| 1 | /* loader-dlopen.c -- dynamic linking with dlopen/dlsym |
| 2 | |
| 3 | Copyright (C) 1998, 1999, 2000, 2004, 2006, |
| 4 | 2007, 2008 Free Software Foundation, Inc. |
| 5 | Written by Thomas Tanner, 1998 |
| 6 | |
| 7 | NOTE: The canonical source of this file is maintained with the |
| 8 | GNU Libtool package. Report bugs to bug-libtool@gnu.org. |
| 9 | |
| 10 | GNU Libltdl is free software; you can redistribute it and/or |
| 11 | modify it under the terms of the GNU Lesser General Public |
| 12 | License as published by the Free Software Foundation; either |
| 13 | version 2 of the License, or (at your option) any later version. |
| 14 | |
| 15 | As a special exception to the GNU Lesser General Public License, |
| 16 | if you distribute this file as part of a program or library that |
| 17 | is built using GNU Libtool, you may include this file under the |
| 18 | same distribution terms that you use for the rest of that program. |
| 19 | |
| 20 | GNU Libltdl is distributed in the hope that it will be useful, |
| 21 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 22 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 23 | GNU Lesser General Public License for more details. |
| 24 | |
| 25 | You should have received a copy of the GNU Lesser General Public |
| 26 | License along with GNU Libltdl; see the file COPYING.LIB. If not, a |
| 27 | copy can be downloaded from http://www.gnu.org/licenses/lgpl.html, |
| 28 | or obtained by writing to the Free Software Foundation, Inc., |
| 29 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| 30 | */ |
| 31 | |
| 32 | #include "lt__private.h" |
| 33 | #include "lt_dlloader.h" |
| 34 | |
| 35 | /* Use the preprocessor to rename non-static symbols to avoid namespace |
| 36 | collisions when the loader code is statically linked into libltdl. |
| 37 | Use the "<module_name>_LTX_" prefix so that the symbol addresses can |
| 38 | be fetched from the preloaded symbol list by lt_dlsym(): */ |
| 39 | #define get_vtable dlopen_LTX_get_vtable |
| 40 | |
| 41 | LT_BEGIN_C_DECLS |
| 42 | LT_SCOPE lt_dlvtable *get_vtable (lt_user_data loader_data); |
| 43 | LT_END_C_DECLS |
| 44 | |
| 45 | |
| 46 | /* Boilerplate code to set up the vtable for hooking this loader into |
| 47 | libltdl's loader list: */ |
| 48 | static int vl_exit (lt_user_data loader_data); |
| 49 | static lt_module vm_open (lt_user_data loader_data, const char *filename, |
| 50 | lt_dladvise advise); |
| 51 | static int vm_close (lt_user_data loader_data, lt_module module); |
| 52 | static void * vm_sym (lt_user_data loader_data, lt_module module, |
| 53 | const char *symbolname); |
| 54 | |
| 55 | static lt_dlvtable *vtable = 0; |
| 56 | |
| 57 | /* Return the vtable for this loader, only the name and sym_prefix |
| 58 | attributes (plus the virtual function implementations, obviously) |
| 59 | change between loaders. */ |
| 60 | lt_dlvtable * |
| 61 | get_vtable (lt_user_data loader_data) |
| 62 | { |
| 63 | if (!vtable) |
| 64 | { |
| 65 | vtable = (lt_dlvtable *) lt__zalloc (sizeof *vtable); |
| 66 | } |
| 67 | |
| 68 | if (vtable && !vtable->name) |
| 69 | { |
| 70 | vtable->name = "lt_dlopen"; |
| 71 | #if defined(DLSYM_USCORE) |
| 72 | vtable->sym_prefix = "_"; |
| 73 | #endif |
| 74 | vtable->module_open = vm_open; |
| 75 | vtable->module_close = vm_close; |
| 76 | vtable->find_sym = vm_sym; |
| 77 | vtable->dlloader_exit = vl_exit; |
| 78 | vtable->dlloader_data = loader_data; |
| 79 | vtable->priority = LT_DLLOADER_PREPEND; |
| 80 | } |
| 81 | |
| 82 | if (vtable && (vtable->dlloader_data != loader_data)) |
| 83 | { |
| 84 | LT__SETERROR (INIT_LOADER); |
| 85 | return 0; |
| 86 | } |
| 87 | |
| 88 | return vtable; |
| 89 | } |
| 90 | |
| 91 | |
| 92 | |
| 93 | /* --- IMPLEMENTATION --- */ |
| 94 | |
| 95 | |
| 96 | #if defined(HAVE_DLFCN_H) |
| 97 | # include <dlfcn.h> |
| 98 | #endif |
| 99 | |
| 100 | #if defined(HAVE_SYS_DL_H) |
| 101 | # include <sys/dl.h> |
| 102 | #endif |
| 103 | |
| 104 | |
| 105 | /* We may have to define LT_LAZY_OR_NOW in the command line if we |
