Refactor mount operations to use procfd and new mount API

src/libcrun/cgroup-utils.c

@@ -210,35 +210,13 @@ libcrun_get_cgroup_mode (libcrun_error_t *err)
   return cgroup_mode;
 }
 
-int
-libcrun_get_cgroup_process (pid_t pid, char **path, bool absolute, libcrun_error_t *err)
+static int
+get_cgroup_process_from_content (char *content, int cgroup_mode, char **path, bool absolute, libcrun_error_t *err)
 {
-  cleanup_free char *content = NULL;
-  char proc_cgroup_file[64];
   char *cg_path = NULL;
-  size_t content_size;
   char *controller;
   char *saveptr;
-  int cgroup_mode;
   bool has_data;
-  int ret;
-
-  cgroup_mode = libcrun_get_cgroup_mode (err);
-  if (UNLIKELY (cgroup_mode < 0))
-    return cgroup_mode;
-
-  if (pid == 0)
-    strcpy (proc_cgroup_file, PROC_SELF_CGROUP);
-  else
-    {
-      int len = snprintf (proc_cgroup_file, sizeof (proc_cgroup_file), "/proc/%d/cgroup", pid);
-      if (UNLIKELY (len >= (int) sizeof (proc_cgroup_file)))
-        return crun_make_error (err, 0, "internal error: static buffer too small");
-    }
-
-  ret = read_all_file (proc_cgroup_file, &content, &content_size, err);
-  if (UNLIKELY (ret < 0))
-    return ret;
 
   for (has_data = read_proc_cgroup (content, &saveptr, NULL, &controller, &cg_path);
        has_data;
@@ -266,6 +244,54 @@ libcrun_get_cgroup_process (pid_t pid, char **path, bool absolute, libcrun_error
   return 0;
 }
 
+int
+libcrun_get_cgroup_process_at (int dirfd, char **path, bool absolute, libcrun_error_t *err)
+{
+  cleanup_free char *content = NULL;
+  size_t content_size;
+  int cgroup_mode;
+  int ret;
+
+  cgroup_mode = libcrun_get_cgroup_mode (err);
+  if (UNLIKELY (cgroup_mode < 0))
+    return cgroup_mode;
+
+  ret = read_all_file_at (dirfd, SELF_CGROUP, &content, &content_size, err);
+  if (UNLIKELY (ret < 0))
+    return ret;
+
+  return get_cgroup_process_from_content (content, cgroup_mode, path, absolute, err);
+}
+
+int
+libcrun_get_cgroup_process (pid_t pid, char **path, bool absolute, libcrun_error_t *err)
+{
+  cleanup_free char *content = NULL;
+  char proc_cgroup_file[64];
+  size_t content_size;
+  int cgroup_mode;
+  int ret;
+
+  cgroup_mode = libcrun_get_cgroup_mode (err);
+  if (UNLIKELY (cgroup_mode < 0))
+    return cgroup_mode;
+
+  if (pid == 0)
+    strcpy (proc_cgroup_file, PROC_SELF_CGROUP);
+  else
+    {
+      int len = snprintf (proc_cgroup_file, sizeof (proc_cgroup_file), "/proc/%d/cgroup", pid);
+      if (UNLIKELY (len >= (int) sizeof (proc_cgroup_file)))
+        return crun_make_error (err, 0, "internal error: static buffer too small");
+    }
+
+  ret = read_all_file (proc_cgroup_file, &content, &content_size, err);
+  if (UNLIKELY (ret < 0))
+    return ret;
+
+  return get_cgroup_process_from_content (content, cgroup_mode, path, absolute, err);
+}
+
 static int
 read_pids_cgroup (int dfd, bool recurse, pid_t **pids, size_t *n_pids, size_t *allocated, libcrun_error_t *err)
 {

src/libcrun/cgroup-utils.h

@@ -28,6 +28,8 @@ int libcrun_cgroups_create_symlinks (int dirfd, libcrun_error_t *err);
 
 int libcrun_get_cgroup_process (pid_t pid, char **path, bool absolute, libcrun_error_t *err);
 
+int libcrun_get_cgroup_process_at (int dirfd, char **path, bool absolute, libcrun_error_t *err);
+
 int libcrun_get_cgroup_mode (libcrun_error_t *err);
 
 int libcrun_get_cgroup_dirfd (struct libcrun_cgroup_status *status, const char *sub_cgroup, libcrun_error_t *err);

src/libcrun/cgroup.h

@@ -26,8 +26,12 @@
 #  define CGROUP_ROOT "/sys/fs/cgroup"
 #endif
 
+#ifndef SELF_CGROUP
+#  define SELF_CGROUP "self/cgroup"
+#endif
+
 #ifndef PROC_SELF_CGROUP
-#  define PROC_SELF_CGROUP "/proc/self/cgroup"
+#  define PROC_SELF_CGROUP "/proc/" SELF_CGROUP
 #endif
 
 enum

src/libcrun/container.c

@@ -1339,11 +1339,6 @@ container_init_setup (void *args, pid_t own_pid, char *notify_socket,
   if (UNLIKELY (ret < 0))
     return ret;
 
-  /* sync 2 and 3 are sent as part of libcrun_set_mounts.  */
-  ret = libcrun_set_mounts (entrypoint_args, container, rootfs, send_sync_cb, &sync_socket, err);
-  if (UNLIKELY (ret < 0))
-    return ret;
-
   if (def->hooks && def->hooks->create_container_len)
     {
       libcrun_error_t tmp_err = NULL;
@@ -1357,6 +1352,15 @@ container_init_setup (void *args, pid_t own_pid, char *notify_socket,
         return ret;
     }
 
+  ret = libcrun_do_pivot_root (container, entrypoint_args->context->no_pivot, &rootfs, err);
+  if (UNLIKELY (ret < 0))
+    return ret;
+
+  /* sync 2 and 3 are sent as part of libcrun_set_mounts.  */
+  ret = libcrun_set_mounts (entrypoint_args, container, rootfs, send_sync_cb, &sync_socket, err);
+  if (UNLIKELY (ret < 0))
+    return ret;
+
   ret = libcrun_finalize_mounts (entrypoint_args, container, rootfs, err);
   if (UNLIKELY (ret < 0))
     return ret;
@@ -1376,13 +1380,6 @@ container_init_setup (void *args, pid_t own_pid, char *notify_socket,
   if (UNLIKELY (ret < 0))
     crun_error_write_warning_and_release (entrypoint_args->context->output_handler_arg, &err);
 
-  if (rootfs)
-    {
-      ret = libcrun_do_pivot_root (container, entrypoint_args->context->no_pivot, rootfs, err);
-      if (UNLIKELY (ret < 0))
-        return ret;
-    }
-
   ret = libcrun_reopen_dev_null (err);
   if (UNLIKELY (ret < 0))
     return ret;