src/common/fd-handle.c

   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.h"
  12 #include <common/error.h>
  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         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 LTTNG_HIDDEN
  35 struct fd_handle *fd_handle_create(int fd)
  36 {
  37         struct fd_handle *handle = NULL;
  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(sizeof(*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 LTTNG_HIDDEN
  59 void fd_handle_get(struct fd_handle *handle)
  60 {
  61         if (!handle) {
  62                 return;
  63         }
  64
  65         urcu_ref_get(&handle->ref);
  66 }
  67
  68 LTTNG_HIDDEN
  69 void fd_handle_put(struct fd_handle *handle)
  70 {
  71         if (!handle) {
  72                 return;
  73         }
  74
  75         urcu_ref_put(&handle->ref, fd_handle_release);
  76 }
  77
  78 LTTNG_HIDDEN
  79 int fd_handle_get_fd(struct fd_handle *handle)
  80 {
  81         assert(handle);
  82         return handle->fd;
  83 }
  84
  85 LTTNG_HIDDEN
  86 struct fd_handle *fd_handle_copy(const struct fd_handle *handle)
  87 {
  88         struct fd_handle *new_handle = NULL;
  89         const int new_fd = dup(handle->fd);
  90
  91         if (new_fd < 0) {
  92                 PERROR("Failed to duplicate file descriptor while copying fd_handle: fd = %d", handle->fd);
  93                 goto end;
  94         }
  95
  96         new_handle = fd_handle_create(new_fd);
  97 end:
  98         return new_handle;
  99 }