sys/boot/common/interp_forth.c

   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  * $FreeBSD: src/sys/boot/common/interp_forth.c,v 1.23 2003/08/25 23:30:41 obrien Exp $
  27  * $DragonFly: src/sys/boot/common/interp_forth.c,v 1.4 2004/01/25 22:50:20 drhodus Exp $
  28  */
  29
  30 #include <sys/param.h>          /* to pick up __DragonFly_version */
  31 #include <string.h>
  32 #include <stand.h>
  33 #include "bootstrap.h"
  34 #include "ficl.h"
  35
  36 extern 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  * BootForth   Interface to Ficl Forth interpreter.
  55  */
  56
  57 FICL_SYSTEM *bf_sys;
  58 FICL_VM *bf_vm;
  59 FICL_WORD *pInterp;
  60
  61 /*
  62  * Shim for taking commands from BF and passing them out to 'standard'
  63  * argv/argc command functions.
  64  */
  65 static void
  66 bf_command(FICL_VM *vm)
  67 {
  68     char                        *name, *line, *tail, *cp;
  69     size_t                      len;
  70     struct bootblk_command      **cmdp;
  71     bootblk_cmd_t               *cmd;
  72     int                         nstrings, i;
  73     int                         argc, result;
  74     char                        **argv;
  75
  76     /* Get the name of the current word */
  77     name = vm->runningWord->name;
  78
  79     /* Find our command structure */
  80     cmd = NULL;
  81     SET_FOREACH(cmdp, Xcommand_set) {
  82         if (((*cmdp)->c_name != NULL) && !strcmp(name, (*cmdp)->c_name))
  83             cmd = (*cmdp)->c_fn;
  84     }
  85     if (cmd == NULL)
  86         panic("callout for unknown command '%s'", name);
  87
  88     /* Check whether we have been compiled or are being interpreted */
  89     if (stackPopINT(vm->pStack)) {
  90         /*
  91          * Get parameters from stack, in the format:
  92          * an un ... a2 u2 a1 u1 n --
  93          * Where n is the number of strings, a/u are pairs of
  94          * address/size for strings, and they will be concatenated
  95          * in LIFO order.
  96          */
  97         nstrings = stackPopINT(vm->pStack);
  98         for (i = 0, len = 0; i < nstrings; i++)
  99             len += stackFetch(vm->pStack, i * 2).i + 1;
 100         line = malloc(strlen(name) + len + 1);
 101         strcpy(line, name);
 102
 103         if (nstrings)
 104             for (i = 0; i < nstrings; i++) {
 105                 len = stackPopINT(vm->pStack);
 106                 cp = stackPopPtr(vm->pStack);
 107                 strcat(line, " ");
 108                 strncat(line, cp, len);
 109             }
 110     } else {
 111         /* Get remainder of invocation */
 112         tail = vmGetInBuf(vm);
 113         for (cp = tail, len = 0; cp != vm->tib.end && *cp != 0 && *cp != '\n'; cp++, len++)
 114             ;
 115
 116         line = malloc(strlen(name) + len + 2);
 117         strcpy(line, name);
 118         if (len > 0) {
 119             strcat(line, " ");
 120             strncat(line, tail, len);
 121             vmUpdateTib(vm, tail + len);
 122         }
 123     }
 124     DEBUG("cmd '%s'", line);
 125
 126     command_errmsg = command_errbuf;
 127     command_errbuf[0] = 0;
 128     if (!parse(&argc, &argv, line)) {
 129         result = (cmd)(argc, argv);
 130         free(argv);
 131     } else {
 132         result=BF_PARSE;
 133     }
 134     free(line);
 135     /* This is going to be thrown!!! */
 136     stackPushINT(vm->pStack,result);
 137 }
 138
 139 /*
 140  * Replace a word definition (a builtin command) with another
 141  * one that:
 142  *
 143  *        - Throw error results instead of returning them on the stack
 144  *        - Pass a flag indicating whether the word was compiled or is
 145  *          being interpreted.
 146  *
 147  * There is one major problem with builtins that cannot be overcome
 148  * in anyway, except by outlawing it. We want builtins to behave
 149  * differently depending on whether they have been compiled or they
 150  * are being interpreted. Notice that this is *not* the interpreter's
 151  * current state. For example:
 152  *
 153  * : example ls ; immediate
 154  * : problem example ;          \ "ls" gets executed while compiling
 155  * example                      \ "ls" gets executed while interpreting
 156  *
 157  * Notice that, though the current state is different in the two
 158  * invocations of "example", in both cases "ls" has been
 159  * *compiled in*, which is what we really want.
 160  *
 161  * The problem arises when you tick the builtin. For example:
 162  *
 163  * : example-1 ['] ls postpone literal ; immediate
 164  * : example-2 example-1 execute ; immediate
 165  * : problem example-2 ;
 166  * example-2
 167  *
 168  * We have no way, when we get EXECUTEd, of knowing what our behavior
 169  * should be. Thus, our only alternative is to "outlaw" this. See RFI
 170  * 0007, and ANS Forth Standard's appendix D, item 6.7 for a related
 171  * problem, concerning compile semantics.
 172  *
 173  * The problem is compounded by the fact that "' builtin CATCH" is valid
 174  * and desirable. The only solution is to create an intermediary word.
