1 /* Run time dynamic linker.
2 Copyright (C) 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
24 #include <sys/mman.h> /* Check if MAP_ANON is defined. */
25 #include <elf/ldsodefs.h>
26 #include <stdio-common/_itoa.h>
28 #include "dynamic-link.h"
29 #include "dl-librecon.h"
33 /* System-specific function to do initial startup for the dynamic linker.
34 After this, file access calls and getenv must work. This is responsible
35 for setting __libc_enable_secure if we need to be secure (e.g. setuid),
36 and for setting _dl_argc and _dl_argv, and then calling _dl_main. */
37 extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
38 void (*dl_main) (const ElfW(Phdr) *phdr,
40 ElfW(Addr) *user_entry));
41 extern void _dl_sysdep_start_cleanup (void);
43 /* System-dependent function to read a file's whole contents
44 in the most convenient manner available. */
45 extern void *_dl_sysdep_read_whole_file (const char *filename,
49 /* Helper function to handle errors while resolving symbols. */
50 static void print_unresolved (int errcode, const char *objname,
51 const char *errsting);
53 /* Helper function to handle errors when a version is missing. */
54 static void print_missing_version (int errcode, const char *objname,
55 const char *errsting);
58 /* This is a list of all the modes the dynamic loader can be in. */
59 enum mode { normal, list, verify, trace };
61 /* Process all environments variables the dynamic linker must recognize.
62 Since all of them start with `LD_' we are a bit smarter while finding
64 static void process_envvars (enum mode *modep, int *lazyp);
68 const char *_dl_rpath;
70 const char *_dl_platform;
71 size_t _dl_platformlen;
72 unsigned long _dl_hwcap;
73 struct r_search_path *_dl_search_paths;
74 const char *_dl_profile;
75 const char *_dl_profile_output;
76 struct link_map *_dl_profile_map;
78 int _dl_debug_impcalls;
79 int _dl_debug_bindings;
80 int _dl_debug_symbols;
81 int _dl_debug_versions;
85 /* Set nonzero during loading and initialization of executable and
86 libraries, cleared before the executable's entry point runs. This
87 must not be initialized to nonzero, because the unused dynamic
88 linker loaded in for libc.so's "ld.so.1" dep will provide the
89 definition seen by libc.so's initializer; that value must be zero,
90 and will be since that dynamic linker's _dl_start and dl_main will
94 static void dl_main (const ElfW(Phdr) *phdr,
96 ElfW(Addr) *user_entry);
98 struct link_map _dl_rtld_map;
99 struct libname_list _dl_rtld_libname;
100 struct libname_list _dl_rtld_libname2;
105 #error "sysdeps/MACHINE/dl-machine.h fails to define RTLD_START"
109 _dl_start (void *arg)
111 struct link_map bootstrap_map;
113 /* This #define produces dynamic linking inline functions for
114 bootstrap relocation instead of general-purpose relocation. */
115 #define RTLD_BOOTSTRAP
116 #define RESOLVE(sym, version, flags) bootstrap_map.l_addr
117 #include "dynamic-link.h"
119 /* Figure out the run-time load address of the dynamic linker itself. */
120 bootstrap_map.l_addr = elf_machine_load_address ();
122 /* Read our own dynamic section and fill in the info array. */
123 bootstrap_map.l_ld = (void *) bootstrap_map.l_addr + elf_machine_dynamic ();
124 elf_get_dynamic_info (bootstrap_map.l_ld, bootstrap_map.l_info);
126 #ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
127 ELF_MACHINE_BEFORE_RTLD_RELOC (bootstrap_map.l_info);
130 /* Relocate ourselves so we can do normal function calls and
131 data access using the global offset table. */
133 ELF_DYNAMIC_RELOCATE (&bootstrap_map, 0, 0);
134 /* Please note that we don't allow profiling of this object and
135 therefore need not test whether we have to allocate the array
136 for the relocation results (as done in dl-reloc.c). */
138 /* Now life is sane; we can call functions and access global data.
