fix(dump,unix sockets): if 'name' is relative, real 'path' does not include that 'name', but 'realpath(name)' resolves to 'path', use 'cwd' as 'name_dir'

Author: kr3v

criu/sk-unix.c

@@ -693,8 +693,37 @@ static int unix_resolve_name(int lfd, uint32_t id, struct unix_sk_desc *d, UnixS
 
 	d->deleted = strip_deleted(path, ret);
 
+    // "time=\"2025-11-07T17:46:45Z\" level=warning msg=\"
+    // 1:Error (criu/sk-unix.c:698):
+    //   unix: Unable too cut
+    //    name=var/run/secrets/workload-spiffe-uds/socket
+    //    path=/run/secrets/workload-spiffe-uds/socket
+    // " container_ids="[09a6920cfb6dda5a538594e8a8272ef2404c093f3dfbaad9677670e80ed51cbb a6b90ec2ffb79c7ddc6425d87f46ad94947f240e7a5ba36d2725054c0fd994f6]" pageserver_address="100.100.149.200:5005" max_iterations="50" container_count="2" fileserver_address="100.100.149.200:5006" intelligent_stopping="true" dirty_pages_threshold="12000" container_id="09a6920c" stage="dump" with_tcp="false"
+
+    //time=2025-11-11T00:44:49.289Z level=DEBUG msg="Error (criu/sk-unix.c:698): unix: Unable too cut ./var/run/sockets/uds/echo.sock from /run/sockets/uds/echo.sock" with_tcp=true max_iterations=50 handler=runc migration_id=1ad9903b-2f45-4731-8844-0373533bc51a container_count=1 pageserver_address=192.168.158.53:5005 fileserver_address=192.168.158.53:5006 intelligent_stopping=true pod_id=efd0ab01-6bd6-4828-97b8-d69d8f547326 container_ids=[04d20a2c443b7d57a8fcfaa282e3a3e59b72aa9d1dec047b70baf2a458fbaedb] container_id=04d20a2c443b7d57a8fcfaa282e3a3e59b72aa9d1dec047b70baf2a458fbaedb stage=dump method=sourceServer.performDumpIteration dirty_pages_threshold=12000 service=cri-proxy
+
+    // i think that:
+    // 1. path is a 'real' path for the socket
+    // 2. name is what was passed to bind() when creating the socket
+    // 3. name_dir is a presumed 'work directory' when the socket was created
+    //    i think the idea during restore:
+    //    > copilot suggestion: "on restore, recreate the socket at name_dir/name" or "cd to name_dir and create the socket at name"
 	if (name[0] != '/') {
 		if (cut_path_ending(path, name)) {
+
+            char resolved[PATH_MAX];
+            if (realpath(name, resolved) != NULL) {
+                if (strcmp(real1, real2) == 0) {
+                    char cwd[PATH_MAX];
+                    if (getcwd(cwd, sizeof(cwd)) != NULL) {
+                        ue->name_dir = xstrdup(cwd);
+                        if (!ue->name_dir)
+                            goto out;
+                        goto set_name_dir;
+                    }
+                }
+            }
+
 			pr_err("Unable too cut %s from %s\n", name, path);
 			goto out;
 		}
@@ -703,6 +732,7 @@ static int unix_resolve_name(int lfd, uint32_t id, struct unix_sk_desc *d, UnixS
 		if (!ue->name_dir)
 			goto out;
 
+set_name_dir:
 		pr_debug("Resolved socket relative name %s to %s/%s\n", name, ue->name_dir, name);
 	}