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f737dfd071
We initialize _r_debug for static binaries to allows debug agents to treat static binaries a little more like dyanmic ones. This simplifies the work a debug agent has to do to access TLS in a static binary via libthread_db. Tested on x86_64. See: https://sourceware.org/ml/libc-alpha/2014-04/msg00183.html [BZ #16831] * csu/libc-start.c (LIBC_START_MAIN) [!SHARED]: Call _dl_debug_initialize.
324 lines
9.4 KiB
C
324 lines
9.4 KiB
C
/* Copyright (C) 1998-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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extern void __libc_init_first (int argc, char **argv, char **envp);
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#ifndef SHARED
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extern void __libc_csu_irel (void);
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#endif
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extern int __libc_multiple_libcs;
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#include <tls.h>
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#ifndef SHARED
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# include <dl-osinfo.h>
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extern void __pthread_initialize_minimal (void);
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# ifndef THREAD_SET_STACK_GUARD
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/* Only exported for architectures that don't store the stack guard canary
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in thread local area. */
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uintptr_t __stack_chk_guard attribute_relro;
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# endif
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# ifndef THREAD_SET_POINTER_GUARD
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/* Only exported for architectures that don't store the pointer guard
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value in thread local area. */
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uintptr_t __pointer_chk_guard_local
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attribute_relro attribute_hidden __attribute__ ((nocommon));
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# endif
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#endif
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#ifdef HAVE_PTR_NTHREADS
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/* We need atomic operations. */
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# include <atomic.h>
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#endif
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#ifndef SHARED
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# include <link.h>
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# include <dl-irel.h>
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# ifdef ELF_MACHINE_IRELA
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# define IREL_T ElfW(Rela)
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# define IPLT_START __rela_iplt_start
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# define IPLT_END __rela_iplt_end
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# define IREL elf_irela
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# elif defined ELF_MACHINE_IREL
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# define IREL_T ElfW(Rel)
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# define IPLT_START __rel_iplt_start
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# define IPLT_END __rel_iplt_end
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# define IREL elf_irel
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# endif
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static void
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apply_irel (void)
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{
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# ifdef IREL
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/* We use weak references for these so that we'll still work with a linker
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that doesn't define them. Such a linker doesn't support IFUNC at all
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and so uses won't work, but a statically-linked program that doesn't
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use any IFUNC symbols won't have a problem. */
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extern const IREL_T IPLT_START[] __attribute__ ((weak));
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extern const IREL_T IPLT_END[] __attribute__ ((weak));
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for (const IREL_T *ipltent = IPLT_START; ipltent < IPLT_END; ++ipltent)
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IREL (ipltent);
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# endif
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}
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#endif
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#ifdef LIBC_START_MAIN
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# ifdef LIBC_START_DISABLE_INLINE
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# define STATIC static
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# else
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# define STATIC static inline __attribute__ ((always_inline))
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# endif
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#else
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# define STATIC
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# define LIBC_START_MAIN __libc_start_main
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#endif
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#ifdef MAIN_AUXVEC_ARG
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/* main gets passed a pointer to the auxiliary. */
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# define MAIN_AUXVEC_DECL , void *
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# define MAIN_AUXVEC_PARAM , auxvec
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#else
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# define MAIN_AUXVEC_DECL
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# define MAIN_AUXVEC_PARAM
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#endif
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STATIC int LIBC_START_MAIN (int (*main) (int, char **, char **
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MAIN_AUXVEC_DECL),
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int argc,
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char **argv,
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#ifdef LIBC_START_MAIN_AUXVEC_ARG
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ElfW(auxv_t) *auxvec,
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#endif
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__typeof (main) init,
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void (*fini) (void),
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void (*rtld_fini) (void),
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void *stack_end)
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__attribute__ ((noreturn));
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/* Note: the fini parameter is ignored here for shared library. It
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is registered with __cxa_atexit. This had the disadvantage that
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finalizers were called in more than one place. */
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STATIC int
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LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
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int argc, char **argv,
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#ifdef LIBC_START_MAIN_AUXVEC_ARG
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ElfW(auxv_t) *auxvec,
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#endif
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__typeof (main) init,
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void (*fini) (void),
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void (*rtld_fini) (void), void *stack_end)
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{
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/* Result of the 'main' function. */
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int result;
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__libc_multiple_libcs = &_dl_starting_up && !_dl_starting_up;
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#ifndef SHARED
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char **ev = &argv[argc + 1];
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__environ = ev;
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/* Store the lowest stack address. This is done in ld.so if this is
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the code for the DSO. */
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__libc_stack_end = stack_end;
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# ifdef HAVE_AUX_VECTOR
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/* First process the auxiliary vector since we need to find the
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program header to locate an eventually present PT_TLS entry. */
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# ifndef LIBC_START_MAIN_AUXVEC_ARG
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ElfW(auxv_t) *auxvec;
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{
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char **evp = ev;
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while (*evp++ != NULL)
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;
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auxvec = (ElfW(auxv_t) *) evp;
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}
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# endif
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_dl_aux_init (auxvec);
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if (GL(dl_phdr) == NULL)
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# endif
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{
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/* Starting from binutils-2.23, the linker will define the
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magic symbol __ehdr_start to point to our own ELF header
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if it is visible in a segment that also includes the phdrs.
