| 1 | /* Look up a symbol in a shared object loaded by `dlopen'. |
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| 2 | Copyright (C) 1995-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #include <dlfcn.h> |
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| 20 | #include <ldsodefs.h> |
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| 21 | #include <shlib-compat.h> |
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| 22 | #include <stddef.h> |
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| 23 | |
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| 24 | struct dlsym_args |
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| 25 | { |
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| 26 | /* The arguments to dlsym_doit. */ |
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| 27 | void *handle; |
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| 28 | const char *name; |
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| 29 | void *who; |
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| 30 | |
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| 31 | /* The return value of dlsym_doit. */ |
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| 32 | void *sym; |
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| 33 | }; |
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| 34 | |
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| 35 | static void |
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| 36 | dlsym_doit (void *a) |
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| 37 | { |
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| 38 | struct dlsym_args *args = (struct dlsym_args *) a; |
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| 39 | |
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| 40 | args->sym = _dl_sym (handle: args->handle, name: args->name, who: args->who); |
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| 41 | } |
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| 42 | |
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| 43 | static void * |
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| 44 | dlsym_implementation (void *handle, const char *name, void *dl_caller) |
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| 45 | { |
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| 46 | struct dlsym_args args; |
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| 47 | args.who = dl_caller; |
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| 48 | args.handle = handle; |
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| 49 | args.name = name; |
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| 50 | |
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| 51 | /* Protect against concurrent loads and unloads. */ |
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| 52 | __rtld_lock_lock_recursive (GL(dl_load_lock)); |
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| 53 | |
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| 54 | void *result = (_dlerror_run (operate: dlsym_doit, args: &args) ? NULL : args.sym); |
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| 55 | |
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| 56 | __rtld_lock_unlock_recursive (GL(dl_load_lock)); |
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| 57 | |
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| 58 | return result; |
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| 59 | } |
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| 60 | |
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| 61 | #ifdef SHARED |
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| 62 | void * |
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| 63 | ___dlsym (void *handle, const char *name) |
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| 64 | { |
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| 65 | if (GLRO (dl_dlfcn_hook) != NULL) |
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| 66 | return GLRO (dl_dlfcn_hook)->dlsym (handle, name, RETURN_ADDRESS (0)); |
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| 67 | else |
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| 68 | return dlsym_implementation (handle, name, RETURN_ADDRESS (0)); |
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| 69 | } |
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| 70 | versioned_symbol (libc, ___dlsym, dlsym, GLIBC_2_34); |
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| 71 | |
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| 72 | # if OTHER_SHLIB_COMPAT (libdl, GLIBC_2_0, GLIBC_2_34) |
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| 73 | compat_symbol (libdl, ___dlsym, dlsym, GLIBC_2_0); |
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| 74 | # endif |
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| 75 | |
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| 76 | #else /* !SHARED */ |
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| 77 | /* Also used with _dlfcn_hook. */ |
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| 78 | void * |
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| 79 | __dlsym (void *handle, const char *name, void *dl_caller) |
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| 80 | { |
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| 81 | return dlsym_implementation (handle, name, dl_caller); |
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| 82 | } |
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| 83 | |
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| 84 | void * |
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| 85 | ___dlsym (void *handle, const char *name) |
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| 86 | { |
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| 87 | return __dlsym (handle, name, RETURN_ADDRESS (0)); |
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| 88 | } |
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| 89 | weak_alias (___dlsym, dlsym) |
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| 90 | #endif /* !SHARED */ |
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| 91 | |
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