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https://github.com/FAUSheppy/colorredstderr-mirror
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61 lines
1.7 KiB
C
61 lines
1.7 KiB
C
/*
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* Helper header for LD_PRELOAD related headers macros. Must be loaded _first_
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* (for RTLD_NEXT)!
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*
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* Copyright (C) 2012-2013 Simon Ruderich
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef LDPRELOAD_H
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#define LDPRELOAD_H 1
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/* Necessary for RTLD_NEXT. */
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#define _GNU_SOURCE
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/* abort() */
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#include <stdlib.h>
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/* dlsym() */
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#include <dlfcn.h>
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#include <errno.h>
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static void *dlsym_function(char const *name) noinline;
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/* Load the function name using dlsym() and return it. Terminate program on
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* failure. Split in function and macro to reduce code inserted into the
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* function using the macro. */
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static void *dlsym_function(char const *name) {
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void *result;
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int saved_errno = errno; /* just in case */
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/* Clear possibly existing error. */
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dlerror();
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result = dlsym(RTLD_NEXT, name);
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/* Not much we can do. Most likely the other output functions failed to
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* load too. */
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if (dlerror() != NULL) {
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abort();
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}
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errno = saved_errno;
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return result;
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}
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#define DLSYM_FUNCTION(pointer, name) \
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if (!(pointer)) { \
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*(void **) (&(pointer)) = dlsym_function(name); \
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}
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#endif
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