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001: /* Data structure for communication from the run-time dynamic linker for
002:    loaded ELF shared objects.
003:    Copyright (C) 1995-2001, 2004, 2005, 2006 Free Software Foundation, Inc.
004:    This file is part of the GNU C Library.
005: 
006:    The GNU C Library is free software; you can redistribute it and/or
007:    modify it under the terms of the GNU Lesser General Public
008:    License as published by the Free Software Foundation; either
009:    version 2.1 of the License, or (at your option) any later version.
010: 
011:    The GNU C Library is distributed in the hope that it will be useful,
012:    but WITHOUT ANY WARRANTY; without even the implied warranty of
013:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014:    Lesser General Public License for more details.
015: 
016:    You should have received a copy of the GNU Lesser General Public
017:    License along with the GNU C Library; if not, write to the Free
018:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
019:    02111-1307 USA.  */
020: 
021: #ifndef _LINK_H
022: #define _LINK_H 1
023: 
024: #include <features.h>
025: #include <elf.h>
026: #include <dlfcn.h>
027: #include <sys/types.h>
028: 
029: /* We use this macro to refer to ELF types independent of the native wordsize.
030:    `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'.  */
031: #define ElfW(type)      _ElfW (Elf, __ELF_NATIVE_CLASS, type)
032: #define _ElfW(e,w,t)    _ElfW_1 (e, w, _##t)
033: #define _ElfW_1(e,w,t)  e##w##t
034: 
035: #include <bits/elfclass.h>              /* Defines __ELF_NATIVE_CLASS.  */
036: #include <bits/link.h>
037: 
038: /* Rendezvous structure used by the run-time dynamic linker to communicate
039:    details of shared object loading to the debugger.  If the executable's
040:    dynamic section has a DT_DEBUG element, the run-time linker sets that
041:    element's value to the address where this structure can be found.  */
042: 
043: struct r_debug
044:   {
045:     int r_version;              /* Version number for this protocol.  */
046: 
047:     struct link_map *r_map;     /* Head of the chain of loaded objects.  */
048: 
049:     /* This is the address of a function internal to the run-time linker,
050:        that will always be called when the linker begins to map in a
051:        library or unmap it, and again when the mapping change is complete.
052:        The debugger can set a breakpoint at this address if it wants to
053:        notice shared object mapping changes.  */
054:     ElfW(Addr) r_brk;
055:     enum
056:       {
057:         /* This state value describes the mapping change taking place when
058:            the `r_brk' address is called.  */
059:         RT_CONSISTENT,          /* Mapping change is complete.  */
060:         RT_ADD,                 /* Beginning to add a new object.  */
061:         RT_DELETE               /* Beginning to remove an object mapping.  */
062:       } r_state;
063: 
064:     ElfW(Addr) r_ldbase;        /* Base address the linker is loaded at.  */
065:   };
066: 
067: /* This is the instance of that structure used by the dynamic linker.  */
068: extern struct r_debug _r_debug;
069: 
070: /* This symbol refers to the "dynamic structure" in the `.dynamic' section
071:    of whatever module refers to `_DYNAMIC'.  So, to find its own
072:    `struct r_debug', a program could do:
073:      for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL; ++dyn)
074:        if (dyn->d_tag == DT_DEBUG)
075:          r_debug = (struct r_debug *) dyn->d_un.d_ptr;
076:    */
077: extern ElfW(Dyn) _DYNAMIC[];
078: 
079: /* Structure describing a loaded shared object.  The `l_next' and `l_prev'
080:    members form a chain of all the shared objects loaded at startup.
081: 
082:    These data structures exist in space used by the run-time dynamic linker;
083:    modifying them may have disastrous results.  */
084: 
085: struct link_map
086:   {
087:     /* These first few members are part of the protocol with the debugger.
