* Problem: In rare cases, afunix.h doesn't contain a definition for struct sockaddr_un
According to https://github.com/microsoft/vcpkg/issues/21623,
struct sockaddr_un might be unavailable on some machines even afunix.h exists.
For example, on some machines, the content of afunix.h looks like this:
typedef struct _SOCKADDR_UN
{
ADDRESS_FAMILY Family;
wchar_t Path[63];
} SOCKADDR_UN, *PSOCKADDR_UN;
but on other machines, it may looks like this:
#define UNIX_PATH_MAX 108
typedef struct sockaddr_un
{
ADDRESS_FAMILY sun_family;
char sun_path[UNIX_PATH_MAX];
} SOCKADDR_UN, *PSOCKADDR_UN;
Fixes#3949
References:
- [Enable Unix-domain sockets support on Windows](8f3ec75de4)
- [AF_UNIX equivalent for Windows](https://stackoverflow.com/questions/9029174/af-unix-equivalent-for-windows)
- https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/
Solution: When compiling with gcc 7 and newer, the program produced by
AC_CHECK_FUNCS(fork) produces a warning, which results in configure
incorrectly disabling fork support. Fix the issue by using an
AC_COMPILE_IFELSE which correctly detects fork availability.
Tested by running configure and make check on a system with gcc 7
installed, and verifying that HAVE_FORK was defined correctly.
See issue #3313.
Solution: add a preprocessor variable ZMQ_NO_EXPORT that, when set, bypasses the automatic ZMQ_EXPORT determination block and just sets ZMQ_EXPORT to empty.
By combining this solution at configuration time with manually passing -fvisibility=hidden to CXXFLAGS, I solved my visibility problem. Just passing -fvisibility=hidden is not enough, because __attribute__ ((visibility ("default"))) has higher priority.
zmq_ppoll mostly mimics zmq_poll behavior, except for the added feature of being able to specify a signal mask. Signals in this mask will be blocked during execution of zmq_ppoll. Switching of the process' active signal mask happens atomically with the actual poll call, so that no race conditions can occur. This behavior is useful when one wants to gracefully handle POSIX signals without race conditions. See e.g. the discussion below https://250bpm.com/blog:12/ for an explanation.
Also includes two new tests:
1. test_zmq_ppoll_fd does the same thing as test_zmq_poll_fd, demonstrating backwards compatibility with zmq_poll when used with a default signal mask.
2. test_zmq_ppoll_signals demonstrates the use of zmq_ppoll with a signal mask, blocking out SIGTERM everywhere except in zmq_ppoll, allowing to handle the signal in one place without having to worry about race conditions.
Solution: switch to Github Actions
Travis recently started enforcing credits for OSS projects without
any funding. While it is possible to get free credits, it is a manual
step that involves contacting customer support via email and asking to
add them, every week. While this does not require money, it requires
something far scarcer: volunteers time.
Drop Travis and migrate to Github Actions.
