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Fix off by one handling MOD directive optional arguments
Fixes an off by one in handling the optional arguments to the MOD directive
as of changeset 928c033c0cd0.
Thanks to Alex Evans <varmfskii@gmail.com> for reporting the problem and a
suggested fix. This fix is different but should be more stable should the
rest of the parsing code be refactored in the future.
author | William Astle <lost@l-w.ca> |
---|---|
date | Fri, 22 Sep 2023 12:15:09 -0600 |
parents | 928c033c0cd0 |
children |
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/* os9.c Copyright © 2009 William Astle This file is part of LWASM. LWASM 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/>. This file implements the various pseudo operations related to OS9 target */ #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <lw_expr.h> #include "lwasm.h" #include "instab.h" // OS9 syscall PARSEFUNC(pseudo_parse_os9) { lw_expr_t e; if (as -> output_format != OUTPUT_OS9 && as -> output_format != OUTPUT_OBJ) { lwasm_register_error2(as, l, E_DIRECTIVE_OS9_ONLY, "%s", "os9"); return; } // fetch immediate value e = lwasm_parse_expr(as, p); if (!e) { lwasm_register_error(as, l, E_OPERAND_BAD); return; } lwasm_save_expr(l, 0, e); l -> len = 3; } EMITFUNC(pseudo_emit_os9) { lw_expr_t e; e = lwasm_fetch_expr(l, 0); lwasm_emitop(l, 0x103f); lwasm_emitexpr(l, e, 1); } PARSEFUNC(pseudo_parse_mod) { lw_expr_t e; int i; if (as -> output_format != OUTPUT_OS9) { lwasm_register_error2(as, l, E_DIRECTIVE_OS9_ONLY, "%s", "mod"); skip_operand(p); return; } if (as -> inmod) { lwasm_register_error(as, l, E_MODULE_IN); skip_operand(p); return; } // parse 6 (or 4) expressions... for (i = 0; i < 5; i++) { e = lwasm_parse_expr(as, p); if (!e) { lwasm_register_error(as, l, E_OPERAND_BAD); return; } lwasm_save_expr(l, i, e); if (**p != ',') { if (i == 3) { // we don't have the extra items; flag it and don't bother // with them later; goto is to short circuit the rest of // the expression parsing l -> lint = 4; goto doneexpr; } lwasm_register_error(as, l, E_OPERAND_BAD); return; } (*p)++; } e = lwasm_parse_expr(as, p); if (!e) { lwasm_register_error(as, l, E_OPERAND_BAD); return; } lwasm_save_expr(l, 5, e); l -> lint = 6; doneexpr: l -> inmod = 1; // we have an implicit ORG 0 with "mod" lw_expr_destroy(l -> addr); l -> addr = lw_expr_build(lw_expr_type_int, 0); // likewise for data pointer lw_expr_destroy(l -> daddr); l -> daddr = lw_expr_build(lw_expr_type_int, 0); // init crc as -> inmod = 1; l -> len = (l -> lint == 6) ? 13 : 9; } EMITFUNC(pseudo_emit_mod) { lw_expr_t e1, e2, e3, e4; int csum; as -> crc[0] = 0xff; as -> crc[1] = 0xff; as -> crc[2] = 0xff; // sync bytes lwasm_emit(l, 0x87); lwasm_emit(l, 0xcd); // mod length lwasm_emitexpr(l, e1 = lwasm_fetch_expr(l, 0), 2); // name offset lwasm_emitexpr(l, e2 = lwasm_fetch_expr(l, 1), 2); // type lwasm_emitexpr(l, e3 = lwasm_fetch_expr(l, 2), 1); // flags/rev lwasm_emitexpr(l, e4 = lwasm_fetch_expr(l, 3), 1); // header check csum = ~(0x87 ^ 0xCD ^(lw_expr_intval(e1) >> 8) ^ (lw_expr_intval(e1) & 0xff) ^ (lw_expr_intval(e2) >> 8) ^ (lw_expr_intval(e2) & 0xff) ^ lw_expr_intval(e3) ^ lw_expr_intval(e4)); lwasm_emit(l, csum); if (l -> lint == 6) { // module type specific output, if provided // note that these are handled the same for all so // there need not be any special casing // exec offset or fmgr name offset lwasm_emitexpr(l, lwasm_fetch_expr(l, 4), 2); // data size or drvr name offset lwasm_emitexpr(l, lwasm_fetch_expr(l, 5), 2); } } PARSEFUNC(pseudo_parse_emod) { skip_operand(p); if (as -> output_format != OUTPUT_OS9) { lwasm_register_error2(as, l, E_DIRECTIVE_OS9_ONLY, "%s", "emod"); return; } if (!(as -> inmod)) { lwasm_register_error(as, l, E_MODULE_NOTIN); return; } as -> inmod = 0; l -> len = 3; } EMITFUNC(pseudo_emit_emod) { unsigned char tcrc[3]; // don't mess with CRC! tcrc[0] = as -> crc[0] ^ 0xff; tcrc[1] = as -> crc[1] ^ 0xff; tcrc[2] = as -> crc[2] ^ 0xff; lwasm_emit(l, tcrc[0]); lwasm_emit(l, tcrc[1]); lwasm_emit(l, tcrc[2]); }