code.delx.au - pulseaudio/blob - 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 <pulsecore/i18n.h>
  40 #include <pulsecore/macro.h>
  41 #include <pulsecore/log.h>
  42
  43 #include "ltdl-bind-now.h"
  44
  45 #ifdef RTLD_NOW
  46 #define PA_BIND_NOW RTLD_NOW
  47 #elif defined(DL_NOW)
  48 #define PA_BIND_NOW DL_NOW
  49 #else
  50 #undef PA_BIND_NOW
  51 #endif
  52
  53 #ifdef OS_IS_WIN32
  54 #undef PA_BIND_NOW
  55 #endif
  56
  57 #ifdef PA_BIND_NOW
  58
  59 /*
  60   To avoid lazy relocations during runtime in our RT threads we add
  61   our own shared object loader with uses RTLD_NOW if it is
  62   available. The standard ltdl loader prefers RTLD_LAZY.
  63
  64   Please note that this loader doesn't have any influence on
  65   relocations on any libraries that are already loaded into our
  66   process, i.e. because the pulseaudio binary links directly to
  67   them. To disable lazy relocations for those libraries it is possible
  68   to set $LT_BIND_NOW before starting the pulseaudio binary.
  69 */
  70
  71 static lt_module bind_now_open(lt_user_data d, const char *fname, lt_dladvise advise) {
  72     lt_module m;
  73
  74     pa_assert(fname);
  75
  76     if (!(m = dlopen(fname, PA_BIND_NOW))) {
  77         pa_log(_("Failed to open module %s: %s"), fname, dlerror());
  78         lt_dlseterror(LT_ERROR_CANNOT_OPEN);
  79         return NULL;
  80     }
  81
  82     return m;
  83 }
  84
  85 static int bind_now_close(lt_user_data d, lt_module m) {
  86
  87     pa_assert(m);
  88
  89     if (dlclose(m) != 0) {
  90         lt_dlseterror(LT_ERROR_CANNOT_CLOSE);
  91         return 1;
  92     }
  93
  94     return 0;
  95 }
  96
  97 static lt_ptr bind_now_find_sym(lt_user_data d, lt_module m, const char *symbol) {
  98     lt_ptr ptr;
  99
 100     pa_assert(m);
 101     pa_assert(symbol);
 102
 103     if (!(ptr = dlsym(m, symbol))) {
 104         lt_dlseterror(LT_ERROR_SYMBOL_NOT_FOUND);
 105         return NULL;
 106     }
 107
 108     return ptr;
 109 }
 110
 111 static lt_dlvtable *bindnow_loader = NULL;
 112 #endif
 113
 114 void pa_ltdl_init(void) {
 115
 116 #ifdef PA_BIND_NOW
 117     const lt_dlvtable *dlopen_loader;
 118 #endif
 119
 120     pa_assert_se(lt_dlinit() == 0);
 121
 122 #ifdef PA_BIND_NOW
 123     /* Already initialised */
 124     if (bindnow_loader)
 125         return;
 126
 127     if (!(dlopen_loader = lt_dlloader_find((char*) "lt_dlopen"))) {
 128         pa_log_warn(_("Failed to find original lt_dlopen loader."));
 129         return;
 130     }
 131
 132     if (!(bindnow_loader = malloc(sizeof(lt_dlvtable)))) {
 133         pa_log_error(_("Failed to allocate new dl loader."));
 134         return;
 135     }
 136
 137     memcpy(bindnow_loader, dlopen_loader, sizeof(*bindnow_loader));
 138     bindnow_loader->name = "bind-now-loader";
 139     bindnow_loader->module_open = bind_now_open;
 140     bindnow_loader->module_close = bind_now_close;
 141     bindnow_loader->find_sym = bind_now_find_sym;
 142     bindnow_loader->priority = LT_DLLOADER_PREPEND;
 143
 144     /* Add our BIND_NOW loader as the default module loader. */
 145     if (lt_dlloader_add(bindnow_loader) != 0) {
 146         pa_log_warn(_("Failed to add bind-now-loader."));
 147         free(bindnow_loader);
 148         bindnow_loader = NULL;
 149     }
 150 #endif
 151 }
 152
 153 void pa_ltdl_done(void) {
 154     pa_assert_se(lt_dlexit() == 0);
 155
 156 #ifdef PA_BIND_NOW
 157     /* lt_dlexit() will free our loader vtable, hence reset our
 158      * pointer to it here */
 159     bindnow_loader = NULL;
 160 #endif
 161 }