syscall: verify that windows uintptr structure fields are not pointers

[alexbrainman]

Recently #21376 (comment) we discovered that using uintptr structure fields to store pointers will confuse GC.

https://go-review.googlesource.com/#/c/go/+/106275/ converts all syscall code used by crypto/x509 package to use syscall.Pointer instead of uintptr. But there are other uintptr fields in syscall.

This issue is so we don't forget to check them all.

Alex

[gopherbot]

Change https://golang.org/cl/106275 mentions this issue: syscall: introduce Pointer type and use it instead of uintptr

[alexbrainman]

@aclements I spent some time looking at windows uintptrs in syscall package.

And the only real pointer remains is AddrinfoW.Addr (see https://msdn.microsoft.com/en-us/library/windows/desktop/ms737529(v=vs.85).aspx for its documentation). I tried changing AddrinfoW.Addr type from uintptr into syscall.Pointer, and nothing else needs to change anywhere in standard library. We do use AddrinfoW.Addr in net package in 2 places, but we already convert all uses of it into unsafe.Pointer. Also the way we use AddrinfoW.Addr it is always set by Windows, never by us, so, while it is, probably, pointing onto Go memory, it could be treated as external memory by garbage collector. I think.

Given we already changed syscall package in CL 106275, I think we should change AddrinfoW.Addr into syscall.Pointer. But leaving this decision up to you. Let me know what you think either way. Happy to send a CL if you agree.

Thank you.

Alex

[ianlancetaylor]

ping @aclements

[gopherbot]

Change https://golang.org/cl/123455 mentions this issue: syscall: convert Windows AddrinfoW.Addr from uintptr to syscall.Pointer