> Hmm. So under what conditions should it continue, and under what 
> conditions should it raise an exception (when errno is EINTR)?

EINTR indicates a temporary failure.  In that case it should always retry.

A common macro for handling that might look like this:

#define RETRY_ON_EINTR(x) ({ \
  typeof(x) rv; \
  do { rv = x; } while (rv < 0 && errno == EINTR); \
  rv;\
})

But from what I understand, braces in parentheses are a GCC extension.