summaryrefslogtreecommitdiffstats
path: root/dom/gamepad/linux/udev.h
blob: 4e3f0b786595092412afe5b7b5ed5aa49e715946 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * This file defines a wrapper around libudev so we can avoid
 * linking directly to it and use dlopen instead.
 */

#ifndef HAL_LINUX_UDEV_H_
#define HAL_LINUX_UDEV_H_

#include <dlfcn.h>

#include "mozilla/ArrayUtils.h"

namespace mozilla {

struct udev;
struct udev_device;
struct udev_enumerate;
struct udev_list_entry;
struct udev_monitor;

class udev_lib {
 public:
  udev_lib() : lib(nullptr), udev(nullptr) {
    // Be careful about ABI compat! 0 -> 1 didn't change any
    // symbols this code relies on, per:
    // https://lists.fedoraproject.org/pipermail/devel/2012-June/168227.html
    const char* lib_names[] = {"libudev.so.0", "libudev.so.1"};
    // Check whether a library is already loaded so we don't load two
    // conflicting libs.
    for (unsigned i = 0; i < ArrayLength(lib_names); i++) {
      lib = dlopen(lib_names[i], RTLD_NOLOAD | RTLD_LAZY | RTLD_GLOBAL);
      if (lib) {
        break;
      }
    }
    // If nothing loads the first time through, it means no version of libudev
    // was already loaded.
    if (!lib) {
      for (unsigned i = 0; i < ArrayLength(lib_names); i++) {
        lib = dlopen(lib_names[i], RTLD_LAZY | RTLD_GLOBAL);
        if (lib) {
          break;
        }
      }
    }
    if (lib && LoadSymbols()) {
      udev = udev_new();
    }
  }

  ~udev_lib() {
    if (udev) {
      udev_unref(udev);
    }

    if (lib) {
      dlclose(lib);
    }
  }

  explicit operator bool() { return udev; }

 private:
#define DLSYM(s)                       \
  do {                                 \
    (s) = (decltype(s))dlsym(lib, #s); \
    if (!(s)) return false;            \
  } while (0)

  bool LoadSymbols() {
    DLSYM(udev_new);
    DLSYM(udev_unref);
    DLSYM(udev_device_unref);
    DLSYM(udev_device_new_from_syspath);
    DLSYM(udev_device_get_devnode);
    DLSYM(udev_device_get_parent_with_subsystem_devtype);
    DLSYM(udev_device_get_property_value);
    DLSYM(udev_device_get_action);
    DLSYM(udev_device_get_sysattr_value);
    DLSYM(udev_enumerate_new);
    DLSYM(udev_enumerate_unref);
    DLSYM(udev_enumerate_add_match_subsystem);
    DLSYM(udev_enumerate_scan_devices);
    DLSYM(udev_enumerate_get_list_entry);
    DLSYM(udev_list_entry_get_next);
    DLSYM(udev_list_entry_get_name);
    DLSYM(udev_monitor_new_from_netlink);
    DLSYM(udev_monitor_filter_add_match_subsystem_devtype);
    DLSYM(udev_monitor_enable_receiving);
    DLSYM(udev_monitor_get_fd);
    DLSYM(udev_monitor_receive_device);
    DLSYM(udev_monitor_unref);

    return true;
  }

#undef DLSYM

  void* lib;

 public:
  struct udev* udev;

  // Function pointers returned from dlsym.
  struct udev* (*udev_new)(void);
  void (*udev_unref)(struct udev*);

  void (*udev_device_unref)(struct udev_device*);
  struct udev_device* (*udev_device_new_from_syspath)(struct udev*,
                                                      const char*);
  const char* (*udev_device_get_devnode)(struct udev_device*);
  struct udev_device* (*udev_device_get_parent_with_subsystem_devtype)(
      struct udev_device*, const char*, const char*);
  const char* (*udev_device_get_property_value)(struct udev_device*,
                                                const char*);
  const char* (*udev_device_get_action)(struct udev_device*);
  const char* (*udev_device_get_sysattr_value)(struct udev_device*,
                                               const char*);

  struct udev_enumerate* (*udev_enumerate_new)(struct udev*);
  void (*udev_enumerate_unref)(struct udev_enumerate*);
  int (*udev_enumerate_add_match_subsystem)(struct udev_enumerate*,
                                            const char*);
  int (*udev_enumerate_scan_devices)(struct udev_enumerate*);
  struct udev_list_entry* (*udev_enumerate_get_list_entry)(
      struct udev_enumerate*);

  struct udev_list_entry* (*udev_list_entry_get_next)(struct udev_list_entry*);
  const char* (*udev_list_entry_get_name)(struct udev_list_entry*);

  struct udev_monitor* (*udev_monitor_new_from_netlink)(struct udev*,
                                                        const char*);
  int (*udev_monitor_filter_add_match_subsystem_devtype)(struct udev_monitor*,
                                                         const char*,
                                                         const char*);
  int (*udev_monitor_enable_receiving)(struct udev_monitor*);
  int (*udev_monitor_get_fd)(struct udev_monitor*);
  struct udev_device* (*udev_monitor_receive_device)(struct udev_monitor*);
  void (*udev_monitor_unref)(struct udev_monitor*);
};

}  // namespace mozilla

#endif  // HAL_LINUX_UDEV_H_