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So we can set up _dl_phdr and _dl_phnum even without any
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information from auxv. */
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extern const ElfW(Ehdr) __ehdr_start
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__attribute__ ((weak, visibility ("hidden")));
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if (&__ehdr_start != NULL)
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{
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assert (__ehdr_start.e_phentsize == sizeof *GL(dl_phdr));
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GL(dl_phdr) = (const void *) &__ehdr_start + __ehdr_start.e_phoff;
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GL(dl_phnum) = __ehdr_start.e_phnum;
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}
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}
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# ifdef DL_SYSDEP_OSCHECK
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if (!__libc_multiple_libcs)
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{
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/* This needs to run to initiliaze _dl_osversion before TLS
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setup might check it. */
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DL_SYSDEP_OSCHECK (__libc_fatal);
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}
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# endif
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/* Perform IREL{,A} relocations. */
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apply_irel ();
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/* Initialize the thread library at least a bit since the libgcc
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functions are using thread functions if these are available and
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we need to setup errno. */
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__pthread_initialize_minimal ();
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/* Set up the stack checker's canary. */
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uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
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# ifdef THREAD_SET_STACK_GUARD
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THREAD_SET_STACK_GUARD (stack_chk_guard);
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# else
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__stack_chk_guard = stack_chk_guard;
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# endif
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/* Set up the pointer guard value. */
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uintptr_t pointer_chk_guard = _dl_setup_pointer_guard (_dl_random,
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stack_chk_guard);
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# ifdef THREAD_SET_POINTER_GUARD
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THREAD_SET_POINTER_GUARD (pointer_chk_guard);
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# else
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__pointer_chk_guard_local = pointer_chk_guard;
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# endif
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#endif
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/* Register the destructor of the dynamic linker if there is any. */
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if (__glibc_likely (rtld_fini != NULL))
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__cxa_atexit ((void (*) (void *)) rtld_fini, NULL, NULL);
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#ifndef SHARED
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/* Call the initializer of the libc. This is only needed here if we
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are compiling for the static library in which case we haven't
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run the constructors in `_dl_start_user'. */
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__libc_init_first (argc, argv, __environ);
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/* Register the destructor of the program, if any. */
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if (fini)
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__cxa_atexit ((void (*) (void *)) fini, NULL, NULL);
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/* Some security at this point. Prevent starting a SUID binary where
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the standard file descriptors are not opened. We have to do this
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only for statically linked applications since otherwise the dynamic
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loader did the work already. */
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if (__builtin_expect (__libc_enable_secure, 0))
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__libc_check_standard_fds ();
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#endif
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/* Call the initializer of the program, if any. */
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#ifdef SHARED
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if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
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GLRO(dl_debug_printf) ("\ninitialize program: %s\n\n", argv[0]);
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#endif
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if (init)
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(*init) (argc, argv, __environ MAIN_AUXVEC_PARAM);
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#ifdef SHARED
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/* Auditing checkpoint: we have a new object. */
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if (__glibc_unlikely (GLRO(dl_naudit) > 0))
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{
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struct audit_ifaces *afct = GLRO(dl_audit);
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struct link_map *head = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
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for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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{
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if (afct->preinit != NULL)
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afct->preinit (&head->l_audit[cnt].cookie);
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afct = afct->next;
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}
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}
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#endif
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#ifdef SHARED
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if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS))
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GLRO(dl_debug_printf) ("\ntransferring control: %s\n\n", argv[0]);
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#endif
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#ifndef SHARED
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_dl_debug_initialize (0, LM_ID_BASE);
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#endif
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#ifdef HAVE_CLEANUP_JMP_BUF
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/* Memory for the cancellation buffer. */
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struct pthread_unwind_buf unwind_buf;
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int not_first_call;
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not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
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if (__glibc_likely (! not_first_call))
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{
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struct pthread *self = THREAD_SELF;
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/* Store old info. */
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unwind_buf.priv.data.prev = THREAD_GETMEM (self, cleanup_jmp_buf);
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unwind_buf.priv.data.cleanup = THREAD_GETMEM (self, cleanup);
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/* Store the new cleanup handler info. */
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THREAD_SETMEM (self, cleanup_jmp_buf, &unwind_buf);
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/* Run the program. */
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result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
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}
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else
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{
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/* Remove the thread-local data. */
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# ifdef SHARED
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PTHFCT_CALL (ptr__nptl_deallocate_tsd, ());
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# else
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extern void __nptl_deallocate_tsd (void) __attribute ((weak));
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__nptl_deallocate_tsd ();
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# endif
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/* One less thread. Decrement the counter. If it is zero we
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terminate the entire process. */
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result = 0;
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# ifdef SHARED
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unsigned int *ptr = __libc_pthread_functions.ptr_nthreads;
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# ifdef PTR_DEMANGLE
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PTR_DEMANGLE (ptr);
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# endif
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# else
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extern unsigned int __nptl_nthreads __attribute ((weak));
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unsigned int *const ptr = &__nptl_nthreads;
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# endif
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if (! atomic_decrement_and_test (ptr))
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/* Not much left to do but to exit the thread, not the process. */
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__exit_thread (0);
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}
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#else
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/* Nothing fancy, just call the function. */
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result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
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#endif
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exit (result);
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}
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