src/common/fd-handle.cpp

   1 /*
   2  * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #include "fd-handle.hpp"
   9
  10 #include <common/error.hpp>
  11
  12 #include <unistd.h>
  13 #include <urcu/ref.h>
  14
  15 struct fd_handle {
  16         struct urcu_ref ref;
  17         int fd;
  18 };
  19
  20 static void fd_handle_release(struct urcu_ref *ref)
  21 {
  22         int ret;
  23         struct fd_handle *handle = lttng::utils::container_of(ref, &fd_handle::ref);
  24
  25         LTTNG_ASSERT(handle->fd >= 0);
  26         ret = close(handle->fd);
  27         if (ret == -1) {
  28                 PERROR("Failed to close file descriptor of fd_handle upon release: fd = %d",
  29                        handle->fd);
  30         }
  31
  32         free(handle);
  33 }
  34
  35 struct fd_handle *fd_handle_create(int fd)
  36 {
  37         struct fd_handle *handle = nullptr;
  38
  39         if (fd < 0) {
  40                 ERR("Attempted to create an fd_handle from an invalid file descriptor: fd = %d",
  41                     fd);
  42                 goto end;
  43         }
  44
  45         handle = zmalloc<fd_handle>();
  46         if (!handle) {
  47                 PERROR("Failed to allocate fd_handle");
  48                 goto end;
  49         }
  50
  51         urcu_ref_init(&handle->ref);
  52         handle->fd = fd;
  53
  54 end:
  55         return handle;
  56 }
  57
  58 void fd_handle_get(struct fd_handle *handle)
  59 {
  60         if (!handle) {
  61                 return;
  62         }
  63
  64         urcu_ref_get(&handle->ref);
  65 }
  66
  67 void fd_handle_put(struct fd_handle *handle)
  68 {
  69         if (!handle) {
  70                 return;
  71         }
  72
  73         urcu_ref_put(&handle->ref, fd_handle_release);
  74 }
  75
  76 int fd_handle_get_fd(struct fd_handle *handle)
  77 {
  78         LTTNG_ASSERT(handle);
  79         return handle->fd;
  80 }
  81
  82 struct fd_handle *fd_handle_copy(const struct fd_handle *handle)
  83 {
  84         struct fd_handle *new_handle = nullptr;
  85         const int new_fd = dup(handle->fd);
  86
  87         if (new_fd < 0) {
  88                 PERROR("Failed to duplicate file descriptor while copying fd_handle: fd = %d",
  89                        handle->fd);
  90                 goto end;
  91         }
  92
  93         new_handle = fd_handle_create(new_fd);
  94 end:
  95         return new_handle;
  96 }