interp_forth.c revision 245148
1/*- 2 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD: head/sys/boot/common/interp_forth.c 245148 2013-01-08 03:27:37Z grehan $"); 29 30#include <sys/param.h> /* to pick up __FreeBSD_version */ 31#include <string.h> 32#include <stand.h> 33#include "bootstrap.h" 34#include "ficl.h" 35 36extern char bootprog_rev[]; 37 38/* #define BFORTH_DEBUG */ 39 40#ifdef BFORTH_DEBUG 41# define DEBUG(fmt, args...) printf("%s: " fmt "\n" , __func__ , ## args) 42#else 43# define DEBUG(fmt, args...) 44#endif 45 46/* 47 * Eventually, all builtin commands throw codes must be defined 48 * elsewhere, possibly bootstrap.h. For now, just this code, used 49 * just in this file, it is getting defined. 50 */ 51#define BF_PARSE 100 52 53/* 54 * FreeBSD loader default dictionary cells 55 */ 56#ifndef BF_DICTSIZE 57#define BF_DICTSIZE 10000 58#endif 59 60/* 61 * BootForth Interface to Ficl Forth interpreter. 62 */ 63 64FICL_SYSTEM *bf_sys; 65FICL_VM *bf_vm; 66FICL_WORD *pInterp; 67 68/* 69 * Shim for taking commands from BF and passing them out to 'standard' 70 * argv/argc command functions. 71 */ 72static void 73bf_command(FICL_VM *vm) 74{ 75 char *name, *line, *tail, *cp; 76 size_t len; 77 struct bootblk_command **cmdp; 78 bootblk_cmd_t *cmd; 79 int nstrings, i; 80 int argc, result; 81 char **argv; 82 83 /* Get the name of the current word */ 84 name = vm->runningWord->name; 85 86 /* Find our command structure */ 87 cmd = NULL; 88 SET_FOREACH(cmdp, Xcommand_set) { 89 if (((*cmdp)->c_name != NULL) && !strcmp(name, (*cmdp)->c_name)) 90 cmd = (*cmdp)->c_fn; 91 } 92 if (cmd == NULL) 93 panic("callout for unknown command '%s'", name); 94 95 /* Check whether we have been compiled or are being interpreted */ 96 if (stackPopINT(vm->pStack)) { 97 /* 98 * Get parameters from stack, in the format: 99 * an un ... a2 u2 a1 u1 n -- 100 * Where n is the number of strings, a/u are pairs of 101 * address/size for strings, and they will be concatenated 102 * in LIFO order. 103 */ 104 nstrings = stackPopINT(vm->pStack); 105 for (i = 0, len = 0; i < nstrings; i++) 106 len += stackFetch(vm->pStack, i * 2).i + 1; 107 line = malloc(strlen(name) + len + 1); 108 strcpy(line, name); 109 110 if (nstrings) 111 for (i = 0; i < nstrings; i++) { 112 len = stackPopINT(vm->pStack); 113 cp = stackPopPtr(vm->pStack); 114 strcat(line, " "); 115 strncat(line, cp, len); 116 } 117 } else { 118 /* Get remainder of invocation */ 119 tail = vmGetInBuf(vm); 120 for (cp = tail, len = 0; cp != vm->tib.end && *cp != 0 && *cp != '\n'; cp++, len++) 121 ; 122 123 line = malloc(strlen(name) + len + 2); 124 strcpy(line, name); 125 if (len > 0) { 126 strcat(line, " "); 127 strncat(line, tail, len); 128 vmUpdateTib(vm, tail + len); 129 } 130 } 131 DEBUG("cmd '%s'", line); 132 133 command_errmsg = command_errbuf; 134 command_errbuf[0] = 0; 135 if (!parse(&argc, &argv, line)) { 136 result = (cmd)(argc, argv); 137 free(argv); 138 } else { 139 result=BF_PARSE; 140 } 141 free(line); 142 /* 143 * If there was error during nested ficlExec(), we may no longer have 144 * valid environment to return. Throw all exceptions from here. 145 */ 146 if (result != 0) 147 vmThrow(vm, result); 148 /* This is going to be thrown!!! */ 149 stackPushINT(vm->pStack,result); 150} 151 152/* 153 * Replace a word definition (a builtin command) with another 154 * one that: 155 * 156 * - Throw error results instead of returning them on the stack 157 * - Pass a flag indicating whether the word was compiled or is 158 * being interpreted. 159 * 160 * There is one major problem with builtins that cannot be overcome 161 * in anyway, except by outlawing it. We want builtins to behave 162 * differently depending on whether they have been compiled or they 163 * are being interpreted. Notice that this is *not* the interpreter's 164 * current state. For example: 165 * 166 * : example ls ; immediate 167 * : problem example ; \ "ls" gets executed while compiling 168 * example \ "ls" gets executed while interpreting 169 * 170 * Notice that, though the current state is different in the two 171 * invocations of "example", in both cases "ls" has been 172 * *compiled in*, which is what we really want. 173 * 174 * The problem arises when you tick the builtin. For example: 175 * 176 * : example-1 ['] ls postpone literal ; immediate 177 * : example-2 example-1 execute ; immediate 178 * : problem example-2 ; 179 * example-2 180 * 181 * We have no way, when we get EXECUTEd, of knowing what our behavior 182 * should be. Thus, our only alternative is to "outlaw" this. See RFI 183 * 0007, and ANS Forth Standard's appendix D, item 6.7 for a related 184 * problem, concerning compile semantics. 