Joel,
Thanks for responding.
Our vendor's development kit uses a variant of 4.11.
It doesn't look like pipes work with the select call, and again there
are dire warnings in the select.h file about how it's not really a good
function to use anyway.
I'll look at VMIN and VTIME. Thank you very much for the pointer.
Thanks,
--Ben
On 10-Sep-19 10:18 AM, Joel Sherrill wrote:
On Tue, Sep 10, 2019 at 12:09 AM Benjamin Ellsworth
<2gigspambuc...@gmail.com> wrote:
Hello,
The code I'm working with currently does a read() on a device that has
been opened with an open() call (a UART if that matters). It nicely
blocks waiting for a character (potentially forever).
I now need that read to be interrupted... I looked for pselect() so it
can block until I tell it to stop (via signal from another thread), but
that doesn't seem to be supported. I looked at the classic work-around
using a pipe in a select call, but pipe() isn't supported and select
apparently only works on sockets (and the comments in the select header
make it sound like even that is a bad idea).
What version? I thought select() on termios devices was added at least
to the master.
You are right that it historically hasn't worked.
pipe() is supported. psxpipe01 is the test. Not sure about the use case
you have in mind.
I can probably make things work with timeouts--basically making it into
a polling loop, but I can't see a way to make the read timeout. I dug
down into the rtems read functions, but didn't see any way to make them
timeout, nor did I see a way to cleanly interrupt them.
read() on a UART should be able to do non-blocking or timeout on read()
with the VMIN and VTIME support from termios. There should be examples
of this around the net.
If anyone has any suggestions/ideas/pointers, I'd appreciate them.
--joel
Thanks.
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