1 /* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2002, 2003 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 Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the 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 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
20 /* This file defines some things that for the dynamic linker are defined in
21 rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking. */
28 #include <dl-machine.h>
29 #include <bits/libc-lock.h>
31 #include <dl-librecon.h>
32 #include <unsecvars.h>
33 #include <hp-timing.h>
35 extern char *__progname;
36 char **_dl_argv = &__progname; /* This is checked for some error messages. */
38 /* Name of the architecture. */
39 const char *_dl_platform;
40 size_t _dl_platformlen;
46 /* If nonzero print warnings about problematic situations. */
49 /* We never do profiling. */
50 const char *_dl_profile;
52 /* Names of shared object for which the RUNPATHs and RPATHs should be
54 const char *_dl_inhibit_rpath;
56 /* The map for the object we will profile. */
57 struct link_map *_dl_profile_map;
59 /* This is the address of the last stack address ever used. */
60 void *__libc_stack_end;
62 /* Path where the binary is found. */
63 const char *_dl_origin_path;
65 /* Nonzero if runtime lookup should not update the .got/.plt. */
68 /* Initially empty list of loaded objects. */
69 struct link_map *_dl_loaded;
70 /* Number of object in the _dl_loaded list. */
71 unsigned int _dl_nloaded;
73 /* Fake scope. In dynamically linked binaries this is the scope of the
74 main application but here we don't have something like this. So
75 create a fake scope containing nothing. */
76 struct r_scope_elem _dl_initial_searchlist;
77 /* Variable which can be used in lookup to process the global scope. */
78 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
79 /* This is a global pointer to this structure which is public. It is
80 used by dlopen/dlclose to add and remove objects from what is regarded
81 to be the global scope. */
82 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
84 /* Nonzero during startup. */
85 int _dl_starting_up = 1;
87 /* Get architecture specific initializer. */
88 #include <dl-procinfo.c>
90 /* We expect less than a second for relocation. */
91 #ifdef HP_SMALL_TIMING_AVAIL
92 # undef HP_TIMING_AVAIL
93 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
96 /* Initial value of the CPU clock. */
97 #ifndef HP_TIMING_NONAVAIL
98 hp_timing_t _dl_cpuclock_offset;
102 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
105 /* This is zero at program start to signal that the global scope map is
106 allocated by rtld. Later it keeps the size of the map. It might be
107 reset if in _dl_close if the last global object is removed. */
108 size_t _dl_global_scope_alloc;
112 unsigned int _dl_osversion;
114 /* All known directories in sorted order. */
115 struct r_search_path_elem *_dl_all_dirs;
117 /* All directories after startup. */
118 struct r_search_path_elem *_dl_init_all_dirs;
120 /* The object to be initialized first. */
121 struct link_map *_dl_initfirst;
123 /* Descriptor to write debug messages to. */
124 int _dl_debug_fd = STDERR_FILENO;
126 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
128 ElfW(Phdr) *_dl_phdr;
130 unsigned long int _dl_hwcap __attribute__ ((nocommon));
132 /* Prevailing state of the stack, PF_X indicating it's executable. */
133 ElfW(Word) _dl_stack_flags = PF_R|PF_W|PF_X;
135 /* If loading a shared object requires that we make the stack executable
136 when it was not, we do it by calling this function.
137 It returns an errno code or zero on success. */
138 int (*_dl_make_stack_executable_hook) (void) internal_function
139 = _dl_make_stack_executable;
142 #ifdef NEED_DL_SYSINFO
143 /* Needed for improved syscall handling on at least x86/Linux. */
144 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
145 /* Address of the ELF headers in the vsyscall page. */
146 const ElfW(Ehdr) *_dl_sysinfo_dso;
149 /* During the program run we must not modify the global data of
150 loaded shared object simultanously in two threads. Therefore we
151 protect `_dl_open' and `_dl_close' in dl-close.c.
153 This must be a recursive lock since the initializer function of
154 the loaded object might as well require a call to this function.
155 At this time it is not anymore a problem to modify the tables. */
156 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
159 #ifdef HAVE_AUX_VECTOR
164 _dl_aux_init (ElfW(auxv_t) *av)
170 for (; av->a_type != AT_NULL; ++av)
174 GL(dl_pagesize) = av->a_un.a_val;
177 GL(dl_clktck) = av->a_un.a_val;
180 GL(dl_phdr) = av->a_un.a_ptr;
183 GL(dl_phnum) = av->a_un.a_val;
186 GL(dl_hwcap) = av->a_un.a_val;
188 #ifdef NEED_DL_SYSINFO
190 GL(dl_sysinfo) = av->a_un.a_val;
194 uid ^= av->a_un.a_val;
198 uid ^= av->a_un.a_val;
202 gid ^= av->a_un.a_val;
206 gid ^= av->a_un.a_val;
211 __libc_enable_secure = av->a_un.a_val;
212 __libc_enable_secure_decided = 1;
217 __libc_enable_secure = uid != 0 || gid != 0;
218 __libc_enable_secure_decided = 1;
226 _dl_non_dynamic_init (void)
229 HP_TIMING_NOW (_dl_cpuclock_offset);
232 _dl_pagesize = __getpagesize ();
234 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
236 /* Initialize the data structures for the search paths for shared
238 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
240 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
242 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
244 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
246 if (__libc_enable_secure)
248 static const char *unsecure_envvars[] =
251 #ifdef EXTRA_UNSECURE_ENVVARS
252 EXTRA_UNSECURE_ENVVARS
258 cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
260 unsetenv (unsecure_envvars[cnt]);
262 if (__access ("/etc/suid-debug", F_OK) != 0)
263 unsetenv ("MALLOC_CHECK_");
266 #ifdef DL_PLATFORM_INIT
270 #ifdef DL_OSVERSION_INIT
274 /* Now determine the length of the platform string. */
275 if (_dl_platform != NULL)
276 _dl_platformlen = strlen (_dl_platform);
278 /* Scan for a program header telling us the stack is nonexecutable. */
279 if (_dl_phdr != NULL)
280 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
281 if (_dl_phdr[i].p_type == PT_GNU_STACK)
283 _dl_stack_flags = _dl_phdr[i].p_flags;
289 const struct r_strlenpair *
291 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
292 size_t *max_capstrlen)
294 static struct r_strlenpair result;
297 result.str = buf; /* Does not really matter. */
305 #ifdef DL_SYSINFO_IMPLEMENTATION
306 DL_SYSINFO_IMPLEMENTATION