1/* ld.so error exception allocation and deallocation.
2 Copyright (C) 1995-2020 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 <https://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#include <_itoa.h>
27
28/* This message we return as a last resort. We define the string in a
29 variable since we have to avoid freeing it and so have to enable
30 a pointer comparison. See below and in dlfcn/dlerror.c. */
31static const char _dl_out_of_memory[] = "out of memory";
32
33/* Dummy allocation object used if allocating the message buffer
34 fails. */
35static void
36oom_exception (struct dl_exception *exception)
37{
38 exception->objname = "";
39 exception->errstring = _dl_out_of_memory;
40 exception->message_buffer = NULL;
41}
42
43static void
44__attribute__ ((noreturn))
45length_mismatch (void)
46{
47 _dl_fatal_printf ("Fatal error: "
48 "length accounting in _dl_exception_create_format\n");
49}
50
51/* Adjust the message buffer to indicate whether it is possible to
52 free it. EXCEPTION->errstring must be a potentially deallocatable
53 pointer. */
54static void
55adjust_message_buffer (struct dl_exception *exception)
56{
57 /* If the main executable is relocated it means the libc's malloc
58 is used. */
59 bool malloced = true;
60#ifdef SHARED
61 malloced = (GL(dl_ns)[LM_ID_BASE]._ns_loaded != NULL
62 && (GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_relocated != 0));
63#endif
64 if (malloced)
65 exception->message_buffer = (char *) exception->errstring;
66 else
67 exception->message_buffer = NULL;
68}
69
70void
71_dl_exception_create (struct dl_exception *exception, const char *objname,
72 const char *errstring)
73{
74 if (objname == NULL)
75 objname = "";
76 size_t len_objname = strlen (objname) + 1;
77 size_t len_errstring = strlen (errstring) + 1;
78 char *errstring_copy = malloc (len_objname + len_errstring);
79 if (errstring_copy != NULL)
80 {
81 /* Make a copy of the object file name and the error string. */
82 exception->objname = memcpy (__mempcpy (errstring_copy,
83 errstring, len_errstring),
84 objname, len_objname);
85 exception->errstring = errstring_copy;
86 adjust_message_buffer (exception);
87 }
88 else
89 oom_exception (exception);
90}
91rtld_hidden_def (_dl_exception_create)
92
93void
94_dl_exception_create_format (struct dl_exception *exception, const char *objname,
95 const char *fmt, ...)
96{
97 if (objname == NULL)
98 objname = "";
99 size_t len_objname = strlen (objname) + 1;
100 /* Compute the length of the result. Include room for two NUL
101 bytes. */
102 size_t length = len_objname + 1;
103 {
104 va_list ap;
105 va_start (ap, fmt);
106 for (const char *p = fmt; *p != '\0'; ++p)
107 if (*p == '%')
108 {
109 ++p;
110 switch (*p)
111 {
112 case 's':
113 length += strlen (va_arg (ap, const char *));
114 break;
115 /* Recognize the l modifier. It is only important on some
116 platforms where long and int have a different size. We
117 can use the same code for size_t. */
118 case 'l':
119 case 'z':
120 if (p[1] == 'x')
121 {
122 length += LONG_WIDTH / 4;
123 ++p;
124 break;
125 }
126 /* Fall through. */
127 case 'x':
128 length += INT_WIDTH / 4;
129 break;
130 default:
131 /* Assumed to be '%'. */
132 ++length;
133 break;
134 }
135 }
136 else
137 ++length;
138 va_end (ap);
139 }
140
141 if (length > PTRDIFF_MAX)
142 {
143 oom_exception (exception);
144 return;
145 }
146 char *errstring = malloc (length);
147 if (errstring == NULL)
148 {
149 oom_exception (exception);
150 return;
151 }
152 exception->errstring = errstring;
153 adjust_message_buffer (exception);
154
155 /* Copy the error message to errstring. */
156 {
157 /* Next byte to be written in errstring. */
158 char *wptr = errstring;
159 /* End of the allocated string. */
160 char *const end = errstring + length;
161
162 va_list ap;
163 va_start (ap, fmt);
164
165 for (const char *p = fmt; *p != '\0'; ++p)
166 if (*p == '%')
167 {
168 ++p;
169 switch (*p)
170 {
171 case 's':
172 {
173 const char *ptr = va_arg (ap, const char *);
174 size_t len_ptr = strlen (ptr);
175 if (len_ptr > end - wptr)
176 length_mismatch ();
177 wptr = __mempcpy (wptr, ptr, len_ptr);
178 }
179 break;
180 case '%':
181 if (wptr == end)
182 length_mismatch ();
183 *wptr = '%';
184 ++wptr;
185 break;
186 case 'x':
187 {
188 unsigned long int num = va_arg (ap, unsigned int);
189 char *start = wptr;
190 wptr += INT_WIDTH / 4;
191 char *cp = _itoa (num, wptr, 16, 0);
192 /* Pad to the full width with 0. */
193 while (cp != start)
194 *--cp = '0';
195 }
196 break;
197 case 'l':
198 case 'z':
199 if (p[1] == 'x')
200 {
201 unsigned long int num = va_arg (ap, unsigned long int);
202 char *start = wptr;
203 wptr += LONG_WIDTH / 4;
204 char *cp = _itoa (num, wptr, 16, 0);
205 /* Pad to the full width with 0. */
206 while (cp != start)
207 *--cp = '0';
208 ++p;
209 break;
210 }
211 /* FALLTHROUGH */
212 default:
213 _dl_fatal_printf ("Fatal error:"
214 " invalid format in exception string\n");
215 }
216 }
217 else
218 {
219 if (wptr == end)
220 length_mismatch ();
221 *wptr = *p;
222 ++wptr;
223 }
224
225 if (wptr == end)
226 length_mismatch ();
227 *wptr = '\0';
228 ++wptr;
229 if (len_objname != end - wptr)
230 length_mismatch ();
231 exception->objname = memcpy (wptr, objname, len_objname);
232 }
233}
234rtld_hidden_def (_dl_exception_create_format)
235
236void
237_dl_exception_free (struct dl_exception *exception)
238{
239 free (exception->message_buffer);
240 exception->objname = NULL;
241 exception->errstring = NULL;
242 exception->message_buffer = NULL;
243}
244rtld_hidden_def (_dl_exception_free)
245