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[glibc.git] / elf / dl-support.c
blob2b53770605b2b5a7f9ec03eef121d05624b6f880
1 /* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2002, 2003, 2004 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
18 02111-1307 USA. */
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. */
23 #include <errno.h>
24 #include <libintl.h>
25 #include <stdlib.h>
26 #include <unistd.h>
27 #include <ldsodefs.h>
28 #include <dl-machine.h>
29 #include <bits/libc-lock.h>
30 #include <dl-cache.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;
42 int _dl_debug_mask;
43 int _dl_lazy;
44 ElfW(Addr) _dl_use_load_bias = -2;
45 int _dl_dynamic_weak;
47 /* If nonzero print warnings about problematic situations. */
48 int _dl_verbose;
50 /* We never do profiling. */
51 const char *_dl_profile;
52 const char *_dl_profile_output;
54 /* Names of shared object for which the RUNPATHs and RPATHs should be
55 ignored. */
56 const char *_dl_inhibit_rpath;
58 /* The map for the object we will profile. */
59 struct link_map *_dl_profile_map;
61 /* This is the address of the last stack address ever used. */
62 void *__libc_stack_end;
64 /* Path where the binary is found. */
65 const char *_dl_origin_path;
67 /* Nonzero if runtime lookup should not update the .got/.plt. */
68 int _dl_bind_not;
70 /* Initially empty list of loaded objects. */
71 struct link_map *_dl_loaded;
72 /* Number of object in the _dl_loaded list. */
73 unsigned int _dl_nloaded;
75 /* Incremented whenever something may have been added to dl_loaded. */
76 unsigned long long _dl_load_adds;
78 /* Fake scope. In dynamically linked binaries this is the scope of the
79 main application but here we don't have something like this. So
80 create a fake scope containing nothing. */
81 struct r_scope_elem _dl_initial_searchlist;
82 /* Variable which can be used in lookup to process the global scope. */
83 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
84 /* This is a global pointer to this structure which is public. It is
85 used by dlopen/dlclose to add and remove objects from what is regarded
86 to be the global scope. */
87 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
89 #ifndef HAVE_INLINED_SYSCALLS
90 /* Nonzero during startup. */
91 int _dl_starting_up = 1;
92 #endif
94 /* Get architecture specific initializer. */
95 #include <dl-procinfo.c>
97 /* We expect less than a second for relocation. */
98 #ifdef HP_SMALL_TIMING_AVAIL
99 # undef HP_TIMING_AVAIL
100 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
101 #endif
103 /* Initial value of the CPU clock. */
104 #ifndef HP_TIMING_NONAVAIL
105 hp_timing_t _dl_cpuclock_offset;
106 #endif
108 #ifdef USE_TLS
109 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
110 #endif
112 /* This is zero at program start to signal that the global scope map is
113 allocated by rtld. Later it keeps the size of the map. It might be
114 reset if in _dl_close if the last global object is removed. */
115 size_t _dl_global_scope_alloc;
117 size_t _dl_pagesize;
119 unsigned int _dl_osversion;
121 /* All known directories in sorted order. */
122 struct r_search_path_elem *_dl_all_dirs;
124 /* All directories after startup. */
125 struct r_search_path_elem *_dl_init_all_dirs;
127 /* The object to be initialized first. */
128 struct link_map *_dl_initfirst;
130 /* Descriptor to write debug messages to. */
131 int _dl_debug_fd = STDERR_FILENO;
133 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
135 ElfW(Phdr) *_dl_phdr;
136 size_t _dl_phnum;
137 unsigned long int _dl_hwcap __attribute__ ((nocommon));
139 /* Prevailing state of the stack, PF_X indicating it's executable. */
140 ElfW(Word) _dl_stack_flags = PF_R|PF_W|PF_X;
142 /* If loading a shared object requires that we make the stack executable
143 when it was not, we do it by calling this function.
144 It returns an errno code or zero on success. */
145 int (*_dl_make_stack_executable_hook) (void **) internal_function
146 = _dl_make_stack_executable;
149 #ifdef NEED_DL_SYSINFO
150 /* Needed for improved syscall handling on at least x86/Linux. */
151 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
152 /* Address of the ELF headers in the vsyscall page. */
153 const ElfW(Ehdr) *_dl_sysinfo_dso;
154 #endif
156 /* During the program run we must not modify the global data of
157 loaded shared object simultanously in two threads. Therefore we
158 protect `_dl_open' and `_dl_close' in dl-close.c.
