Solution: return -1 (no event) instead of 0 (event)
For some reason, this just returns 0 if there are no sockets registered
on the poller. Usually this would mean there has been an event. So the
caller would have to check the return value AND the event, or write code
that takes the number of registered sockets into consideration.
By returning -1 and setting errno = ETIMEDOUT like in the usual timeout
cases, it's more consistent and convenient.
Test case included.
Solution: The Coverity Static Code Analyzer was used on libzmq code and found
many issues with uninitialized member variables, some redefinition of variables
hidding previous instances of same variable name and a couple of functions
where return values were not checked, even though all other occurrences were
checked (e.g. init_size() return).
This commit addresses the following warnings reported on gcc 5.2.1. In
the future, this will help reduce the "noise" and help catch warnings
revealing a serious problem.
It was originally introduce in the refactoring associated with
zeromq/libzmq@da2bc60 (Removing zmq_pollfd as it is replaced by zmq_poller).
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/path/to/libzmq/src/socket_poller.cpp: In member function ‘int zmq::socket_poller_t::add(zmq::socket_base_t*, void*, short int)’:
/path/to/libzmq/src/socket_poller.cpp:92:51: warning: missing initializer for member ‘zmq::socket_poller_t::item_t::pollfd_index’ [-Wmissing-field-initializers]
item_t item = {socket_, 0, user_data_, events_};
^
/path/to/libzmq/src/socket_poller.cpp: In member function ‘int zmq::socket_poller_t::add_fd(zmq::fd_t, void*, short int)’:
/path/to/libzmq/src/socket_poller.cpp:108:50: warning: missing initializer for member ‘zmq::socket_poller_t::item_t::pollfd_index’ [-Wmissing-field-initializers]
item_t item = {NULL, fd_, user_data_, events_};
^
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