1: /* Data structure for communication from the run-time dynamic linker for 2: loaded ELF shared objects. 3: Copyright (C) 1995-2001, 2004, 2005, 2006 Free Software Foundation, Inc. 4: This file is part of the GNU C Library. 5: 6: The GNU C Library is free software; you can redistribute it and/or 7: modify it under the terms of the GNU Lesser General Public 8: License as published by the Free Software Foundation; either 9: version 2.1 of the License, or (at your option) any later version. 10: 11: The GNU C Library is distributed in the hope that it will be useful, 12: but WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: Lesser General Public License for more details. 15: 16: You should have received a copy of the GNU Lesser General Public 17: License along with the GNU C Library; if not, write to the Free 18: Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 19: 02111-1307 USA. */ 20: 21: #ifndef _LINK_H 22: #define _LINK_H 1 23: 24: #include <features.h> 25: #include <elf.h> 26: #include <dlfcn.h> 27: #include <sys/types.h> 28: 29: /* We use this macro to refer to ELF types independent of the native wordsize. 30: `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */ 31: #define ElfW(type) _ElfW (Elf, __ELF_NATIVE_CLASS, type) 32: #define _ElfW(e,w,t) _ElfW_1 (e, w, _##t) 33: #define _ElfW_1(e,w,t) e##w##t 34: 35: #include <bits/elfclass.h> /* Defines __ELF_NATIVE_CLASS. */ 36: #include <bits/link.h> 37: 38: /* Rendezvous structure used by the run-time dynamic linker to communicate 39: details of shared object loading to the debugger. If the executable's 40: dynamic section has a DT_DEBUG element, the run-time linker sets that 41: element's value to the address where this structure can be found. */ 42: 43: struct r_debug 44: { 45: int r_version; /* Version number for this protocol. */ 46: 47: struct link_map *r_map; /* Head of the chain of loaded objects. */ 48: 49: /* This is the address of a function internal to the run-time linker, 50: that will always be called when the linker begins to map in a 51: library or unmap it, and again when the mapping change is complete. 52: The debugger can set a breakpoint at this address if it wants to 53: notice shared object mapping changes. */ 54: ElfW(Addr) r_brk; 55: enum 56: { 57: /* This state value describes the mapping change taking place when 58: the `r_brk' address is called. */ 59: RT_CONSISTENT, /* Mapping change is complete. */ 60: RT_ADD, /* Beginning to add a new object. */ 61: RT_DELETE /* Beginning to remove an object mapping. */ 62: } r_state; 63: 64: ElfW(Addr) r_ldbase; /* Base address the linker is loaded at. */ 65: }; 66: 67: /* This is the instance of that structure used by the dynamic linker. */ 68: extern struct r_debug _r_debug; 69: 70: /* This symbol refers to the "dynamic structure" in the `.dynamic' section 71: of whatever module refers to `_DYNAMIC'. So, to find its own 72: `struct r_debug', a program could do: 73: for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL; ++dyn) 74: if (dyn->d_tag == DT_DEBUG) 75: r_debug = (struct r_debug *) dyn->d_un.d_ptr; 76: */ 77: extern ElfW(Dyn) _DYNAMIC[]; 78: 79: /* Structure describing a loaded shared object. The `l_next' and `l_prev' 80: members form a chain of all the shared objects loaded at startup. 81: 82: These data structures exist in space used by the run-time dynamic linker; 83: modifying them may have disastrous results. */ 84: 85: struct link_map 86: { 87: /* These first few members are part of the protocol with the debugger. 88: This is the same format used in SVR4. */ 89: 90: ElfW(Addr) l_addr; /* Base address shared object is loaded at. */ 91: char *l_name; /* Absolute file name object was found in. */ 92: ElfW(Dyn) *l_ld; /* Dynamic section of the shared object. */ 93: struct link_map *l_next, *l_prev; /* Chain of loaded objects. */ 94: }; 95: 96: #ifdef __USE_GNU 97: 98: /* Version numbers for la_version handshake interface. */ 99: #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 */