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2449ae7b | 1 | /* ld.so error exception allocation and deallocation. |
688903eb | 2 | Copyright (C) 1995-2018 Free Software Foundation, Inc. |
2449ae7b FW |
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 <ldsodefs.h> | |
20 | #include <limits.h> | |
21 | #include <stdarg.h> | |
22 | #include <stdbool.h> | |
23 | #include <stdint.h> | |
24 | #include <string.h> | |
25 | #include <unistd.h> | |
26 | ||
27 | /* This message we return as a last resort. We define the string in a | |
28 | variable since we have to avoid freeing it and so have to enable | |
29 | a pointer comparison. See below and in dlfcn/dlerror.c. */ | |
30 | static const char _dl_out_of_memory[] = "out of memory"; | |
31 | ||
32 | /* Dummy allocation object used if allocating the message buffer | |
33 | fails. */ | |
34 | static void | |
35 | oom_exception (struct dl_exception *exception) | |
36 | { | |
37 | exception->objname = ""; | |
38 | exception->errstring = _dl_out_of_memory; | |
39 | exception->message_buffer = NULL; | |
40 | } | |
41 | ||
42 | static void | |
43 | __attribute__ ((noreturn)) | |
44 | length_mismatch (void) | |
45 | { | |
46 | _dl_fatal_printf ("Fatal error: " | |
47 | "length accounting in _dl_exception_create_format\n"); | |
48 | } | |
49 | ||
50 | /* Adjust the message buffer to indicate whether it is possible to | |
51 | free it. EXCEPTION->errstring must be a potentially deallocatable | |
52 | pointer. */ | |
53 | static void | |
54 | adjust_message_buffer (struct dl_exception *exception) | |
55 | { | |
56 | /* If the main executable is relocated it means the libc's malloc | |
57 | is used. */ | |
58 | bool malloced = true; | |
59 | #ifdef SHARED | |
60 | malloced = (GL(dl_ns)[LM_ID_BASE]._ns_loaded != NULL | |
61 | && (GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_relocated != 0)); | |
62 | #endif | |
63 | if (malloced) | |
64 | exception->message_buffer = (char *) exception->errstring; | |
65 | else | |
66 | exception->message_buffer = NULL; | |
67 | } | |
68 | ||
69 | void | |
70 | _dl_exception_create (struct dl_exception *exception, const char *objname, | |
71 | const char *errstring) | |
72 | { | |
73 | if (objname == NULL) | |
74 | objname = ""; | |
75 | size_t len_objname = strlen (objname) + 1; | |
76 | size_t len_errstring = strlen (errstring) + 1; | |
77 | char *errstring_copy = malloc (len_objname + len_errstring); | |
78 | if (errstring_copy != NULL) | |
79 | { | |
80 | /* Make a copy of the object file name and the error string. */ | |
81 | exception->objname = memcpy (__mempcpy (errstring_copy, | |
82 | errstring, len_errstring), | |
83 | objname, len_objname); | |
84 | exception->errstring = errstring_copy; | |
85 | adjust_message_buffer (exception); | |
86 | } | |
87 | else | |
88 | oom_exception (exception); | |
89 | } | |
90 | rtld_hidden_def (_dl_exception_create) | |
91 | ||
92 | void | |
93 | _dl_exception_create_format (struct dl_exception *exception, const char *objname, | |
94 | const char *fmt, ...) | |
95 | { | |
96 | if (objname == NULL) | |
97 | objname = ""; | |
98 | size_t len_objname = strlen (objname) + 1; | |
99 | /* Compute the length of the result. Include room for two NUL | |
100 | bytes. */ | |
101 | size_t length = len_objname + 1; | |
102 | { | |
103 | va_list ap; | |
104 | va_start (ap, fmt); | |
105 | for (const char *p = fmt; *p != '\0'; ++p) | |
106 | if (*p == '%') | |
107 | { | |
108 | ++p; | |
109 | switch (*p) | |
110 | { | |
111 | case 's': | |
112 | length += strlen (va_arg (ap, const char *)); | |
113 | break; | |
114 | default: | |
115 | /* Assumed to be '%'. */ | |
116 | ++length; | |
117 | break; | |
118 | } | |
119 | } | |
120 | else | |
121 | ++length; | |
122 | va_end (ap); | |
123 | } | |
124 | ||
125 | if (length > PTRDIFF_MAX) | |
126 | { | |
127 | oom_exception (exception); | |
128 | return; | |
129 | } | |
130 | char *errstring = malloc (length); | |
131 | if (errstring == NULL) | |
132 | { | |
133 | oom_exception (exception); | |
134 | return; | |
135 | } | |
136 | exception->errstring = errstring; | |
137 | adjust_message_buffer (exception); | |
138 | ||
139 | /* Copy the error message to errstring. */ | |
140 | { | |
141 | /* Next byte to be written in errstring. */ | |
142 | char *wptr = errstring; | |
143 | /* End of the allocated string. */ | |
144 | char *const end = errstring + length; | |
145 | ||
146 | va_list ap; | |
147 | va_start (ap, fmt); | |
148 | ||
149 | for (const char *p = fmt; *p != '\0'; ++p) | |
150 | if (*p == '%') | |
151 | { | |
152 | ++p; | |
153 | switch (*p) | |
154 | { | |
155 | case 's': | |
156 | { | |
157 | const char *ptr = va_arg (ap, const char *); | |
158 | size_t len_ptr = strlen (ptr); | |
159 | if (len_ptr > end - wptr) | |
160 | length_mismatch (); | |
161 | wptr = __mempcpy (wptr, ptr, len_ptr); | |
162 | } | |
163 | break; | |
164 | case '%': | |
165 | if (wptr == end) | |
166 | length_mismatch (); | |
167 | *wptr = '%'; | |
168 | ++wptr; | |
169 | break; | |
170 | default: | |
171 | _dl_fatal_printf ("Fatal error:" | |
172 | " invalid format in exception string\n"); | |
173 | } | |
174 | } | |
175 | else | |
176 | { | |
177 | if (wptr == end) | |
178 | length_mismatch (); | |
179 | *wptr = *p; | |
180 | ++wptr; | |
181 | } | |
182 | ||
183 | if (wptr == end) | |
184 | length_mismatch (); | |
185 | *wptr = '\0'; | |
186 | ++wptr; | |
187 | if (len_objname != end - wptr) | |
188 | length_mismatch (); | |
189 | exception->objname = memcpy (wptr, objname, len_objname); | |
190 | } | |
191 | } | |
192 | rtld_hidden_def (_dl_exception_create_format) | |
193 | ||
194 | void | |
195 | _dl_exception_free (struct dl_exception *exception) | |
196 | { | |
197 | free (exception->message_buffer); | |
198 | exception->objname = NULL; | |
199 | exception->errstring = NULL; | |
200 | exception->message_buffer = NULL; | |
201 | } | |
202 | rtld_hidden_def (_dl_exception_free) |