160 This must be a recursive lock since the initializer function of
161 the loaded object might as well require a call to this function.
162 At this time it is not anymore a problem to modify the tables. */
163 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
166 #ifdef HAVE_AUX_VECTOR
167 int _dl_clktck;
169 void
170 internal_function
171 _dl_aux_init (ElfW(auxv_t) *av)
173 int seen = 0;
174 uid_t uid = 0;
175 gid_t gid = 0;
177 for (; av->a_type != AT_NULL; ++av)
178 switch (av->a_type)
180 case AT_PAGESZ:
181 GLRO(dl_pagesize) = av->a_un.a_val;
182 break;
183 case AT_CLKTCK:
184 GLRO(dl_clktck) = av->a_un.a_val;
185 break;
186 case AT_PHDR:
187 GL(dl_phdr) = av->a_un.a_ptr;
188 break;
189 case AT_PHNUM:
190 GL(dl_phnum) = av->a_un.a_val;
191 break;
192 case AT_HWCAP:
193 GLRO(dl_hwcap) = av->a_un.a_val;
194 break;
195 #ifdef NEED_DL_SYSINFO
196 case AT_SYSINFO:
197 GL(dl_sysinfo) = av->a_un.a_val;
198 break;
199 #endif
200 case AT_UID:
201 uid ^= av->a_un.a_val;
202 seen |= 1;
203 break;
204 case AT_EUID:
205 uid ^= av->a_un.a_val;
206 seen |= 2;
207 break;
208 case AT_GID:
209 gid ^= av->a_un.a_val;
210 seen |= 4;
211 break;
212 case AT_EGID:
213 gid ^= av->a_un.a_val;
214 seen |= 8;
215 break;
216 case AT_SECURE:
217 seen = -1;
218 __libc_enable_secure = av->a_un.a_val;
219 __libc_enable_secure_decided = 1;
220 break;
222 if (seen == 0xf)
224 __libc_enable_secure = uid != 0 || gid != 0;
225 __libc_enable_secure_decided = 1;
228 #endif
231 void
232 internal_function
233 _dl_non_dynamic_init (void)
235 if (HP_TIMING_AVAIL)
236 HP_TIMING_NOW (_dl_cpuclock_offset);
238 if (!_dl_pagesize)
239 _dl_pagesize = __getpagesize ();
241 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
243 /* Initialize the data structures for the search paths for shared
244 objects. */
245 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
247 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
249 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
251 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
253 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
254 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
255 _dl_profile_output
256 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
258 if (__libc_enable_secure)
260 static const char *unsecure_envvars[] =
262 UNSECURE_ENVVARS,
263 #ifdef EXTRA_UNSECURE_ENVVARS
264 EXTRA_UNSECURE_ENVVARS
265 #endif
267 size_t cnt;
269 for (cnt = 0;
270 cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
271 ++cnt)
272 unsetenv (unsecure_envvars[cnt]);
274 if (__access ("/etc/suid-debug", F_OK) != 0)
275 unsetenv ("MALLOC_CHECK_");
278 #ifdef DL_PLATFORM_INIT
279 DL_PLATFORM_INIT;
280 #endif
282 #ifdef DL_OSVERSION_INIT
283 DL_OSVERSION_INIT;
284 #endif
286 /* Now determine the length of the platform string. */
287 if (_dl_platform != NULL)
288 _dl_platformlen = strlen (_dl_platform);
290 /* Scan for a program header telling us the stack is nonexecutable. */
291 if (_dl_phdr != NULL)
292 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
293 if (_dl_phdr[i].p_type == PT_GNU_STACK)
295 _dl_stack_flags = _dl_phdr[i].p_flags;
296 break;
301 const struct r_strlenpair *
302 internal_function
303 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
304 size_t *max_capstrlen)
306 static struct r_strlenpair result;
307 static char buf[1];
309 result.str = buf; /* Does not really matter. */
310 result.len = 0;
312 *sz = 1;
313 return &result;
317 #ifdef DL_SYSINFO_IMPLEMENTATION
318 DL_SYSINFO_IMPLEMENTATION
319 #endif