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Annotation of src/lib/libc/misc/initfini.c, Revision 1.14

1.14    ! joerg       1: /*     $NetBSD: initfini.c,v 1.13 2016/11/26 21:17:06 dholland Exp $    */
1.1       ad          2:
                      3: /*-
                      4:  * Copyright (c) 2007 The NetBSD Foundation, Inc.
                      5:  * All rights reserved.
                      6:  *
                      7:  * This code is derived from software contributed to The NetBSD Foundation
                      8:  * by Andrew Doran.
                      9:  *
                     10:  * Redistribution and use in source and binary forms, with or without
                     11:  * modification, are permitted provided that the following conditions
                     12:  * are met:
                     13:  * 1. Redistributions of source code must retain the above copyright
                     14:  *    notice, this list of conditions and the following disclaimer.
                     15:  * 2. Redistributions in binary form must reproduce the above copyright
                     16:  *    notice, this list of conditions and the following disclaimer in the
                     17:  *    documentation and/or other materials provided with the distribution.
                     18:  *
                     19:  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
                     20:  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
                     21:  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
                     22:  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
                     23:  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
                     24:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
                     25:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
                     26:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
                     27:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
                     28:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
                     29:  * POSSIBILITY OF SUCH DAMAGE.
                     30:  */
                     31:
1.2       ad         32: #include <sys/cdefs.h>
1.14    ! joerg      33: __RCSID("$NetBSD: initfini.c,v 1.13 2016/11/26 21:17:06 dholland Exp $");
1.2       ad         34:
                     35: #ifdef _LIBC
                     36: #include "namespace.h"
                     37: #endif
                     38:
1.8       joerg      39: #include <sys/param.h>
                     40: #include <sys/exec.h>
1.9       joerg      41: #include <sys/tls.h>
1.8       joerg      42: #include <stdbool.h>
                     43:
                     44: void   _libc_init(void) __attribute__((__constructor__, __used__));
1.1       ad         45:
                     46: void   __guard_setup(void);
                     47: void   __libc_thr_init(void);
1.3       ad         48: void   __libc_atomic_init(void);
1.4       xtraeme    49: void   __libc_atexit_init(void);
1.7       tron       50: void   __libc_env_init(void);
1.1       ad         51:
1.9       joerg      52: #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
                     53: __dso_hidden void      __libc_static_tls_setup(void);
                     54: #endif
                     55:
1.10      joerg      56: #ifdef __weak_alias
                     57: __weak_alias(_dlauxinfo,___dlauxinfo)
                     58: static void *__libc_dlauxinfo;
                     59:
                     60: void *___dlauxinfo(void) __pure;
1.14    ! joerg      61: __weakref_visible void * real_dlauxinfo(void) __weak_reference(_dlauxinfo);
1.10      joerg      62:
                     63: void *
                     64: ___dlauxinfo(void)
                     65: {
                     66:        return __libc_dlauxinfo;
                     67: }
                     68: #endif
                     69:
1.8       joerg      70: static bool libc_initialised;
                     71:
                     72: void _libc_init(void);
                     73:
1.10      joerg      74: /*
                     75:  * Declare as common symbol to allow new libc with older binaries to
                     76:  * not trigger an undefined reference.
                     77:  */
1.8       joerg      78: struct ps_strings *__ps_strings;
                     79:
                     80: /*
1.12      dholland   81:  * _libc_init is called twice.  One call comes explicitly from crt0.o
                     82:  * (for newer versions) and the other is via global constructor handling.
                     83:  *
                     84:  * In static binaries the explicit call is first; in dynamically linked
                     85:  * binaries the global constructors of libc are called from ld.elf_so
                     86:  * before crt0.o is reached.
1.13      dholland   87:  *
                     88:  * Note that __ps_strings is set by crt0.o. So in the dynamic case, it
                     89:  * hasn't been set yet when we get here, and __libc_dlauxinfo is not
                     90:  * (ever) assigned. But this is ok because __libc_dlauxinfo is only
                     91:  * used in static binaries, because it's there to substitute for the
                     92:  * dynamic linker. In static binaries __ps_strings will have been set
                     93:  * up when we get here and we get a valid __libc_dlauxinfo.
                     94:  *
                     95:  * This code causes problems for Emacs because Emacs's undump
                     96:  * mechanism saves the __ps_strings value from the startup execution;
                     97:  * then running the resulting binary it gets here before crt0 has
                     98:  * assigned the current execution's value to __ps_strings, and in an
                     99:  * environment with ASLR this can cause the assignment of
                    100:  * __libc_dlauxinfo to receive SIGSEGV.
1.8       joerg     101:  */
1.11      matt      102: void __section(".text.startup")
1.8       joerg     103: _libc_init(void)
1.1       ad        104: {
                    105:
1.8       joerg     106:        if (libc_initialised)
                    107:                return;
                    108:
                    109:        libc_initialised = 1;
                    110:
1.14    ! joerg     111:        /* Only initialize _dlauxinfo for static binaries. */
        !           112:        if (__ps_strings != NULL && real_dlauxinfo == ___dlauxinfo)
1.10      joerg     113:                __libc_dlauxinfo = __ps_strings->ps_argvstr +
1.8       joerg     114:                    __ps_strings->ps_nargvstr + __ps_strings->ps_nenvstr + 2;
                    115:
1.1       ad        116:        /* For -fstack-protector */
                    117:        __guard_setup();
                    118:
1.3       ad        119:        /* Atomic operations */
                    120:        __libc_atomic_init();
                    121:
1.9       joerg     122: #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
                    123:        /* Initialize TLS for statically linked programs. */
                    124:        __libc_static_tls_setup();
                    125: #endif
                    126:
1.1       ad        127:        /* Threads */
                    128:        __libc_thr_init();
1.4       xtraeme   129:
                    130:        /* Initialize the atexit mutexes */
                    131:        __libc_atexit_init();
1.7       tron      132:
                    133:        /* Initialize environment memory RB tree. */
                    134:        __libc_env_init();
1.1       ad        135: }

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