| 106 | find out it does not work in some platform. */ |
| 107 | #if !defined(LT_LAZY_OR_NOW) |
| 108 | # if defined(RTLD_LAZY) |
| 109 | # define LT_LAZY_OR_NOW RTLD_LAZY |
| 110 | # else |
| 111 | # if defined(DL_LAZY) |
| 112 | # define LT_LAZY_OR_NOW DL_LAZY |
| 113 | # endif |
| 114 | # endif /* !RTLD_LAZY */ |
| 115 | #endif |
| 116 | #if !defined(LT_LAZY_OR_NOW) |
| 117 | # if defined(RTLD_NOW) |
| 118 | # define LT_LAZY_OR_NOW RTLD_NOW |
| 119 | # else |
| 120 | # if defined(DL_NOW) |
| 121 | # define LT_LAZY_OR_NOW DL_NOW |
| 122 | # endif |
| 123 | # endif /* !RTLD_NOW */ |
| 124 | #endif |
| 125 | #if !defined(LT_LAZY_OR_NOW) |
| 126 | # define LT_LAZY_OR_NOW 0 |
| 127 | #endif /* !LT_LAZY_OR_NOW */ |
| 128 | |
| 129 | /* We only support local and global symbols from modules for loaders |
| 130 | that provide such a thing, otherwise the system default is used. */ |
| 131 | #if !defined(RTLD_GLOBAL) |
| 132 | # if defined(DL_GLOBAL) |
| 133 | # define RTLD_GLOBAL DL_GLOBAL |
| 134 | # endif |
| 135 | #endif /* !RTLD_GLOBAL */ |
| 136 | #if !defined(RTLD_LOCAL) |
| 137 | # if defined(DL_LOCAL) |
| 138 | # define RTLD_LOCAL DL_LOCAL |
| 139 | # endif |
| 140 | #endif /* !RTLD_LOCAL */ |
| 141 | |
| 142 | #if defined(HAVE_DLERROR) |
| 143 | # define DLERROR(arg) dlerror () |
| 144 | #else |
| 145 | # define DLERROR(arg) LT__STRERROR (arg) |
| 146 | #endif |
| 147 | |
| 148 | #define DL__SETERROR(errorcode) \ |
| 149 | LT__SETERRORSTR (DLERROR (errorcode)) |
| 150 | |
| 151 | |
| 152 | /* A function called through the vtable when this loader is no |
| 153 | longer needed by the application. */ |
| 154 | static int |
| 155 | vl_exit (lt_user_data LT__UNUSED loader_data) |
| 156 | { |
| 157 | vtable = NULL; |
| 158 | return 0; |
| 159 | } |
| 160 | |
| 161 | |
| 162 | /* A function called through the vtable to open a module with this |
| 163 | loader. Returns an opaque representation of the newly opened |
| 164 | module for processing with this loader's other vtable functions. */ |
| 165 | static lt_module |
| 166 | vm_open (lt_user_data LT__UNUSED loader_data, const char *filename, |
| 167 | lt_dladvise advise) |
| 168 | { |
| 169 | int module_flags = LT_LAZY_OR_NOW; |
| 170 | lt_module module; |
| 171 | |
| 172 | if (advise) |
| 173 | { |
| 174 | #ifdef RTLD_GLOBAL |
| 175 | /* If there is some means of asking for global symbol resolution, |
| 176 | do so. */ |
| 177 | if (advise->is_symglobal) |
| 178 | module_flags |= RTLD_GLOBAL; |
| 179 | #else |
| 180 | /* Otherwise, reset that bit so the caller can tell it wasn't |
| 181 | acted on. */ |
| 182 | advise->is_symglobal = 0; |
| 183 | #endif |
| 184 | |
| 185 | /* And similarly for local only symbol resolution. */ |
| 186 | #ifdef RTLD_LOCAL |
| 187 | if (advise->is_symlocal) |
| 188 | module_flags |= RTLD_LOCAL; |
| 189 | #else |
| 190 | advise->is_symlocal = 0; |
| 191 | #endif |
| 192 | } |
| 193 | |
| 194 | module = dlopen (filename, module_flags); |
| 195 | |
| 196 | if (!module) |
| 197 | { |
| 198 | DL__SETERROR (CANNOT_OPEN); |
| 199 | } |
| 200 | |
| 201 | return module; |
| 202 | } |
| 203 | |
| 204 | |
| 205 | /* A function called through the vtable when a particular module |
| 206 | should be unloaded. */ |
| 207 | static int |
| 208 | vm_close (lt_user_data LT__UNUSED loader_data, lt_module module) |
| 209 | { |
| 210 | int errors = 0; |
| 211 | |
| 212 | if (dlclose (module) != 0) |
| 213 | { |
| 214 | DL__SETERROR (CANNOT_CLOSE); |
| 215 | ++errors; |
| 216 | } |
| 217 | |
| 218 | return errors; |
| 219 | } |
| 220 | |
| 221 | |
| 222 | /* A function called through the vtable to get the address of |
| 223 | a symbol loaded from a particular module. */ |
| 224 | static void * |
| 225 | vm_sym (lt_user_data LT__UNUSED loader_data, lt_module module, const char *name) |
| 226 | { |
| 227 | void *address = dlsym (module, name); |
| 228 | |
| 229 | if (!address) |
| 230 | { |
| 231 | DL__SETERROR (SYMBOL_NOT_FOUND); |
| 232 | } |
| 233 | |
| 234 | return address; |
| 235 | } |