139 Set up to use the operating system facilities, and find out from
140 the operating system's program loader where to find the program
141 header table in core. */
143 /* Transfer data about ourselves to the permanent link_map structure. */
144 _dl_rtld_map.l_addr = bootstrap_map.l_addr;
145 _dl_rtld_map.l_ld = bootstrap_map.l_ld;
146 _dl_rtld_map.l_opencount = 1;
147 memcpy (_dl_rtld_map.l_info, bootstrap_map.l_info,
148 sizeof _dl_rtld_map.l_info);
149 _dl_setup_hash (&_dl_rtld_map);
151 /* Cache the DT_RPATH stored in ld.so itself; this will be
152 the default search path. */
153 if (_dl_rtld_map.l_info[DT_STRTAB] && _dl_rtld_map.l_info[DT_RPATH])
155 _dl_rpath = (void *) (_dl_rtld_map.l_addr +
156 _dl_rtld_map.l_info[DT_STRTAB]->d_un.d_ptr +
157 _dl_rtld_map.l_info[DT_RPATH]->d_un.d_val);
160 /* Call the OS-dependent function to set up life so we can do things like
161 file access. It will call `dl_main' (below) to do all the real work
162 of the dynamic linker, and then unwind our frame and run the user
163 entry point on the same stack we entered on. */
164 return _dl_sysdep_start (arg, &dl_main);
167 /* Now life is peachy; we can do all normal operations.
168 On to the real work. */
170 void ENTRY_POINT (void);
172 /* Some helper functions. */
174 /* Arguments to relocate_doit. */
183 /* Argument to map_doit. */
185 /* Return value of map_doit. */
186 struct link_map *main_map;
189 /* Arguments to version_check_doit. */
190 struct version_check_args
192 struct link_map *main_map;
197 relocate_doit (void *a)
199 struct relocate_args *args = (struct relocate_args *) a;
201 _dl_relocate_object (args->l, _dl_object_relocation_scope (args->l),
208 struct map_args *args = (struct map_args *)a;
209 args->main_map = _dl_map_object (NULL, args->str, 0, lt_library, 0);
213 version_check_doit (void *a)
215 struct version_check_args *args = (struct version_check_args *)a;
216 if (_dl_check_all_versions (args->main_map, 1) && args->doexit)
217 /* We cannot start the application. Abort now. */
222 static inline struct link_map *
223 find_needed (const char *name)
227 for (n = 0; n < _dl_loaded->l_nsearchlist; ++n)
228 if (_dl_name_match_p (name, _dl_loaded->l_searchlist[n]))
229 return _dl_loaded->l_searchlist[n];
231 /* Should never happen. */
236 match_version (const char *string, struct link_map *map)
238 const char *strtab = (const char *) (map->l_addr
239 + map->l_info[DT_STRTAB]->d_un.d_ptr);
242 #define VERDEFTAG (DT_NUM + DT_PROCNUM + DT_VERSIONTAGIDX (DT_VERDEF))
243 if (map->l_info[VERDEFTAG] == NULL)
244 /* The file has no symbol versioning. */
247 def = (ElfW(Verdef) *) ((char *) map->l_addr
248 + map->l_info[VERDEFTAG]->d_un.d_ptr);
251 ElfW(Verdaux) *aux = (ElfW(Verdaux) *) ((char *) def + def->vd_aux);
253 /* Compare the version strings. */
254 if (strcmp (string, strtab + aux->vda_name) == 0)
258 /* If no more definitions we failed to find what we want. */
259 if (def->vd_next == 0)
262 /* Next definition. */
263 def = (ElfW(Verdef) *) ((char *) def + def->vd_next);
269 static unsigned int _dl_skip_args; /* Nonzero if we were run directly. */
270 static const char *library_path; /* The library search path. */
271 static const char *preloadlist; /* The list preloaded objects. */
272 static int version_info; /* Nonzero if information about
273 versions has to be printed. */
276 dl_main (const ElfW(Phdr) *phdr,
278 ElfW(Addr) *user_entry)
280 const ElfW(Phdr) *ph;
281 struct link_map *main_map;
284 struct link_map **preloads;
285 unsigned int npreloads;
290 int paths_initialized = 0;
292 /* Process the environment variable which control the behaviour. */
293 process_envvars (&mode, &lazy);
295 /* Set up a flag which tells we are just starting. */
298 if (*user_entry == (ElfW(Addr)) &ENTRY_POINT)
300 /* Ho ho. We are not the program interpreter! We are the program
301 itself! This means someone ran ld.so as a command. Well, that
302 might be convenient to do sometimes. We support it by
303 interpreting the args like this:
305 ld.so PROGRAM ARGS...
