1 | /* Minimal replacements for basic facilities used in the dynamic linker. |
2 | Copyright (C) 1995-2019 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 <errno.h> |
20 | #include <limits.h> |
21 | #include <stdio.h> |
22 | #include <string.h> |
23 | #include <tls.h> |
24 | #include <unistd.h> |
25 | #include <sys/mman.h> |
26 | #include <sys/param.h> |
27 | #include <sys/types.h> |
28 | #include <ldsodefs.h> |
29 | #include <_itoa.h> |
30 | #include <malloc/malloc-internal.h> |
31 | |
32 | #include <assert.h> |
33 | |
34 | /* Minimal malloc allocator for used during initial link. After the |
35 | initial link, a full malloc implementation is interposed, either |
36 | the one in libc, or a different one supplied by the user through |
37 | interposition. */ |
38 | |
39 | static void *alloc_ptr, *alloc_end, *alloc_last_block; |
40 | |
41 | /* Declarations of global functions. */ |
42 | extern void weak_function free (void *ptr); |
43 | extern void * weak_function realloc (void *ptr, size_t n); |
44 | |
45 | |
46 | /* Allocate an aligned memory block. */ |
47 | void * weak_function |
48 | malloc (size_t n) |
49 | { |
50 | if (alloc_end == 0) |
51 | { |
52 | /* Consume any unused space in the last page of our data segment. */ |
53 | extern int _end attribute_hidden; |
54 | alloc_ptr = &_end; |
55 | alloc_end = (void *) 0 + (((alloc_ptr - (void *) 0) |
56 | + GLRO(dl_pagesize) - 1) |
57 | & ~(GLRO(dl_pagesize) - 1)); |
58 | } |
59 | |
60 | /* Make sure the allocation pointer is ideally aligned. */ |
61 | alloc_ptr = (void *) 0 + (((alloc_ptr - (void *) 0) + MALLOC_ALIGNMENT - 1) |
62 | & ~(MALLOC_ALIGNMENT - 1)); |
63 | |
64 | if (alloc_ptr + n >= alloc_end || n >= -(uintptr_t) alloc_ptr) |
65 | { |
66 | /* Insufficient space left; allocate another page plus one extra |
67 | page to reduce number of mmap calls. */ |
68 | caddr_t page; |
69 | size_t nup = (n + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1); |
70 | if (__glibc_unlikely (nup == 0 && n != 0)) |
71 | return NULL; |
72 | nup += GLRO(dl_pagesize); |
73 | page = __mmap (0, nup, PROT_READ|PROT_WRITE, |
74 | MAP_ANON|MAP_PRIVATE, -1, 0); |
75 | if (page == MAP_FAILED) |
76 | return NULL; |
77 | if (page != alloc_end) |
78 | alloc_ptr = page; |
79 | alloc_end = page + nup; |
80 | } |
81 | |
82 | alloc_last_block = (void *) alloc_ptr; |
83 | alloc_ptr += n; |
84 | return alloc_last_block; |
85 | } |
86 | |
87 | /* We use this function occasionally since the real implementation may |
88 | be optimized when it can assume the memory it returns already is |
89 | set to NUL. */ |
90 | void * weak_function |
91 | calloc (size_t nmemb, size_t size) |
92 | { |
93 | /* New memory from the trivial malloc above is always already cleared. |
94 | (We make sure that's true in the rare occasion it might not be, |
95 | by clearing memory in free, below.) */ |
96 | size_t bytes = nmemb * size; |
97 | |
98 | #define HALF_SIZE_T (((size_t) 1) << (8 * sizeof (size_t) / 2)) |
99 | if (__builtin_expect ((nmemb | size) >= HALF_SIZE_T, 0) |
100 | && size != 0 && bytes / size != nmemb) |
101 | return NULL; |
102 | |
103 | return malloc (bytes); |
104 | } |
105 | |
106 | /* This will rarely be called. */ |
107 | void weak_function |
108 | free (void *ptr) |
109 | { |
110 | /* We can free only the last block allocated. */ |
111 | if (ptr == alloc_last_block) |
112 | { |
113 | /* Since this is rare, we clear the freed block here |
114 | so that calloc can presume malloc returns cleared memory. */ |
115 | memset (alloc_last_block, '\0', alloc_ptr - alloc_last_block); |
116 | alloc_ptr = alloc_last_block; |
117 | } |
118 | } |
119 | |
120 | /* This is only called with the most recent block returned by malloc. */ |
121 | void * weak_function |
122 | realloc (void *ptr, size_t n) |
123 | { |
124 | if (ptr == NULL) |
125 | return malloc (n); |
126 | assert (ptr == alloc_last_block); |
127 | size_t old_size = alloc_ptr - alloc_last_block; |
128 | alloc_ptr = alloc_last_block; |
129 | void *new = malloc (n); |
130 | return new != ptr ? memcpy (new, ptr, old_size) : new; |
131 | } |
132 | |
133 | /* Avoid signal frobnication in setjmp/longjmp. Keeps things smaller. */ |
134 | |
135 | #include <setjmp.h> |
136 | |
137 | int weak_function |
138 | __sigjmp_save (sigjmp_buf env, int savemask __attribute__ ((unused))) |
139 | { |
140 | env[0].__mask_was_saved = 0; |
141 | return 0; |
142 | } |
143 | |
