| 1 | /*
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| 2 | Unix SMB/CIFS implementation.
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| 3 | Samba utility functions
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| 4 | Copyright (C) Martin Pool 2003
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| 5 | Copyright (C) Andrew Bartlett 2003
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| 6 |
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| 7 | This program is free software; you can redistribute it and/or modify
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| 8 | it under the terms of the GNU General Public License as published by
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| 9 | the Free Software Foundation; either version 3 of the License, or
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| 10 | (at your option) any later version.
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| 11 |
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| 12 | This program is distributed in the hope that it will be useful,
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| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | GNU General Public License for more details.
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| 16 |
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| 17 | You should have received a copy of the GNU General Public License
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| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>.
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| 19 | */
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| 20 |
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| 21 | #include "includes.h"
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| 22 |
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| 23 | #ifdef DEVELOPER
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| 24 | const char *global_clobber_region_function;
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| 25 | unsigned int global_clobber_region_line;
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| 26 | #endif
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| 27 |
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| 28 | /**
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| 29 | * In developer builds, clobber a region of memory.
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| 30 | *
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| 31 | * If we think a string buffer is longer than it really is, this ought
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| 32 | * to make the failure obvious, by segfaulting (if in the heap) or by
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| 33 | * killing the return address (on the stack), or by trapping under a
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| 34 | * memory debugger.
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| 35 | *
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| 36 | * This is meant to catch possible string overflows, even if the
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| 37 | * actual string copied is not big enough to cause an overflow.
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| 38 | *
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| 39 | * In addition, under Valgrind the buffer is marked as uninitialized.
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| 40 | **/
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| 41 | void clobber_region(const char *fn, unsigned int line, char *dest, size_t len)
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| 42 | {
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| 43 | #ifdef DEVELOPER
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| 44 | global_clobber_region_function = fn;
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| 45 | global_clobber_region_line = line;
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| 46 |
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| 47 | /* F1 is odd and 0xf1f1f1f1 shouldn't be a valid pointer */
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| 48 | memset(dest, 0xF1, len);
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| 49 | #ifdef VALGRIND
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| 50 | /* Even though we just wrote to this, from the application's
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| 51 | * point of view it is not initialized.
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| 52 | *
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| 53 | * (This is not redundant with the clobbering above. The
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| 54 | * marking might not actually take effect if we're not running
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| 55 | * under valgrind.) */
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| 56 | #if defined(VALGRIND_MAKE_MEM_UNDEFINED)
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| 57 | VALGRIND_MAKE_MEM_UNDEFINED(dest, len);
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| 58 | #elif defined(VALGRIND_MAKE_WRITABLE)
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| 59 | VALGRIND_MAKE_WRITABLE(dest, len);
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| 60 | #endif
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| 61 | #endif /* VALGRIND */
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| 62 | #endif /* DEVELOPER */
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| 63 | }
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