1 /* Minimal replacements for basic facilities used in the dynamic linker.
2 Copyright (C) 1995-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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/>. */
23 #include <dl-sym-post.h>
25 #include <dl-minimal-malloc.h>
30 /* The rtld startup code calls __rtld_malloc_init_stubs after the
31 first self-relocation to adjust the pointers to the minimal
32 implementation below. Before the final relocation,
33 __rtld_malloc_init_real is called to replace the pointers with the
34 real implementation. */
35 __typeof (calloc) *__rtld_calloc attribute_relro;
36 __typeof (free) *__rtld_free attribute_relro;
37 __typeof (malloc) *__rtld_malloc attribute_relro;
38 __typeof (realloc) *__rtld_realloc attribute_relro;
41 __rtld_malloc_init_stubs (void)
43 __rtld_calloc = &__minimal_calloc;
44 __rtld_free = &__minimal_free;
45 __rtld_malloc = &__minimal_malloc;
46 __rtld_realloc = &__minimal_realloc;
50 __rtld_malloc_is_complete (void)
52 /* The caller assumes that there is an active malloc. */
53 assert (__rtld_malloc != NULL);
54 return __rtld_malloc != &__minimal_malloc;
57 /* Lookup NAME at VERSION in the scope of MATCH. */
59 lookup_malloc_symbol (struct link_map *main_map, const char *name,
60 struct r_found_version *version)
63 const ElfW(Sym) *ref = NULL;
64 lookup_t result = _dl_lookup_symbol_x (name, main_map, &ref,
68 assert (ELFW(ST_TYPE) (ref->st_info) != STT_TLS);
69 void *value = DL_SYMBOL_ADDRESS (result, ref);
71 return _dl_sym_post (result, ref, value, 0, main_map);
75 __rtld_malloc_init_real (struct link_map *main_map)
77 /* We cannot use relocations and initializers for this because the
78 changes made by __rtld_malloc_init_stubs break REL-style
79 (non-RELA) relocations that depend on the previous pointer
80 contents. Also avoid direct relocation depedencies for the
81 malloc symbols so this function can be called before the final
82 rtld relocation (which enables RELRO, after which the pointer
83 variables cannot be written to). */
85 struct r_found_version version;
86 version.name = symbol_version_string (libc, GLIBC_2_0);
88 version.hash = _dl_elf_hash (version.name);
89 version.filename = NULL;
91 void *new_calloc = lookup_malloc_symbol (main_map, "calloc", &version);
92 void *new_free = lookup_malloc_symbol (main_map, "free", &version);
93 void *new_malloc = lookup_malloc_symbol (main_map, "malloc", &version);
94 void *new_realloc = lookup_malloc_symbol (main_map, "realloc", &version);
96 /* Update the pointers in one go, so that any internal allocations
97 performed by lookup_malloc_symbol see a consistent
99 __rtld_calloc = new_calloc;
100 __rtld_free = new_free;
101 __rtld_malloc = new_malloc;
102 __rtld_realloc = new_realloc;
106 /* Avoid signal frobnication in setjmp/longjmp. Keeps things smaller. */
111 __sigjmp_save (sigjmp_buf env, int savemask __attribute__ ((unused)))
113 env[0].__mask_was_saved = 0;
117 /* Define our own version of the internal function used by strerror. We
118 only provide the messages for some common errors. This avoids pulling
119 in the whole error list. */
122 __strerror_r (int errnum, char *buf, size_t buflen)
129 msg = (char *) "Cannot allocate memory";
132 msg = (char *) "Invalid argument";
135 msg = (char *) "No such file or directory";
138 msg = (char *) "Operation not permitted";
141 msg = (char *) "Input/output error";
144 msg = (char *) "Permission denied";
147 /* No need to check buffer size, all calls in the dynamic linker
148 provide enough space. */
149 buf[buflen - 1] = '\0';
150 msg = _itoa (errnum, buf + buflen - 1, 10, 0);
151 msg = memcpy (msg - (sizeof ("Error ") - 1), "Error ",
152 sizeof ("Error ") - 1);
160 __libc_fatal (const char *message)
162 _dl_fatal_printf ("%s", message);
164 rtld_hidden_def (__libc_fatal)
167 __attribute__ ((noreturn))
172 rtld_hidden_def (__chk_fail)
175 /* Define (weakly) our own assert failure function which doesn't use stdio.
176 If we are linked into the user program (-ldl), the normal __assert_fail
177 defn can override this one. */
180 __assert_fail (const char *assertion,
181 const char *file, unsigned int line, const char *function)
184 Inconsistency detected by ld.so: %s: %u: %s%sAssertion `%s' failed!\n",
185 file, line, function ?: "", function ? ": " : "",
189 # ifndef NO_RTLD_HIDDEN
190 rtld_hidden_weak (__assert_fail)
194 __assert_perror_fail (int errnum,
195 const char *file, unsigned int line,
196 const char *function)
200 Inconsistency detected by ld.so: %s: %u: %s%sUnexpected error: %s.\n",
201 file, line, function ?: "", function ? ": " : "",
202 __strerror_r (errnum, errbuf, sizeof errbuf));
205 # ifndef NO_RTLD_HIDDEN
206 rtld_hidden_weak (__assert_perror_fail)
211 /* We always use _itoa instead of _itoa_word in ld.so since the former
212 also has to be present and it is never about speed when these
213 functions are used. */
215 _itoa (unsigned long long int value, char *buflim, unsigned int base,
218 assert (! upper_case);
221 *--buflim = _itoa_lower_digits[value % base];
222 while ((value /= base) != 0);
227 /* The '_itoa_lower_digits' variable in libc.so is able to handle bases
228 up to 36. We don't need this here. */
229 const char _itoa_lower_digits[16] = "0123456789abcdef";
230 rtld_hidden_data_def (_itoa_lower_digits)
232 /* The following is not a complete strsep implementation. It cannot
233 handle empty delimiter strings. But this isn't necessary for the
234 execution of ld.so. */
238 __strsep (char **stringp, const char *delim)
242 assert (delim[0] != '\0');
249 while (*end != '\0' || (end = NULL))
251 const char *dp = delim;
256 while (*++dp != '\0');
272 weak_alias (__strsep, strsep)
273 strong_alias (__strsep, __strsep_g)