307 The first argument is the name of a file containing an ELF
308 executable we will load and run with the following arguments.
309 To simplify life here, PROGRAM is searched for using the
310 normal rules for shared objects, rather than $PATH or anything
311 like that. We just load it and use its entry point; we don't
312 pay attention to its PT_INTERP command (we are the interpreter
313 ourselves). This is an easy way to test a new ld.so before
316 /* Note the place where the dynamic linker actually came from. */
317 _dl_rtld_map.l_name = _dl_argv[0];
320 if (! strcmp (_dl_argv[1], "--list"))
323 lazy = -1; /* This means do no dependency analysis. */
329 else if (! strcmp (_dl_argv[1], "--verify"))
337 else if (! strcmp (_dl_argv[1], "--library-path")
340 library_path = _dl_argv[2];
349 /* If we have no further argument the program was called incorrectly.
350 Grant the user some education. */
353 Usage: ld.so [OPTION]... EXECUTABLE-FILE [ARGS-FOR-PROGRAM...]\n\
354 You have invoked `ld.so', the helper program for shared library executables.\n\
355 This program usually lives in the file `/lib/ld.so', and special directives\n\
356 in executable files using ELF shared libraries tell the system's program\n\
357 loader to load the helper program from this file. This helper program loads\n\
358 the shared libraries needed by the program executable, prepares the program\n\
359 to run, and runs it. You may invoke this helper program directly from the\n\
360 command line to load and run an ELF executable file; this is like executing\n\
361 that file itself, but always uses this helper program from the file you\n\
362 specified, instead of the helper program file specified in the executable\n\
363 file you run. This is mostly of use for maintainers to test new versions\n\
364 of this helper program; chances are you did not intend to run this program.\n\
366 --list list all dependencies and how they are resolved\n\
367 --verify verify that given object really is a dynamically linked\n\
368 object we get handle\n\
369 --library-path PATH use given PATH instead of content of the environment\n\
370 variable LD_LIBRARY_PATH\n",
377 /* Initialize the data structures for the search paths for shared
379 _dl_init_paths (library_path);
380 paths_initialized = 1;
384 char *err_str = NULL;
385 struct map_args args;
387 args.str = _dl_argv[0];
388 (void) _dl_catch_error (&err_str, map_doit, &args);
389 main_map = args.main_map;
393 _exit (EXIT_FAILURE);
397 main_map = _dl_map_object (NULL, _dl_argv[0], 0, lt_library, 0);
399 phdr = main_map->l_phdr;
400 phent = main_map->l_phnum;
401 main_map->l_name = (char *) "";
402 *user_entry = main_map->l_entry;
406 /* Create a link_map for the executable itself.
407 This will be what dlopen on "" returns. */
408 main_map = _dl_new_object ((char *) "", "", lt_executable);
409 if (main_map == NULL)
410 _dl_sysdep_fatal ("cannot allocate memory for link map\n", NULL);
411 main_map->l_phdr = phdr;
412 main_map->l_phnum = phent;
413 main_map->l_entry = *user_entry;
414 main_map->l_opencount = 1;
416 /* We delay initializing the path structure until we got the dynamic
417 information for the program. */
420 /* Scan the program header table for the dynamic section. */
421 for (ph = phdr; ph < &phdr[phent]; ++ph)
425 /* Find out the load address. */
426 main_map->l_addr = (ElfW(Addr)) phdr - ph->p_vaddr;
429 /* This tells us where to find the dynamic section,
430 which tells us everything we need to do. */
431 main_map->l_ld = (void *) main_map->l_addr + ph->p_vaddr;
434 /* This "interpreter segment" was used by the program loader to
435 find the program interpreter, which is this program itself, the
436 dynamic linker. We note what name finds us, so that a future
437 dlopen call or DT_NEEDED entry, for something that wants to link
438 against the dynamic linker as a shared library, will know that
439 the shared object is already loaded. */
440 _dl_rtld_libname.name = (const char *) main_map->l_addr + ph->p_vaddr;
441 _dl_rtld_libname.next = NULL;
442 _dl_rtld_map.l_libname = &_dl_rtld_libname;
444 /* Ordinarilly, we would get additional names for the loader from
445 our DT_SONAME. This can't happen if we were actually linked as
446 a static executable (detect this case when we have no DYNAMIC).
