Opening COM2
Fergus Henderson
fjh@cs.mu.OZ.AU
Thu Apr 3 23:05:00 GMT 1997
Bob Wilson, you wrote:
>
> I have a program which ran correctly when compiled on a gnu-win32
> package from about a year ago, but is failing when compiled with 17.1
> beta. The machine is running NT 3.51 and COM2 is connected to a
> microprocessor with only td, rd and ground connected. The open:
>
> if ((comfd = open("com2", O_RDWR | O_TEXT)) <= 0) {
> fprintf(stderr, "Cmd: Unable to open terminal\n");
> exit(1);
> }
>
> hangs. It doesn't help to tie the modem control lines high, but if I
> generate a few characters on the rd line, the open completes. In no
> case is there an error return.
My guess is that this is due to the symbolic link handling.
When you open a file, cygwin will read the first few bytes
of the file to see if it has the special marker that is used
to indicate a symbolic link; if so, then cygwin will open the
file that the link points to. Obviously this won't work
correctly in the case of device files such as `com2'...
--
Fergus Henderson <fjh@cs.mu.oz.au> | "I have always known that the pursuit
WWW: < http://www.cs.mu.oz.au/~fjh > | of excellence is a lethal habit"
PGP: finger fjh@128.250.37.3 | -- the last words of T. S. Garp.
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