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/*
* libpulp - User-space Livepatching Library
*
* Copyright (C) 2021 SUSE Software Solutions GmbH
*
* This file is part of libpulp.
*
* libpulp is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* libpulp is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with libpulp. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <unistd.h>
__attribute__((constructor)) static void
init(void)
{
char message1[] = "malloc returned NULL\n";
char message2[] = "malloc returned Non-NULL\n";
void *result;
ssize_t retcode __attribute__((unused));
/*
* Libpulp interposes several functions from libc, such as malloc, but
* it doesn't actually reimplement them. Instead, during process
* startup, libpulp finds the original addresses of the functions, and
* saves; afterwards, it uses these addresses to redirect calls made
* from the program (or from other libraries). However, this only
* works if libpulp's initialization happens before other constructors
* try to access the interposed functions. The following call to
* malloc tries to detect if other constructors also try to access
* malloc before libpulp gets a chance to initialize itself.
*/
result = malloc(1);
if (result == NULL)
retcode = write(STDOUT_FILENO, message1, sizeof(message1));
else
retcode = write(STDOUT_FILENO, message2, sizeof(message2));
}
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