github.com/meulengracht/snapd@v0.0.0-20210719210640-8bde69bcc84e/cmd/libsnap-confine-private/cgroup-support.h (about)

     1  /*
     2   * Copyright (C) 2019-2021 Canonical Ltd
     3   *
     4   * This program is free software: you can redistribute it and/or modify
     5   * it under the terms of the GNU General Public License version 3 as
     6   * published by the Free Software Foundation.
     7   *
     8   * This program is distributed in the hope that it will be useful,
     9   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    10   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    11   * GNU General Public License for more details.
    12   *
    13   * You should have received a copy of the GNU General Public License
    14   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    15   *
    16   */
    17  
    18  #ifndef SC_CGROUP_SUPPORT_H
    19  #define SC_CGROUP_SUPPORT_H
    20  
    21  #include <fcntl.h>
    22  #include <stdbool.h>
    23  
    24  /**
    25   * sc_cgroup_create_and_join joins, perhaps creating, a cgroup hierarchy.
    26   *
    27   * The code assumes that an existing hierarchy rooted at "parent". It follows
    28   * up with a sub-hierarchy called "name", creating it if necessary. The created
    29   * sub-hierarchy is made to belong to root.root and the specified process is
    30   * moved there.
    31   **/
    32  void sc_cgroup_create_and_join(const char *parent, const char *name, pid_t pid);
    33  
    34  /**
    35   * sc_cgroup_is_v2() returns true if running on cgroups v2
    36   *
    37   **/
    38  bool sc_cgroup_is_v2(void);
    39  
    40  /**
    41   * sc_cgroup_is_tracking_snap checks whether any snap process other than the
    42   * caller are currently being tracked in a cgroup.
    43   *
    44   * Note that this call will traverse the cgroups hierarchy looking for a group
    45   * name with a specific prefix corresponding to the snap name. This is
    46   * inherently racy. The caller must have taken the per snap instance lock to
    47   * prevent new applications of that snap from being started. However, it is
    48   * still possible that the application may exit but the cgroup has not been
    49   * cleaned up yet, in which case this call will return a false positive.
    50   *
    51   * It is possible that the current process is already being tracked in cgroup,
    52   * in which case the code will skip its own group.
    53   */
    54  bool sc_cgroup_v2_is_tracking_snap(const char *snap_instance);
    55  
    56  /**
    57   * sc_cgroup_v2_own_path_full return the full path of the owning cgroup as
    58   * reported by the kernel.
    59   *
    60   * Returns the full path of the group in the unified hierarchy relative to its
    61   * root. The string is owned by the caller.
    62   */
    63  char *sc_cgroup_v2_own_path_full(void);
    64  
    65  #endif