FreeBSD-5.3/sys/boot/common/interp_forth.c
/*-
* Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/boot/common/interp_forth.c,v 1.23 2003/08/25 23:30:41 obrien Exp $");
#include <sys/param.h> /* to pick up __FreeBSD_version */
#include <string.h>
#include <stand.h>
#include "bootstrap.h"
#include "ficl.h"
extern char bootprog_rev[];
/* #define BFORTH_DEBUG */
#ifdef BFORTH_DEBUG
# define DEBUG(fmt, args...) printf("%s: " fmt "\n" , __func__ , ## args)
#else
# define DEBUG(fmt, args...)
#endif
/*
* Eventually, all builtin commands throw codes must be defined
* elsewhere, possibly bootstrap.h. For now, just this code, used
* just in this file, it is getting defined.
*/
#define BF_PARSE 100
/*
* BootForth Interface to Ficl Forth interpreter.
*/
FICL_SYSTEM *bf_sys;
FICL_VM *bf_vm;
FICL_WORD *pInterp;
/*
* Shim for taking commands from BF and passing them out to 'standard'
* argv/argc command functions.
*/
static void
bf_command(FICL_VM *vm)
{
char *name, *line, *tail, *cp;
size_t len;
struct bootblk_command **cmdp;
bootblk_cmd_t *cmd;
int nstrings, i;
int argc, result;
char **argv;
/* Get the name of the current word */
name = vm->runningWord->name;
/* Find our command structure */
cmd = NULL;
SET_FOREACH(cmdp, Xcommand_set) {
if (((*cmdp)->c_name != NULL) && !strcmp(name, (*cmdp)->c_name))
cmd = (*cmdp)->c_fn;
}
if (cmd == NULL)
panic("callout for unknown command '%s'", name);
/* Check whether we have been compiled or are being interpreted */
if (stackPopINT(vm->pStack)) {
/*
* Get parameters from stack, in the format:
* an un ... a2 u2 a1 u1 n --
* Where n is the number of strings, a/u are pairs of
* address/size for strings, and they will be concatenated
* in LIFO order.
*/
nstrings = stackPopINT(vm->pStack);
for (i = 0, len = 0; i < nstrings; i++)
len += stackFetch(vm->pStack, i * 2).i + 1;
line = malloc(strlen(name) + len + 1);
strcpy(line, name);
if (nstrings)
for (i = 0; i < nstrings; i++) {
len = stackPopINT(vm->pStack);
cp = stackPopPtr(vm->pStack);
strcat(line, " ");
strncat(line, cp, len);
}
} else {
/* Get remainder of invocation */
tail = vmGetInBuf(vm);
for (cp = tail, len = 0; cp != vm->tib.end && *cp != 0 && *cp != '\n'; cp++, len++)
;
line = malloc(strlen(name) + len + 2);
strcpy(line, name);
if (len > 0) {
strcat(line, " ");
strncat(line, tail, len);
vmUpdateTib(vm, tail + len);
}
}
DEBUG("cmd '%s'", line);
command_errmsg = command_errbuf;
command_errbuf[0] = 0;
if (!parse(&argc, &argv, line)) {
result = (cmd)(argc, argv);
free(argv);
} else {
result=BF_PARSE;
}
free(line);
/* This is going to be thrown!!! */
stackPushINT(vm->pStack,result);
}
/*
* Replace a word definition (a builtin command) with another
* one that:
*
* - Throw error results instead of returning them on the stack
* - Pass a flag indicating whether the word was compiled or is
* being interpreted.
*
* There is one major problem with builtins that cannot be overcome
* in anyway, except by outlawing it. We want builtins to behave
* differently depending on whether they have been compiled or they
* are being interpreted. Notice that this is *not* the interpreter's
* current state. For example:
*
* : example ls ; immediate
* : problem example ; \ "ls" gets executed while compiling
* example \ "ls" gets executed while interpreting
*
* Notice that, though the current state is different in the two
* invocations of "example", in both cases "ls" has been
* *compiled in*, which is what we really want.
*
* The problem arises when you tick the builtin. For example:
*
* : example-1 ['] ls postpone literal ; immediate
* : example-2 example-1 execute ; immediate
* : problem example-2 ;
* example-2
*
* We have no way, when we get EXECUTEd, of knowing what our behavior
* should be. Thus, our only alternative is to "outlaw" this. See RFI
* 0007, and ANS Forth Standard's appendix D, item 6.7 for a related
* problem, concerning compile semantics.
*
* The problem is compounded by the fact that "' builtin CATCH" is valid
* and desirable. The only solution is to create an intermediary word.
