Annotation of sql/pgsql/libltdl/loaders/dlopen.c, revision 1.1
1.1 ! moko 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: }
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