447 If so, assume the filename component of the interpreter path to
448 be our SONAME, and add it to our name list. */
449 if (_dl_rtld_map.l_ld == NULL)
451 char *p = strrchr (_dl_rtld_libname.name, '/');
454 _dl_rtld_libname2.name = p+1;
455 _dl_rtld_libname2.next = NULL;
456 _dl_rtld_libname.next = &_dl_rtld_libname2;
463 if (! _dl_rtld_map.l_libname && _dl_rtld_map.l_name)
465 /* We were invoked directly, so the program might not have a
467 _dl_rtld_libname.name = _dl_rtld_map.l_name;
468 _dl_rtld_libname.next = NULL;
469 _dl_rtld_map.l_libname = &_dl_rtld_libname;
472 assert (_dl_rtld_map.l_libname); /* How else did we get here? */
474 /* Extract the contents of the dynamic section for easy access. */
475 elf_get_dynamic_info (main_map->l_ld, main_map->l_info);
476 if (main_map->l_info[DT_HASH])
477 /* Set up our cache of pointers into the hash table. */
478 _dl_setup_hash (main_map);
482 /* We were called just to verify that this is a dynamic
483 executable using us as the program interpreter. Exit with an
484 error if we were not able to load the binary or no interpreter
485 is specified (i.e., this is no dynamically linked binary. */
486 if (main_map->l_ld == NULL)
489 /* We allow here some platform specific code. */
490 #ifdef DISTINGUISH_LIB_VERSIONS
491 DISTINGUISH_LIB_VERSIONS;
493 _exit (has_interp ? 0 : 2);
496 if (! paths_initialized)
497 /* Initialize the data structures for the search paths for shared
499 _dl_init_paths (library_path);
501 /* Put the link_map for ourselves on the chain so it can be found by
502 name. Note that at this point the global chain of link maps contains
503 exactly one element, which is pointed to by main_map. */
504 if (! _dl_rtld_map.l_name)
505 /* If not invoked directly, the dynamic linker shared object file was
506 found by the PT_INTERP name. */
507 _dl_rtld_map.l_name = (char *) _dl_rtld_map.l_libname->name;
508 _dl_rtld_map.l_type = lt_library;
509 main_map->l_next = &_dl_rtld_map;
510 _dl_rtld_map.l_prev = main_map;
512 /* We have two ways to specify objects to preload: via environment
513 variable and via the file /etc/ld.so.preload. The later can also
514 be used when security is enabled. */
520 /* The LD_PRELOAD environment variable gives list of libraries
521 separated by white space or colons that are loaded before the
522 executable's dependencies and prepended to the global scope
523 list. If the binary is running setuid all elements
524 containing a '/' are ignored since it is insecure. */
525 char *list = strdupa (preloadlist);
527 while ((p = strsep (&list, " :")) != NULL)
529 && (! __libc_enable_secure || strchr (p, '/') == NULL))
531 struct link_map *new_map = _dl_map_object (main_map, p, 1,
533 if (new_map->l_opencount == 1)
534 /* It is no duplicate. */
539 /* Read the contents of the file. */
540 file = _dl_sysdep_read_whole_file ("/etc/ld.so.preload", &file_size,
541 PROT_READ | PROT_WRITE);
544 /* Parse the file. It contains names of libraries to be loaded,
545 separated by white spaces or `:'. It may also contain
546 comments introduced by `#'. */
551 /* Eliminate comments. */
556 char *comment = memchr (runp, '#', rest);
560 rest -= comment - runp;
563 while (--rest > 0 && *++comment != '\n');
566 /* We have one problematic case: if we have a name at the end of
567 the file without a trailing terminating characters, we cannot
