| 1 | /* Redirection of malloc inside the dynamic linker. |
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| 2 | Copyright (C) 2020-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | /* The dynamic linker needs to use its own minimal malloc before libc |
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| 20 | has been relocated, and the libc malloc afterwards. The active |
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| 21 | malloc implementation is reached via the __rtld_* function pointers |
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| 22 | declared below. They are initialized to the minimal malloc by |
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| 23 | __rtld_malloc_init_stubs, and set to the final implementation by |
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| 24 | __rtld_malloc_init_real. */ |
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| 25 | |
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| 26 | #ifndef _RTLD_MALLOC_H |
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| 27 | #define _RTLD_MALLOC_H |
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| 28 | |
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| 29 | #if IS_IN (rtld) |
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| 30 | |
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| 31 | extern __typeof (calloc) *__rtld_calloc attribute_hidden; |
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| 32 | extern __typeof (free) *__rtld_free attribute_hidden; |
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| 33 | extern __typeof (malloc) *__rtld_malloc attribute_hidden; |
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| 34 | extern __typeof (realloc) *__rtld_realloc attribute_hidden; |
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| 35 | |
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| 36 | /* Wrapper functions which call through the function pointers above. |
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| 37 | Note that it is not supported to take the address of those |
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| 38 | functions. Instead the function pointers must be used |
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| 39 | directly. */ |
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| 40 | |
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| 41 | __extern_inline void * |
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| 42 | calloc (size_t a, size_t b) |
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| 43 | { |
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| 44 | return __rtld_calloc (a, b); |
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| 45 | } |
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| 46 | |
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| 47 | __extern_inline void |
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| 48 | free (void *ptr) |
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| 49 | { |
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| 50 | __rtld_free (ptr); |
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| 51 | } |
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| 52 | |
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| 53 | __extern_inline void * |
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| 54 | malloc (size_t size) |
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| 55 | { |
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| 56 | return __rtld_malloc (size); |
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| 57 | } |
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| 58 | |
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| 59 | __extern_inline void * |
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| 60 | realloc (void *ptr, size_t size) |
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| 61 | { |
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| 62 | return __rtld_realloc (ptr, size); |
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| 63 | } |
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| 64 | |
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| 65 | /* Called after the first self-relocation to activate the minimal malloc |
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| 66 | implementation. */ |
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| 67 | void __rtld_malloc_init_stubs (void) attribute_hidden; |
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| 68 | |
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| 69 | /* Return false if the active malloc is the ld.so minimal malloc, true |
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| 70 | if it is the full implementation from libc.so. */ |
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| 71 | _Bool __rtld_malloc_is_complete (void) attribute_hidden; |
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| 72 | |
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| 73 | /* Called shortly before the final self-relocation (when RELRO |
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| 74 | variables are still writable) to activate the real malloc |
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| 75 | implementation. MAIN_MAP is the link map of the executable. */ |
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| 76 | struct link_map; |
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| 77 | void __rtld_malloc_init_real (struct link_map *main_map) attribute_hidden; |
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| 78 | |
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| 79 | #else /* !IS_IN (rtld) */ |
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| 80 | |
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| 81 | /* This allows static/non-rtld builds to get a pointer to the |
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| 82 | functions, in the same way that is required inside rtld. */ |
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| 83 | # define __rtld_calloc (&calloc) |
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| 84 | # define __rtld_free (&free) |
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| 85 | # define __rtld_malloc (&malloc) |
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| 86 | # define __rtld_realloc (&realloc) |
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| 87 | |
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| 88 | #endif /* !IS_IN (rtld) */ |
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| 89 | #endif /* _RTLD_MALLOC_H */ |
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| 90 | |
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