1 | /* Error handling for runtime dynamic linker. |
2 | Copyright (C) 1995-2016 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
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 <libintl.h> |
20 | #include <setjmp.h> |
21 | #include <stdbool.h> |
22 | #include <stdlib.h> |
23 | #include <string.h> |
24 | #include <unistd.h> |
25 | #include <ldsodefs.h> |
26 | |
27 | /* This structure communicates state between _dl_catch_error and |
28 | _dl_signal_error. */ |
29 | struct catch |
30 | { |
31 | const char **objname; /* Object/File name. */ |
32 | const char **errstring; /* Error detail filled in here. */ |
33 | bool *malloced; /* Nonzero if the string is malloced |
34 | by the libc malloc. */ |
35 | volatile int *errcode; /* Return value of _dl_signal_error. */ |
36 | jmp_buf env; /* longjmp here on error. */ |
37 | }; |
38 | |
39 | /* Multiple threads at once can use the `_dl_catch_error' function. The |
40 | calls can come from `_dl_map_object_deps', `_dlerror_run', or from |
41 | any of the libc functionality which loads dynamic objects (NSS, iconv). |
42 | Therefore we have to be prepared to save the state in thread-local |
43 | memory. The _dl_error_catch_tsd function pointer is reset by the thread |
44 | library so that it returns the address of a thread-local variable. */ |
45 | |
46 | |
47 | /* This message we return as a last resort. We define the string in a |
48 | variable since we have to avoid freeing it and so have to enable |
49 | a pointer comparison. See below and in dlfcn/dlerror.c. */ |
50 | static const char _dl_out_of_memory[] = "out of memory" ; |
51 | |
52 | |
53 | /* This points to a function which is called when an continuable error is |
54 | received. Unlike the handling of `catch' this function may return. |
55 | The arguments will be the `errstring' and `objname'. |
56 | |
57 | Since this functionality is not used in normal programs (only in ld.so) |
58 | we do not care about multi-threaded programs here. We keep this as a |
59 | global variable. */ |
60 | static receiver_fct receiver; |
61 | |
62 | #ifdef _LIBC_REENTRANT |
63 | # define CATCH_HOOK (*(struct catch **) (*GL(dl_error_catch_tsd)) ()) |
64 | #else |
65 | static struct catch *catch_hook; |
66 | # define CATCH_HOOK catch_hook |
67 | #endif |
68 | |
69 | void |
70 | internal_function |
71 | _dl_signal_error (int errcode, const char *objname, const char *occation, |
72 | const char *errstring) |
73 | { |
74 | struct catch *lcatch; |
75 | |
76 | if (! errstring) |
77 | errstring = N_("DYNAMIC LINKER BUG!!!" ); |
78 | |
79 | lcatch = CATCH_HOOK; |
80 | if (objname == NULL) |
81 | objname = "" ; |
82 | if (lcatch != NULL) |
83 | { |
84 | /* We are inside _dl_catch_error. Return to it. We have to |
85 | duplicate the error string since it might be allocated on the |
86 | stack. The object name is always a string constant. */ |
87 | size_t len_objname = strlen (objname) + 1; |
88 | size_t len_errstring = strlen (errstring) + 1; |
89 | |
90 | char *errstring_copy = malloc (len_objname + len_errstring); |
91 | if (errstring_copy != NULL) |
92 | { |
93 | /* Make a copy of the object file name and the error string. */ |
94 | *lcatch->objname = memcpy (__mempcpy (errstring_copy, |
95 | errstring, len_errstring), |
96 | objname, len_objname); |
97 | *lcatch->errstring = errstring_copy; |
98 | |
99 | /* If the main executable is relocated it means the libc's malloc |
100 | is used. */ |
101 | bool malloced = true; |
102 | #ifdef SHARED |
103 | malloced = (GL(dl_ns)[LM_ID_BASE]._ns_loaded != NULL |
104 | && (GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_relocated != 0)); |
105 | #endif |