568 place the \0. Handle the case separately. */
569 if (file[file_size - 1] != ' ' && file[file_size - 1] != '\t'
570 && file[file_size - 1] != '\n' && file[file_size - 1] != ':')
572 problem = &file[file_size];
573 while (problem > file && problem[-1] != ' ' && problem[-1] != '\t'
574 && problem[-1] != '\n' && problem[-1] != ':')
583 file[file_size - 1] = '\0';
590 while ((p = strsep (&runp, ": \t\n")) != NULL)
593 struct link_map *new_map = _dl_map_object (main_map, p, 1,
595 if (new_map->l_opencount == 1)
596 /* It is no duplicate. */
603 char *p = strndupa (problem, file_size - (problem - file));
604 struct link_map *new_map = _dl_map_object (main_map, p, 1,
606 if (new_map->l_opencount == 1)
607 /* It is no duplicate. */
611 /* We don't need the file anymore. */
612 __munmap (file, file_size);
617 /* Set up PRELOADS with a vector of the preloaded libraries. */
619 preloads = __alloca (npreloads * sizeof preloads[0]);
620 l = _dl_rtld_map.l_next; /* End of the chain before preloads. */
627 assert (i == npreloads);
630 /* Load all the libraries specified by DT_NEEDED entries. If LD_PRELOAD
631 specified some libraries to load, these are inserted before the actual
632 dependencies in the executable's searchlist for symbol resolution. */
633 _dl_map_object_deps (main_map, preloads, npreloads, mode == trace);
636 /* We are done mapping things, so close the zero-fill descriptor. */
637 __close (_dl_zerofd);
641 /* Remove _dl_rtld_map from the chain. */
642 _dl_rtld_map.l_prev->l_next = _dl_rtld_map.l_next;
643 if (_dl_rtld_map.l_next)
644 _dl_rtld_map.l_next->l_prev = _dl_rtld_map.l_prev;
646 if (_dl_rtld_map.l_opencount > 1)
648 /* Some DT_NEEDED entry referred to the interpreter object itself, so
649 put it back in the list of visible objects. We insert it into the
650 chain in symbol search order because gdb uses the chain's order as
651 its symbol search order. */
653 while (main_map->l_searchlist[i] != &_dl_rtld_map)
655 _dl_rtld_map.l_prev = main_map->l_searchlist[i - 1];
656 _dl_rtld_map.l_next = (i + 1 < main_map->l_nsearchlist ?
657 main_map->l_searchlist[i + 1] : NULL);
658 assert (_dl_rtld_map.l_prev->l_next == _dl_rtld_map.l_next);
659 _dl_rtld_map.l_prev->l_next = &_dl_rtld_map;
660 if (_dl_rtld_map.l_next)
662 assert (_dl_rtld_map.l_next->l_prev == _dl_rtld_map.l_prev);
663 _dl_rtld_map.l_next->l_prev = &_dl_rtld_map;
667 /* Now let us see whether all libraries are available in the
670 struct version_check_args args;
671 args.doexit = mode == normal;
672 args.main_map = main_map;
673 _dl_receive_error (print_missing_version, version_check_doit, &args);
678 /* We were run just to list the shared libraries. It is
679 important that we do this before real relocation, because the
680 functions we call below for output may no longer work properly
682 if (! _dl_loaded->l_info[DT_NEEDED])
683 _dl_sysdep_message ("\t", "statically linked\n", NULL);
688 for (l = _dl_loaded->l_next; l; l = l->l_next)
689 if (l->l_opencount == 0)
690 /* The library was not found. */
691 _dl_sysdep_message ("\t", l->l_libname->name, " => not found\n",
696 buf[sizeof buf - 1] = '\0';
697 bp = _itoa_word (l->l_addr, &buf[sizeof buf - 1], 16, 0);
698 while ((size_t) (&buf[sizeof buf - 1] - bp)
699 < sizeof l->l_addr * 2)
701 _dl_sysdep_message ("\t", l->l_libname->name, " => ",
