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/* -*- 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
/*
* 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:
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 < std::size(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 < std::size(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_