185 * 186 * The problem is compounded by the fact that "' builtin CATCH" is valid 187 * and desirable. The only solution is to create an intermediary word. 188 * For example: 189 * 190 * : my-ls ls ; 191 * : example ['] my-ls catch ; 192 * 193 * So, with the below implementation, here is a summary of the behavior 194 * of builtins: 195 * 196 * ls -l \ "interpret" behavior, ie, 197 * \ takes parameters from TIB 198 * : ex-1 s" -l" 1 ls ; \ "compile" behavior, ie, 199 * \ takes parameters from the stack 200 * : ex-2 ['] ls catch ; immediate \ undefined behavior 201 * : ex-3 ['] ls catch ; \ undefined behavior 202 * ex-2 ex-3 \ "interpret" behavior, 203 * \ catch works 204 * : ex-4 ex-2 ; \ "compile" behavior, 205 * \ catch does not work 206 * : ex-5 ex-3 ; immediate \ same as ex-2 207 * : ex-6 ex-3 ; \ same as ex-3 208 * : ex-7 ['] ex-1 catch ; \ "compile" behavior, 209 * \ catch works 210 * : ex-8 postpone ls ; immediate \ same as ex-2 211 * : ex-9 postpone ls ; \ same as ex-3 212 * 213 * As the definition below is particularly tricky, and it's side effects 214 * must be well understood by those playing with it, I'll be heavy on 215 * the comments. 216 * 217 * (if you edit this definition, pay attention to trailing spaces after 218 * each word -- I warned you! :-) ) 219 */ 220#define BUILTIN_CONSTRUCTOR \ 221": builtin: " \ 222 ">in @ " /* save the tib index pointer */ \ 223 "' " /* get next word's xt */ \ 224 "swap >in ! " /* point again to next word */ \ 225 "create " /* create a new definition of the next word */ \ 226 ", " /* save previous definition's xt */ \ 227 "immediate " /* make the new definition an immediate word */ \ 228 \ 229 "does> " /* Now, the *new* definition will: */ \ 230 "state @ if " /* if in compiling state: */ \ 231 "1 postpone literal " /* pass 1 flag to indicate compile */ \ 232 "@ compile, " /* compile in previous definition */ \ 233 "postpone throw " /* throw stack-returned result */ \ 234 "else " /* if in interpreting state: */ \ 235 "0 swap " /* pass 0 flag to indicate interpret */ \ 236 "@ execute " /* call previous definition */ \ 237 "throw " /* throw stack-returned result */ \ 238 "then ; " 239 240/* 241 * Initialise the Forth interpreter, create all our commands as words. 242 */ 243void 244bf_init(void) 245{ 246 struct bootblk_command **cmdp; 247 char create_buf[41]; /* 31 characters-long builtins */ 248 int fd; 249 250 bf_sys = ficlInitSystem(BF_DICTSIZE); 251 bf_vm = ficlNewVM(bf_sys); 252 253 /* Put all private definitions in a "builtins" vocabulary */ 254 ficlExec(bf_vm, "vocabulary builtins also builtins definitions"); 255 256 /* Builtin constructor word */ 257 ficlExec(bf_vm, BUILTIN_CONSTRUCTOR); 258 259 /* make all commands appear as Forth words */ 260 SET_FOREACH(cmdp, Xcommand_set) { 261 ficlBuild(bf_sys, (char *)(*cmdp)->c_name, bf_command, FW_DEFAULT); 262 ficlExec(bf_vm, "forth definitions builtins"); 263 sprintf(create_buf, "builtin: %s", (*cmdp)->c_name); 264 ficlExec(bf_vm, create_buf); 265 ficlExec(bf_vm, "builtins definitions"); 266 } 267 ficlExec(bf_vm, "only forth definitions"); 268 269 /* Export some version numbers so that code can detect the loader/host version */ 270 ficlSetEnv(bf_sys, "FreeBSD_version", __FreeBSD_version); 271 ficlSetEnv(bf_sys, "loader_version", 272 (bootprog_rev[0] - '0') * 10 + (bootprog_rev[2] - '0')); 273 274 /* try to load and run init file if present */ 275 if ((fd = open("/boot/boot.4th", O_RDONLY)) != -1) { 276 (void)ficlExecFD(bf_vm, fd); 277 close(fd); 278 } 279 280 /* Do this last, so /boot/boot.4th can change it */ 281 pInterp = ficlLookup(bf_sys, "interpret"); 282} 283 284/* 285 * Feed a line of user input to the Forth interpreter 286 */ 287int 288bf_run(char *line) 289{ 290 int result; 291 292 result = ficlExec(bf_vm, line); 293 294 DEBUG("ficlExec '%s' = %d", line, result); 295 switch (result) { 296 case VM_OUTOFTEXT: 297 case VM_ABORTQ: 298 case VM_QUIT: 299 case VM_ERREXIT: 300 break; 301 case VM_USEREXIT: 302 printf("No where to leave to!\n"); 303 break; 304 case VM_ABORT: 305 printf("Aborted!\n"); 306 break; 307 case BF_PARSE: 308 printf("Parse error!\n"); 309 break; 310 default: 311 /* Hopefully, all other codes filled this buffer */ 312 printf("%s\n", command_errmsg); 313 } 314 315 if (result == VM_USEREXIT) 316 panic("interpreter exit"); 317 setenv("interpret", bf_vm->state ? "" : "OK", 1); 318 319 return result; 320} 321