Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : /*
       8             :  * This file defines a wrapper around libudev so we can avoid
       9             :  * linking directly to it and use dlopen instead.
      10             :  */
      11             : 
      12             : #ifndef HAL_LINUX_UDEV_H_
      13             : #define HAL_LINUX_UDEV_H_
      14             : 
      15             : #include <dlfcn.h>
      16             : 
      17             : #include "mozilla/ArrayUtils.h"
      18             : 
      19             : namespace mozilla {
      20             : 
      21             : struct udev;
      22             : struct udev_device;
      23             : struct udev_enumerate;
      24             : struct udev_list_entry;
      25             : struct udev_monitor;
      26             : 
      27             : class udev_lib {
      28             :  public:
      29           0 :   udev_lib() : lib(nullptr),
      30           0 :                udev(nullptr) {
      31             :     // Be careful about ABI compat! 0 -> 1 didn't change any
      32             :     // symbols this code relies on, per:
      33             :     // https://lists.fedoraproject.org/pipermail/devel/2012-June/168227.html
      34           0 :     const char* lib_names[] = {"libudev.so.0", "libudev.so.1"};
      35             :     // Check whether a library is already loaded so we don't load two
      36             :     // conflicting libs.
      37           0 :     for (unsigned i = 0; i < ArrayLength(lib_names); i++) {
      38           0 :       lib = dlopen(lib_names[i], RTLD_NOLOAD | RTLD_LAZY | RTLD_GLOBAL);
      39           0 :       if (lib) {
      40           0 :         break;
      41             :       }
      42             :     }
      43             :     // If nothing loads the first time through, it means no version of libudev
      44             :     // was already loaded.
      45           0 :     if (!lib) {
      46           0 :       for (unsigned i = 0; i < ArrayLength(lib_names); i++) {
      47           0 :         lib = dlopen(lib_names[i], RTLD_LAZY | RTLD_GLOBAL);
      48           0 :         if (lib) {
      49           0 :           break;
      50             :         }
      51             :       }
      52             :     }
      53           0 :     if (lib && LoadSymbols()) {
      54           0 :       udev = udev_new();
      55             :     }
      56           0 :   }
      57             : 
      58           0 :   ~udev_lib() {
      59           0 :     if (udev) {
      60           0 :       udev_unref(udev);
      61             :     }
      62             : 
      63           0 :     if (lib) {
      64           0 :       dlclose(lib);
      65             :     }
      66           0 :   }
      67             : 
      68           0 :   explicit operator bool() {
      69           0 :     return udev;
      70             :   }
      71             : 
      72             :  private:
      73           0 :   bool LoadSymbols() {
      74             : #define DLSYM(s) \
      75             :   do { \
      76             :     s = (typeof(s))dlsym(lib, #s); \
      77             :     if (!s) return false; \
      78             :   } while (0)
      79             : 
      80           0 :     DLSYM(udev_new);
      81           0 :     DLSYM(udev_unref);
      82           0 :     DLSYM(udev_device_unref);
      83           0 :     DLSYM(udev_device_new_from_syspath);
      84           0 :     DLSYM(udev_device_get_devnode);
      85           0 :     DLSYM(udev_device_get_parent_with_subsystem_devtype);
      86           0 :     DLSYM(udev_device_get_property_value);
      87           0 :     DLSYM(udev_device_get_action);
      88           0 :     DLSYM(udev_device_get_sysattr_value);
      89           0 :     DLSYM(udev_enumerate_new);
      90           0 :     DLSYM(udev_enumerate_unref);
      91           0 :     DLSYM(udev_enumerate_add_match_subsystem);
      92           0 :     DLSYM(udev_enumerate_scan_devices);
      93           0 :     DLSYM(udev_enumerate_get_list_entry);
      94           0 :     DLSYM(udev_list_entry_get_next);
      95           0 :     DLSYM(udev_list_entry_get_name);
      96           0 :     DLSYM(udev_monitor_new_from_netlink);
      97           0 :     DLSYM(udev_monitor_filter_add_match_subsystem_devtype);
      98           0 :     DLSYM(udev_monitor_enable_receiving);
      99           0 :     DLSYM(udev_monitor_get_fd);
     100           0 :     DLSYM(udev_monitor_receive_device);
     101           0 :     DLSYM(udev_monitor_unref);
     102             : #undef DLSYM
     103           0 :     return true;
     104             :   }
     105             : 
     106             :   void* lib;
     107             : 
     108             :  public:
     109             :   struct udev* udev;
     110             : 
     111             :   // Function pointers returned from dlsym.
     112             :   struct udev* (*udev_new)(void);
     113             :   void (*udev_unref)(struct udev*);
     114             : 
     115             :   void (*udev_device_unref)(struct udev_device*);
     116             :   struct udev_device* (*udev_device_new_from_syspath)(struct udev*,
     117             :                                                       const char*);
     118             :   const char* (*udev_device_get_devnode)(struct udev_device*);
     119             :   struct udev_device* (*udev_device_get_parent_with_subsystem_devtype)
     120             :     (struct udev_device*, const char*, const char*);
     121             :   const char* (*udev_device_get_property_value)(struct udev_device*,
     122             :                                                 const char*);
     123             :   const char* (*udev_device_get_action)(struct udev_device*);
     124             :   const char* (*udev_device_get_sysattr_value)(struct udev_device*,
     125             :                                                const char*);
     126             : 
     127             :   struct udev_enumerate* (*udev_enumerate_new)(struct udev*);
     128             :   void (*udev_enumerate_unref)(struct udev_enumerate*);
     129             :   int (*udev_enumerate_add_match_subsystem)(struct udev_enumerate*,
     130             :                                             const char*);
     131             :   int (*udev_enumerate_scan_devices)(struct udev_enumerate*);
     132             :   struct udev_list_entry* (*udev_enumerate_get_list_entry)
     133             :     (struct udev_enumerate*);
     134             : 
     135             :   struct udev_list_entry* (*udev_list_entry_get_next)(struct udev_list_entry *);
     136             :   const char* (*udev_list_entry_get_name)(struct udev_list_entry*);
     137             : 
     138             :   struct udev_monitor* (*udev_monitor_new_from_netlink)(struct udev*,
     139             :                                                         const char*);
     140             :   int (*udev_monitor_filter_add_match_subsystem_devtype)
     141             :     (struct udev_monitor*, const char*, const char*);
     142             :   int (*udev_monitor_enable_receiving)(struct udev_monitor*);
     143             :   int (*udev_monitor_get_fd)(struct udev_monitor*);
     144             :   struct udev_device* (*udev_monitor_receive_device)(struct udev_monitor*);
     145             :   void (*udev_monitor_unref)(struct udev_monitor*);
     146             : };
     147             : 
     148             : } // namespace mozilla
     149             : 
     150             : #endif // HAL_LINUX_UDEV_H_