41 lines
1.4 KiB
Rust
41 lines
1.4 KiB
Rust
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//! The car unit has no RTC battery: the clock boots stale and is stepped later by
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//! chrony (NTP or GNSS). Recordings therefore carry enough to correct timestamps
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//! afterwards — sync state at start, monotonic time, and every step observed.
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use serde_json::{json, Value};
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fn clock(id: libc::clockid_t) -> f64 {
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let mut ts: libc::timespec = unsafe { std::mem::zeroed() };
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unsafe { libc::clock_gettime(id, &mut ts) };
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ts.tv_sec as f64 + ts.tv_nsec as f64 * 1e-9
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}
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pub fn realtime() -> f64 {
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clock(libc::CLOCK_REALTIME)
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}
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pub fn monotonic() -> f64 {
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clock(libc::CLOCK_MONOTONIC)
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}
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/// realtime − monotonic. Constant while the clock only slews; a jump means a step.
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pub fn offset() -> f64 {
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realtime() - monotonic()
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}
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pub fn boot_id() -> String {
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std::fs::read_to_string("/proc/sys/kernel/random/boot_id").map(|s| s.trim().to_string()).unwrap_or_default()
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}
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/// Kernel view of synchronisation, read without privilege (adjtimex with modes = 0).
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pub fn sync_state() -> Value {
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let mut tx: libc::timex = unsafe { std::mem::zeroed() };
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let state = unsafe { libc::adjtimex(&mut tx) };
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let unsync = state == libc::TIME_ERROR || tx.status & libc::STA_UNSYNC != 0;
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json!({ "synced": !unsync, "maxerror_us": tx.maxerror, "esterror_us": tx.esterror })
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}
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pub fn hostname() -> String {
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std::fs::read_to_string("/proc/sys/kernel/hostname").map(|s| s.trim().to_string()).unwrap_or_default()
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}
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