106 | *lcatch->malloced = malloced; |
107 | } |
108 | else |
109 | { |
110 | /* This is better than nothing. */ |
111 | *lcatch->objname = "" ; |
112 | *lcatch->errstring = _dl_out_of_memory; |
113 | *lcatch->malloced = false; |
114 | } |
115 | |
116 | *lcatch->errcode = errcode; |
117 | |
118 | /* We do not restore the signal mask because none was saved. */ |
119 | __longjmp (lcatch->env[0].__jmpbuf, 1); |
120 | } |
121 | else |
122 | { |
123 | /* Lossage while resolving the program's own symbols is always fatal. */ |
124 | char buffer[1024]; |
125 | _dl_fatal_printf ("%s: %s: %s%s%s%s%s\n" , |
126 | RTLD_PROGNAME, |
127 | occation ?: N_("error while loading shared libraries" ), |
128 | objname, *objname ? ": " : "" , |
129 | errstring, errcode ? ": " : "" , |
130 | (errcode |
131 | ? __strerror_r (errcode, buffer, sizeof buffer) |
132 | : "" )); |
133 | } |
134 | } |
135 | |
136 | |
137 | void |
138 | internal_function |
139 | _dl_signal_cerror (int errcode, const char *objname, const char *occation, |
140 | const char *errstring) |
141 | { |
142 | if (__builtin_expect (GLRO(dl_debug_mask) |
143 | & ~(DL_DEBUG_STATISTICS|DL_DEBUG_PRELINK), 0)) |
144 | _dl_debug_printf ("%s: error: %s: %s (%s)\n" , objname, occation, |
145 | errstring, receiver ? "continued" : "fatal" ); |
146 | |
147 | if (receiver) |
148 | { |
149 | /* We are inside _dl_receive_error. Call the user supplied |
150 | handler and resume the work. The receiver will still be |
151 | installed. */ |
152 | (*receiver) (errcode, objname, errstring); |
153 | } |
154 | else |
155 | _dl_signal_error (errcode, objname, occation, errstring); |
156 | } |
157 | |
158 | |
159 | int |
160 | internal_function |
161 | _dl_catch_error (const char **objname, const char **errstring, |
162 | bool *mallocedp, void (*operate) (void *), void *args) |
163 | { |
164 | /* We need not handle `receiver' since setting a `catch' is handled |
165 | before it. */ |
166 | |
167 | /* Only this needs to be marked volatile, because it is the only local |
168 | variable that gets changed between the setjmp invocation and the |
169 | longjmp call. All others are just set here (before setjmp) and read |
170 | in _dl_signal_error (before longjmp). */ |
171 | volatile int errcode; |
172 | |
173 | struct catch c; |
174 | /* Don't use an initializer since we don't need to clear C.env. */ |
175 | c.objname = objname; |
176 | c.errstring = errstring; |
177 | c.malloced = mallocedp; |
178 | c.errcode = &errcode; |
179 | |
180 | struct catch **const catchp = &CATCH_HOOK; |
181 | struct catch *const old = *catchp; |
182 | *catchp = &c; |
183 | |
184 | /* Do not save the signal mask. */ |
185 | if (__builtin_expect (__sigsetjmp (c.env, 0), 0) == 0) |
186 | { |
187 | (*operate) (args); |
188 | *catchp = old; |
189 | *objname = NULL; |
190 | *errstring = NULL; |
191 | *mallocedp = false; |
192 | return 0; |
193 | } |
194 | |
195 | /* We get here only if we longjmp'd out of OPERATE. _dl_signal_error has |
196 | already stored values into *OBJNAME, *ERRSTRING, and *MALLOCEDP. */ |
197 | *catchp = old; |
198 | return errcode; |
199 | } |
200 | |
201 | |
202 | void |
203 | internal_function |
204 | _dl_receive_error (receiver_fct fct, void (*operate) (void *), void *args) |
205 | { |
206 | struct catch **const catchp = &CATCH_HOOK; |
207 | struct catch *old_catch; |
208 | receiver_fct old_receiver; |
209 | |
210 | old_catch = *catchp; |
211 | old_receiver = receiver; |
212 | |
213 | /* Set the new values. */ |
214 | *catchp = NULL; |
215 | receiver = fct; |
216 | |
217 | (*operate) (args); |
218 | |
219 | *catchp = old_catch; |
220 | receiver = old_receiver; |
221 | } |
222 | |