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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* libc_init_dynamic.c
*
* This source files provides two important functions for dynamic
* executables:
*
* - a C runtime initializer (__libc_preinit), which is called by
* the dynamic linker when libc.so is loaded. This happens before
* any other initializer (e.g. static C++ constructors in other
* shared libraries the program depends on).
*
* - a program launch function (__libc_init), which is called after
* all dynamic linking has been performed. Technically, it is called
* from arch-$ARCH/bionic/crtbegin_dynamic.S which is itself called
* by the dynamic linker after all libraries have been loaded and
* initialized.
*/
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <elf.h>
#include "atexit.h"
#include "libc_init_common.h"
#include <bionic_tls.h>
/* We flag the __libc_preinit function as a constructor to ensure
* that its address is listed in libc.so's .init_array section.
* This ensures that the function is called by the dynamic linker
* as soon as the shared library is loaded.
*/
void __attribute__((constructor)) __libc_preinit(void);
void __libc_preinit(void)
{
/* Read the ELF data pointer form a special slot of the
* TLS area, then call __libc_init_common with it.
*
* Note that:
* - we clear the slot so no other initializer sees its value.
* - __libc_init_common() will change the TLS area so the old one
* won't be accessible anyway.
*/
void** tls_area = (void**)__get_tls();
unsigned* elfdata = tls_area[TLS_SLOT_BIONIC_PREINIT];
tls_area[TLS_SLOT_BIONIC_PREINIT] = NULL;
__libc_init_common(elfdata);
/* Setup malloc routines accordingly to the environment.
* Requires system properties
*/
extern void malloc_debug_init(void);
malloc_debug_init();
}
/* This function is called from the executable's _start entry point
* (see arch-$ARCH/bionic/crtbegin_dynamic.S), which is itself
* called by the dynamic linker after it has loaded all shared
* libraries the executable depends on.
*
* Note that the dynamic linker has also run all constructors in the
* executable at this point.
*/
__noreturn void __libc_init(uintptr_t *elfdata,
void (*onexit)(void),
int (*slingshot)(int, char**, char**),
structors_array_t const * const structors)
{
int argc = (int)*elfdata;
char** argv = (char**)(elfdata + 1);
char** envp = argv + argc + 1;
/* Several Linux ABIs don't pass the onexit pointer, and the ones that
* do never use it. Therefore, we ignore it.
*/
/* The executable may have its own destructors listed in its .fini_array
* so we need to ensure that these are called when the program exits
* normally.
*/
if (structors->fini_array)
__cxa_atexit(__libc_fini,structors->fini_array,NULL);
exit(slingshot(argc, argv, envp));
}
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