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Question about Cygwin's select()

I'm trying to debug an emacs problem, and I'm running into something I don't understand involving Cygwin's select. I'll try to make an STC if necessary, but I thought I'd start with a verbal description in case there's an easy answer. Here's the situation:

emacs creates a subprocess running gdb and sends a bunch of commands to gdb without immediately reading the resulting output. emacs then goes into a loop in which it waits for keyboard input and periodically calls select to check for output from subprocesses. The first call to select has a 30 second timeout and *always* fails with EINTR. As a result, emacs doesn't read the output from gdb right away and doesn't properly initialize the gdb buffer. Subsequent calls to select sometimes succeed and sometimes fail. When I'm running emacs under gdb and stepping through it, the buffer eventually gets initialized. When I'm running emacs outside of gdb, the buffer doesn't get initialized until I press Return.

I have a simple workaround for this, but I'd like to be sure there isn't some underlying bug that I'm masking with the workaround. So my question is this: Is there some reason that I should expect that first call to select to consistently fail with EINTR, or might this indicate a bug?

I realize that it might not be possible to answer the question based on the information I've provided, but I thought it was worth a try.


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