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Derive Linux process creation timestamps from procfs

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Meta Vens 2026-07-17 03:15:00 +01:00
commit ebc1dc3dae
1 changed files with 23 additions and 1 deletions
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24
epiphany-core/src/process_observation.rs
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@ -321,6 +321,7 @@ mod platform {
#[cfg(target_os = "linux")]
mod platform {
use super::*;
use chrono::{DateTime, SecondsFormat, Utc};
fn stat(process_id: u32) -> Result<(u64, char)> {
let raw = std::fs::read_to_string(format!("/proc/{process_id}/stat"))
@ -338,6 +339,26 @@ mod platform {
Ok((starttime, state))
}
fn created_at_rfc3339(starttime: u64) -> Result<String> {
let ticks_per_second = unsafe { libc::sysconf(libc::_SC_CLK_TCK) };
if ticks_per_second <= 0 {
bail!("operating system returned an invalid process clock frequency");
}
let boot_seconds = std::fs::read_to_string("/proc/stat")?
.lines()
.find_map(|line| line.strip_prefix("btime "))
.context("proc stat has no boot time")?
.parse::<i64>()?;
let ticks_per_second = ticks_per_second as u64;
let seconds = boot_seconds
.checked_add((starttime / ticks_per_second) as i64)
.context("process creation time overflow")?;
let nanos = ((starttime % ticks_per_second) * 1_000_000_000 / ticks_per_second) as u32;
let created = DateTime::<Utc>::from_timestamp(seconds, nanos)
.context("process creation time is out of range")?;
Ok(created.to_rfc3339_opts(SecondsFormat::Nanos, true))
}
pub(super) fn capture(process_id: u32) -> Result<ProcessInstanceIdentity> {
let (creation_token, _) = stat(process_id)?;
if creation_token == 0 {
@ -348,7 +369,7 @@ mod platform {
Ok(ProcessInstanceIdentity {
process_id,
creation_token,
created_at_rfc3339: None,
created_at_rfc3339: Some(created_at_rfc3339(creation_token)?),
executable_path,
})
}
@ -433,6 +454,7 @@ mod tests {
fn live_current_process_has_stable_exact_identity() {
let identity = capture_process_instance(std::process::id()).unwrap();
assert_ne!(identity.creation_token, 0);
assert!(identity.created_at_rfc3339.is_some());
assert!(identity.executable_path.is_absolute());
assert_eq!(
observe_process_instance(&identity),