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annotate lwlib/lw_strbuf.c @ 577:e49d24f4a9a5
Correct bug in the object file output code leading to stack corruption
It turns out leaving a pointer to a stack allocated temporary in a
persistent data structure is not conducive to correct program operation.
Undo the export check setup in the object file output sequence so a
pointer to stack allocated memory is not left hanging when the function
returns. This seems to correct at least one mysterious crash bug, and
possibly others.
Thanks to Boisy Pitre for reporting the crash bug that led to this
discovery, as well as a previous crash bug that likely has the same
root cause.
Additional thanks to Ciaran Anscomb whose debugger wielding wizardry
revealed the exact location of this particular bit of unbrilliance.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Sat, 03 Aug 2024 14:30:06 -0600 |
| parents | 670ea8f90212 |
| children |
| rev | line source |
|---|---|
| 295 | 1 /* |
|
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parents:
295
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2 lwlib/lw_strbuf.c |
| 295 | 3 |
| 4 Copyright © 2013 William Astle | |
| 5 | |
| 6 This file is part of LWTOOLS. | |
| 7 | |
| 8 LWTOOLS is free software: you can redistribute it and/or modify it under the | |
| 9 terms of the GNU General Public License as published by the Free Software | |
| 10 Foundation, either version 3 of the License, or (at your option) any later | |
| 11 version. | |
| 12 | |
| 13 This program is distributed in the hope that it will be useful, but WITHOUT | |
| 14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
| 16 more details. | |
| 17 | |
| 18 You should have received a copy of the GNU General Public License along with | |
| 19 this program. If not, see <http://www.gnu.org/licenses/>. | |
| 20 */ | |
| 21 | |
| 22 #include <stdlib.h> | |
| 23 | |
|
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parents:
295
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24 #include "lw_alloc.h" |
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25 #include "lw_strbuf.h" |
| 295 | 26 |
|
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27 struct lw_strbuf *lw_strbuf_new(void) |
| 295 | 28 { |
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parents:
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29 struct lw_strbuf *lw_strbuf; |
| 295 | 30 |
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31 lw_strbuf = lw_alloc(sizeof(struct lw_strbuf)); |
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parents:
295
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32 lw_strbuf -> str = NULL; |
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parents:
295
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33 lw_strbuf -> bo = 0; |
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parents:
295
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changeset
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34 lw_strbuf -> bl = 0; |
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parents:
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35 return lw_strbuf; |
| 295 | 36 } |
| 37 | |
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38 void lw_strbuf_add(struct lw_strbuf *lw_strbuf, int c) |
| 295 | 39 { |
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40 if (lw_strbuf -> bo >= lw_strbuf -> bl) |
| 295 | 41 { |
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42 lw_strbuf -> bl += 100; |
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parents:
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43 lw_strbuf -> str = lw_realloc(lw_strbuf -> str, lw_strbuf -> bl); |
| 295 | 44 } |
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parents:
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45 lw_strbuf -> str[lw_strbuf -> bo++] = c; |
| 295 | 46 } |
| 47 | |
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48 char *lw_strbuf_end(struct lw_strbuf *lw_strbuf) |
| 295 | 49 { |
| 50 char *rv; | |
| 51 | |
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52 lw_strbuf_add(lw_strbuf, 0); |
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parents:
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53 rv = lw_strbuf -> str; |
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parents:
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54 lw_free(lw_strbuf); |
| 295 | 55 return rv; |
| 56 } |