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view lwcc/tree.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 | 7e8298f7bc0a |
children |
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/* lwcc/tree.c Copyright © 2013 William Astle This file is part of LWTOOLS. LWTOOLS is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <stdarg.h> #include <string.h> #include <lw_alloc.h> #include <lw_string.h> #include "tree.h" static char *node_names[] = { "NONE", "PROGRAM", "DECL", "TYPE_CHAR", "TYPE_SHORT", "TYPE_INT", "TYPE_LONG", "TYPE_LONGLONG", "IDENT", "TYPE_PTR", "TYPE_SCHAR", "TYPE_UCHAR", "TYPE_USHORT", "TYPE_UINT", "TYPE_ULONG", "TYPE_ULONGLONG", "TYPE_VOID", "TYPE_FLOAT", "TYPE_DOUBLE", "TYPE_LDOUBLE", "FUNDEF", "FUNDECL", "FUNARGS", "BLOCK", "STMT_RETURN", "CONST_INT", "OPER_PLUS", "OPER_MINUS", "OPER_TIMES", "OPER_DIVIDE", "OPER_MOD", "OPER_COND", "OPER_FNCALL", "OPER_SUBSCRIPT", "OPER_POSTINC", "OPER_POSTDEC", "OPER_PTRMEM", "OPER_OBJMEM", "OPER_LSH", "OPER_RSH", "OPER_LT", "OPER_LE", "OPER_GT", "OPER_GE", "OPER_EQ", "OPER_NE", "OPER_BWAND", "OPER_BWXOR", "OPER_BWOR", "OPER_BAND", "OPER_BOR", "OPER_ASS", "OPER_ADDASS", "OPER_SUBASS", "OPER_MULASS", "OPER_DIVASS", "OPER_MODASS", "OPER_LSHASS", "OPER_RSHASS", "OPER_BWANDASS", "OPER_BWXORASS", "OPER_BWORASS", "OPER_COMMA", "TYPECAST", }; node_t *node_create(int type, ...) { node_t *r; int nargs = 0; va_list args; va_start(args, type); r = lw_alloc(sizeof(node_t)); memset(r, 0, sizeof(node_t)); r -> type = type; switch (type) { case NODE_OPER_PLUS: case NODE_OPER_MINUS: case NODE_OPER_TIMES: case NODE_OPER_DIVIDE: case NODE_OPER_MOD: case NODE_OPER_BWAND: case NODE_OPER_BWXOR: case NODE_OPER_BWOR: case NODE_OPER_BAND: case NODE_OPER_BOR: case NODE_OPER_SUBSCRIPT: case NODE_OPER_PTRMEM: case NODE_OPER_OBJMEM: case NODE_OPER_ASS: case NODE_OPER_ADDASS: case NODE_OPER_SUBASS: case NODE_OPER_MULASS: case NODE_OPER_DIVASS: case NODE_OPER_MODASS: case NODE_OPER_LSH: case NODE_OPER_LSHASS: case NODE_OPER_RSH: case NODE_OPER_RSHASS: case NODE_OPER_BWANDASS: case NODE_OPER_BWORASS: case NODE_OPER_BWXORASS: case NODE_OPER_LT: case NODE_OPER_LE: case NODE_OPER_GT: case NODE_OPER_GE: case NODE_OPER_EQ: case NODE_OPER_NE: case NODE_OPER_COMMA: nargs = 2; break; case NODE_OPER_FNCALL: nargs = 2; break; case NODE_DECL: nargs = 2; break; case NODE_TYPECAST: nargs = 2; break; case NODE_OPER_POSTINC: case NODE_OPER_POSTDEC: nargs = 1; break; case NODE_TYPE_PTR: nargs = 1; break; case NODE_IDENT: case NODE_CONST_INT: r -> strval = lw_strdup(va_arg(args, char *)); break; case NODE_FUNDEF: nargs = 4; break; case NODE_OPER_COND: nargs = 3; break; case NODE_FUNDECL: nargs = 3; break; } while (nargs--) { node_addchild(r, va_arg(args, node_t *)); } va_end(args); return r; } void node_destroy(node_t *node) { node_t *n; while (node -> children) { n = node -> children -> next_child; node_destroy(node -> children); node -> children = n; } lw_free(node -> strval); lw_free(node); } void node_addchild(node_t *node, node_t *nn) { node_t *tmp; if (!nn) return; nn -> parent = node; nn -> next_child = NULL; if (node -> children) { for (tmp = node -> children; tmp -> next_child; tmp = tmp -> next_child) /* do nothing */ ; tmp -> next_child = nn; } else { node -> children = nn; } } void node_removechild(node_t *node, node_t *nn) { node_t **pp; node_t *np; if (!node) node = nn -> parent; pp = &(node -> children); for (np = node -> children; np; np = np -> next_child) { if (np -> next_child == nn) break; pp = &((*pp) -> next_child); } if (!np) return; *pp = nn -> next_child; nn -> parent = NULL; nn -> next_child = NULL; } void node_removechild_destroy(node_t *node, node_t *nn) { node_removechild(node, nn); node_destroy(nn); } static void node_display_aux(node_t *node, FILE *f, int level) { node_t *nn; int i; for (i = 0; i < level * 4; i++) fputc(' ', f); fprintf(f, "(%s ", node_names[node -> type]); if (node -> strval) fprintf(f, "\"%s\" ", node -> strval); fputc('\n', f); for (nn = node -> children; nn; nn = nn -> next_child) node_display_aux(nn, f, level + 1); for (i = 0; i < level * 4; i++) fputc(' ', f); fputc(')', f); fputc('\n', f); } void node_display(node_t *node, FILE *f) { node_display_aux(node, f, 0); }