external/gpl2/lvm2/dist/lib/locking/external_locking.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
   5  * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
   6  *
   7  * This file is part of LVM2.
   8  *
   9  * This copyrighted material is made available to anyone wishing to use,
  10  * modify, copy, or redistribute it subject to the terms and conditions
  11  * of the GNU Lesser General Public License v.2.1.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this program; if not, write to the Free Software Foundation,
  15  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  16  */
  17
  18 #include "lib.h"
  19 #include "locking_types.h"
  20 #include "defaults.h"
  21 #include "sharedlib.h"
  22 #include "toolcontext.h"
  23
  24 static void *_locking_lib = NULL;
  25 static void (*_reset_fn) (void) = NULL;
  26 static void (*_end_fn) (void) = NULL;
  27 static int (*_lock_fn) (struct cmd_context * cmd, const char *resource,
  28                         uint32_t flags) = NULL;
  29 static int (*_init_fn) (int type, struct config_tree * cft,
  30                         uint32_t *flags) = NULL;
  31 static int (*_lock_query_fn) (const char *resource, int *mode) = NULL;
  32
  33 static int _lock_resource(struct cmd_context *cmd, const char *resource,
  34                           uint32_t flags)
  35 {
  36         if (_lock_fn)
  37                 return _lock_fn(cmd, resource, flags);
  38         else
  39                 return 0;
  40 }
  41
  42 static void _fin_external_locking(void)
  43 {
  44         if (_end_fn)
  45                 _end_fn();
  46
  47         dlclose(_locking_lib);
  48
  49         _locking_lib = NULL;
  50         _init_fn = NULL;
  51         _end_fn = NULL;
  52         _lock_fn = NULL;
  53         _reset_fn = NULL;
  54 }
  55
  56 static void _reset_external_locking(void)
  57 {
  58         if (_reset_fn)
  59                 _reset_fn();
  60 }
  61
  62 int init_external_locking(struct locking_type *locking, struct cmd_context *cmd)
  63 {
  64         const char *libname;
  65
  66         if (_locking_lib) {
  67                 log_error("External locking already initialised");
  68                 return 1;
  69         }
  70
  71         locking->lock_resource = _lock_resource;
  72         locking->fin_locking = _fin_external_locking;
  73         locking->reset_locking = _reset_external_locking;
  74         locking->flags = 0;
  75
  76         libname = find_config_tree_str(cmd, "global/locking_library",
  77                                        DEFAULT_LOCKING_LIB);
  78
  79         if (!(_locking_lib = load_shared_library(cmd, libname, "locking", 1)))
  80                 return_0;
  81
  82         /* Get the functions we need */
  83         if (!(_init_fn = dlsym(_locking_lib, "locking_init")) ||
  84             !(_lock_fn = dlsym(_locking_lib, "lock_resource")) ||
  85             !(_reset_fn = dlsym(_locking_lib, "reset_locking")) ||
  86             !(_end_fn = dlsym(_locking_lib, "locking_end"))) {
  87                 log_error("Shared library %s does not contain locking "
  88                           "functions", libname);
  89                 dlclose(_locking_lib);
  90                 _locking_lib = NULL;
  91                 return 0;
  92         }
  93
  94         if (!(_lock_query_fn = dlsym(_locking_lib, "query_resource")))
  95                 log_warn("WARNING: %s: _query_resource() missing: "
  96                          "Using inferior activation method.", libname);
  97
  98         log_verbose("Loaded external locking library %s", libname);
  99         return _init_fn(2, cmd->cft, &locking->flags);
 100 }