 175  * For example:
 176  *
 177  * : my-ls ls ;
 178  * : example ['] my-ls catch ;
 179  *
 180  * So, with the below implementation, here is a summary of the behavior
 181  * of builtins:
 182  *
 183  * ls -l                                \ "interpret" behavior, ie,
 184  *                                      \ takes parameters from TIB
 185  * : ex-1 s" -l" 1 ls ;                 \ "compile" behavior, ie,
 186  *                                      \ takes parameters from the stack
 187  * : ex-2 ['] ls catch ; immediate      \ undefined behavior
 188  * : ex-3 ['] ls catch ;                \ undefined behavior
 189  * ex-2 ex-3                            \ "interpret" behavior,
 190  *                                      \ catch works
 191  * : ex-4 ex-2 ;                        \ "compile" behavior,
 192  *                                      \ catch does not work
 193  * : ex-5 ex-3 ; immediate              \ same as ex-2
 194  * : ex-6 ex-3 ;                        \ same as ex-3
 195  * : ex-7 ['] ex-1 catch ;              \ "compile" behavior,
 196  *                                      \ catch works
 197  * : ex-8 postpone ls ; immediate       \ same as ex-2
 198  * : ex-9 postpone ls ;                 \ same as ex-3
 199  *
 200  * As the definition below is particularly tricky, and it's side effects
 201  * must be well understood by those playing with it, I'll be heavy on
 202  * the comments.
 203  *
 204  * (if you edit this definition, pay attention to trailing spaces after
 205  *  each word -- I warned you! :-) )
 206  */
 207 #define BUILTIN_CONSTRUCTOR \
 208 ": builtin: "           \
 209   ">in @ "              /* save the tib index pointer */ \
 210   "' "                  /* get next word's xt */ \
 211   "swap >in ! "         /* point again to next word */ \
 212   "create "             /* create a new definition of the next word */ \
 213   ", "                  /* save previous definition's xt */ \
 214   "immediate "          /* make the new definition an immediate word */ \
 215                         \
 216   "does> "              /* Now, the *new* definition will: */ \
 217   "state @ if "         /* if in compiling state: */ \
 218     "1 postpone literal "       /* pass 1 flag to indicate compile */ \
 219     "@ compile, "               /* compile in previous definition */ \
 220     "postpone throw "           /* throw stack-returned result */ \
 221   "else "               /* if in interpreting state: */ \
 222     "0 swap "                   /* pass 0 flag to indicate interpret */ \
 223     "@ execute "                /* call previous definition */ \
 224     "throw "                    /* throw stack-returned result */ \
 225   "then ; "
 226
 227 /*
 228  * Initialise the Forth interpreter, create all our commands as words.
 229  */
 230 void
 231 bf_init(void)
 232 {
 233     struct bootblk_command      **cmdp;
 234     char create_buf[41];        /* 31 characters-long builtins */
 235     int fd;
 236
 237     bf_sys = ficlInitSystem(10000);     /* Default dictionary ~4000 cells */
 238     bf_vm = ficlNewVM(bf_sys);
 239
 240     /* Put all private definitions in a "builtins" vocabulary */
 241     ficlExec(bf_vm, "vocabulary builtins also builtins definitions");
 242
 243     /* Builtin constructor word  */
 244     ficlExec(bf_vm, BUILTIN_CONSTRUCTOR);
 245
 246     /* make all commands appear as Forth words */
 247     SET_FOREACH(cmdp, Xcommand_set) {
 248         ficlBuild(bf_sys, (char *)(*cmdp)->c_name, bf_command, FW_DEFAULT);
 249         ficlExec(bf_vm, "forth definitions builtins");
 250         sprintf(create_buf, "builtin: %s", (*cmdp)->c_name);
 251         ficlExec(bf_vm, create_buf);
 252         ficlExec(bf_vm, "builtins definitions");
 253     }
 254     ficlExec(bf_vm, "only forth definitions");
 255
 256     /* Export some version numbers so that code can detect the loader/host version */
 257     ficlSetEnv(bf_sys, "DragonFly_version", __DragonFly_version);
 258     ficlSetEnv(bf_sys, "loader_version",
 259                (bootprog_rev[0] - '0') * 10 + (bootprog_rev[2] - '0'));
 260
 261     /* try to load and run init file if present */
 262     if ((fd = open("/boot/boot.4th", O_RDONLY)) != -1) {
 263         (void)ficlExecFD(bf_vm, fd);
 264         close(fd);
 265     }
 266
 267     /* Do this last, so /boot/boot.4th can change it */
 268     pInterp = ficlLookup(bf_sys, "interpret");
 269 }
 270
 271 /*
 272  * Feed a line of user input to the Forth interpreter
 273  */
 274 int
 275 bf_run(char *line)
 276 {
 277     int         result;
 278
 279     result = ficlExec(bf_vm, line);
 280
 281     DEBUG("ficlExec '%s' = %d", line, result);
 282     switch (result) {
 283     case VM_OUTOFTEXT:
 284     case VM_ABORTQ:
 285     case VM_QUIT:
 286     case VM_ERREXIT:
 287         break;
 288     case VM_USEREXIT:
 289         printf("No where to leave to!\n");
 290         break;
 291     case VM_ABORT:
 292         printf("Aborted!\n");
 293         break;
 294     case BF_PARSE:
 295         printf("Parse error!\n");
 296         break;
 297     default:
 298         /* Hopefully, all other codes filled this buffer */
 299         printf("%s\n", command_errmsg);
 300     }
 301
 302     if (result == VM_USEREXIT)
 303         panic("interpreter exit");
 304     setenv("interpret", bf_vm->state ? "" : "OK", 1);
 305
 306     return result;
 307 }