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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 "libc_init_common.h"
#include "private/bionic_globals.h"
#include "private/bionic_macros.h"
#include "private/bionic_ssp.h"
#include "private/bionic_tls.h"
#include "private/KernelArgumentBlock.h"
extern "C" {
extern void netdClientInit(void);
extern int __cxa_atexit(void (*)(void *), void *, void *);
};
// Use an initializer so __libc_sysinfo will have a fallback implementation
// while .preinit_array constructors run.
#if defined(__i386__)
static __attribute__((__naked__)) void __libc_int0x80() {
__asm__ volatile("int $0x80; ret");
}
__LIBC_HIDDEN__ void* __libc_sysinfo = reinterpret_cast<void*>(__libc_int0x80);
#endif
// We need a helper function for __libc_preinit because compiling with LTO may
// inline functions requiring a stack protector check, but __stack_chk_guard is
// not initialized at the start of __libc_preinit. __libc_preinit_impl will run
// after __stack_chk_guard is initialized and therefore can safely have a stack
// protector.
__attribute__((noinline))
static void __libc_preinit_impl(KernelArgumentBlock& args) {
__libc_shared_globals = args.shared_globals;
__libc_init_globals(args);
__libc_init_common(args);
// Hooks for various libraries to let them know that we're starting up.
__libc_globals.mutate(__libc_init_malloc);
netdClientInit();
}
// We flag the __libc_preinit function as a constructor to ensure that
// its address is listed in libc.so's .init_array section.
// This ensures that the function is called by the dynamic linker as
// soon as the shared library is loaded.
// We give this constructor priority 1 because we want libc's constructor
// to run before any others (such as the jemalloc constructor), and lower
// is better (http://b/68046352).
__attribute__((constructor(1))) static void __libc_preinit() {
// Read the kernel argument block pointer from TLS, then clear the slot so no
// other initializer sees its value.
void** tls = __get_tls();
KernelArgumentBlock* args = static_cast<KernelArgumentBlock*>(tls[TLS_SLOT_BIONIC_PREINIT]);
tls[TLS_SLOT_BIONIC_PREINIT] = nullptr;
// The linker has initialized its copy of the global stack_chk_guard, and filled in the main
// thread's TLS slot with that value. Initialize the local global stack guard with its value.
__stack_chk_guard = reinterpret_cast<uintptr_t>(tls[TLS_SLOT_STACK_GUARD]);
__libc_preinit_impl(*args);
}
// This function is called from the executable's _start entry point
// (see arch-$ARCH/bionic/crtbegin.c), 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(void* raw_args,
void (*onexit)(void) __unused,
int (*slingshot)(int, char**, char**),
structors_array_t const * const structors) {
BIONIC_STOP_UNWIND;
KernelArgumentBlock args(raw_args);
// 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,nullptr);
}
exit(slingshot(args.argc, args.argv, args.envp));
}
extern "C" uint32_t android_get_application_target_sdk_version();
uint32_t bionic_get_application_target_sdk_version() {
return android_get_application_target_sdk_version();
}
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