1/* Copyright (C) 1998-2016 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
17
18#include <assert.h>
19#include <stdlib.h>
20#include <stdio.h>
21#include <unistd.h>
22#include <ldsodefs.h>
23#include <exit-thread.h>
24
25extern void __libc_init_first (int argc, char **argv, char **envp);
26#ifndef SHARED
27extern void __libc_csu_irel (void);
28#endif
29
30extern int __libc_multiple_libcs;
31
32#include <tls.h>
33#ifndef SHARED
34# include <dl-osinfo.h>
35extern void __pthread_initialize_minimal (void);
36# ifndef THREAD_SET_STACK_GUARD
37/* Only exported for architectures that don't store the stack guard canary
38 in thread local area. */
39uintptr_t __stack_chk_guard attribute_relro;
40# endif
41# ifndef THREAD_SET_POINTER_GUARD
42/* Only exported for architectures that don't store the pointer guard
43 value in thread local area. */
44uintptr_t __pointer_chk_guard_local
45 attribute_relro attribute_hidden __attribute__ ((nocommon));
46# endif
47#endif
48
49#ifdef HAVE_PTR_NTHREADS
50/* We need atomic operations. */
51# include <atomic.h>
52#endif
53
54
55#ifndef SHARED
56# include <link.h>
57# include <dl-irel.h>
58
59# ifdef ELF_MACHINE_IRELA
60# define IREL_T ElfW(Rela)
61# define IPLT_START __rela_iplt_start
62# define IPLT_END __rela_iplt_end
63# define IREL elf_irela
64# elif defined ELF_MACHINE_IREL
65# define IREL_T ElfW(Rel)
66# define IPLT_START __rel_iplt_start
67# define IPLT_END __rel_iplt_end
68# define IREL elf_irel
69# endif
70
71static void
72apply_irel (void)
73{
74# ifdef IREL
75 /* We use weak references for these so that we'll still work with a linker
76 that doesn't define them. Such a linker doesn't support IFUNC at all
77 and so uses won't work, but a statically-linked program that doesn't
78 use any IFUNC symbols won't have a problem. */
79 extern const IREL_T IPLT_START[] __attribute__ ((weak));
80 extern const IREL_T IPLT_END[] __attribute__ ((weak));
81 for (const IREL_T *ipltent = IPLT_START; ipltent < IPLT_END; ++ipltent)
82 IREL (ipltent);
83# endif
84}
85#endif
86
87
88#ifdef LIBC_START_MAIN
89# ifdef LIBC_START_DISABLE_INLINE
90# define STATIC static
91# else
92# define STATIC static inline __attribute__ ((always_inline))
93# endif
94#else
95# define STATIC
96# define LIBC_START_MAIN __libc_start_main
97#endif
98
99#ifdef MAIN_AUXVEC_ARG
100/* main gets passed a pointer to the auxiliary. */
101# define MAIN_AUXVEC_DECL , void *
102# define MAIN_AUXVEC_PARAM , auxvec
103#else
104# define MAIN_AUXVEC_DECL
105# define MAIN_AUXVEC_PARAM
106#endif
107
108STATIC int LIBC_START_MAIN (int (*main) (int, char **, char **
109 MAIN_AUXVEC_DECL),
110 int argc,
111 char **argv,
112#ifdef LIBC_START_MAIN_AUXVEC_ARG
113 ElfW(auxv_t) *auxvec,
114#endif
115 __typeof (main) init,
116 void (*fini) (void),
117 void (*rtld_fini) (void),
118 void *stack_end)
119 __attribute__ ((noreturn));
120
121
122/* Note: the fini parameter is ignored here for shared library. It
123 is registered with __cxa_atexit. This had the disadvantage that
124 finalizers were called in more than one place. */
125STATIC int
126LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
127 int argc, char **argv,
128#ifdef LIBC_START_MAIN_AUXVEC_ARG
129 ElfW(auxv_t) *auxvec,
130#endif
131 __typeof (main) init,
132 void (*fini) (void),
133 void (*rtld_fini) (void), void *stack_end)
134{
135 /* Result of the 'main' function. */
136 int result;
137
138 __libc_multiple_libcs = &_dl_starting_up && !_dl_starting_up;
139
140#ifndef SHARED
141 char **ev = &argv[argc + 1];
142
143 __environ = ev;
144
145 /* Store the lowest stack address. This is done in ld.so if this is
146 the code for the DSO. */
147 __libc_stack_end = stack_end;
148
149# ifdef HAVE_AUX_VECTOR
150 /* First process the auxiliary vector since we need to find the
151 program header to locate an eventually present PT_TLS entry. */
152# ifndef LIBC_START_MAIN_AUXVEC_ARG
153 ElfW(auxv_t) *auxvec;
154 {
155 char **evp = ev;
156 while (*evp++ != NULL)
157 ;
158 auxvec = (ElfW(auxv_t) *) evp;
159 }
160# endif
161 _dl_aux_init (auxvec);
162 if (GL(dl_phdr) == NULL)
163# endif
164 {
165 /* Starting from binutils-2.23, the linker will define the
166 magic symbol __ehdr_start to point to our own ELF header
167 if it is visible in a segment that also includes the phdrs.