* For example:
*
* : my-ls ls ;
* : example ['] my-ls catch ;
*
* So, with the below implementation, here is a summary of the behavior
* of builtins:
*
* ls -l \ "interpret" behavior, ie,
* \ takes parameters from TIB
* : ex-1 s" -l" 1 ls ; \ "compile" behavior, ie,
* \ takes parameters from the stack
* : ex-2 ['] ls catch ; immediate \ undefined behavior
* : ex-3 ['] ls catch ; \ undefined behavior
* ex-2 ex-3 \ "interpret" behavior,
* \ catch works
* : ex-4 ex-2 ; \ "compile" behavior,
* \ catch does not work
* : ex-5 ex-3 ; immediate \ same as ex-2
* : ex-6 ex-3 ; \ same as ex-3
* : ex-7 ['] ex-1 catch ; \ "compile" behavior,
* \ catch works
* : ex-8 postpone ls ; immediate \ same as ex-2
* : ex-9 postpone ls ; \ same as ex-3
*
* As the definition below is particularly tricky, and it's side effects
* must be well understood by those playing with it, I'll be heavy on
* the comments.
*
* (if you edit this definition, pay attention to trailing spaces after
* each word -- I warned you! :-) )
*/
#define BUILTIN_CONSTRUCTOR \
": builtin: " \
">in @ " /* save the tib index pointer */ \
"' " /* get next word's xt */ \
"swap >in ! " /* point again to next word */ \
"create " /* create a new definition of the next word */ \
", " /* save previous definition's xt */ \
"immediate " /* make the new definition an immediate word */ \
\
"does> " /* Now, the *new* definition will: */ \
"state @ if " /* if in compiling state: */ \
"1 postpone literal " /* pass 1 flag to indicate compile */ \
"@ compile, " /* compile in previous definition */ \
"postpone throw " /* throw stack-returned result */ \
"else " /* if in interpreting state: */ \
"0 swap " /* pass 0 flag to indicate interpret */ \
"@ execute " /* call previous definition */ \
"throw " /* throw stack-returned result */ \
"then ; "
/*
* Initialise the Forth interpreter, create all our commands as words.
*/
void
bf_init(void)
{
struct bootblk_command **cmdp;
char create_buf[41]; /* 31 characters-long builtins */
int fd;
bf_sys = ficlInitSystem(10000); /* Default dictionary ~4000 cells */
bf_vm = ficlNewVM(bf_sys);
/* Put all private definitions in a "builtins" vocabulary */
ficlExec(bf_vm, "vocabulary builtins also builtins definitions");
/* Builtin constructor word */
ficlExec(bf_vm, BUILTIN_CONSTRUCTOR);
/* make all commands appear as Forth words */
SET_FOREACH(cmdp, Xcommand_set) {
ficlBuild(bf_sys, (char *)(*cmdp)->c_name, bf_command, FW_DEFAULT);
ficlExec(bf_vm, "forth definitions builtins");
sprintf(create_buf, "builtin: %s", (*cmdp)->c_name);
ficlExec(bf_vm, create_buf);
ficlExec(bf_vm, "builtins definitions");
}
ficlExec(bf_vm, "only forth definitions");
/* Export some version numbers so that code can detect the loader/host version */
ficlSetEnv(bf_sys, "FreeBSD_version", __FreeBSD_version);
ficlSetEnv(bf_sys, "loader_version",
(bootprog_rev[0] - '0') * 10 + (bootprog_rev[2] - '0'));
/* try to load and run init file if present */
if ((fd = open("/boot/boot.4th", O_RDONLY)) != -1) {
(void)ficlExecFD(bf_vm, fd);
close(fd);
}
/* Do this last, so /boot/boot.4th can change it */
pInterp = ficlLookup(bf_sys, "interpret");
}
/*
* Feed a line of user input to the Forth interpreter
*/
int
bf_run(char *line)
{
int result;
result = ficlExec(bf_vm, line);
DEBUG("ficlExec '%s' = %d", line, result);
switch (result) {
case VM_OUTOFTEXT:
case VM_ABORTQ:
case VM_QUIT:
case VM_ERREXIT:
break;
case VM_USEREXIT:
printf("No where to leave to!\n");
break;
case VM_ABORT:
printf("Aborted!\n");
break;
case BF_PARSE:
printf("Parse error!\n");
break;
default:
/* Hopefully, all other codes filled this buffer */
printf("%s\n", command_errmsg);
}
if (result == VM_USEREXIT)
panic("interpreter exit");
setenv("interpret", bf_vm->state ? "" : "OK", 1);
return result;
}