src/daemon/ltdl-bind-now.c

   1 /***
   2   This file is part of PulseAudio.
   3
   4   Copyright 2004-2008 Lennart Poettering
   5   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
   6
   7   PulseAudio is free software; you can redistribute it and/or modify
   8   it under the terms of the GNU Lesser General Public License as published
   9   by the Free Software Foundation; either version 2.1 of the License,
  10   or (at your option) any later version.
  11
  12   PulseAudio is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with PulseAudio; if not, write to the Free Software
  19   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  20   USA.
  21 ***/
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include <config.h>
  25 #endif
  26
  27 #ifdef HAVE_DLFCN_H
  28 #include <dlfcn.h>
  29 #endif
  30
  31 #ifdef HAVE_SYS_DL_H
  32 #include <sys/dl.h>
  33 #endif
  34
  35 #include <string.h>
  36
  37 #include <ltdl.h>
  38
  39 #include <pulse/i18n.h>
  40
  41 #include <pulsecore/macro.h>
  42 #include <pulsecore/log.h>
  43
  44 #include "ltdl-bind-now.h"
  45
  46 #ifdef RTLD_NOW
  47 #define PA_BIND_NOW RTLD_NOW
  48 #elif defined(DL_NOW)
  49 #define PA_BIND_NOW DL_NOW
  50 #else
  51 #undef PA_BIND_NOW
  52 #endif
  53
  54 #ifdef PA_BIND_NOW
  55
  56 /*
  57   To avoid lazy relocations during runtime in our RT threads we add
  58   our own shared object loader with uses RTLD_NOW if it is
  59   available. The standard ltdl loader prefers RTLD_LAZY.
  60
  61   Please note that this loader doesn't have any influence on
  62   relocations on any libraries that are already loaded into our
  63   process, i.e. because the pulseaudio binary links directly to
  64   them. To disable lazy relocations for those libraries it is possible
  65   to set $LT_BIND_NOW before starting the pulsaudio binary.
  66 */
  67
  68 static lt_module bind_now_open(lt_user_data d, const char *fname, lt_dladvise advise) {
  69     lt_module m;
  70
  71     pa_assert(fname);
  72
  73     if (!(m = dlopen(fname, PA_BIND_NOW))) {
  74         lt_dlseterror(LT_ERROR_CANNOT_OPEN);
  75         return NULL;
  76     }
  77
  78     return m;
  79 }
  80
  81 static int bind_now_close(lt_user_data d, lt_module m) {
  82
  83     pa_assert(m);
  84
  85     if (dlclose(m) != 0){
  86         lt_dlseterror(LT_ERROR_CANNOT_CLOSE);
  87         return 1;
  88     }
  89
  90     return 0;
  91 }
  92
  93 static lt_ptr bind_now_find_sym(lt_user_data d, lt_module m, const char *symbol) {
  94     lt_ptr ptr;
  95
  96     pa_assert(m);
  97     pa_assert(symbol);
  98
  99     if (!(ptr = dlsym(m, symbol))) {
 100         lt_dlseterror(LT_ERROR_SYMBOL_NOT_FOUND);
 101         return NULL;
 102     }
 103
 104     return ptr;
 105 }
 106
 107 static lt_dlvtable *bindnow_loader = NULL;
 108 #endif
 109
 110 void pa_ltdl_init(void) {
 111
 112 #ifdef PA_BIND_NOW
 113     const lt_dlvtable *dlopen_loader;
 114 #endif
 115
 116     pa_assert_se(lt_dlinit() == 0);
 117
 118 #ifdef PA_BIND_NOW
 119     /* Already initialised */
 120     if (bindnow_loader)
 121         return;
 122
 123     if (!(dlopen_loader = lt_dlloader_find((char*) "lt_dlopen"))) {
 124         pa_log_warn(_("Failed to find original lt_dlopen loader."));
 125         return;
 126     }
 127
 128     if (!(bindnow_loader = malloc(sizeof(lt_dlvtable)))) {
 129         pa_log_error(_("Failed to allocate new dl loader."));
 130         return;
 131     }
 132
 133     memcpy(bindnow_loader, dlopen_loader, sizeof(*bindnow_loader));
 134     bindnow_loader->name = "bind-now-loader";
 135     bindnow_loader->module_open = bind_now_open;
 136     bindnow_loader->module_close = bind_now_close;
 137     bindnow_loader->find_sym = bind_now_find_sym;
 138     bindnow_loader->priority = LT_DLLOADER_PREPEND;
 139
 140     /* Add our BIND_NOW loader as the default module loader. */
 141     if (lt_dlloader_add(bindnow_loader) != 0) {
 142         pa_log_warn(_("Failed to add bind-now-loader."));
 143         free(bindnow_loader);
 144         bindnow_loader = NULL;
 145     }
 146 #endif
 147 }
 148
 149 void pa_ltdl_done(void) {
 150     pa_assert_se(lt_dlexit() == 0);
 151
 152 #ifdef PA_BIND_NOW
 153     /* lt_dlexit() will free our loader vtable, hence reset our
 154      * pointer to it here */
 155     bindnow_loader = NULL;
 156 #endif
 157 }