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