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. */
29struct 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. */
50static 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. */
60static receiver_fct receiver;
61
62#ifdef _LIBC_REENTRANT
63# define CATCH_HOOK (*(struct catch **) (*GL(dl_error_catch_tsd)) ())
64#else
65static struct catch *catch_hook;
66# define CATCH_HOOK catch_hook
67#endif
68
69void
70internal_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
137void
138internal_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
159int
160internal_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
202void
203internal_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