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annotate lwcc/symbol.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 | 54f213c8fb81 |
| children |
| rev | line source |
|---|---|
| 296 | 1 /* |
| 2 lwcc/symbol.c | |
| 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 <string.h> | |
| 23 | |
| 24 #include <lw_alloc.h> | |
| 25 #include <lw_string.h> | |
| 26 | |
| 27 #include "cpp.h" | |
| 28 #include "symbol.h" | |
| 29 #include "token.h" | |
| 30 | |
| 31 void symbol_free(struct symtab_e *s) | |
| 32 { | |
| 33 int i; | |
|
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34 |
| 296 | 35 lw_free(s -> name); |
| 36 | |
| 37 for (i = 0; i < s -> nargs; i++) | |
| 38 lw_free(s -> params[i]); | |
| 39 lw_free(s -> params); | |
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40 token_list_destroy(s -> tl); |
| 296 | 41 } |
| 42 | |
| 43 struct symtab_e *symtab_find(struct preproc_info *pp, char *name) | |
| 44 { | |
| 45 struct symtab_e *s; | |
| 46 | |
| 47 for (s = pp -> sh; s; s = s -> next) | |
| 48 { | |
| 49 if (strcmp(s -> name, name) == 0) | |
| 50 { | |
| 51 return s; | |
| 52 } | |
| 53 } | |
| 54 return NULL; | |
| 55 } | |
| 56 | |
| 57 void symtab_undef(struct preproc_info *pp, char *name) | |
| 58 { | |
| 59 struct symtab_e *s, **p; | |
| 60 | |
| 61 p = &(pp -> sh); | |
| 62 for (s = pp -> sh; s; s = s -> next) | |
| 63 { | |
| 64 if (strcmp(s -> name, name) == 0) | |
| 65 { | |
| 66 (*p) -> next = s -> next; | |
| 67 symbol_free(s); | |
| 68 return; | |
| 69 } | |
| 70 p = &((*p) -> next); | |
| 71 } | |
| 72 } | |
| 73 | |
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74 void symtab_define(struct preproc_info *pp, char *name, struct token_list *def, int nargs, char **params, int vargs) |
| 296 | 75 { |
| 76 struct symtab_e *s; | |
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77 int i; |
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78 |
| 296 | 79 s = lw_alloc(sizeof(struct symtab_e)); |
| 80 s -> name = lw_strdup(name); | |
| 81 s -> tl = def; | |
| 82 s -> nargs = nargs; | |
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83 s -> params = NULL; |
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84 if (params) |
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85 { |
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86 s -> params = lw_alloc(sizeof(char *) * nargs); |
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87 for (i = 0; i < nargs; i++) |
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88 s -> params[i] = lw_strdup(params[i]); |
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89 } |
| 296 | 90 s -> vargs = vargs; |
| 91 s -> next = pp -> sh; | |
| 92 pp -> sh = s; | |
| 93 } | |
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94 |
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95 void symtab_dump(struct preproc_info *pp) |
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96 { |
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97 struct symtab_e *s; |
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98 struct token *t; |
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99 int i; |
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100 |
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101 for (s = pp -> sh; s; s = s -> next) |
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102 { |
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103 printf("%s", s -> name); |
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104 if (s -> nargs >= 0) |
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105 { |
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106 printf("("); |
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107 for (i = 0; i < s -> nargs; i++) |
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108 { |
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109 if (i) |
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110 printf(","); |
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111 printf("%s", s -> params[i]); |
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112 } |
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113 if (s -> vargs) |
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114 { |
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115 if (s -> nargs) |
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116 printf(","); |
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117 printf("..."); |
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118 } |
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119 printf(")"); |
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120 } |
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121 printf(" => "); |
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122 if (s -> tl) |
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123 { |
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124 for (t = s -> tl -> head; t; t = t -> next) |
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125 { |
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126 token_print(t, stdout); |
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127 } |
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128 } |
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129 printf("\n"); |
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130 } |
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131 } |