Fix network connect poll interuption handling

[bukka]

When connecting to socket, it is possible to get EINTR. In such case, there should be an another attempt to connect if we are not over the timeout. The timeout should be adjusted accordingly in that case.

This should fix phpredis/phpredis#1881 . It is inspired by redis/hiredis#1213 that had a similar issue.

[bukka]

This should be now ready for review. I will see if there is anyway how I could create an EINTR at least manually and test it a bit but code wise, it should be ready.

[nielsdos]

Note that gettimeofday() may not be the appropriate method here because that is not a monotonic clock. I.e. your time difference may become negative
In the patch I was developing I was using php_hrtime_current to compute the time difference.

[bukka]

Isn't that covered by timercmp check? I used what was already there actually and this case is pretty unlikely because EINTR happens quite rarely so even not changing timeout is probably not the end of the world. I wouldn't worry about some small inaccuracy though. Unless it can somehow overflow ofc?

[nielsdos]

It's indeed covered by timercmp. In the case of a clock time update you can get a shorter timeout than expected, which is not 100% correct but I see your point that this is rare.

Unless it can somehow overflow ofc?

I don't think so.

[nielsdos]

Looks fine, just one silly nit

[bukka]

@nielsdos Just a note that I struggled a bit to find some good way how to test those paths reliably. So I decided to introduce unit testing setup using cmocka to mock the libc functions and be able to cover those paths. I will ping other devs for feedback as well.

[bukka]

I merged just the code change without the tests - the tests are now in #16987

[nielsdos]

@nielsdos Just a note that I struggled a bit to find some good way how to test those paths reliably. So I decided to introduce unit testing setup using cmocka to mock the libc functions and be able to cover those paths. I will ping other devs for feedback as well.

Thanks, I'll have a look tonight.
I previously used an interposer in zend_test with an INI toggle to achieve something similar:

php-src/ext/zend_test/test.c

Lines 1499 to 1514 in 284c4e3

	#ifdef HAVE_COPY_FILE_RANGE
	/**
	* This function allows us to simulate early return of copy_file_range by setting the limit_copy_file_range ini setting.
	*/
	#ifdef __MUSL__
	typedef off_t off64_t;
	#endif
	PHP_ZEND_TEST_API ssize_t copy_file_range(int fd_in, off64_t *off_in, int fd_out, off64_t *off_out, size_t len, unsigned int flags)
	{
	ssize_t (*original_copy_file_range)(int, off64_t *, int, off64_t *, size_t, unsigned int) = dlsym(RTLD_NEXT, "copy_file_range");
	if (ZT_G(limit_copy_file_range) >= Z_L(0)) {
	len = ZT_G(limit_copy_file_range);
	}
	return original_copy_file_range(fd_in, off_in, fd_out, off_out, len, flags);
	}
	#endif