runtime-rs: Introduce a helper to check if process/container exists

Returns `true` if the error indicates that the target process/container
no longer exists.

This is used to determine if an operation, like signaling a process,
failed because the target is no longer available. The function checks
for standard OS error codes (`ESRCH`, `ENOENT`) and common error message
patterns.

Signed-off-by: Alex Lyn <alex.lyn@antgroup.com>

src/runtime-rs/crates/runtimes/common/src/error.rs

@@ -4,6 +4,8 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
+use nix::libc;
+
 use crate::types::{ContainerProcess, SandboxResponse, TaskResponse};
 
 #[derive(thiserror::Error, Debug)]
@@ -51,3 +53,33 @@ pub fn is_normal_oom_shutdown_error(err: &anyhow::Error) -> bool {
         .iter()
         .any(|pattern| error_string.contains(&pattern.to_lowercase()))
 }
+
+/// List of common error message patterns indicating that a process or container is missing.
+const NO_SUCH_PROCESS_MESSAGES: &[&str] = &[
+    "no such process",
+    "process not found",
+    "init process not found",
+    "cannot find init process",
+];
+
+/// Returns `true` if the error indicates that the target process/container no longer exists.
+/// This is used to determine if an operation, like signaling a process, failed because the
+/// target is no longer available.
+/// The function checks for standard OS error codes (`ESRCH`, `ENOENT`) and common error message patterns.
+pub fn is_no_such_process_error(err: &anyhow::Error) -> bool {
+    // Check for standard OS error codes.
+    if let Some(io_err) = err.downcast_ref::<std::io::Error>() {
+        if let Some(raw_os_error) = io_err.raw_os_error() {
+            // standard "no such process" error.
+            if raw_os_error == libc::ESRCH || raw_os_error == libc::ENOENT {
+                return true;
+            }
+        }
+    }
+
+    // Fallback to checking the error message for known patterns.
+    let error_string = err.to_string().to_lowercase();
+    NO_SUCH_PROCESS_MESSAGES
+        .iter()
+        .any(|pattern| error_string.contains(&pattern.to_lowercase()))
+}