702 l->l_name, " (0x", bp, ")\n", NULL);
707 for (i = 1; i < _dl_argc; ++i)
709 const ElfW(Sym) *ref = NULL;
710 ElfW(Addr) loadbase = _dl_lookup_symbol (_dl_argv[i], &ref,
711 &_dl_default_scope[2],
713 ELF_MACHINE_JMP_SLOT);
715 buf[sizeof buf - 1] = '\0';
716 bp = _itoa_word (ref->st_value, &buf[sizeof buf - 1], 16, 0);
717 while ((size_t) (&buf[sizeof buf - 1] - bp) < sizeof loadbase * 2)
719 _dl_sysdep_message (_dl_argv[i], " found at 0x", bp, NULL);
720 buf[sizeof buf - 1] = '\0';
721 bp = _itoa_word (loadbase, &buf[sizeof buf - 1], 16, 0);
722 while ((size_t) (&buf[sizeof buf - 1] - bp) < sizeof loadbase * 2)
724 _dl_sysdep_message (" in object at 0x", bp, "\n", NULL);
730 /* We have to do symbol dependency testing. */
731 struct relocate_args args;
741 if (l != &_dl_rtld_map && l->l_opencount > 0)
744 _dl_receive_error (print_unresolved, relocate_doit,
746 *_dl_global_scope_end = NULL;
752 #define VERNEEDTAG (DT_NUM + DT_PROCNUM + DT_VERSIONTAGIDX (DT_VERNEED))
755 /* Print more information. This means here, print information
756 about the versions needed. */
758 struct link_map *map = _dl_loaded;
760 for (map = _dl_loaded; map != NULL; map = map->l_next)
763 ElfW(Dyn) *dyn = map->l_info[VERNEEDTAG];
769 strtab = (const char *)
770 (map->l_addr + map->l_info[DT_STRTAB]->d_un.d_ptr);
771 ent = (ElfW(Verneed) *) (map->l_addr + dyn->d_un.d_ptr);
775 _dl_sysdep_message ("\n\tVersion information:\n", NULL);
779 _dl_sysdep_message ("\t", (map->l_name[0]
780 ? map->l_name : _dl_argv[0]),
786 struct link_map *needed;
788 needed = find_needed (strtab + ent->vn_file);
789 aux = (ElfW(Vernaux) *) ((char *) ent + ent->vn_aux);
793 const char *fname = NULL;
795 _dl_sysdep_message ("\t\t",
796 strtab + ent->vn_file,
797 " (", strtab + aux->vna_name,
805 && match_version (strtab+aux->vna_name, needed))
806 fname = needed->l_name;
808 _dl_sysdep_message (fname ?: "not found", "\n",
811 if (aux->vna_next == 0)
812 /* No more symbols. */
816 aux = (ElfW(Vernaux) *) ((char *) aux
820 if (ent->vn_next == 0)
821 /* No more dependencies. */
824 /* Next dependency. */
825 ent = (ElfW(Verneed) *) ((char *) ent + ent->vn_next);
835 /* Now we have all the objects loaded. Relocate them all except for
836 the dynamic linker itself. We do this in reverse order so that copy
837 relocs of earlier objects overwrite the data written by later
838 objects. We do not re-relocate the dynamic linker itself in this
839 loop because that could result in the GOT entries for functions we
840 call being changed, and that would break us. It is safe to relocate
841 the dynamic linker out of order because it has no copy relocs (we
842 know that because it is self-contained). */
850 if (l != &_dl_rtld_map)
852 _dl_relocate_object (l, _dl_object_relocation_scope (l), lazy);
853 *_dl_global_scope_end = NULL;
858 /* Do any necessary cleanups for the startup OS interface code.
859 We do these now so that no calls are made after rtld re-relocation
860 which might be resolved to different functions than we expect.
861 We cannot do this before relocating the other objects because
862 _dl_relocate_object might need to call `mprotect' for DT_TEXTREL. */
863 _dl_sysdep_start_cleanup ();
865 if (_dl_rtld_map.l_opencount > 0)
866 /* There was an explicit ref to the dynamic linker as a shared lib.