144 | /* Define our own version of the internal function used by strerror. We |
145 | only provide the messages for some common errors. This avoids pulling |
146 | in the whole error list. */ |
147 | |
148 | char * weak_function |
149 | __strerror_r (int errnum, char *buf, size_t buflen) |
150 | { |
151 | char *msg; |
152 | |
153 | switch (errnum) |
154 | { |
155 | case ENOMEM: |
156 | msg = (char *) "Cannot allocate memory" ; |
157 | break; |
158 | case EINVAL: |
159 | msg = (char *) "Invalid argument" ; |
160 | break; |
161 | case ENOENT: |
162 | msg = (char *) "No such file or directory" ; |
163 | break; |
164 | case EPERM: |
165 | msg = (char *) "Operation not permitted" ; |
166 | break; |
167 | case EIO: |
168 | msg = (char *) "Input/output error" ; |
169 | break; |
170 | case EACCES: |
171 | msg = (char *) "Permission denied" ; |
172 | break; |
173 | default: |
174 | /* No need to check buffer size, all calls in the dynamic linker |
175 | provide enough space. */ |
176 | buf[buflen - 1] = '\0'; |
177 | msg = _itoa (errnum, buf + buflen - 1, 10, 0); |
178 | msg = memcpy (msg - (sizeof ("Error " ) - 1), "Error " , |
179 | sizeof ("Error " ) - 1); |
180 | break; |
181 | } |
182 | |
183 | return msg; |
184 | } |
185 | |
186 | void |
187 | __libc_fatal (const char *message) |
188 | { |
189 | _dl_fatal_printf ("%s" , message); |
190 | } |
191 | rtld_hidden_def (__libc_fatal) |
192 | |
193 | void |
194 | __attribute__ ((noreturn)) |
195 | __chk_fail (void) |
196 | { |
197 | _exit (127); |
198 | } |
199 | rtld_hidden_def (__chk_fail) |
200 | |
201 | #ifndef NDEBUG |
202 | /* Define (weakly) our own assert failure function which doesn't use stdio. |
203 | If we are linked into the user program (-ldl), the normal __assert_fail |
204 | defn can override this one. */ |
205 | |
206 | void weak_function |
207 | __assert_fail (const char *assertion, |
208 | const char *file, unsigned int line, const char *function) |
209 | { |
210 | _dl_fatal_printf ("\ |
211 | Inconsistency detected by ld.so: %s: %u: %s%sAssertion `%s' failed!\n" , |
212 | file, line, function ?: "" , function ? ": " : "" , |
213 | assertion); |
214 | |
215 | } |
216 | rtld_hidden_weak (__assert_fail) |
217 | |
218 | void weak_function |
219 | __assert_perror_fail (int errnum, |
220 | const char *file, unsigned int line, |
221 | const char *function) |
222 | { |
223 | char errbuf[400]; |
224 | _dl_fatal_printf ("\ |
225 | Inconsistency detected by ld.so: %s: %u: %s%sUnexpected error: %s.\n" , |
226 | file, line, function ?: "" , function ? ": " : "" , |
227 | __strerror_r (errnum, errbuf, sizeof errbuf)); |
228 | |
229 | } |
230 | rtld_hidden_weak (__assert_perror_fail) |
231 | #endif |
232 | |
233 | #undef _itoa |
234 | /* We always use _itoa instead of _itoa_word in ld.so since the former |
235 | also has to be present and it is never about speed when these |
236 | functions are used. */ |
237 | char * |
238 | _itoa (unsigned long long int value, char *buflim, unsigned int base, |
239 | int upper_case) |
240 | { |
241 | assert (! upper_case); |
242 | |
243 | do |
244 | *--buflim = _itoa_lower_digits[value % base]; |
245 | while ((value /= base) != 0); |
246 | |
247 | return buflim; |
248 | } |
249 | |
250 | /* The '_itoa_lower_digits' variable in libc.so is able to handle bases |
251 | up to 36. We don't need this here. */ |
252 | const char _itoa_lower_digits[16] = "0123456789abcdef" ; |
253 | rtld_hidden_data_def (_itoa_lower_digits) |
254 | |
255 | /* The following is not a complete strsep implementation. It cannot |
256 | handle empty delimiter strings. But this isn't necessary for the |
257 | execution of ld.so. */ |
258 | #undef strsep |
259 | #undef __strsep |
260 | char * |
261 | __strsep (char **stringp, const char *delim) |
262 | { |
263 | char *begin; |
264 | |
265 | assert (delim[0] != '\0'); |
266 | |
267 | begin = *stringp; |
268 | if (begin != NULL) |
269 | { |
270 | char *end = begin; |
271 | |
272 | while (*end != '\0' || (end = NULL)) |
273 | { |
274 | const char *dp = delim; |
275 | |
276 | do |
277 | if (*dp == *end) |
278 | break; |
279 | while (*++dp != '\0'); |
280 | |
281 | if (*dp != '\0') |
282 | { |
283 | *end++ = '\0'; |
284 | break; |
285 | } |
286 | |
287 | ++end; |
288 | } |
289 | |
290 | *stringp = end; |
291 | } |
292 | |
293 | return begin; |
294 | } |
295 | weak_alias (__strsep, strsep) |
296 | strong_alias (__strsep, __strsep_g) |
297 | |