While open[1] is documented for macOS to be able to return EINTR, the documentation for sigaction[2] seems to specify (in confusing wording) that setting SA_RESTART prevents that. It seems to me like a bug in macOS, since they're going against their own documentation.

[1]: https://developer.apple.com/library/archive/documentation/Sy...

[2]: https://developer.apple.com/library/archive/documentation/Sy...

specifically:

> If a signal is caught during the system calls listed below, the call may be forced to terminate with the error EINTR, the call may return with a data transfer shorter than requested, or the call may be restarted. Restart of pending calls is requested by setting the SA_RESTART bit in sa_flags. The affected system calls include open(2), read(2), write(2), sendto(2), recvfrom(2), sendmsg(2) and recvmsg(2) on a communications channel or a slow device (such as a terminal, but not a regular file) and during a wait(2) or ioctl(2). However, calls that have already committed are not restarted, but instead return a partial success (for example, a short read count).