Linuxulator: complete LOCAL_PEERCRED support.

[dchagin]

Summary

Cache pid of the remote process in the struct xucred. Do not bump XUCRED_VERSION as struct layout is not changed.

PR: 215202

[dchagin]

Also cache client process pid

[tijl]

I assume you used a union in struct xucred because a pointer has a different size on different architectures? You could use something like this:

pid_t cr_pid;
u_char _cr_unused1[sizeof(void *)-sizeof(pid_t)];

But perhaps that's not really an improvement.

[dchagin]

In D20415#440959, @tijl wrote:

I assume you used a union in struct xucred because a pointer has a different size on different architectures? You could use something like this:

sure

pid_t cr_pid;
u_char _cr_unused1[sizeof(void *)-sizeof(pid_t)];

But perhaps that's not really an improvement.

my variant is better for static struct xucred initialization
thanks