1 | /* ld.so error exception allocation and deallocation. |
2 | Copyright (C) 1995-2018 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 <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) |
203 | |