168 So we can set up _dl_phdr and _dl_phnum even without any
169 information from auxv. */
170
171 extern const ElfW(Ehdr) __ehdr_start
172 __attribute__ ((weak, visibility ("hidden")));
173 if (&__ehdr_start != NULL)
174 {
175 assert (__ehdr_start.e_phentsize == sizeof *GL(dl_phdr));
176 GL(dl_phdr) = (const void *) &__ehdr_start + __ehdr_start.e_phoff;
177 GL(dl_phnum) = __ehdr_start.e_phnum;
178 }
179 }
180
181# ifdef DL_SYSDEP_OSCHECK
182 if (!__libc_multiple_libcs)
183 {
184 /* This needs to run to initiliaze _dl_osversion before TLS
185 setup might check it. */
186 DL_SYSDEP_OSCHECK (__libc_fatal);
187 }
188# endif
189
190 /* Perform IREL{,A} relocations. */
191 apply_irel ();
192
193 /* Initialize the thread library at least a bit since the libgcc
194 functions are using thread functions if these are available and
195 we need to setup errno. */
196 __pthread_initialize_minimal ();
197
198 /* Set up the stack checker's canary. */
199 uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
200# ifdef THREAD_SET_STACK_GUARD
201 THREAD_SET_STACK_GUARD (stack_chk_guard);
202# else
203 __stack_chk_guard = stack_chk_guard;
204# endif
205
206 /* Set up the pointer guard value. */
207 uintptr_t pointer_chk_guard = _dl_setup_pointer_guard (_dl_random,
208 stack_chk_guard);
209# ifdef THREAD_SET_POINTER_GUARD
210 THREAD_SET_POINTER_GUARD (pointer_chk_guard);
211# else
212 __pointer_chk_guard_local = pointer_chk_guard;
213# endif
214
215#endif
216
217 /* Register the destructor of the dynamic linker if there is any. */
218 if (__glibc_likely (rtld_fini != NULL))
219 __cxa_atexit ((void (*) (void *)) rtld_fini, NULL, NULL);
220
221#ifndef SHARED
222 /* Call the initializer of the libc. This is only needed here if we
223 are compiling for the static library in which case we haven't
224 run the constructors in `_dl_start_user'. */
225 __libc_init_first (argc, argv, __environ);
226
227 /* Register the destructor of the program, if any. */
228 if (fini)
229 __cxa_atexit ((void (*) (void *)) fini, NULL, NULL);
230
231 /* Some security at this point. Prevent starting a SUID binary where
232 the standard file descriptors are not opened. We have to do this
233 only for statically linked applications since otherwise the dynamic
234 loader did the work already. */
235 if (__builtin_expect (__libc_enable_secure, 0))
236 __libc_check_standard_fds ();
237#endif
238
239 /* Call the initializer of the program, if any. */
240#ifdef SHARED
241 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
242 GLRO(dl_debug_printf) ("\ninitialize program: %s\n\n", argv[0]);
243#endif
244 if (init)
245 (*init) (argc, argv, __environ MAIN_AUXVEC_PARAM);
246
247#ifdef SHARED
248 /* Auditing checkpoint: we have a new object. */
249 if (__glibc_unlikely (GLRO(dl_naudit) > 0))
250 {
251 struct audit_ifaces *afct = GLRO(dl_audit);
252 struct link_map *head = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
253 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
254 {
255 if (afct->preinit != NULL)
256 afct->preinit (&head->l_audit[cnt].cookie);
257
258 afct = afct->next;
259 }
260 }
261#endif
262
263#ifdef SHARED
264 if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS))
265 GLRO(dl_debug_printf) ("\ntransferring control: %s\n\n", argv[0]);
266#endif
267
268#ifndef SHARED
269 _dl_debug_initialize (0, LM_ID_BASE);
270#endif
271#ifdef HAVE_CLEANUP_JMP_BUF
272 /* Memory for the cancellation buffer. */
273 struct pthread_unwind_buf unwind_buf;
274
275 int not_first_call;
276 not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
277 if (__glibc_likely (! not_first_call))
278 {
279 struct pthread *self = THREAD_SELF;
280
281 /* Store old info. */
282 unwind_buf.priv.data.prev = THREAD_GETMEM (self, cleanup_jmp_buf);
283 unwind_buf.priv.data.cleanup = THREAD_GETMEM (self, cleanup);
284
285 /* Store the new cleanup handler info. */
286 THREAD_SETMEM (self, cleanup_jmp_buf, &unwind_buf);
287
288 /* Run the program. */
289 result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
290 }
291 else
292 {
293 /* Remove the thread-local data. */
294# ifdef SHARED
295 PTHFCT_CALL (ptr__nptl_deallocate_tsd, ());
296# else
297 extern void __nptl_deallocate_tsd (void) __attribute ((weak));
298 __nptl_deallocate_tsd ();
299# endif
300
301 /* One less thread. Decrement the counter. If it is zero we
302 terminate the entire process. */
303 result = 0;
304# ifdef SHARED
305 unsigned int *ptr = __libc_pthread_functions.ptr_nthreads;
306# ifdef PTR_DEMANGLE
307 PTR_DEMANGLE (ptr);
308# endif
309# else
310 extern unsigned int __nptl_nthreads __attribute ((weak));
311 unsigned int *const ptr = &__nptl_nthreads;
312# endif
313
314 if (! atomic_decrement_and_test (ptr))
315 /* Not much left to do but to exit the thread, not the process. */
316 __exit_thread ();
317 }
318#else
319 /* Nothing fancy, just call the function. */
320 result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
321#endif
322
323 exit (result);
324}
325