On Wed, 19 Jul 2006 16:35:27 +0200, Stefan Lucke wrote > Quoting Frank Schmirler <vdr@xxxxxxxxxxxx>: > > > On Wed, 19 Jul 2006 14:20:26 +0200, Stefan Lucke wrote > > > But safe_read() has to be modified, as socket is non- > > > blocking (oldflags |= O_NONBLOCK;), EAGAIN should be handled too: > > > > Before safe_read() select() is called through file.Ready(). So EAGAIN should > > not occur with SVDRP. But of course you're right if safe_read() is intended to > > be called for nonblocking IO without prior select(). > > > > But select() on files with O_NONBLOCK is like a noop according to this: > > http://man.linuxquestions.org/index.php?query=select&type=2§ion=2 > > Three independent sets of descriptors are watched. Those > listed in readfds will be watched to see if characters > become available for read- ing (more precisely, to see if a > read will not block - in particular, a file descriptor is > also ready on end-of-file), those in writefds will be watched > to see if a write will not block, and those in exceptfds > will be watched for exceptions. On exit, the sets are modified > in place to indicate which descriptors actually changed status. > > as with O_NONBLOCK a read would never block :-) . This is from the posix standard IEEE Std 1003.1 definition of select(): "A descriptor shall be considered ready for reading when a call to an input function with O_NONBLOCK clear would not block, whether or not the function would transfer data successfully. (The function might return data, an end-of-file indication, or an error other than one indicating that it is blocked, and in each of these cases the descriptor shall be considered ready for reading.)" Cheers, Frank