867 Re-relocate ourselves with user-controlled symbol definitions. */
868 _dl_relocate_object (&_dl_rtld_map, &_dl_default_scope[2], 0);
872 /* Initialize _r_debug. */
873 struct r_debug *r = _dl_debug_initialize (_dl_rtld_map.l_addr);
878 #ifdef ELF_MACHINE_DEBUG_SETUP
880 /* Some machines (e.g. MIPS) don't use DT_DEBUG in this way. */
882 ELF_MACHINE_DEBUG_SETUP (l, r);
883 ELF_MACHINE_DEBUG_SETUP (&_dl_rtld_map, r);
887 if (l->l_info[DT_DEBUG])
888 /* There is a DT_DEBUG entry in the dynamic section. Fill it in
889 with the run-time address of the r_debug structure */
890 l->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
892 /* Fill in the pointer in the dynamic linker's own dynamic section, in
893 case you run gdb on the dynamic linker directly. */
894 if (_dl_rtld_map.l_info[DT_DEBUG])
895 _dl_rtld_map.l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
899 /* Notify the debugger that all objects are now mapped in. */
904 /* Now enable profiling if needed. */
905 if (_dl_profile_map != NULL)
906 /* We must prepare the profiling. */
907 _dl_start_profile (_dl_profile_map, _dl_profile_output);
909 /* Once we return, _dl_sysdep_start will invoke
910 the DT_INIT functions and then *USER_ENTRY. */
913 /* This is a little helper function for resolving symbols while
914 tracing the binary. */
916 print_unresolved (int errcode __attribute__ ((unused)), const char *objname,
917 const char *errstring)
919 if (objname[0] == '\0')
920 objname = _dl_argv[0] ?: "<main program>";
921 _dl_sysdep_error (errstring, " (", objname, ")\n", NULL);
924 /* This is a little helper function for resolving symbols while
925 tracing the binary. */
927 print_missing_version (int errcode __attribute__ ((unused)),
928 const char *objname, const char *errstring)
930 _dl_sysdep_error (_dl_argv[0] ?: "<program name unknown>", ": ",
931 objname, ": ", errstring, "\n", NULL);
934 /* Nonzero if any of the debugging options is enabled. */
935 static int any_debug;
937 /* Process the string given as the parameter which explains which debugging
938 options are enabled. */
940 process_dl_debug (const char *dl_debug)
943 #define separators " ,:"
947 /* Skip separating white spaces and commas. */
948 dl_debug += strspn (dl_debug, separators);
949 if (*dl_debug != '\0')
951 len = strcspn (dl_debug, separators);
956 if (memcmp (dl_debug, "help", 4) == 0)
958 _dl_sysdep_message ("\
959 Valid options for the LD_DEBUG environment variable are:\n\
961 bindings display information about symbol binding\n\
962 files display processing of files and libraries\n\
963 help display this help message and exit\n\
964 libs display library search paths\n\
965 reloc display relocation processing\n\
966 symbols display symbol table processing\n\
967 versions display version dependencies\n\
969 To direct the debugging output into a file instead of standard output\n\
970 a filename can be specified using the LD_DEBUG_OUTPUT environment variable.\n",
975 if (memcmp (dl_debug, "libs", 4) == 0)
978 _dl_debug_impcalls = 1;
985 if (memcmp (dl_debug, "reloc", 5) == 0)
988 _dl_debug_impcalls = 1;
993 if (memcmp (dl_debug, "files", 5) == 0)
996 _dl_debug_impcalls = 1;
1003 if (memcmp (dl_debug, "symbols", 7) == 0)
1005 _dl_debug_symbols = 1;
1006 _dl_debug_impcalls = 1;
1013 if (memcmp (dl_debug, "bindings", 8) == 0)
1015 _dl_debug_bindings = 1;
1016 _dl_debug_impcalls = 1;
1021 if (memcmp (dl_debug, "versions", 8) == 0)
1023 _dl_debug_versions = 1;
1024 _dl_debug_impcalls = 1;
1035 /* Display a warning and skip everything until next separator. */
1036 char *startp = strndupa (dl_debug, len);
1037 _dl_sysdep_error ("warning: debug option `", startp,
1038 "' unknown; try LD_DEBUG=help\n", NULL);
1042 while (*(dl_debug += len) != '\0');
1045 /* Process all environments variables the dynamic linker must recognize.
