195 lines
7.0 KiB
C
195 lines
7.0 KiB
C
/* Data structure for communication from the run-time dynamic linker for
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loaded ELF shared objects.
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Copyright (C) 1995-2015 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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#ifndef _LINK_H
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#define _LINK_H 1
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#include <features.h>
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#include <elf.h>
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#include <dlfcn.h>
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#include <sys/types.h>
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/* We use this macro to refer to ELF types independent of the native wordsize.
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`ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */
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#define ElfW(type) _ElfW (Elf, __ELF_NATIVE_CLASS, type)
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#define _ElfW(e,w,t) _ElfW_1 (e, w, _##t)
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#define _ElfW_1(e,w,t) e##w##t
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#include <bits/elfclass.h> /* Defines __ELF_NATIVE_CLASS. */
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#include <bits/link.h>
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/* Rendezvous structure used by the run-time dynamic linker to communicate
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details of shared object loading to the debugger. If the executable's
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dynamic section has a DT_DEBUG element, the run-time linker sets that
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element's value to the address where this structure can be found. */
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struct r_debug
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{
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int r_version; /* Version number for this protocol. */
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struct link_map *r_map; /* Head of the chain of loaded objects. */
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/* This is the address of a function internal to the run-time linker,
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that will always be called when the linker begins to map in a
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library or unmap it, and again when the mapping change is complete.
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The debugger can set a breakpoint at this address if it wants to
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notice shared object mapping changes. */
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ElfW(Addr) r_brk;
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enum
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{
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/* This state value describes the mapping change taking place when
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the `r_brk' address is called. */
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RT_CONSISTENT, /* Mapping change is complete. */
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RT_ADD, /* Beginning to add a new object. */
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RT_DELETE /* Beginning to remove an object mapping. */
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} r_state;
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ElfW(Addr) r_ldbase; /* Base address the linker is loaded at. */
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};
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/* This is the instance of that structure used by the dynamic linker. */
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extern struct r_debug _r_debug;
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/* This symbol refers to the "dynamic structure" in the `.dynamic' section
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of whatever module refers to `_DYNAMIC'. So, to find its own
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`struct r_debug', a program could do:
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for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL; ++dyn)
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if (dyn->d_tag == DT_DEBUG)
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r_debug = (struct r_debug *) dyn->d_un.d_ptr;
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*/
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extern ElfW(Dyn) _DYNAMIC[];
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/* Structure describing a loaded shared object. The `l_next' and `l_prev'
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members form a chain of all the shared objects loaded at startup.
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These data structures exist in space used by the run-time dynamic linker;
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modifying them may have disastrous results. */
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struct link_map
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{
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/* These first few members are part of the protocol with the debugger.
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This is the same format used in SVR4. */
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ElfW(Addr) l_addr; /* Difference between the address in the ELF
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file and the addresses in memory. */
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char *l_name; /* Absolute file name object was found in. */
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ElfW(Dyn) *l_ld; /* Dynamic section of the shared object. */
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struct link_map *l_next, *l_prev; /* Chain of loaded objects. */
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};
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#ifdef __USE_GNU
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/* Version numbers for la_version handshake interface. */
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#define LAV_CURRENT 1
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/* Activity types signaled through la_activity. */
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enum
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{
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LA_ACT_CONSISTENT, /* Link map consistent again. */
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LA_ACT_ADD, /* New object will be added. */
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LA_ACT_DELETE /* Objects will be removed. */
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};
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/* Values representing origin of name for dynamic loading. */
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enum
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{
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LA_SER_ORIG = 0x01, /* Original name. */
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LA_SER_LIBPATH = 0x02, /* Directory from LD_LIBRARY_PATH. */
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LA_SER_RUNPATH = 0x04, /* Directory from RPATH/RUNPATH. */
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LA_SER_CONFIG = 0x08, /* Found through ldconfig. */
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LA_SER_DEFAULT = 0x40, /* Default directory. */
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LA_SER_SECURE = 0x80 /* Unused. */
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};
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/* Values for la_objopen return value. */
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enum
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{
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LA_FLG_BINDTO = 0x01, /* Audit symbols bound to this object. */
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LA_FLG_BINDFROM = 0x02 /* Audit symbols bound from this object. */
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};
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/* Values for la_symbind flags parameter. */
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enum
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{
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LA_SYMB_NOPLTENTER = 0x01, /* la_pltenter will not be called. */
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LA_SYMB_NOPLTEXIT = 0x02, /* la_pltexit will not be called. */
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LA_SYMB_STRUCTCALL = 0x04, /* Return value is a structure. */
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LA_SYMB_DLSYM = 0x08, /* Binding due to dlsym call. */
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LA_SYMB_ALTVALUE = 0x10 /* Value has been changed by a previous
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la_symbind call. */
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};
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struct dl_phdr_info
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{
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ElfW(Addr) dlpi_addr;
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const char *dlpi_name;
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const ElfW(Phdr) *dlpi_phdr;
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ElfW(Half) dlpi_phnum;
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/* Note: Following members were introduced after the first
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version of this structure was available. Check the SIZE
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argument passed to the dl_iterate_phdr callback to determine
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whether or not each later member is available. */
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/* Incremented when a new object may have been added. */
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__extension__ unsigned long long int dlpi_adds;
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/* Incremented when an object may have been removed. */
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__extension__ unsigned long long int dlpi_subs;
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/* If there is a PT_TLS segment, its module ID as used in
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TLS relocations, else zero. */
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size_t dlpi_tls_modid;
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/* The address of the calling thread's instance of this module's
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PT_TLS segment, if it has one and it has been allocated
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in the calling thread, otherwise a null pointer. */
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void *dlpi_tls_data;
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};
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__BEGIN_DECLS
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extern int dl_iterate_phdr (int (*__callback) (struct dl_phdr_info *,
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size_t, void *),
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void *__data);
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/* Prototypes for the ld.so auditing interfaces. These are not
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defined anywhere in ld.so but instead have to be provided by the
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auditing DSO. */
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extern unsigned int la_version (unsigned int __version);
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extern void la_activity (uintptr_t *__cookie, unsigned int __flag);
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extern char *la_objsearch (const char *__name, uintptr_t *__cookie,
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unsigned int __flag);
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extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid,
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uintptr_t *__cookie);
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extern void la_preinit (uintptr_t *__cookie);
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extern uintptr_t la_symbind32 (Elf32_Sym *__sym, unsigned int __ndx,
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uintptr_t *__refcook, uintptr_t *__defcook,
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unsigned int *__flags, const char *__symname);
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extern uintptr_t la_symbind64 (Elf64_Sym *__sym, unsigned int __ndx,
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uintptr_t *__refcook, uintptr_t *__defcook,
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unsigned int *__flags, const char *__symname);
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extern unsigned int la_objclose (uintptr_t *__cookie);
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__END_DECLS
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#endif
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#endif /* link.h */
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