
number (one outside of the priv. range).  The port might also be in
use, though you should receive EINUSE in this case.  The only signal
I usually catch in my apps that use sockets (aside from those to
catch UI related signals) is SIGCHILD, to avoid zombies when I fork
a child in an app where the child process is blocking on accept()
after a listen().

Hope this helps.  Good luck.
- Larry Morley

P.S. While I generally compile my own gcc, the versions I've checked
out on the sunfreeware site have seemed to work fine.  I've got one
machine using a version from that site, and several colleagues that
use their packages; I haven't heard any negative feedback or had any
problems of my own with their software.

> Tom Carter wrote:
> 
> I am using Solaris 8 and the Solaris Free Ware version of gcc, gtk,
> and glib.
> 
> I am using gtk to add xwindowing capabilities to our application
> (message switching).
> 
> 
> I connect the application to the xwindows programs via sockets.
> 
> The application starts from the command line in a dtterm window.
> 
> Once started, it the application forks and executes the initial gtk
> program and then creates a socket.
> 
> The gtk xwindows program then connects to the socket established by
> the application.
> 
> In general this works great.
> 
> However, if I use a command line argument when starting the
> application, the gtk xwindows program can connect and read the socket,
> but cannot write to the socket.  It always gets a SIGPIPE error when
> it tries.  I am confused and baffled why a single command line
> argument could cause this.
> 
> I have also tried this under SCO OpenServer 5.0.5 with an older
> version of gtk, gcc, and glib, and this particular problem does not
> occur.
> 
> Is this an OS problem?  A Linking problem?
> 
> Thanks
> 
> Tcarter