088:        This is the same format used in SVR4.  */
089: 
090:     ElfW(Addr) l_addr;          /* Base address shared object is loaded at.  */
091:     char *l_name;               /* Absolute file name object was found in.  */
092:     ElfW(Dyn) *l_ld;            /* Dynamic section of the shared object.  */
093:     struct link_map *l_next, *l_prev; /* Chain of loaded objects.  */
094:   };
095: 
096: #ifdef __USE_GNU
097: 
098: /* Version numbers for la_version handshake interface.  */
099: #define LAV_CURRENT     1
100: 
101: /* Activity types signaled through la_activity.  */
102: enum
103:   {
104:     LA_ACT_CONSISTENT,          /* Link map consistent again.  */
105:     LA_ACT_ADD,                 /* New object will be added.  */
106:     LA_ACT_DELETE               /* Objects will be removed.  */
107:   };
108: 
109: /* Values representing origin of name for dynamic loading.  */
110: enum
111:   {
112:     LA_SER_ORIG = 0x01,         /* Original name.  */
113:     LA_SER_LIBPATH = 0x02,      /* Directory from LD_LIBRARY_PATH.  */
114:     LA_SER_RUNPATH = 0x04,      /* Directory from RPATH/RUNPATH.  */
115:     LA_SER_CONFIG = 0x08,       /* Found through ldconfig.  */
116:     LA_SER_DEFAULT = 0x40,      /* Default directory.  */
117:     LA_SER_SECURE = 0x80        /* Unused.  */
118:   };
119: 
120: /* Values for la_objopen return value.  */
121: enum
122:   {
123:     LA_FLG_BINDTO = 0x01,       /* Audit symbols bound to this object.  */
124:     LA_FLG_BINDFROM = 0x02      /* Audit symbols bound from this object.  */
125:   };
126: 
127: /* Values for la_symbind flags parameter.  */
128: enum
129:   {
130:     LA_SYMB_NOPLTENTER = 0x01,  /* la_pltenter will not be called.  */
131:     LA_SYMB_NOPLTEXIT = 0x02,   /* la_pltexit will not be called.  */
132:     LA_SYMB_STRUCTCALL = 0x04,  /* Return value is a structure.  */
133:     LA_SYMB_DLSYM = 0x08,       /* Binding due to dlsym call.  */
134:     LA_SYMB_ALTVALUE = 0x10     /* Value has been changed by a previous
135:                                    la_symbind call.  */
136:   };
137: 
138: struct dl_phdr_info
139:   {
140:     ElfW(Addr) dlpi_addr;
141:     const char *dlpi_name;
142:     const ElfW(Phdr) *dlpi_phdr;
143:     ElfW(Half) dlpi_phnum;
144: 
145:     /* Note: Following members were introduced after the first
146:        version of this structure was available.  Check the SIZE
147:        argument passed to the dl_iterate_phdr callback to determine
148:        whether or not each later member is available.  */
149: 
150:     /* Incremented when a new object may have been added.  */
151:     unsigned long long int dlpi_adds;
152:     /* Incremented when an object may have been removed.  */
153:     unsigned long long int dlpi_subs;
154: 
155:     /* If there is a PT_TLS segment, its module ID as used in
156:        TLS relocations, else zero.  */
157:     size_t dlpi_tls_modid;
158: 
159:     /* The address of the calling thread's instance of this module's
160:        PT_TLS segment, if it has one and it has been allocated
161:        in the calling thread, otherwise a null pointer.  */
162:     void *dlpi_tls_data;
163:   };
164: 
165: __BEGIN_DECLS
166: 
167: extern int dl_iterate_phdr (int (*__callback) (struct dl_phdr_info *,
168:                                                size_t, void *),
169:                             void *__data);
170: 
171: 
172: /* Prototypes for the ld.so auditing interfaces.  These are not
173:    defined anywhere in ld.so but instead have to be provided by the
174:    auditing DSO.  */
175: extern unsigned int la_version (unsigned int __version);
176: extern void la_activity (uintptr_t *__cookie, unsigned int __flag);
177: extern char *la_objsearch (const char *__name, uintptr_t *__cookie,
178:                            unsigned int __flag);
179: extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid,
180:                                 uintptr_t *__cookie);
181: extern void la_preinit (uintptr_t *__cookie);
182: extern uintptr_t la_symbind32 (Elf32_Sym *__sym, unsigned int __ndx,
183:                                uintptr_t *__refcook, uintptr_t *__defcook,
184:                                unsigned int *__flags, const char *__symname);
185: extern uintptr_t la_symbind64 (Elf64_Sym *__sym, unsigned int __ndx,
186:                                uintptr_t *__refcook, uintptr_t *__defcook,
187:                                unsigned int *__flags, const char *__symname);
188: extern unsigned int la_objclose (uintptr_t *__cookie);
189: 
190: __END_DECLS
191: 
192: #endif
193: 
194: #endif /* link.h */
195: 

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