1046 Since all of them start with `LD_' we are a bit smarter while finding
1049 process_envvars (enum mode *modep, int *lazyp)
1053 enum mode mode = normal;
1055 char *debug_output = NULL;
1057 /* This is the default place for profiling data file. */
1058 _dl_profile_output = "/var/tmp";
1060 while ((envline = _dl_next_ld_env_entry (&runp)) != NULL)
1062 size_t len = strcspn (envline, "=") - 3;
1067 /* Warning level, verbose or not. */
1068 if (memcmp (&envline[3], "WARN", 4) == 0)
1069 _dl_verbose = envline[8] != '\0';
1073 /* Debugging of the dynamic linker? */
1074 if (memcmp (&envline[3], "DEBUG", 5) == 0)
1075 process_dl_debug (&envline[9]);
1079 /* Print information about versions. */
1080 if (memcmp (&envline[3], "VERBOSE", 7) == 0)
1082 version_info = envline[11] != '\0';
1086 /* List of objects to be preloaded. */
1087 if (memcmp (&envline[3], "PRELOAD", 7) == 0)
1089 preloadlist = &envline[11];
1093 /* Which shared object shall be profiled. */
1094 if (memcmp (&envline[3], "PROFILE", 7) == 0)
1096 _dl_profile = &envline[11];
1097 if (*_dl_profile == '\0')
1103 /* Do we bind early? */
1104 if (memcmp (&envline[3], "BIND_NOW", 8) == 0)
1109 /* Test whether we want to see the content of the auxiliary
1110 array passed up from the kernel. */
1111 if (memcmp (&envline[3], "SHOW_AUXV", 9) == 0)
1116 /* Mask for the important hardware capabilities. */
1117 if (memcmp (&envline[3], "HWCAP_MASK", 10) == 0)
1118 _dl_hwcap_mask = strtoul (&envline[14], NULL, 0);
1122 /* Where to place the profiling data file. */
1123 if (memcmp (&envline[3], "DEBUG_OUTPUT", 12) == 0)
1125 debug_output = &envline[16];
1129 /* The library search path. */
1130 if (memcmp (&envline[3], "LIBRARY_PATH", 12) == 0)
1131 library_path = &envline[16];
1135 /* Where to place the profiling data file. */
1136 if (!__libc_enable_secure
1137 && memcmp (&envline[3], "PROFILE_OUTPUT", 14) == 0)
1139 _dl_profile_output = &envline[18];
1140 if (*_dl_profile_output == '\0')
1141 _dl_profile_output = "/var/tmp";
1146 /* The mode of the dynamic linker can be set. */
1147 if (memcmp (&envline[3], "TRACE_LOADED_OBJECTS", 20) == 0)
1151 /* We might have some extra environment variable to handle. This
1152 is tricky due to the pre-processing of the length of the name
1153 in the switch statement here. The code here assumes that added
1154 environment variables have a different length. */
1155 #ifdef EXTRA_LD_ENVVARS
1161 /* If we have to run the dynamic linker in debugging mode and the
1162 LD_DEBUG_OUTPUT environment variable is given, we write the debug
1163 messages to this file. */
1164 if (any_debug && debug_output != NULL && !__libc_enable_secure)
1166 _dl_debug_fd = __open (debug_output, O_WRONLY | O_APPEND | O_CREAT,
1168 if (_dl_debug_fd == -1)
1169 /* We use standard output if opening the file failed. */
1170 _dl_debug_fd = STDOUT_FILENO;
1173 /* LAZY is determined by the environment variable LD_WARN and
1174 LD_BIND_NOW if we trace the binary. */
1176 *lazyp = _dl_verbose ? !bind_now : -1;
1178 *lazyp = !__libc_enable_secure && !bind_now;