#pragma once

// Identifies the process on the other end of a connected Unix-domain socket, for the
// same-UID check that is the Unix transport's authorization boundary (docs/01 §2,
// CLAUDE.md §4). `SO_PEERCRED`/`struct ucred` is Linux-only; macOS has `getpeereid`,
// Windows named pipes carry a token instead (docs/08-porting.md "The seams" /
// "API mapping"). The same-UID check itself is the security property and must not change
// per-OS (docs/adr/0020 decision 2).

#include <system_error>

namespace velox::daemon::rpc::platform {

struct PeerId {
    unsigned int uid = 0;
};

// On success, fills `out` with the peer's identity of the already-connected `fd`. On
// failure, `out` is untouched and the error_code explains why (matches errno on Linux).
std::error_code peer_of(int fd, PeerId& out);

}  // namespace velox::daemon::rpc::platform