1 | /* Copyright (C) 2002-2017 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. |
4 | |
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. |
9 | |
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. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <unistd.h> |
20 | #include <list.h> |
21 | #include <fork.h> |
22 | #include <dl-sysdep.h> |
23 | #include <tls.h> |
24 | #include <string.h> |
25 | #include <pthreadP.h> |
26 | #include <libc-lock.h> |
27 | #include <sysdep.h> |
28 | #include <ldsodefs.h> |
29 | |
30 | |
31 | unsigned long int *__fork_generation_pointer; |
32 | |
33 | |
34 | #ifdef TLS_MULTIPLE_THREADS_IN_TCB |
35 | void |
36 | #else |
37 | extern int __libc_multiple_threads attribute_hidden; |
38 | |
39 | int * |
40 | #endif |
41 | internal_function |
42 | __libc_pthread_init (unsigned long int *ptr, void (*reclaim) (void), |
43 | const struct pthread_functions *functions) |
44 | { |
45 | /* Remember the pointer to the generation counter in libpthread. */ |
46 | __fork_generation_pointer = ptr; |
47 | |
48 | /* Called by a child after fork. */ |
49 | __register_atfork (NULL, NULL, reclaim, NULL); |
50 | |
51 | #ifdef SHARED |
52 | /* Copy the function pointers into an array in libc. This enables |
53 | access with just one memory reference but moreso, it prevents |
54 | hijacking the function pointers with just one pointer change. We |
55 | "encrypt" the function pointers since we cannot write-protect the |
56 | array easily enough. */ |
57 | union ptrhack |
58 | { |
59 | struct pthread_functions pf; |
60 | # define NPTRS (sizeof (struct pthread_functions) / sizeof (void *)) |
61 | void *parr[NPTRS]; |
62 | } __attribute__ ((may_alias)) const *src; |
63 | union ptrhack *dest; |
64 | |
65 | src = (const void *) functions; |
66 | dest = (void *) &__libc_pthread_functions; |
67 | |
68 | for (size_t cnt = 0; cnt < NPTRS; ++cnt) |
69 | { |
70 | void *p = src->parr[cnt]; |
71 | PTR_MANGLE (p); |
72 | dest->parr[cnt] = p; |
73 | } |
74 | __libc_pthread_functions_init = 1; |
75 | #endif |
76 | |
77 | #ifndef TLS_MULTIPLE_THREADS_IN_TCB |
78 | return &__libc_multiple_threads; |
79 | #endif |
80 | } |
81 | |
82 | #ifdef SHARED |
83 | libc_freeres_fn (freeres_libptread) |
84 | { |
85 | if (__libc_pthread_functions_init) |
86 | PTHFCT_CALL (ptr_freeres, ()); |
87 | } |
88 | #endif |
89 | |