ce532721aa
A mangled symbol in libc.so is a symbol that shouldn't be exported by libc.so. Change-Id: Id92d1e1968b3d11d111a5d9ef692adb1ac7694a1
113 lines
4.4 KiB
C++
113 lines
4.4 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* libc_init_dynamic.c
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*
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* This source files provides two important functions for dynamic
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* executables:
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*
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* - a C runtime initializer (__libc_preinit), which is called by
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* the dynamic linker when libc.so is loaded. This happens before
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* any other initializer (e.g. static C++ constructors in other
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* shared libraries the program depends on).
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*
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* - a program launch function (__libc_init), which is called after
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* all dynamic linking has been performed. Technically, it is called
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* from arch-$ARCH/bionic/crtbegin_dynamic.S which is itself called
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* by the dynamic linker after all libraries have been loaded and
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* initialized.
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*/
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <elf.h>
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#include "atexit.h"
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#include "KernelArgumentBlock.h"
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#include "libc_init_common.h"
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#include <bionic_tls.h>
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extern "C" {
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extern void pthread_debug_init(void);
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extern void malloc_debug_init(void);
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extern void malloc_debug_fini(void);
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};
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// We flag the __libc_preinit function as a constructor to ensure
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// that its address is listed in libc.so's .init_array section.
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// This ensures that the function is called by the dynamic linker
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// as soon as the shared library is loaded.
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__attribute__((constructor)) static void __libc_preinit() {
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// Read the kernel argument block pointer from TLS.
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void* tls = const_cast<void*>(__get_tls());
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KernelArgumentBlock** args_slot = &reinterpret_cast<KernelArgumentBlock**>(tls)[TLS_SLOT_BIONIC_PREINIT];
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KernelArgumentBlock* args = *args_slot;
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// Clear the slot so no other initializer sees its value.
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// __libc_init_common() will change the TLS area so the old one won't be accessible anyway.
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*args_slot = NULL;
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__libc_init_common(*args);
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// Hooks for the debug malloc and pthread libraries to let them know that we're starting up.
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pthread_debug_init();
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malloc_debug_init();
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}
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__LIBC_HIDDEN__ void __libc_postfini() {
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// A hook for the debug malloc library to let it know that we're shutting down.
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malloc_debug_fini();
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}
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// This function is called from the executable's _start entry point
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// (see arch-$ARCH/bionic/crtbegin_dynamic.S), which is itself
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// called by the dynamic linker after it has loaded all shared
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// libraries the executable depends on.
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//
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// Note that the dynamic linker has also run all constructors in the
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// executable at this point.
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__noreturn void __libc_init(void* raw_args,
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void (*onexit)(void),
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int (*slingshot)(int, char**, char**),
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structors_array_t const * const structors) {
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KernelArgumentBlock args(raw_args);
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// Several Linux ABIs don't pass the onexit pointer, and the ones that
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// do never use it. Therefore, we ignore it.
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// The executable may have its own destructors listed in its .fini_array
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// so we need to ensure that these are called when the program exits
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// normally.
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if (structors->fini_array) {
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__cxa_atexit(__libc_fini,structors->fini_array,NULL);
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}
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exit(slingshot(args.argc, args.argv, args.envp));
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}
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